Production system of composite side panel for urban city …562082/FULLTEXT01.pdf5 Master of Science...

Production system of composite side panel for urban city car

LISA NÄÄS

Master of Science Thesis Stockholm, Sweden 2011

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Lisa Nääs

Master of Science Thesis MMK 2011:069 {IDE 080} KTH Industrial Engineering and Management

Machine Design SE‐100 44 STOCKHOLM

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Master of Science Thesis MMK 2011:069 {IDE 080}


Lisa Nääs

Approved

Examiner

Carl Michael Johannesson

Supervisor

Anna Hedlund Åström Commissioner

Team H2politO

Contact person

Massimiliana Carello

Abstract

A theoretical study of possible production systems for future production of a side panel made of composite material and belonging to an urban city car has been carried out. The study has taken place within Team H2politO at the Polytechnic University of Turin in Italy. Three different production volumes have been analyzed considering dimensional limits, economy, production rate, machinery, material and environment. These have been set to 1 000, 10 000 and 100 000 components/year. Previous studies within the field have been analyzed, combined and used as a basis in order to arrive at an appropriate choice of production methodology regarding the different production volumes. A comparison with production methods for the side panel if it would have been manufactured with aluminum has been made and the profitability of composite production has been evaluated. Production‐ and material data have been collected from the software CES EduPack and revised based on study visits and interviews. The side panel has thereafter been edited and dimensioned in terms of recommendations for optimization of a future production. Modeling has been made using Autodesk Alias Design, Photoshop and Edraw Max. Furthermore, overview plan drawings of production plants have been made.

The study has given results in terms of recommendations and requirement specifications for future projects within the field. For continued studies about the profitability of composite production, an accurate study about different composite materials including tests of material characteristics is suggested. A detailed plan of the production plant with exact dimensions and technical data for optimization of production time is also recommended. In addition to this, it is essential to develop a better assembly system between the side panel and the roof panel as well as investigate the possibility of a more profitable production method for medium‐ to large scale production of composite details.

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Examensarbete MMK 2011:069 {IDE 080}

Produktionssystem av komposit sidopanel på en stadsbil

Lisa Nääs

Godkänt

Examinator

Carl Michael Johannesson

Handledare

Anna Hedlund Åström

Uppdragsgivare

Team H2politO

Kontaktperson

Massimiliana Carello

Sammanfattning

En teoretisk studie av möjliga produktionssystem för framtida produktion av en sidopanel i kompositmaterial på en stadsbil har utförsts. Studien har ägt rum inom Team H2politO på Tekniska Högskolan i Turin i Italien. Tre olika produktionsvolymer har analyserats med avseende på dimensionsgränser, ekonomi, produktionstid, maskineri, material och miljö. Dessa har valts till 1 000, 10 000 respektive 100 000 komponenter/år. Tidigare studier inom ämnet har analyserats, kombinerats och använts som underlag för att komma fram till lämpligt val av produktionsmetod för de olika produktionsvolymerna. En jämförelse med produktionsmetoder för sidopanelen om den skulle ha varit tillverkad i aluminium har gjorts och lönsamheten av komposittillverkning för komponenten har utvärderats. Produktions‐ och materialdata har hämtats ur datorprogrammet CES EduPack samt reviderats utifrån studiebesök och intervjuer. Sidopanelen har därefter med hjälp av rekommendationer anpassats och dimensionerats för att optimera en framtida produktion. Modellering har skett i datorprogrammet Autodesk Alias Design, Photoshop och Edraw Max. Ytterligare har översiktsritningar på produktionsanläggningar gjorts.

Studien har gett resultat i form av rekommendationer och kravspecifikationer för framtida projekt inom området. För fortsatta studier inom lönsamheten av kompositproduktion föreslås en noggrannare analys av olika kompositmaterial samt tester av materialegenskaper. En detaljritning av produktionsanläggningen med mer exakta mått och tekniska data för optimering av produktionstid rekommenderas också. Utöver dessa förslag, är det nödvändigt att utveckla en bättre lösning på montering mellan sidopanelen och takpanelen samt en mer lönsam produktionsmetod för medel‐ till massproduktion av kompositdetaljer.

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Table of Contents

Chapter 1. Introduction and Background .................................................................................... 11

1.1. A Short Introduction to Team H2politO ................................................................................ 11

1.2. Purpose .................................................................................................................................. 13

1.3. Method .................................................................................................................................. 14

Chapter 2. Case Study of the Prototype Production of the Side Panel ....................................... 17

2.1. Background ............................................................................................................................ 17

2.2. Prototype Production ............................................................................................................ 18

2.3. Summary and Observations .................................................................................................. 23

2.4. Recommendations................................................................................................................. 23

2.5. Conclusion ............................................................................................................................. 23

Chapter 3. Case Study of the Design of the Side Panel ............................................................... 25

3.1. Background ............................................................................................................................ 25

3.2. Dimensional Limits ................................................................................................................ 26

3.3. Manufacturing and Assembly ................................................................................................ 27

3.4. Aero Dynamics ....................................................................................................................... 30

3.5. Overall Summary and Conclusion ......................................................................................... 32

Chapter 4. Bench Marking – an Introduction to Composite Production Systems ...................... 33

4.1. Background ............................................................................................................................ 33

4.2. Flax Fiber ............................................................................................................................... 33

4.3. Composite Production ........................................................................................................... 34

4.4. Recommendations and Conclusion ....................................................................................... 41

Chapter 5. Composite Production with respect to the Side Panel .............................................. 43

5.1. Background ............................................................................................................................ 43


5.3. Economical Characteristics .................................................................................................... 47

5.4. Production Rate ..................................................................................................................... 51


Chapter 6. Metal Production with Respect to the Composite Production of the Side Panel ..... 54

6.1. Background ............................................................................................................................ 54

6.2. An Introduction to Aluminum Production ............................................................................. 54


6.4. Economical Characteristics .................................................................................................... 56

6.5. Production Rate ..................................................................................................................... 58

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Chapter 7. Proposal of Medium to Large Scale Composite Production of the Side Panel .......... 60

7.1. Background ............................................................................................................................ 60

7.2. Machinery, Equipment and Plant Lay‐out ............................................................................. 60

7.3. Manufacturers ....................................................................................................................... 63

7.4. Environment and Life Cycle ................................................................................................... 66


Chapter 8. Recommended Future Projects and Requirement Specifications ............................. 68

8.1. Assembly System ................................................................................................................... 68

8.2. Material Study ....................................................................................................................... 68

8.3. Plant Lay‐out .......................................................................................................................... 69

8.4. Recycling ................................................................................................................................ 70

Chapter 9. Discussion and Conclusions ....................................................................................... 72

Bibliography ........................................................................................................................................... 74

Appendix 1 – Interviews ........................................................................................................................ 76

Appendix 2 – Data Sheet of FlaxPreg .................................................................................................... 80

Appendix 3 – Data Sheet of Aluminum ................................................................................................. 82

Appendix 4 – Physical Attributes ........................................................................................................... 84

Appendix 5 – Economical attributes ..................................................................................................... 86

Appendix 6 – Press Data Sheet, Dieffenbacher ..................................................................................... 88

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Chapter 1. Introduction and Background A theoretical study of possible production systems for future composite production of the side panel of an urban city car is under development at the Polytechnic University of Turin in Italy. The development takes place as part of a student project were students within different fields of study amplify and improve different parts of the car that at the end affiliate a manufacturing base for the entire car. A prototype of the car is built and the results are analyzed and tested for improvement.

This master thesis took place within Team H2politO, subdivision XAM ‐ a team whose aim is to improve the performance of the low energy consumption urban city vehicle XAM that is illustrated in Figure 1.1.

Figure 1.1. XAM ‐ a low energy consumption vehicle1

1.1. A Short Introduction to Team H2politO Team H2politO was founded in 2007 by 13 engineering students within different fields of expertise at the Polytechnic University of Turin by the help of Eng. Cozzari and the Faculty Advisor Eng. Carello. In 2011, the number of team members had increased to approximately 45 students [1]. Figure 1.2 illustrates part of the team outside of the Polytechnic University of Turin in July 2011.

Figure 1.2. The team H2PolitO outside of the Polytechnic University of Turin

2

The team is divided into two subdivisions – XAM and IDRA – whose prototype data is listed on the following page [2].

1 Figure from report: Team H2politO, Urban Concept 534: Technical Innovation Award, page 2 [2011.06.22] 2 Figure from website: Facebook, Team H2politO, URL: http://www.facebook.com [2011‐08‐15]

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XAM – Figure 1.1 – is a prototype of an urban vehicle with low energy consumption • Length: 2800 mm

• Height: 1280 mm

• Width: 1300 mm

• Mass: 190 kg

• Power: 1 kW

• Propulsion: parallel hybrid

• Storage energy type: Ultra cap

• Motor: internal combustion engine + electric motor

• Body: natural fiber composites – FlaxPreg (epoxy resin and flax fiber)

• Human interface: embedded system + LCD screen

IDRA – Figure 1.3 – is a prototype of a competition vehicle with low energy consumption • Propulsion: hydrogen fuel cell (1 kW)

• Motor: one brushed electric motor (200 W)

• Transmission: cogwheels with direct engaging

• Electronics: digital engine control

• Tank: hydrogen cylinder (200 bars)

• Body: carbon fiber monocoque

• Mass: 38 kg

Figure 1.3. IDRA3

“The Team work and the prototypes can be considered as a business laboratory in which it is necessary to have the right balance of technical and managerial capabilities. Therefore, within H2politO, the technological competencies concerning the prototypes/products and the organizational skills are both developed.” [3]

Figure 1.4 shows the different areas of expertise (educational paths) vs. the management and organization of Team H2politO for the development of the innovative prototypes XAM and IDRA.

3 Figure from website: Politecnico di Torino, Idra, URL: http://srvh2polito.polito.it/en/prototypes.html [2011.06.22]

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The considered material for the side panel in all of the above mentioned analysis of composite material production was kept the same as the material used for the prototype production of the urban city car XAM. The reason was to be able to compare the medium to mass scale production to the already made small scale production. The material was:

• FlaxPreg – thermosetting epoxy resin reinforced with flax fiber.

A study of a possible metal production system was made for the purpose of getting an overview of the differences and similarities of metal production compared to composite production. For the study of possible metal production systems, the material was chosen after a recommendation by Professor Settineri [4] and thereby set to:

• Aluminum Al 2024.

Additional reasons for choosing Al 2024 is its properties of high damage tolerance and low density making it a popular alloy for automotive and aerospace production.

1.3. Method The project methodology was carried out in steps, the different steps being presented and explained below. After every step a conclusion and recommendations were to be presented.

Step 1: Case Study – Prototype Production of the Side Panel of XAM a) Case study of the prototype production system used for the production of the side panel of

XAM in 2011, also considering its surface finish through interviews and a study visit. b) A theoretical material study of the physical and mechanical characteristics of the material

used for the production of the side panel through literature research. c) Design study of the side panel through interviews.

Step 2: Bench Marking – Production Systems a) To do a bench marking of possible composite production systems for future medium to large

scale production of the side panel in the course of literature studies. b) To do a general bench marking of possible production systems for the current production of

aluminum car components including a study of the characteristics of the material Al 2024 through literature studies.

Step 3: Choose Suitable Systems for Different Production Volumes considering a) Dimensional limits b) Economical characteristics c) Production rate

Step 4: Investigate the Producibility of the Side Panel of XAM a) Investigation of the producibility of the side panel with respect to the chosen production

systems and give recommendations of possible changes in design of the side panel of XAM for facilitating its future production.

b) Choosing possible material, machinery and equipment manufacturers for the production of the side panel through literature studies and recommendations by team members.

c) Considering the life cycle of the side panel.

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The main reason for choosing to put the focus of the study on the production of the side panel as a means of analysis throughout this project was the representative composition of the side panel. The production system of the side panel could be applied to the future production of many other body parts because of its representative design. The design of the side panel and thereby also the production system share similarity with many other body parts. Amongst others these include the roof panel, the front hood as well as some components of the door panels and interior design.

Before choosing the side panel, the focus was put first on the front hood, then on the door panel and finally on the aluminum chassis of the vehicle. All of these were iteratively excluded because of different reasons. The shape of the front hood was too simple for being sure of the possibility of applying the production systems found for proposed future production to other parts of the car, while the composition of the door panel was found to be too complex. The door panel is made of many different parts of complex designs where each part might require its own analysis and study. The chassis was excluded on the basis of being made of aluminum instead of composite materials. Before considering a change of material of the chassis, a material study with mechanical tests has to be done considering the desired properties of a car frame regarding the security.

2.2. Prototype Production Each step of the production of the side panel and the surface finish of the final product is here explained in more detail including the time taken and the number of employees needed.

Step 1: Mold Preparation What? ‐ The surface of the mold was finished and a “release painting” was

sprayed onto the mold. See Figure 2.3 for an example of surface finishing of a mold

Why? ‐ To facilitate the detachment of the final component from the mold Time needed ‐ 8 hours Employees ‐ 1 person Method ‐ Manual Equipment/material ‐ Sandpaper, rasp, filler and release paint

Figure 2.3. Surface finishing at EXP8

8 Photographer: Francesco Avesio. Student – Industrial Design. Politecnico di Torino [2011]

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Step 2: Lamination (Hand lay‐up) What? ‐ A matrix brushing (resin + gel coat lay‐up) of fiber was manually put

onto the mold. Simultaneously, linen cloths were cut in accordance with the shape of the side panel. Figure 2.4 shows an example of matrix brushing and linen cloth cutting for the production of the front hood of XAM

Why? ‐ To create different fiber structures (unidirectional or bidirectional) layer by layer in order to achieve the desired mechanical and physical characteristics of the side panel

Time needed ‐ 6 hours Employees ‐ 4 people Method ‐ Manual Equipment/material ‐ Scissors, linen cloths, resin and gel coat

Figure 2.4. Matrix brushing and linen cloth cutting of the front hood of XAM9

Step 3: Preparation for Autoclave Treatment 1 What? ‐ The top layer of the fiber and resin was covered with a breather (a

plastic film with holes) and an absorbent. Figure 2.5 shows breathers with different characteristics at EXP

Why? ‐ The breather allows the excess of resin out for absorption to avoid discontinuities in the section thickness of the component ‐The absorbent takes up the excess of resin to facilitate the separation of the final component from the vacuum bag

Time needed ‐ 0.5 hours Employees ‐ 4 people Method ‐ Manual Equipment/material ‐ Scissors, breather and absorbent

9 Photographer: Andrea Serra. Student – Industrial Design. Politecnico di Torino [2011]

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Figure 2.5. Examples of breathers with different structures and hole dimensions at EXP10

Step 4: Preparation for Autoclave Treatment 2 What? ‐ A vacuum bag is sealed around the component together with its mold

and air is extracted through one or more valves by the help of a vacuum pump. Figure 2.6 shows a vacuum bag closed around a component

Why? ‐ To create a vacuum around the component for initiating the curing of the resin

Time needed ‐ 1 hour Employees ‐ 2 people Method ‐ Manual Equipment/material ‐ Vacuum bag, vacuum pump

Figure 2.6. A vacuum bag closed around a component. The white part being an absorber11

Step 5: Polarization 1 – Room Temperature Curing What? ‐ The piece that is now inside of the vacuum bag was put to cure in

room temperature (20‐25 °C) Why? ‐ For the purpose of the polarization of the component Time needed ‐ 35 hours Employees ‐ 0 people Method ‐ Automatic Equipment/material ‐ No equipment needed

10 Photographer: Lisa Nääs. Student – Design and Product Realization. KTH Royal Institute of Technology [2011] 11 Photographer: Andrea Serra. Student – Industrial Design. Politecnico di Torino [2011]

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Step 6: Polarization 2 ‐ Autoclave Treatment What? ‐ The component – covered with a vacuum bag – is put into the

autoclave where the temperature and pressure are controlled and vacuum kept. The autoclave at EXP is shown in Figure 2.7

Why? ‐ For the polarization of the component Time needed ‐ 3 hours Employees ‐ 0 people Method ‐ Automatic Equipment/material ‐ Autoclave

Figure 2.7. The autoclave at EXP that was used for curing process of the side panel12

Step 7: Extraction What? ‐ The piece is taken out from the vacuum bag and separated from the

mold as shown in Figure 2.8. Why? ‐ To receive the final component Time needed ‐ 1 hour Employees ‐ 4 people Method ‐ Manual Equipment/material ‐ Scissors and tools for separating the component from the mold

Figure 2.8. The piece is extracted from the mold13

12 Photographer: Lisa Nääs. Student – Design and Product Realization. KTH Royal Institute of Technology [2011] 13 Photographer: Francesco Avesio. Student – Industrial Design. Politecnico di Torino [2011]

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Step 8: Surface Finishing What? ‐ The piece was grinded and filled. In Figure 2.9 one can see the surface

finish of one component of the body of XAM Why? ‐ To obtain the wanted surface Time needed ‐ 8 hours Employees ‐ 2 people Method ‐ Manual Equipment/material ‐ Sand paper, rasp, sander and filler

Figure 2.9. Surface finishing of a component at EXP14

Step 9: Wrapping What? ‐ The outer surface of piece was wrapped Why? ‐ To obtain the wanted surface color and design Time needed ‐ 8 hours Employees ‐ 2 people Method ‐ Manual Equipment/material ‐ Wrapping paper

The total time taken to produce the side panel of XAM was approximately 70 hours. In Figure 2.1015, a Gantt chart gives an overview of the time taken and the number of employees needed for each of the step included in the production process.

14 Photographer: Andrea Serra. Student – Industrial Design. Politecnico di Torino [2011] 15 Producer: Lisa Nääs. Student – Design and Product Realization. KTH Royal Institute of Technology, Software used to create table: Microsoft Office Excel: version, 2007

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2.3. Summary and Observations A small scale production of the side panel, as the one explained in this chapter, is time consuming and thereby out of question for medium to large scale production. An overview shows that the method is mostly manual except for the polarization step where the autoclave is used for curing. This step does not require any employees. Lamination, autoclave treatment 1 and extraction of the side panel from the mold are the three steps requiring the largest number of employees with four employees/operation. Two employees/operation are needed during the second preparation for autoclave treatment, surface finishing and wrapping while the mold preparation only involves one employee. Step 5 (polarization 1) takes the longest amount of time with a span of 35 hours. The fastest operation is the first autoclave treatment lasting 0.5 hours.

All equipment used for the manual steps of this prototype production can be obtained at low costs and include simple tools such as sandpaper, rasps, scissors and a vacuum pump. The automated second polarization step however, requires the usage of an autoclave which results in the highest investment throughout the entire process.

2.4. Recommendations Decreasing or entirely excluding the first polarization step (room temperature curing) is possible by using the autoclave for all of the curing process. This would increase the second polarization step from 3 hours to 12 hours but eliminate the first polarization and thereby decrease the total production time by 26 hours.

Experimenting with the amount of people at each of the stations of the production line is of importance for optimizing the production rate of future prototype production. This could be done by decreasing or increasing the number of employees at each station studying how the time of the operation changes in relation to the number of workers and thereby make a suitable design of production line for the wanted purpose.

2.5. Conclusion To document the process of prototype production of the side panel, facilitates the understanding of the procedure and makes it possible to come with recommendations for future studies regarding

Figure 2.10. A Gantt chart showing the time taken for each step and the amount of people required. The x‐axis shows the time taken in hours while the y‐axis shows the different steps from 1‐9

24

small scale composite production. Underlining the knowledge of the time taken and the number of employees needed for each of the production step gives an advantage for future studies about how to optimize the production line and increase the production rate. Experiments can be made by changing the parameter of number of workers and studying how the time per operation is affected by this change. This documentation applies only to the prototype composite production of the side panel. For a more general study about small scale composite production, research would have to be done at a variety of different production plants manufacturing different kinds of components.

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Chapter 3. Case Study of the Design of the Side Panel A case study of the design of the side panel was made for the purpose of finding possible solutions and recommendations for improvements in design as well as for facilitating future production. The fields covered were dimensional limits, manufacturing, aero dynamical restrictions and assembly.

3.1. Background The side panel of XAM was designed by Andrea Serra [7] and Francesco Avesio [8], two industrial design students within Team H2politO. An interview with Andrea Serra took place in order to find out more about the thoughts behind the design, eventual experienced problems during the production process, critical parts and unchangeable parts. For more details about the questions asked during the interview, go to the second interview in Appendix 1 – Interviews. In Figure 3.1, one can see the position of the side panels (dark blue) in relation to the other parts of the vehicle.

Figure 3.1. Parts for assembly of XAM16

16 Figure from report: Carello, Massimiliana and Airale, Andrea. Urban Concept 534: Technical Innovation Award. Team H2politO [2011]

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For the assembly it is also essential to know more about the properties of these neighboring components. The external body parts can be divided into three groups shown in different colors as in Figure 3.5 where the moving parts are represented in green, the fixed parts bounded to the chassis are shown in blue and the dismountable parts threaded to the chassis are illustrated in red [10]. The side panel belongs to the blue group being a fixed part bounded to the chassis. The position of the side panel in relationship with the car chassis is further illustrated in Figure 3.6 on the following page. The blue side panel in a) is attached to the aluminum chassis in c). The green door in a) can be removed as shown in b) and is attached to the side panel.

Figure 3.5. The external components of XAM20


29

Figure 3.6. The placement of the side panel with respect to the car chassis21


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32

Summary and Observations The most important part of the side panel in terms of aero dynamics is the wheel arch. Other than that the side panel does not have any major influence of the total aero dynamics of the vehicle as long as its shape is continuous and smooth avoiding drastic changes. Being part of a city car with a low maximum speed, the current design of the side panel has not experienced any major difficulties in terms of aero dynamics.

Recommendations There is always room for improvements regardless of the essentialness of these. One advice of how to improve the aero dynamics further could be to add a brake cooling duct to the frontal wheel arch passing through it to the rear wheel arch. This would be done to decrease the air volume around the wheels further in order to not loose kinetic energy when the speed of the car increases. This is not an essentially important change because of the current speed limits of XAM, but might be necessary for future development of the car if it will be able to drive faster in the future. Another possibility with similar results would be to add a sill below the side panel. For an exact shape and design of a possible sill or brake cooling duct, a deeper study within the field would have to be made.

3.5. Overall Summary and Conclusion To have an understanding of the different factors behind the design of the side panel is essential when looking for improvements. The recommendations are given for the possibility of continuing the development of the side panel for future production. The problems were spotted so that solutions could be found. It is important to know that the recommendations are given as a brief foundation for creating ideas for future detail studies.

The sharp corners have caused problems during the production of the side panel that can easily be decreased by increasing the radius of the sharp corners. It is shown that the manufacturing methodology and the assembly of the side panel to the neighboring components are closely related. By studying the assembly for improvement, the manufacturing costs and time can decrease. The goal is to make the mold for small scale production in one piece instead of two.

When it comes to aero dynamics, many solutions exist. The question is if these improvements are necessary in the case of an urban city car with a low maximum speed. Further studies within these fields are recommended for more details within all of these areas.

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33

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34

Figure 4.1. Flax fiber cloth with epoxy resin and then gel coat providing a black color25

The mechanical properties of the FlaxPreg are:

• Density ρ: 1.45 kg/m3

• Tensile strength σ: 330 MPa (traction)

• Young’s modulus E: 35 GPa (traction)

For more specific technical data about FlaxPreg, see Appendix 2 – Data Sheet of FlaxPreg [14].

4.3. Composite Production The composite production methods are presented in short throughout this chapter by briefly explaining the different steps of each method.

Compression molding For large scale production, compression molding is economically effective. One steel die is capable of producing up to 200 000 components so even if expensive in itself, a production volume exceeding 10 000 parts would pay for the die. The method is applied to simple shape production and commonly used for thermosetting short fiber filled composites (25 mm). In compression molding, the following simplified methodology is used [15] and Figure 4.2 illustrates the process.

Step 1: Mold Preparation The surface of the mold is finished and heated.

Step 2: Polymer Placed in Mold Granules or a tablet of polymer (most commonly thermoset resin and hardener) is placed in the heated mold.

Step 3: Closure of Mold The mold is closed with a pressure big enough to make the polymer fill the mold cavity.

Step 4: Polarization The polymer is left inside of the closed mold for curing.

Step 5: Extraction After opening the mold, the cured component is removed for surface finishing.

Step 6: Surface Finishing and Painting The surface of the component is finished and then painted.

25 Photographer: Lisa Nääs Student – Design and Product Realization. KTH Royal Institute of Technology [2011]

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36

Sheet Molding Compound (SMC Molding) SMC molding is also a form of compression molding but where the production rates are smaller and the cost per unit is less than that of the compression molding due to the use of sheet molding compounds. With today’s technology, the production rate can go down to no more than 60 seconds per unit produced [15]. Only components of sheet shape can be manufactured with this methodology. Epoxy resin reinforced with long fibers (25‐75 mm) is common. SMC molding follows the simplified methodology explained in steps below [13].

Step 1: Mold Preparation The surface of the mold is finished and heated.

Step 2: Mold Placed in Press The mold is placed into a heated press.

Step 3: Polymer Placed in Mold A sheet molding compound (most commonly a premix of thermoset resin, reinforcement, catalyst and additives) is placed in the mold.

Step 4: Closure of Mold and Polarization The mold is closed and the panel is formed and cured due to an applied pressure of 3‐7 Mpa and heat.

Step 5: Extraction After opening the mold, the cured component is removed for surface finishing.


Resin transfer molding (RTM) Resin transfer molding is an effective method for producing complex shapes. The system most commonly uses a thermosetting resin reinforced with 25‐30% of filament cloth. As it is a closed mold system, the contact between employees and damaging chemicals is less than in the case of open mold systems. The following steps and Figure 4.3 illustrate how resin transfer molding is carried out [13].

Step 1: Mold Preparation The surface of the mold is finished and the mold is closed around a reinforcement + inserts or fittings.

Step 2: Injection A low viscosity resin (thermosetting) is injected with a pressure of approximately 2 MPa into the closed mold through mixing heads and injection points. In the mixing heads, the resin is combined with a hardener. Due to the low pressure, the tools can be used for a long time and at a low cost.

Step 3: Polarization The polymer is left inside of the closed mold for curing in room temperature.

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41

Vacuum assisted resin transfer molding (VARTM) Complex shapes are here possible and the process is economic for small scale production volumes. The method of VARTM is introduced in steps below [15].

Step 1: Mold Preparation The surface of the mold is finished.

Step 2: Reinforcement Placed in Mold The reinforcement (dry woven fabric) is put in the mold.

Step 3: Peel Ply Peel ply covers the reinforcement.

Step 4: Vacuum Bag The mold plus the reinforcement and the peel ply is covered with a vacuum bag.

Step 5: Release of Excess Resin Excess resin is extracted when vacuum is created around the component (by the help of a breather and an absorbent).

Step 6: Curing The component is cured.

Step 7: Extraction The vacuum bag is opened and the component separated from the mold.

Step 8: Surface Finishing and Painting The surface of the component is finished and painted.

4.4. Recommendations and Conclusion These methods are all found in the software CES EduPack 2011 [13] which presents basic descriptions and data. It is important to remember that current technology of the methodologies are constantly improving and might develop into new methods even more suitable for the application of the side panel in the near future. This is why this chapter might be in need of modifications before the actual medium to large scale production of the side panel is transferred from theory into practice.

43

Chapter 5. Composite Production with respect to the Side Panel

The different production systems for composite production are evaluated with respect to the side panel of XAM and its future medium to large scale production in terms of dimensional limits, economical characteristics and production rates. All data are approximate values achieved by the help of the software CES EduPack 2011 [13] and the graphs are made thereafter. For numerical values, see Appendix 4 – Physical Attributes and Appendix 5 – Economical attributes. The costs were converted from Swedish crowns to Euros by the help of Forex Currency Converter [16].

5.1. Background The main idea and purpose behind these comparisons was to get a deeper insight into whether the different factors could be applied to the production of the side panel or not and thereafter, on the basis of the results, eliminate or keep the production methods for further analysis.

5.2. Dimensional Limits A general analysis of some of the dimensional limits ‐ including the possible mass range, range of section thickness, roughness and shape ‐ of the 10 composite methods was done with respect to the physical characteristics and dimensional limits of the side panel. The purpose was to understand if the dimensional limits of the side panel would be applicable to all of the chosen production systems.

Mass Range The mass of the side panel is approximately 5 kg and can be considered a small or medium sized component. Table 5.1 shows the recommended mass range in kg for a component produced with the 10 composite methods that were introduced in Chapter 4.

Table 5.1. The recommended mass range of a component produced using different methods31

Mass Range [kg]

min max

Compression molding 0.1 20

Autoclave molding 0.8 2000

Hand/spray lay‐up 1 6000

Filament winding 0.01 3000

RTM 0.8 50

BMC/DMC molding 0.03 50Pultrusion 0.1 200SMC molding 0.03 50Vacuum bag molding 0.8 2000VARTM 0.5 600

Having this data as a reference, all of the mentioned production systems would be applicable for the future production of the side panel. For a mass up to 20 kg, any of the production methods can be used. When exceeding 50 kg however, compression molding, RTM, BMC/DMC molding and SMC molding are no longer recommended because of the large compression force required for bigger components. Products with a mass larger than 1000 kg are recommended to be produced with 31 Producer: Lisa Nääs. Student – Design and Product Realization. KTH Royal Institute of Technology, Software used to create table: Microsoft Office Excel: version, 2007

44

autoclave molding, hand/spray lay‐up, filament winding, vacuum bag molding or a combination of these. Components produced with these methods do not necessarily have to be of a high mass, but the mass range is a lot bigger for them than for the other production methods.

Section Thickness The side panel has a section thickness of approximately 2 mm. The recommended section thicknesses in mm for giving a result with good mechanical characteristics for the different composite production methods are illustrated in Table 5.2.

Table 5.2. The recommended range of section thickness of a component produced using different methods32

Range of section thickness [mm]

min max

Compression molding 1.5 25

Autoclave molding 2 30

Hand/spray lay‐up 2 10

Filament winding 2 25

RTM 2 6

BMC/DMC molding 1.5 25

Pultrusion 3 15

SMC molding 1.5 25Vacuum bag molding 2 6VARTM 1 20

For the purpose of keeping the recommended mechanical characteristics of the side panel, all of the above mentioned production systems could be used for its future production. It is noted that the maximum recommended section thickness for composite production is 30 mm (in the case of autoclave molding), while the minimum is 1 mm (VARTM). Having a larger section thickness requires more material than necessary resulting in higher costs of both material supply and production process. For a section thickness below 1 mm, the mechanical properties might become too low. The smallest range of section thickness is that for RTM and vacuum bag molding, while the method of autoclave molding has the possibility of creating products with a greater range of section thickness compared to all of the other mentioned composite production methods.

Surface Roughness The surface quality of the side panel must be of Class‐A in accordance with high quality car production. A Class‐A surface is usually a surface that the customer can see, and can thereby include both the exterior and the interior surfaces of a car.

According to the company Design Engine [18] a Class‐A surface is a surface following the criteria listed below (quoted):

32 Producer: Lisa Nääs. Student – Design and Product Realization. KTH Royal Institute of Technology, Software used to create table: Microsoft Office Excel: version, 2007

45

• The fillets: generally for Class‐A, the requirement is continuous curvature and uniform flow of flow lines from fillet to parent surface with a value of 0.005 mm or better (position 0.001 mm and tangency to about 0.016°).

• The flow of the highlight lines: the lines should form a uniform family of lines, gradually widening or narrowing but in general never pinching in and out.

• The control points should form a very ordered structure: again varying in angle from one row to the next in a gradual manner (this will yield the good highlights required).

• For a Class‐A model the fillet boundary should be edited and moved to form a gentle line and then re‐matched into the base surface.

• Matched ISO‐parameters in U & V direction are also a good representation of Class‐A.

• The draft angle, symmetry, gaps and matching of surfaces should apply to parent or reference surfaces.

There is nothing stated about the values of surface roughness for a Class‐A surface. The lower the possible surface roughness of a production method however, the easier it is to create a result with a surface of high quality. Table 5.3 thereby shows the roughness in µm of a component produced using composite manufacturing methods.

Table 5.3. The range of roughness in µm of the surface of a component produced using different production methods33

Roughness [µm]

min max

Compression molding 0.2 1.6

Autoclave molding 0.5 3.2

Hand/spray lay‐up 0.5 3.2

Filament winding 0.5 1.6

RTM 0.25 1.6

BMC/DMC molding 0.3 1.6

Pultrusion 0.3 1.6

SMC molding 0.3 1.6Vacuum bag molding 0.5 3.2VARTM 1 2.4

All of the mentioned production methods have the possibility of generating a component with a surface of low roughness (≤ 1 µm) and thus also the possibility of creating a surface quality of Class‐A [17]. None of them have to be excluded with respect to the surface roughness of the side panel.

Shape It is essential to know the different groups of shape that a certain production method can create for understanding if it could be relevant to the future production of the side panel. In Figure 5.1, one can see these different groups – prismatic, sheet and 3‐D shapes – in the form of a block diagram inspired by a similar diagram in Materials engineering, science, processing and design [18].


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47

the two that have the possibility of producing a component with a shape of both dished sheet and solid 3‐D while BMC/DMC molding is more fit for solid 3‐D shapes than for dished sheets. Autoclave molding, hand/spray lay‐up, SMC molding, vacuum and pressure bag molding as well as vacuum assisted RTM are all methods in which a dished sheet is to prefer in front of a solid 3‐D shape.

Summary and Observations The recommended mass range, section thickness and surface roughness of the composite production methods are all within the boundaries of the dimensional limits of the side panel. Up to a mass of 20 kg, the side panel can still be produced regardless of the production method. The section thickness is not recommended to be less than 2 mm due to the dimensional limits of the equipment, but also because of the difficulty of parting the cured component from the mold as explained in Chapter 3. The surface roughness needed for achieving a Class‐A surface quality can be attained using all of the declared composite methods. The limitations in terms of the shape of the side panel exclude filament winding and pultrusion from the list of possible manufacturing methods for future production.

Recommendations The recommendation given regarding the dimensional limits of the side panel is to not consider the two excluded methods for future production of the side panel.

5.3. Economical Characteristics A general analysis of some of the economical characteristics ‐ including the labor intensity, economic batch size, capital cost and tool life ‐ of the 10 composite methods was done with respect to the side panel. The purpose was to get an overview of the most fundamental economic factors for understanding which methods might be suitable for a future production of the side panel.

Table 5.5 shows the relative ranking of what is considered to be low, medium, high and very high costs of production systems. The costs taken in account are approximate and consist of tooling cost, equipment cost and labor intensity. All of the definitions of the economic terms used in this chapter can be found in Appendix 5 – Economical attributes [13].

Table 5.5. The relative ranking corresponding to the costs36

Relative ranking

Tooling cost[€]

Equipment cost,[€]

Labor intensity [hours/unit]

Low < 700 < 7∙103 < 0.1 Medium 700 – 7∙103 7∙103 – 7∙104 0.1 – 30 High 7∙103 – 7∙104 7∙104 – 7∙105 30 – 300 Very high > 7∙104 > 7∙105 > 300

Labor Intensity The labor intensity identifies if a production system requires a lot of employees which also indicates how much manual work versus automatic work is needed. Usually when the labor intensity is high, the process is predominantly manual while low labor intensity indicates that a greater portion of the process is automatic. Table 5.6 shows the labor intensity for different composite production systems. The ranking is made in accordance with Table 5.5.


48

Table 5.6. The labor intensity of different composite production systems37

Labor intensity

Compression molding LowAutoclave molding High Hand/spray lay‐up High RTM High BMC/DMC molding MediumSMC molding Medium Vacuum bag molding Medium VARTM Medium

The only method with low labor intensity is compression molding, while all of the other methods have a medium to high labor intensity. Autoclave molding, hand/spray lay‐up and resin transfer molding are the methods requiring the highest labor intensity.

Economic Batch Size The economic batch size gives an idea about the approximate production volume that would have to be manufactured to make a process economically imperishable. A summary of the economic batch size is listed below in terms of different scales of production for profitability of the different composite methods and the economic batch sizes in units are shown in Table 5.7.

Table 5.7. The economic batch size in units of different composite production systems38

Economic batch size [units]

Compression molding 500‐2∙106 Autoclave molding 1‐500 Hand/spray lay‐up 1‐500 RTM 1∙103‐1∙106

BMC/DMC molding 5∙103‐1∙106 SMC molding 5∙103‐1∙106 Vacuum bag molding 1‐1∙103 VARTM 10‐500

Small scale production (≤ 1 000 pieces/year) • Compression molding

• Autoclave molding

• Hand lay‐up/ spray lay‐up

• RTM

• Vacuum and pressure bag molding

• VARTM

37 Producer: Lisa Nääs. Student – Design and Product Realization. KTH Royal Institute of Technology, Software used to create table: Microsoft Office Excel: version, 2007 38 Producer: Lisa Nääs. Student – Design and Product Realization. KTH Royal Institute of Technology, Software used to create table: Microsoft Office Excel: version, 2007

49

Medium scale production (10 000 pieces/year) • Compression molding

• Resin transfer molding (RTM)

• BMC/DMC molding

• SMC molding

Large scale production (100 000 pieces/year) • Compression molding

• RTM

• BMC/DMC molding

• SMC molding

Compression molding and RTM are economically suitable for all of the different production volumes while BMC/DMC molding and SMC molding are fit for medium to large scale production. Other than compression molding and RTM; autoclave molding, hand/spray lay‐up, vacuum and pressure bag molding and vacuum assisted resin transfer molding are able to produce an economic batch size within the limits of small scale production only. The remaining methods of interest for a future medium to large scale composite production are thereby compression molding, RTM, BMC/DMC molding and SMC molding.

Capital Cost Tool and equipment cost make up the capital cost of a production system. Table 5.8 shows the capital cost in 1 000 € for the different systems.

Table 5.8. The capital cost of the different production systems39

Capital cost [1 000 €] min maxCompression molding

11.8 70.6 High

Autoclave molding 47 588 MediumHand/spray lay‐up 0.058 0.588 LowRTM 5.88 35.3 Medium/highBMC/DMC molding

0.353 353 Medium

SMC molding 35.3 353 MediumVacuum bag molding

23.6 588 Low/medium

VARTM 0.588 11.8 Low/medium

The methods with highest capital cost are autoclave molding, filament winding and vacuum and pressure bag molding indicating that an autoclave has a high cost. The methods with low capital cost are hand/spray lay‐up, RTM and VARTM which all have an economic batch size within the limits of a small scale production while the labor intensity is medium to high causing higher employment costs.


50

Tool Life Table 5.9 shows the tool life in units produced before the tool is torn out and has to be replaced or repaired.

Table 5.9. The tool life in units for the different production systems40

Tool life [units] min max

Compression molding 2 000 200 000Autoclave molding 99 100Hand/spray lay‐up 200 1 000Filament winding 1 000 10 000RTM 500 5 000BMC/DMC molding 100 000 200 000Vacuum bag molding 1 040 17 800VARTM 100 1 000

The tools used in compression molding and BMC/DMC molding have a life of up to 200 000 units/tool. These two methods can thereby be used for a mass scale production being able to produce more than 100 000 units/tool. On the other hand, if using methods with low capital cost the economic benefits might still be able to cover large scale production since a change of tool does not result in a big investment for the production company. The tool life of filament winding and SMC molding falls in the category of medium scale production while autoclave molding, hand/spray lay‐up, vacuum bag molding and VARTM all go within the limits of medium scale production. The RTM method have tools with a tool life of 5 000 units/tool leaving it somewhere in between a small scale and a medium scale production before changing tool, but since the capital cost of the tools is low, it can easily be replaced and a higher scale production is possible.

Summary and Observations It is essential to know the combination of labor intensity, economic batch size, capital cost and tool life in order to get an understanding of where to place the different production volumes for future production. Labor intensity, capital cost, economic batch size and tool life are all factors that are related to each other. The economic batch size depends on the combination of the level of labor intensity, capital cost and tool life. The economically most profitable combination for all production volumes would be a low labor intensity, low capital cost and long tool life resulting in a wide range of economic batch size. The worst case would be having a high labor intensity, high capital cost and short tool life making it almost impossible to reach an economic batch size.

When the economic batch size lies within a small scale production volume, it can be seen that the labor intensity in five out of six cases (autoclave molding, hand/spray lay‐up, RTM, VARTM and vacuum and pressure bag molding) is medium to high while the capital cost for four of these methods are low to medium, the exception being RTM with a medium to high capital cost. The last method within the group of small scale production based on the economic batch size is compression molding which goes against the other methods with a high capital cost and low labor intensity. Another difference of compression molding in comparison with four of the other small scale production methods based on economic batch size is that it is also considered to lie within its


51

economic batch size for medium and large scale production. The RTM production also has an economic batch size ranging from small to medium and large scale production. The tool life for four out of the six small scale production methods is 1 000 units/tool or less. The exceptions once again being compression molding and RTM with tool lives of up to 200 000 units/tool and 5 000 units/tool respectively.

There are four methods within the range of medium to large scale production regarding the economic batch size. These are compression molding, RTM, BMC/DMC molding and SMC molding. The labor intensity of these are spread and range between low to medium and high, while the capital cost for all of them range from medium to high. The shortest tool lives are those of RTM with 5 000 units/tool and SMC molding with a tool life of 17 500 units/tool. The compression molding and BMC/DMC molding on the other hand have tool lives of 200 000 units/tool.

Recommendations A study based on tests made by a test group within the study team of H2politO is recommended in order to clarify if the data in this chapter is up to date and reliable. All data used in this report is based on a theoretical literature study and a real life test is needed. An example of test would be to interview composite production companies for accurate figures and numbers of small, medium and large scale production and compare the results achieved with the theoretical results in this chapter.

5.4. Production Rate In order to find a suitable production system for different production volumes, the production rate is of great importance. In accordance with a basic calculation below, a year was considered to contain 47 working weeks. With this in mind, an approximate production rate for each of the production system can be given.

Calculating the units produced/year: 1 year → 52 weeks → 5 weeks of vacation

→ 47 working weeks → 40 hours/week → 1880 hours/year

units/year = (hours/year) ∙ (units/hour)

Knowing the production rate in units/hour, the production rate in units/year is easily achieved and shown in Table 5.10.

Table 5.10. The production rate in units produced per year of 10 different production systems41

Production rate [units/year]

PRODUCT

ION SYSTEM

Compression molding 18800‐188000

Autoclave molding 94‐1880 Hand lay‐up/ Spray lay‐up 188‐940 Resin transfer molding (RTM) 9400‐37600 BMC (DMC) molding 22560‐112800 SMC molding 22560‐112800

Vacuum and pressure bag molding 94‐1880

Vacuum assisted resin transfer molding VARTM 376‐940


52

The production volumes are divided into small, medium and large scale production and by knowing the approximate possible range of production rate for the different methods it was possible to divide them up into the three groups of production volume/year.

Small scale production (≤ 1 000 pieces/year) • Autoclave molding

• Hand/spray lay‐up

• Vacuum and pressure bag molding

• VARTM

Medium scale production (10 000 pieces/year) • RTM

• BMC/DMC molding

• SMC molding

Large scale production (100 000 pieces/year) • Compression molding

• BMC/DMC molding

• SMC molding

Recommendations Like in the case of the economical characteristics of composite production systems with respect to the future production of the side panel, the data used for the analysis of the production rate would have to be double checked through practical tests or interviews. This is necessary for getting a more reliable and complete analysis regarding the matter of optimizing the future production of the side panel.

5.5. Overall Summary and Conclusion A combination of the observations made for the dimensional limits, economical characteristics and production rate makes it possible to eliminate certain production methods while keeping others. The ones that are left for small scale production are autoclave molding, hand/spray lay‐up, vacuum and pressure bag molding and vacuum assisted resin transfer molding. BMC/DMC and SMC molding can be used for both medium and large scale production, while RTM is recommended for only medium scale production and compression molding for large scale production. In total there are four possible methods for a future medium to large scale production. Table 5.11 gives an overview of all the different aspects discussed throughout this chapter.

53

Table 5.11. Overview of the different aspects to consider when choosing a composite production system for the manufacturing of the side panel42


54

Chapter 6. Metal Production with Respect to the Composite Production of the Side Panel

The future production of the side panel of XAM is meant to be produced in composite materials, but in order to get a good result it is important to know more about today’s most common production method for body parts. The most commonly used metal (specifically aluminum) production method for car body parts is forging. The dimensional limits, economical characteristics and production rates of metal production are here being generally analyzed with respect to the production of the side panel. The results are compared to the composite production results from Chapter 5 listing advantages and disadvantages of both in order to get an understanding of how composite production differs from metal production.

6.1. Background The main idea behind this analysis was to get a deeper insight into the differences between composite and metal production. The information received in Chapter 5 is used and compared to additional information about forging methods for aluminum production. A summary of the strengths and downfalls of the two methods are given at the end of each section.

6.2. An Introduction to Aluminum Production The main focus of this project is laid on composite production, but it is also of interest to know some features regarding metal production. The reason is to be able to complete a comparison between composite production and metal production on the basis of the reasonability of a future medium to large scale production of the side panel using composites rather than metal.

Background Team H2politO works to decrease the damages on the environment caused by humanity and therefore they strive to develop a green city car. To have a light weight car helps to decrease both the fuel emission as well as other damaging chemical emissions during the entire life cycle of a car. If the result shows that a composite production of the side panel would not be suitable for one reason or another, the whish is to still keep the weight of the car as low as possible. For the case of metal production, a good option would therefore be aluminum with a lower weight in comparison to steel.

Aluminum AL2024 For comparison of composite production to metal production, the alloy Al 2024 was chosen as a result of a recommendation given by Professor Settineri [4] after a meeting with him the 21st of October 2011 at the Polytechnic University of Turin. For light weight metal production, the aluminum is a good option and to focus on one specific alloy facilitates future studies within the field of material choice of the side panel.

The composition of Al 2024 is 93.50 % Al, 4.4 % Cu, 0.6 % Mn and 1.5 % Mg [19]. Its mechanical properties are listed below:

• Density ρ: 27700 kg/m3

• Tensile strength σ: 185 MPa

• Young’s modulus E: 70‐80 GPa

For more specific technical data about Al 2024, see Appendix 3 – Data Sheet of Aluminum.

55

Forging For production of aluminum components, forging is a common method for medium to mass scale production and this method will be used in this study for the comparison with composite manufacturing. The reason for choosing to use forging as a generalized method for aluminum production is that it is representative regarding the costs and production rates of a well‐developed metal production method giving good results. Composite production is not as well developed as metal production, but the goal is to reach a similar level as that of metal production. Comparing it to forging for metal production thereby sets a high goal for the future of composite production.

The aluminum blank is forced into shape when subjected to plastic deformation by the dies. Hot die forging differs from cold die forging since the aluminum is heated before initiating it to compression. The mechanical characteristics of forged components are usually good because of some advantages in the way in which the deformation is carried out. The deformation decreases the porosity of the component and improves the surface roughness by making it smoother. Hot die forging makes the aluminum re‐crystallize while cold die forging increases the strength of the final component [18]. The steps below give a basic overview of how forging is carried out.

Step 1: Metal Placed in Die The aluminum (heated or cold) is placed in a die.

Step 2: Closure of Die The die is closed with a pressure big enough to squeeze the aluminum to fill the die cavity.

Step 3: Opening of Die and Extraction After opening the mold, the component is removed for surface finishing.


Recommendations and Conclusion When doing a bench marking within the field of choosing a possible change of material for the future production of the side panel of XAM, it would be beneficial to not only include composite materials but also different kinds of metal. This is recommended in order to gain a complete understanding and motivation of why or why not to continue the usage of composite material instead of metals. It is also of importance to keep new production methods up to date not only for composite production, but also for metal production.

6.3. Dimensional Limits As in Chapter 5, the dimensional limits include the possible mass range, range of section thickness, roughness and shape. A general description of these with respect to aluminum production is made and thereafter compared to composite production. The purpose was to understand the difference of aluminum and composite production of the side panel with respect to the dimensional limits.

Mass Range With forging methods the mass range of aluminum components lies between 0.01 and 5 000 kg and can thereby be used for the production of the side panel (5 kg). For composite production, the mass of the side panel also lies within the recommended mass range and no difference is spotted between

56

the two materials with respect to its possible mass range. On the other hand, aluminum has a higher density than flax fibers, which would increase the actual mass of a side panel with identical dimensions if produced in aluminum. This is not a problem in terms of production, but rather a matter of the increase of total mass of the car.

Section Thickness The recommended section thickness of forging is 3 – 250 mm indicating that the current section thickness of the side panel (2mm) would have to be increased resulting in an increase of material supply and thereby also mass. To keep the section thickness small without decreasing the mechanical properties of the component is preferable. Regarding the section thickness, composite material thereby has an advantage in comparison to aluminum since a smaller section thickness is a possibility.

Surface Roughness Forging gives a Class‐A surface and so does all of the composite production systems introduced in Chapter 4. No difference concerning the final result of surface roughness is spotted between aluminum and composite production. The difference is found in the step of surface finishing. Finishing of all materials changes the mechanical properties of the surface of the material but the changes are different depending on the material and the method used for finishing. A detailed study within the field of surface finishing of different materials in combination with different methods is recommended for optimization.

Shape Forging allows non‐circular prismatic and 3‐D shapes. For the purpose of the production of the side panel, this does not cause any problems. The possible shapes of composite production systems are also suitable for the purpose of the production of the side panel.

Summary and Observations There is no major difference between aluminum and composite production regarding the possible mass range and shapes. The dimensions of the side panel lies within the limits of both for aluminum and composite production. To achieve a Class‐A surface is also possible for both aluminum and composite production methods. The dimensional limit that would result in a major change if using aluminum production is the section thickness. Forging methods would require an increase of section thickness from 2 mm to 3 mm resulting in an increase of mass and dimensions of the side panel. This is not desirable when wanting to produce a light weight vehicle and thereby a notable disadvantage of aluminum production.

Recommendations The surface roughness depends on the material of the component, the production system and the method used for surface finishing. Before choosing a finite material for the future medium to mass scale production of the side panel of XAM, a study of how these factors are related to each other as well as the results of different combinations is recommended for optimization of material choice.

6.4. Economical Characteristics The economical characteristics include labor intensity, economic batch size, capital cost and tool life. A general description of these with respect to aluminum production is made and thereafter

57

compared to composite production. The purpose was to understand the difference of aluminum and composite production of the side panel with respect to the economical attributes.

Labor Intensity The labor intensity of forging is low compared to most composite methods that have a medium to high labor intensity. The only composite production method where the labor intensity is considered low is that of compression molding. The aluminum production is completely automated while the composite production with the technology of today would require some manual controlling steps and thereby require more personnel.

Economic Batch Size The economic batch size of forging reaches a value of between 1 000 and 100 000 pieces/year and can thereby preferably be used for medium to large scale production. The composite production methods with equivalent batch sizes include compression molding, RTM, BMC/DMC molding and SMC molding. The other composite production methods are not recommended for the purpose of medium to large scale production.

Capital Cost The capital cost of forging is high in comparison to any composite method. Comparing it to the composite methods for medium to large scale production, the capital cost of forging is approximately 7 times higher. The investment of a composite production plant including all of the needed machinery and equipment is estimated to 3 400 000€ while the same for the aluminum production would be 22 200 000 €.

Tool Life The tools of forging can last for a production volume of between 1 000 and 1 000 000 units depending on the characteristics of the component. For composite medium to large scale production the maximum tool life is approximately 200 000 units (compression molding and BMC/DMC molding) while that for RTM is noticeably lower with a tool life of only 500 units. The equipment used for aluminum production thereby has the possibility of a tool life of 5 times the longest tool life of composite production which is a clear advantage of aluminum manufacturing.

Summary and Observations The labor intensity of aluminum production is low compared to that of most composite production. A possible reason is that forging is automated to a higher extent than the composite production methods and that composite production requires more manual work. The economic batch size of forging is high in comparison to the composite production methods. This is usually related to the capital cost which is a lot higher for forging than for composite production indicating that a higher volume of components have to be produced in order for the production to be economically beneficial. The tool life of forging on the other hand is higher than that of composite production, which is economically beneficial for the manufacturer since the need of changing tools is lower.

Recommendations The observations give an overview that can be used for future planning of the production line of the side panel. An exact calculation cannot be done until the production line is in actual use, but a general estimation is useful.

58

6.5. Production Rate Forging methods for aluminum production can manufacture up to 1 000 000 pieces/year/hydraulic press while the fastest composite production methods are compression molding, BMC/DMC molding and SMC molding with a production rate of up to 150 000 – 180 000 pieces/year/hydraulic press. The slowest methods for composite production are hand/spray lay‐up and VARTM.

Summary and Observations The production rate of aluminum production and forging is five times greater than the fastest composite production methods. This is a huge difference that makes an essential difference over long term production in terms of total amount of components manufactured.

Recommendations If wanting to increase the amount of components produced/year for a composite production plant, a serial production plant might be considered – hence to use more than one hydraulic press simultaneously. On the other hand this would increase the capital cost of the production method as well as the labor intensity causing an increase in total cost. A study of whether or not composite serial production would be beneficial for the purpose of the production of the side panel of XAM is recommended to be done and analyzed.

6.6. Overall Summary and Conclusion It is important to consider all of the different factors of aluminum and composite production when comparing the two. The overview given throughout this chapter can be used when studying the specifications of material choice for the future production of the side panel of XAM.

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64

• 2 layers of FlaxPreg UD180

• 2 layers of FlaxPreg BL200

• 1 000 pieces

FlaxPreg UD180: 1 300 ∙ 2 200 mm2 ∙ 2 layers ∙ 1 000 pieces = 5 720 m2 → 5 000 m2 of FlaxPreg will be bought for a price of 18.60 €

FlaxPreg BL200: 1 300 ∙ 2 200 mm2 ∙ 2 layers ∙ 1 000 pieces = 5 720 m2 → 5 000 m2 of FlaxPreg will be bought for a price of 20.21 €

Medium Scale Production (10 000 pieces/year) • 1 300 ∙ 2 200 mm2

• 2 layers of FlaxPreg‐E UD180

• 2 layers of FlaxPreg‐E BL200

• 10 000 pieces

FlaxPreg UD180: 1 300 ∙ 2 200 mm2 ∙ 2 layers ∙ 10 000 pieces = 57 200 m2 → 10 ∙ 5 000 m2 of FlaxPreg will be bought for a price of 10 ∙ 18.60 €

FlaxPreg BL200: 1 300 ∙ 2 200 mm2 ∙ 2 layers ∙ 10 000 pieces = 57 200 m2 → 10 ∙ 5 000 m2 of FlaxPreg will be bought for a price of 10 ∙ 20.21 €

Large Scale Production (100 000 pieces/year) • 1 300 ∙ 2 200 mm2

• 2 layers of FlaxPreg‐E UD180

• 2 layers of FlaxPreg‐E BL200

• 100 000 pieces

FlaxPreg UD180: 1 300 ∙ 2 200 mm2 ∙ 2 layers ∙ 100 000 pieces = 572 000 m2 → 100 ∙ 5 000 m2 of FlaxPreg will be bought for a price of 100 ∙ 18.60 €

FlaxPreg BL200: 1 300 ∙ 2 200 mm2 ∙ 2 layers ∙ 100 000 pieces = 572 000 m2 → 100 ∙ 5 000 m2 of FlaxPreg will be bought for a price of 100 ∙ 20.21 €

The material supply consists of FlaxPreg (see Chapter 4 for more details about the material) and the chosen manufacturer is LINEO. The prices were received from the contact person Dominique Andreis from LINEO [22].

Weighing Cell A weighing cell for the purpose of measuring the material taken from the material supply can be bought at for instance Eilerssen Industrial Sensors in Denmark [23] or Applied Weighing, UK [24].

Hydraulic Press, Mold, Gripper Change System and Cooling Station For choosing a suitable press, the wanted press force has to be known. Knowing the dimensions and characteristics of the side panel, the wanted press force is approximated to 2 500 tons and a compress eco 400 is chosen from . See Figure 7.5 for an example of one of the hydraulic presses from the Compress Eco Series. The mold is also recommended to be bought at Dieffenbacher and is

65

usually bought together with the press. The gripper change system, the cooling station and the gate out belt are also bought from Dieffenbaher.

Figure 7.5. Compress Eco, Dieffenbacher47

Robots There are three robots included in the plant lay‐out – a loading robot with gripping system, an unloading robot and a cleaning robot. Other than at Dieffenbacher, these could be found at for example Kuka Robotics, ABB and Comau [20]. A comparison between the advantages and disadvantages of these different manufacturers and their products has to be done.

Reworking Station The reworking station is manual and a need of rasps, sandpaper, and rasp machines are recommended. These can be bought at many companies in Turin, Italy, for example at several stores in Grugliasco shopping center.

Security For security reasons a protection fence is recommended for surrounding the machines, protecting the workers from injuries and accidents. This can be found at Dieffenbacher too and is adapted to the dimensions of the hydraulic press.

Summary and Observations The suggested manufacturers are examples of possible places where to invest in new equipment for a possible future medium to large scale manufacturing. They are given in order to facilitate future studies within the field but can easily be changed if other equivalent manufacturers are to be found. Most equipment is seemed to be found at Dieffenbacher, while some can be delivered from other manufacturers as well.

Recommendations Before choosing a definite manufacturer of the machinery and equipment, one should consider and compare cost, transportation distance and life time of the machine/equipment in order to optimize the choice.

47 Figure from: Dieffenbacher. Hydraulische Pressensysteme und Direktverfahren. http://www.dieffenbacher.de/fileadmin/bilder/Sonstiges/Broschueren_PDFs/Umformtechnik/Kunststoff/BR_Kunststoff_D_SQ.pdf [2011‐11‐11]

7.4. The life cdifferent pin Figure 7while the

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67

7.5. Overall Summary and Conclusion The machinery, equipment and material needed for a plant lay‐out adapted to medium to large scale production of the side panel can all be found in Europe and the mentioned manufacturers include Dieffenbacher, Lineo, Kuka Robotics, ABB, Comau, Eilerssen Industrial Sensors and Applied Weighing. The life cycle of the side panel include material, manufacturing, transport, use and disposal. A future detail study within the recycling process of the side panel is recommended as a future project within Team H2politO as well as a project including a more specific plant lay‐out of the production plant.

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Chapter 8. Recommended Future Projects and Requirement Specifications

This study has introduced the necessity of new areas of study that could be used as subjects for future thesis projects. The four major fields of study that have been noted are the change of assembly system of the side panel to the chassis, a material study for possible change of composite material to use for the body of XAM, a detailed plant lay‐out including European manufacturers of machinery and equipment needed and finally a recycling study of the composite material for a closure of the life cycle of the side panel. Proposals of these projects including requirement specifications based on earlier chapters throughout this reports are given.

8.1. Assembly System One of the key problems of the design of the side panel is its current assembly system to the roof panel. For making the production less time consuming and decrease the investment of the press mold, a new assembly system between the side panel and the roof panel is essential. The purpose of changing assembly system is to facilitate the production of the side panel for medium to large scale composite production using RTM, compression molding, BMC/DMC molding or SMC molding following specific requirements and keeping the desires in mind.

Requirements • The press mold should be made of a single upper mold and a single lower mold, hence a total

of no more than two parts.

• The parting of the side panel from its mold should be simple (through for example an increase of the corner radiuses of the current side panel).

• The design of the side panel should not be changed to the extent that more than a maximum of two of its neighboring parts have to change.

• The recommendations for aerodynamics should be taken into account.

• The complexity and thereby the time of assembly should be adapted to a medium to large scale production (10 000 – 100 000 units/year).

Desires • The amount of material used for 1) the mold production and 2) the side panel itself should

be kept as low as possible.

• The number of employees needed for assembly should be kept as low as possible.

• The production rate should be as high as possible.

8.2. Material Study The current material used for the production of the body of XAM is epoxy resin reinforced with flax fiber. For this study the side panel is analyzed with respect to the mechanical properties. These will be given through tests and compared to the same mechanical properties of other composite materials. The purpose is to compare different composites and after the result choose the best suitable material for the body of an urban city car considering specific requirements and desires. The different composite materials are to be chosen after a bench marking with reasonable motivations.

69

Mechanical Properties for Testing • Compare the static strength of the different material samples by loading through impact,

shock and repeated cyclic exposure.

• Compare the fatigue of the different material samples by loading through impact, shock and repeated cyclic exposure.

• Compare the damage tolerance of the different material samples by loading through impact, shock and repeated cyclic exposure.

• Do tensile and compression tests.

When having the data of the mechanical properties for the different composite materials, the results are to be compared to the theoretical mechanical properties of aluminum.

Requirements • Motivations have to be given of how the mechanical properties of the chosen composite

material fulfill reasonable values for the purpose of a car body design of an urban city car.

• The material has to be able to leave a result with a Class‐A quality surface.

• The section thickness should be 2 – 5 mm.

• The total weight of the side panel should not exceed 8 kg.

• The other dimensions of the side panel should not be changed.

Desires • The total weight of the side panel should not exceed 5 kg.

• The section thickness should not exceed 3 mm.

• The curing time of the material should be kept as low as possible.

8.3. Plant Layout A detailed design of the plant lay‐out for a medium to large scale production of the side panel of XAM is necessary before putting the production into practice. The purpose of a detailed plant lay‐out is to be able to make an approximation of the investment required for a future production of the side panel including security systems for employees and assembly workers. An economic overview of the chosen manufacturers of machinery and equipment should also be made. Data sheets of the chosen machinery and equipment including tool life, price, technical data, physical dimensions and working speeds are to be introduced for all included machinery and equipment.

Requirements • The production method/s to be used are RTM, compression molding, BMC/DMC molding

and/or SMC molding.

• The production plant should have the capacity of manufacturing a production volume of minimum 10 000 – 100 000 components/year.

• The manufacturers of the machinery and equipment needed for the design of the plant lay‐out are to be located in Europe.

• The location of the production plant is Turin, Italy.

• The investment should not exceed the approximated income.

• The design of the production plant has to follow security regulations.

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Desires • The production line should be as automatic as possible, hence minimize the amount of

manual stations.

• The number of employees needed within the production plant should be kept as low as possible.

• The production rate should be kept as high as possible.

8.4. Recycling The recycling of the composite material of the body of the car has to be considered and planned in detail. The purpose of this study is to make a plan of possible recycling methods for completing the life cycle of the body of XAM. What is the composition of the material? Is it recyclable? Are there any possible areas of usability for a reuse of the recycled material when the car is being dismantled? If yes, which are those areas? What are the energy emissions during the product life and how big is the CO2 foot prints? Is it possible to reduce these? How?

Requirements • Requirements for recycling regulations should be followed for the plan. The regulations

should be found during the research phase of the project.

• A detailed plan for at least two areas for reuse of the recycled material.

Desires • Keep the CO2 footprint as low as possible.

• Keep the energy emissions as low as possible.

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Chapter 9. Discussion and Conclusions This study has given a general idea about possible production systems for future medium and large scale production of the side panel as well as a description of the production system already used for small scale production. The project gives a base for future development and detail research within the area by recommending changes in design, production systems to use, manufacturers and some guide lines for production plant lay‐out.

The case study of the composite production and design of the side panel shows that the current manual production method used is only suitable for prototype and small scale production because of long production cycle and a large number of employees. A future prototype production might go faster now that the method and its problems are known.

Recommended changes in the design of the side panel would facilitate the production. These include an increase of corner radius and a change of assembly system. A possible improvement of aero dynamics is to add a brake cooling duct to the frontal wheel arch and a sill to the lower side panel in order to decrease the air volume around the wheels so that the loss of kinetic energy decreases. In accordance with these recommendations, a new assembly system has to be designed and developed in detail as a construction base.

For a future medium scale composite production of the side panel, BMC/DMC molding, SMC molding and RTM are the best out of the 10 methods that were introduced in the beginning. These have a production rate which lies within the economic batch size for a medium scale production volume even though the tooling cost and labor intensity are medium to high. The mass range, section thickness, surface roughness and shape of the side panel all lie within the range of those possible.

The most suitable composite production systems for large scale production of the side panel is compression molding, BMC/DMC molding and SMC molding. With these methods, a production volume of up to 180 000 pieces/year can be manufactured and just like in the case of medium size production, all of the dimensional properties of the side panel are possible.

The market and technology of improved or new production methods are constantly under development and it is therefore of great importance to keep the market under observation for improvements or change in production methods.

The machinery and equipment needed for a medium to large scale production plant include material supply, a weighing cell, a loading robot with gripping system, a gripper change station, a hydraulic press compress eco 400, a press mold made of iron, an unloading robot, a cleaning robot, a cooling station, a reworking station and a gate out belt. All of these can be bought at Dieffenbacher with a total investment is approximately 3 400 000 €. The considered material is FlaxPreg consisting of epoxy resin reinforced with flax fiber and the manufacturer is Lineo.

In the case of aluminum production, forging is a common method for medium to mass scale production. An aluminum production plant would need a total investment of 7 times that of composite production, but can on the other hand manufacture up to 5 000 000 pieces/year which is approximately 27 times more than any composite production can manufacture in a year.

A future continuation of this theoretical study is recommended and includes a study of possible assembly system between the side panel and the roof panel, a material study, a more detailed

73

production plant lay‐out for more specific economic analyses and a study of possible recycling methods for the chosen material. The results achieved throughout this project thereby form a general basis for future detail studies within the same field of study.

74

Bibliography

[1] Politecnico di Torino. Team H2politO. URL: http://areeweb.polito.it/didattica/h2polito.html [2011‐06‐22] website

[2] Team H2politO. Ready to be Different. Politecnico di Torino [2011] flyer [3] Politecnico di Torino. Team H2politO.

URL: http://srvh2polito.polito.it/en/team/who‐we‐are.html [2011‐06‐23] website [4] Settineri, Luca. Professor. Politecnico di Torino [2011‐10‐21] meeting

[5] Danilo. Production employee. EXP Torino [2011‐07‐01] interview [6] Cozzari, Giuliano. Proffessor. Politecnico di Torino [2011‐10‐10] meeting [7] Serra, Andrea. Student – Industrial Design. Politecnico di Torino [2011‐10‐04]

interview [8] Avesio, Francesco. Student – Industrial Design. Politecnico di Torino [2011‐10‐04]

interview preparation [9] Viebke, Lars. KTH‐Kista. Institutionen flr tillämpad IT. Fiberkompositlaminering.

http://www.carbontrikes.se/komposit/Fiberkompositlaminering.pdf [2011‐10‐15] website

[10] Carello, Massimiliana and Airale, Andrea. Urban Concept 534: Technical Innovation

Award. Team H2politO [2011] article [11] Hashemi, Roozbeh. Student Automotive Engineering. Politecnico di Torino [2011‐11‐

15] interview [12] Massai, Paolo. Professor. Politecnico di Torino. Land Vehicle Aero Dynamics, Chapter 2

[2011‐04‐10] lecture slide

[13] Ashby, Mike. CES EduPack 2011. Cambridge: Department of Engineering, University of Cambridge [2011] software

[14] Lineo. FlaxPreg. URL: http://www.lineo.eu/#!products [2011‐09‐26] website [15] Composites One. About Composites. URL: http://www.compositesone.com

[2011‐09‐15] website

[16] Forex Bank. Currency Converter. URL: http://www.forex.se/en/ [2011‐09‐26] website

[17] Design Engine. A Resource for Design and Engineering. URL: http://design‐engine.com/stories/classa.htm [2011‐09‐22] website

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[18] Ashby, Michael. Shercliff, Hugh. Cebon, David. Materials engineering, science, processing and design. 2nd Edition [2007] book

[19] Efunda. Properties of Aluminum Alloys. URL: http://www.efunda.com/materials/alloys/aluminum/properties.cfm [2011‐10‐25] website

[20] Fernandez Mas, Antoni and Peano, Fabio. Students. Politechnic University of Turin [2011‐11‐17] interview/meeting

[21] Graf, Matthias. Technical Director. Dieffenbacher [2011‐11‐22] interview

[22] Andreis, Dominique. Engineer. Lineo [2011] contact person of Team H2politO

[23] Eilersen. Industrial Sensors. URL: http://www.eilersen.com/default.asp?ContentId= {EB 954457‐3932‐4700‐9F47‐DE2E1900AD1E}&gclid=CJ_a‐5GW7q0CFagumAodm0yN6g [2011‐12‐08] website

[24] Applied Weighing. Load cells. URL: http://www.appliedweighing.co.uk/about_us.php [2011‐12‐08] website

[25] Google. Google Maps. URL: http://maps.google.se [2011] website

76

Appendix 1 – Interviews During the thesis, some interviews and study visits were made. A summary of the interviews are found in this appendix.

Interview 1 – Production of the Side Panel at EXP Danilo at EXP: is an expert of composite small scale production and works at the company EXP in Turin. At the company they produce all sorts of prototypes made of composite materials, mostly carbon fibers.

Purpose: An interview with Danilo in combination with a study visit at the company EXP was made for the purpose of getting to know more about the production of the side panel of XAM for the case study of its production methodology.

Questionnaire: 1. Which were the different stages of the production process used for producing the side panel

of XAM? 2. What machinery was used? 3. How long did the production process take? 4. What materials were used? 5. How was the final side panel surface finished?

The answers can be found in 0.

Interview 2 – Design of the Side Panel Andrea Serra: is a student at the Polytechnic University of Turin within the area of industrial design and a member of the Team H2politO. In the academic year of 2010/2011, he worked with the design of the body of XAM.

Purpose: An interview with Andrea Serra was held for the purpose of doing a case study of the production of the side panel and the ideas of the design behind it.

Questionnaire: What are the approximate dimensions of the side panel? Section thickness, length and width.

1. Why was the side panel designed in the way it was? 2. Did you experience any problems during the production? If yes, what kind of problems? 3. Would you have done anything different knowing the result? In that case what and why? 4. Which parts are critical in terms of mechanical properties? Is there any brittle part that could

need some change of design? 5. What parts cannot be changed due to assembly or similar issues? 6. How was the side panel produced? 7. How much time did each step take and how many people were needed? 8. Could the process have been made faster in any way? 9. How was the mold made? 10. Which parts are designed for assembly to the rest of the body?

77

Interview 3 – Aerodynamics and Design Roozbeh Hashemi: is a student from Iran currently studying his master’s course within automotive engineering at the Polytechnic University of Turin and a member of the Team H2politO. He has been working with car design during 4 years in different student projects both in Iran and Italy and knows a lot about electric and hybrid vehicles.

Purpose: An interview with Roozbeh Hashemi was held for the purpose of understanding the limits of design of some critical part of the side panel for aero dynamical reasons.

Questionnaire: 1. Which parts of the side panel are critical in terms of aero dynamics? Why are these parts

critical? 2. What parts of the neighboring components of the side panel are critical in terms of aero

dynamics? Why are these parts critical? 3. What should one think about when designing a side panel of a car in terms of aero

dynamics? Why?

Interview 4 – Material of the Side Panel Antoni Fernandez Mas and Fabio Peano: are students at the Polytechnic University of Turin and members of the Team H2politO. In the team they work on a study about possible composite materials for the production of the urban vehicle XAM.

Purpose: An interview with Antoni Fernandez Mas and Fabio Peano was held for the purpose of getting a deeper understanding about flax fibers and epoxy resin.

Questionnaire: 1. What is flax fiber? 2. What are the mechanical properties of flax fiber? 3. Where can they be bought? 4. What was the price of the material used for the production of the body of XAM? 5. From where was the material for the production of the body of XAM bought? 6. How many layers of FlaxPreg were used for the production of the side panel of XAM? 7. What are the mechanical properties of the different layers? 8. Why was this material chosen?

Interview 5 – Machinery (Medium to Mass Scale Production) Dieffenbacher: is an internationally active group of companies that develop and manufacture press systems and composite production systems for the wood panel industry, the automotive and components industries.

Purpose: An interview with one of the Technical Directors, Mr. Matthias Graf was held for the purpose of getting a deeper understanding about machinery and production plants.

Side panel:

• Section thickness: 2 mm

• Weight: 5 kg

• Height x length: 1,280 x 1,800 mm2

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• Surface quality: A‐class

• Tolerance values: 0.2‐1 mm

Compress Plus:

• Press forces from 15,000 to 50,000 kN

• Bolster sizes from 2,400 x 1,800 mm to 4,000 x 2,800 mm

• Closing speed under load up to 80 mm/s, depending on the press force

Compress Eco:

• Press forces from 4,000 to 25,000 kN

• Bolster sizes from 2,000 x 1,400 mm to 3,600 x 2,400 mm

• Speeds under load from 18 to 40 mm/s

Questionnaire: 1. We are doing a theoretical study about the composite production of a side panel of a car.

The size of the panel is 1,280 x 1,800 mm, section thickness 2 mm and weight 5 kg. We are looking at a production volume of 1,000; 10,000 and 100,000 pieces/year. What press series would you recommend us to “buy”? Compress Plus or Compress Eco?

For the purpose of a production of the side panel, one of the presses from the Compress Eco series would be recommended to buy because of the cheaper price and the dimensions of the side panel.

2. What is an approximate price of that machine?

1,000,000 – 1,300,000 € for one press

3. What are the physical dimensions of the press?

The mold of the press has a dimension of approximately 2.4 m x 1.8 m, while the needed floor space in a production plant would be approximately 4 m x 3 m

4. What are the physical dimensions of an average production plant for RTM and SCM production of small sized products?

For the entire production system for the production of the side panel, a floor area of 10 m x 15 m is needed

5. Do you also sell other equipment for machine lay‐out? For example weighing cells, gripping robot, cooling systems and safety fences? If not, do you have any recommendations of where to buy them?

Yes, we sell the needed equipment for an entire production system including press pits, unwinding and rewinding of prepreg, cooling station etc. The total investment for all of the production system for composite production (SMC) is approximately 3,000,000€ for the equipment plus 400,000€ for the press mold.

6. We read on your web‐page about bolster size, what does it stand for?

The bolster size indicates the size of the press table – hence the size of the maximum mold that can fit into the press.

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7. What is a typical production rate using your presses and processes?

In the case of a side panel of the given dimensions, the production rate using SMC molding would be 150,000 – 180,000 pieces/year.

8. Can the same press be used for SMC and HP‐RTM?

The same press series with a smaller size.

9. What is the range of curing time for different production systems?

30 second to 5 minutes, the fasted one being LFTD and the slowest one being RTM.

10. What is the percentage of resin in a piece made carbon fiber using different processes?

For carbon fiber production, the percentage of resin (epoxy resin) is 25% for SMC and 40% for RTM.

11. What are the maximum dimensions of a mold?

4 m x 3 m.

12. Within what range can the section thickness vary for production using your machinery?

The most common section thickness is 1.8 mm – 3 mm but the maximum section thickness is 4 mm – 5 mm.

13. What is the needed press force for the production of the side panel?

2,500 tons for SMC production

14. What would the investment of a production system for the production of the side panel if it would have been produced in aluminum?

20,000,000 € plus 5 x 400,000 € for the presses plus 2,000,000 € for mold investment

15. What would the production rate of aluminum production of the side panel be?

4,000,000 – 5,000,000 pieces/year

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Appendix 2 – Data Sheet of FlaxPreg PrePreg made of Flax Fibers / Epoxy Resin General information LINEO FLAX PREPREG is a range of pre‐impregnated material based on an Epoxy Resin system and pre‐treated Flax Fibers using the LINEO patented sizing technology. This range of flax prepreg, named FLAXPREG has been developed to mainly enhance the vibration absorption qualities of the final composite parts. It also allows the development of greener material.

Applications: High performance composite parts

• Sporting equipment (bike frames, hockey sticks, tennis rackets, skis, baseball bats)

• Marine, especially sailing boats

• Transport (body panels, interiors)

• Aerospace (secondary parts, interiors)

Main Advantages

• High Vibration Absorption

• Electrical Insulation

• CTE near 0

• Low Density (1.3)

• Tg from 239°F to 302°C depending on curing cycle

• Easy and ready to use

• Made from natural and renewable resources

• Long Shelf life

Use of FLAXPREG in composite design

• Use the FLAXPLY© with a 60deg orientation for optimal vibration absorption

• Substitute between 15 to 25% of Carbon or Glass prepreg with FLAXPLY© (Higher rate is possible depending on the mechanical constraints applied on the part)

• Carbon or Glass prepreg should be used for exterior/interior layers ensuring the strength and the rigidity of the part

• FLAXPLY© should be used for intermediate layers for damping properties and vibration absorption

Properties of FLAXPREG Epoxy Formulation Curing Cycle and Tg (IEC 1006, DSC, 10 K/min)

• 2h @ 230°F Tg = 235°F to 251°F

• 1h @ 248°F Tg = 257°F to 273°F

• 30min @ 266°F Tg = 260°F to 276°F

• 1h @ 266°F Tg = 273°F to 293°F

• 15min @ 284°F Tg = 273°F to 291°F

• 30min @ 284°F Tg = 275°F to 293°F

• 1h @ 284°F Tg = 275°F to 293°F

• 15min @ 302°F Tg = 262°F to 277°F

• 30min @ 302°F Tg = 275°F to 294°F

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FLAXPLY© Shelf Life

• Under 40°F: 1 year

• at 73°F: 6‐8 weeks

• at 86°F: 3‐4 weeks

Available range of FLAXPREG

• 150 g/m2 UD Flax Fiber ‐ 50% resin content

• 180 g/m2 UD Flax Fiber ‐ 50% resin content

• 200 g/m2 Balanced Fabrics 0/90 Flax Fabrics – 50% resin content



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Appendix 3 – Data Sheet of Aluminum AL 2024 Composition

• Al: 93,50 %

• Cu: 4,4 %

• Mn: 0,6 %

• Mg: 1,5 % Mechanical Properties

• Density: 27700 kg/m3

• Poisson’s ratio: 0,33

• Elastic modulus: 70‐80 GPa

• Tensile strength: 185 MPa

• Yield strength: 76 MPa

• Elongation: 20 %

• Hardness: 47 HB500

• Shear strength: 125 MPa

• Fatigue strength: 90 MPa Thermal Properties

• Thermal expansion: 22,8∙10‐6/°C

• Thermal conductivity: 190 W/m‐K Electric Properties

• Electric resistivity: 34∙10‐9Ω‐m

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Appendix 4 – Physical Attributes The numerical values of the physical characteristics mentioned and shown in tables in Chapter 5 are demonstrated and summarized in Table 1 below.

Table 1. Physical attributes of each production system.

PHYSICAL ATTRIBUTE Mass range

[kg] Range of section thickness [mm]

Tolerance [mm]

Roughness [µm]

Surface roughness

PRODUCT

ION SYSTEM

Compression molding

0.1‐20 1.5‐25 0.15‐1 0.2‐1.6 Very smooth

Autoclave molding

0.8‐2∙103 2‐30 0.8‐1 0.5‐3.2 Very smooth

Hand lay‐up/ Spray lay‐up

1‐6∙103 2‐10 0.8‐2 0.5‐3.2 Very smooth

Filament winding

0.01‐3∙103 2‐25 0.5‐1.6 0.5‐1.6 Very smooth

Resin transfer molding (RTM)

0.8‐50 2‐6 0.25‐1 0.25‐1.6 Very smooth

BMC (DMC) molding

0.03‐20 1.5‐25 0.12‐1 0.3‐1.6 Very smooth

Pultrusion

0.1‐200 3‐15 0.25‐1 0.3‐1.6 Very smooth

SMC molding

0.03‐50 1.5‐25 0.2‐1 0.3‐1.6 Very smooth

Vacuum and pressure bag molding

0.8‐2∙103 2‐6 0.8‐1.2 0.5‐3.2 Very smooth

Vacuum assisted resin transfer molding VARTM

0.5‐600 1‐20 0.3‐1 1‐2.4 Very smooth

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86

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87

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88

Data Sheett, Dieffenbbacher

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