Thermoforming Workbook Draft

Higher Institute for Plastics Fabrication

WORKBOOK

for

Thermoforming

Practical Course

Prepared by

Thermoforming Department

1st Edition 2009

Workbook for Thermoforming Pract ica l Course

ACKNOWLEDGEMENT

In its program to continuously improve the quality of instructions at the

Higher Institute for Plastics Fabrication, the Curriculum Steering Committee

initiated the creation of the workbooks for all practical courses being offered

in the Institute. The Committee is headed by Dr. Khaled Al-Ghefaili, and the

members are Dr. Ahmad Al-Ghamdi, Mr. Hiroshi Takeshita, Engr. Issa Al-

Khormi, Mr. Sumio Iwase, Mr. Kazuhiko Sawada, Mr. Sanjay Rawat, Mr.

Zakaria Musa, and Mr. Virgilio Calpe.

This is the HIPF Workbook for Thermoforming Practical Course. The

contents of this workbook were compiled through the efforts of the members

of the Thermoforming Department, namely, Antonio Pasaoa (Head of the

Department), Rameshwar Selukar, Joy Falaminiano, and Koichi Inagaki

(Japanese Expert Adviser). Editing, formatting and design by Virgilio

Calpe.

April 2009


TABLE OF CONTENTS

Introduction … … … … … … … … … … … … … … … … … … . 4

Course Objectives … … … … … … … … … … … … … … … … . 5

Grades Summary Sheet … … … … … … … … … … … … … … ... 6

Workshop Activities

Activity 1—Introduction– Basic Principles of Thermoforming… … .. 7

Activity 2—Thermoforming General Safety Instructions… … … … . 16

Activity 3—Materials and Their Applications… … … … … … … ... 30

Activity 4—The Thermoforming Machine and Mold … … … … … . 40

Activity 5—Thermoforming Methods & Processes… … … … … … 53

Activity 6—Manpower and Standard Operating Procedures … … … 64

Activity 7—Product Quality, Defects and Troubleshooting … … … .. 74

Activity 8—Hands–on and Practical Training (1)… … … … … … ... 83

Activity 9—Hands–on and Practical Training (2) … … … … … … . 89

Activity 10—Hands–on and Practical Training (3) … … … … … … 95

Glossary … … … … … … … … … … … … … … … … … … … . 101

References … … … … … … … … … … … … … … … … … … ... 118


INTRODUCTION

As the demand for plastics continuously grow through the years, invention of

many plastics manufacturing processes took place. Thermoforming is one of

them.

Thermoforming is the process of forming a thermoplastic sheet into a three-

dimensional shape by heating it to render it soft and formable, then applying

different vacuum and pressure to make the sheet conform to the shape of a

mold or die.

Initially, thermoforming was more of manual operation and used for very

specific and limited application and selected materials with only single

cavity and longer cycle time. But due to technological breakthrough and

rapid development through the years, thermoforming has improved and, so

far, is now one of the best improved technology in terms of efficiency.

In today's rapid research and product development, consumers are working

continuously with major resin suppliers, rigid sheet extruders and original

equipment manufacturers in developing high-tech, multi-layered plastic

systems, which equal or outperform traditional materials in many

applications. Thermoforming production processes nowadays are employed

for engineering applications to an extent that only a few decades earlier

would have been deemed impossible. Continually improving thermoplastics,

in conjunction with the most modern machinery, have not only increased

output rates but also the quality and precision of the moldings.

Besides traditional applications, thermoforming has conquered an important

market share with the pressure forming method of packaging particularly the

food packaging industries.


COURSE OBJECTIVES

The purpose of this workbook is to enable the trainees to understand and

carry out important activities in relation to Thermoforming. Focus will be on

the functions in Thermoforming and the terminologies used in the industry.

Upon completion of this course, the trainee shall be able to:

• Have awareness in the importance of Thermoforming Plastic Fabrication

technology.

• Discuss and explain the concept, theories and practices of

Thermoforming plastic fabrication.

• To operate the Thermoforming machine safely and appropriately.


GRADES SUMMARY SHEET

Trainee Name: _________________________ Group: ________

Semester ___ School Year ___________

ACTIVITIES GRADE

Activity 1—Introduction: Basic Principles of Thermoforming

Activity 2—Thermoforming General Safety Instructions

Activity 3—Materials and Their Applications

Activity 4—The Thermoforming Machine and Mold

Activity 5—Thermoforming Methods & Processes

Activity 6—Manpower and Standard Operating Procedures

Activity 7—Product Quality, Defects and Troubleshooting

Activity 8—Hands–on and Practical Training (1)



AVERAGE GRADE


THEORETICAL BACKGROUND

In Thermoforming, the plastic sheet material in rolls will be thermally

heated to make it soft and formable, and then vacuum and/or pressure is

applied to form the shape of the mold. The formed products will be cut &

separated from the skeleton or the runner while the molded products will be

collected and packed accordingly. The runner or skeleton will be crushed

and pelletized to convert it back again into pellet form which will then be

mixed with virgin materials, normally at 20-30% ,to re-process back again

into sheets.

The Six (6) Main Processes of a Thermoforming Machine:

1. Unwinding or Unreeling of Sheet Roll—The sheet is unrolled to dispense

the material into the feed zone. Using a guided chain, the sheet is

conveyed and is passed through the heater.

2. Heating—The sheet is heated to make it soft at a set parameters.

3. Forming (Shaping & Cooling)—The soft sheet is formed to the shape of

the mold and then allowed to cool.

WORKSHOP ACTIVITY #1

Introduction: Basic Principles of Thermoforming


Theoretical Background … continued

4. Cutting—The molded product is separated from the runner or skeleton

5. Stacking—The product is collected in a stack and then ejected to the

conveyor for packing

6. Winding of skeleton—The skeleton is collected and removed for

recycling.

Thermoforming process is different from the other plastic fabrication

processes because its raw material is not the usual pellets being melted

through the use of extruder to produce the desired shape using a die or molds

but rather using the finished product of Sheet Extrusion which is the rolled

sheet as its raw material.

WORKSHOP ACTIVITY #1—Introduction: Basic Principles of Thermoforming



The Thermoforming industry started from Vacuum Forming using rigid PVC

sheet. Since polystyrene (PS) was developed, PS sheet penetrated rapidly the

Thermoforming industry due to easier formability. Process development for

Pressure Forming and Plug Assist Forming expanded further the industry.

Recently, polypropylene (PP) sheet is used in applications, in which heat

resistance or oil resistance is required, where PS sheet can not be used.

There are actually many thermoforming processes now available in the

market but the three most commonly used basic processes are:

1. Vacuum Forming Process—The oldest and cheapest process in terms of

equipment cost.

2. Pressure Forming Process—The fastest among the processes in terms of

production speed (more than three times that of Vacuum Forming) due to

higher pressure.

3. Plug-Assist Forming Process—For deep draw shapes like drinking cups

& bowls.

Applications:

Packaging trays, cups, bowls, automotive panels, car roof top, boat hulls,

large panels, spa baths, kitchen sinks… possibilities are endless…

One of the most important industries that thermoforming serves, however, is

the packaging industry.

Advantages of Thermoforming are:

1. Cheaper equipment and mold cost

2. Higher productivity due to its high speed

3. Thinner wall product, therefore, lesser material consumption and cheaper

products

4. Lower production cost due to above features

The only disadvantage of thermoforming so far is its high scrap rate due to

its inevitable runner being generated as part of it production processes.



OBJECTIVES OF THE ACTIVITY

1. To learn the basics of the Thermoforming processes

2. To identify the main parts of Thermoforming machine and their functions

PROCEDURE

PART I—The Basics of Thermoforming Processes

1. Go to the Workshop floor (per group) and observe how the

Thermoforming machine run. The process will be explained to you by

your Instructor.

2. Using the data sheet form, list down the different stages or functions of

the Thermoforming machine.

3. Using a stop watch, take the actual time needed to complete each of the

stages and compute for the total cycle time.

4. Look at the monitor of the control panel and compare the total cycle time

(actual cycle time versus the recorded cycle time in the machine).

5. Write down your observation in your data sheet.

PART II—The Six (6) Main Parts of Thermoforming Machine

1. Using the drawing of Thermoforming machine in your data sheet, label

the six (6) main parts of the machine in the space provided.

2. Write down the corresponding functions of each of the six main parts of

the Thermoforming machine.


DATA SHEET

PART I—The Basics of Thermoforming Processes

PART II—The Six (6) Main Parts of Thermoforming Machine

ACTIVITY #1—Introduction: Basic Principles of Thermoforming

TRAINEE NAME GROUP NO.

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Report Form Report Form Report Form Report Form ---- Page 1 of 4 Page 1 of 4 Page 1 of 4 Page 1 of 4

STAGES OF THERMOFORMING

FUNCTION CYCLE TIME

1.

2.

3.

4.

5.

6.

TOTAL RECORDED CYCLE TIME (STOP WATCH)

TOTAL CYCLE TIME FROM CONTROL PANEL


QUESTIONS & EXERCISES

Select the correct answer.

1. Thermoforming is the process of forming a thermoplastic sheet into a

desired shape, by __________ heating it to make it soft and formable,

then applying vacuum and/or pressure to make the sheet formed to the

shape of the mold.

a. mechanically

b. conductively

c. thermally

d. electrically

2. In thermoforming process, after the forming takes place, the sheet is

held against the mold surface until __________.

a. heated

b. cooled

c. warmed

d. shaped

3. In thermoforming process, after the forming takes place the formed

product parts are then __________ off from the sheet.

a. trimmed

b. stacked

c. ejected

d. contracted

4. In thermoforming process, after the forming, cutting and punching take

place, the punched out sheet or the runner is usually __________,

mixed with virgin material, and reprocessed into usable sheet again.

a. reground

b. scraped

c. recycled

d. as is

5. __________ is the one of the four resources of thermoforming process.

a. Water

b. Electricity

c. Manpower

d. Compressed air


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QUESTIONS & EXERCISES … continued

6. __________ is a device used to make or transform a thermoplastic

sheet into any desired shape using a mold by applying heat and

pressure.

a. Sheet extrusion machine

b. Advanced molding machine

c. Thermoforming machine

d. Injection molding machine

7. One of the main functions of the mold is to __________ the material to

the surfaces of the mold.

a. receive and distribute

b. heat

c. cut

d. separate

8. Thermoforming machine process arrangement is designed in such a

way that the __________ station comes after the heating work station

to form the shape of the mold.

a. winding

b. stacking

c. forming

d. heating

9. Besides traditional applications, thermoforming has conquered an

important market share of packaging with the __________ forming

method.

a. pressure

b. vacuum

c. simple

d. plug-assist

10. The only disadvantage of thermoforming so far is its high _______ rate

due to its inevitable runner being generated as part of it production

processes.

a. economical

b. scrap

c. productivity

d. rejection


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CONCLUSION & RECOMMENDATIONS

INSTRUCTOR’S COMMENTS


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TRAINEE’S GRADE

FOR THIS ACTIVITY

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INSTRUCTOR’S SIGNATURE

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DATE: __________________

DATE: __________________

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TRAINEE’S SIGNATURE



Figure 2.0—Objectives of Safety Management

A company manages safety to achieve the objectives shown in Figure 2.

Safety when it comes in Manufacturing environment has the following

meanings:

• There are no accidents that result in personal injuries.

• There are no accidents that result in damage to property such as

facilities, machinery, equipment, materials, or products.

• There are no accidents that affect residents and areas around the

factory.

• The factory is managed to ensure that the above conditions are

maintained continuously.

Why Is Safety Important?

The importance of safety at work place can't be over exemplified. It is

mostly felt in factories where the laborers are exposed to sustained risk in

their daily operations. Adaptation of safety measures not only ensures safety

of the life of the workers, but also of their families and their dependents.


Thermoforming General Safety Instructions

The Lives of Workers are Protected

A Safe workplace has positive effects on

operations of the company.

A safety-oriented corporation is trusted

by Society.

Safety Management

Respect for Human Life

Corporate Management

Social Credibility



2.1.2 Who is Responsible for Safety?

Figure 2.1—Safety Responsibility

From the employer down to the lowest level of position in the company, each

person has his own safety responsibilities. It is a requirement in an corporate

institution that all employees are properly instructed and supervised in the

safe operation of any machinery, tool, equipment, process, or practice which

they are authorized to use or apply.

Basically, the employer must provide training to each employee to do each

aspect of their job safely, and must provide adequate supervision of each

employee to assure that the training was effective and that the employees are

following safe procedures.

Thermoforming Machine Safety As an operator, you must always follow the signs and symbols, and you must

be safety conscious to avoid accident. Ignorance is not an excuse when

accident happens. Therefore, developing a safety habit is the best policy that

should be adopted by everybody.

Remember, the life you save, maybe your own!

Safety Instructions

1. Machine is a potential source of danger if it is operated by untrained

operator.

2. The general directives on work safety, accident prevention must be

complied as per the Instructor’s instructions.

WORKSHOP ACTIVITY #2—Thermoforming General Safety Instructions

Factory Factory Factory Factory

Manager/s Company Executives

Supervisor/s Personnel / Machine Operators



3. Always work with concentration and be conscious of safety aspects!

4. Prior to starting work, check the orderly condition of the machine, in

particular the operability of the safety devices.

5. Clarify any queries or unclear matters you may have regarding the work

with and on the machine before starting work!

Warnings and Symbols

The following designations and symbols are used to convey important

information.


Caution:

Warning of a general source of danger, the consequence of

which can be personal injury and/or damage to property

Danger caused by electrical current or voltage!

Warning against injury such as electric shock through

electrically conducting devices.

Hot parts or surfaces!

Warning against danger of burns from parts or surfaces

that have high temperatures even after the machine has

been switched off.

Not allowed for person with cardiac pacemaker!

Persons with a cardiac pacemakers are not allowed to work

on subassemblies that bear this symbol because there is

danger from noise influences due to the static charging of

the plastics film.

Stay Away!

Don’t move close to the part, it is dangerous area.



Safety Measures


Emergency Buttons

Actuation of an EMERGENCY STOP button

interrupts the control voltage, switches off the

compressed-air supply and de-aerates the

compressed-air network up to the inlets of the

solenoid valves.

Mechanical Locking of the Sliding Doors

Safeguard against reaching into the machine while

it is running. Machine cannot be switch ON “O”

when sliding door is open; it also advices not to

open the sliding door during operation.

Hand Lever with Securing Pin

For limiting the travel range of the reel mounting,

in order to avoid the danger of crushing.

Safety Limit Switch on the Door of the Skeletal

Re-winder

Safeguard against reaching into the rotating

skeletal mounting.



Safety Measures … continued


Back-pressure valves in the connections of the

pneumatic cylinders on pneumatically operated

machine parts

To prevent these machine parts from moving when

the machine is at a standstill.

An electrical pressure switch, with a fixed set-

ting of 4 bar

If the operating pressure falls below this value, the

control voltage is switched off and the compressed

air system is de-aerated.

Safety valves with a spring-centered, disabled

middle position for the top and bottom frames

of the forming station

To safeguard against any undesired movements.

Mechanically lockable main switch on the

switch cabinet.

If the main switch is in position "0", all electrical

subassemblies (control unit, heaters, electronic sys-

tem) are de-energized. The compressed-air network

is deaerated up to the inlets to the solenoid valves.

See Actual

Machine

Part



Special Danger and Measures


CO2 Fire Extinguisher

Fires can occur if the plastic being molded is

overheated.

Gases and Vapors

Depending on the plastics to be molded, gases and

vapors can be formed at the heating-up tempera-

ture. Therefore, consult your Instructors or super-

visor, should you need to make necessary provision

for suitable extraction.

Technical Data Sheet (Technical Bulletin)

Important to keep the Technical Data / Safety Data

Sheet from the Thermoforming Sheet manufac-

turer / supplier, in particular the permissible maxi-

mum temperature values. Certain plastics may

burn explosively on heating, e.g., cellulose-based

plastics. Foam films may be processed only if they

are foamed with non-inflammable gases.



Special Danger and Measures … continued

Personal Protective Equipment (PPE)

a. Wearing of an appropriate protective helmet:

• Auxiliary equipment temporarily attached to the machine at

head height during tool changing poses a risk.

b. Wearing of an appropriate safety shoes (have a high anti-static

action) :

• During the thermoforming process, the guidance, unwinding,

steering and winding of thermoplastic materials can create very

high static charges, which cannot always be discharged safely.

c. Wearing of an appropriate protective gloves (with sufficient

level of protection):

• Danger of cuts from sharp edges


Do not touch the heaters!

There is a danger of burning the heaters even after

the main switch had been switched off.

Compliance with the Safety Standards

If the machine is linked to special devices (e.g.,

filling devices, crusher device, packers), compli-

ance with the safety standards attachment of these

devices must be properly observed.

Heater

Approved

Approved

Approved

Approved



1. To learn the basics of safety and safety signs

2. To develop safety awareness among trainees and learn the most common

hazards that may lead to injuries like amputations, lacerations, crushing

injuries and abrasions in Workshop and Machine Operations.

PROCEDURE

PART I—Safety and Warning Signs

1. Walk around the Workshop area and locate all the safety signs.

2. Observe the Machine area for unsafe points and try to identify safety /

warning signs found.

3. In your data sheet, correctly write the names of the safety devices and

warning signs in the pictures.

PART II—Safety Devices Commonly Found in Thermoforming Machines

1. Walk around the Thermoforming Machine and try to locate all the safety

devices present.

2. In your data sheet, write down the names of the safety devices and their

functions.


DATA SHEET

PART I—Safety and Warning Signs

ACTIVITY #2—Thermoforming General Safety Instructions


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1.

2.

3.

4.

5.

6.

7.

8.

9.

SAFETY DEVICES AND SAFETY SIGNS IN THE

HIPF Thermoforming area

DATA SHEET

PART II—Safety Devices Commonly Found in Thermoforming Machines

ACTIVITY #2—Thermoforming General Safety Instructions


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1. ________________ 2. ________________ 3. ________________

4. ________________ 5. ________________ 6. ________________

7. ________________ 8. ________________ 9. ________________



Part I—Fill in the blanks from the given choices.

1. What are accidents?

Accidents usually result from a combination of factors that includes both

_____________________machine condition and ___________________

human actions.

2. Write down the names of PPE equipment to be used for each category.

Eye - ___________________________________

Face - __________________________________

Head - __________________________________

Feet - ___________________________________

Hands and arms - _________________________

Bodies - _________________________________

Hearing - ________________________________

3. A _________ colored warning triangle with black graphical symbol

indicates what the hazard is.

4. A _________ colored circle-with-slash with black graphical symbol

indicates a prohibited action to avoid the hazard.

5. A __________ colored mandatory action circle with white graphical

symbol indicates an action to take to avoid the hazard.


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ANSWERS:

hazardous / careless / safety glasses, goggles / face shields / hard hats / safety shoes /gloves / vests / ear-

plugs, earmuffs / Yellow / Red / Blue



Part II—Choose the correct answer.


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1. Which is the correct shape and color for a “Prohibitory Sign”?

2. Which is the correct color and shape for a “Mandatory Sign”?

3. Which is the correct color and shape for a “Fire Sign”?

4. Which is the correct color and shape for a “Fire Sign”?

5. Which is the correct color and shape for an “Information Sign”?




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6. Which is the correct meaning of the given sign below?

7. What do blue and white safety signs tell you?

a. Things you must not do

b. Things you must do

c. The nearest fire exit

d. There is a hazard in the area

8. Which is the correct image below which represents “Danger, electricity”?

9. When used on site what does this sign mean?

10. What is the correct meaning of this sign?

a. No naked lights

b. Smoke-free rest area

c. No smoking

d. Smoking allowed

a. Mandatory

b. Safe condition

c. Warning

d. Prohibited

a. Ear protection may be worn

b. This is a noisy area

c. Caution, deaf people nearby

d. Ear protection must be worn





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TRAINEE’S GRADE

FOR THIS ACTIVITY

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DATE: __________________

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As an operator, you must always know the material properties and

processing conditions such as temperature, density, shrinkage, and other

factors, so that it would be easy to set the processing parameters when using

different thermoforming machines and molds.

What are Plastics?

• Plastics are man made chemicals extracted mainly from petroleum.

• They are basically composed of hydrocarbons: groups of linked hydrogen

and carbon atoms. (Imagine them as a small train and carriage!)

• Most plastics are made up of long chains of hydrocarbons. (Identical

small trains joined together to form one very long train.)

• More than 50,000 molecules (long trains) may be joined in chains to

produce polyethylene (or polythene).

• Very long straight or branched chains are present in thermoplastics: for

example, polyethylene and polystyrene.

• Thermoplastics always soften when heated and harden when cooled

down.

• This makes these plastics ideal for the vacuum forming process.


Materials and Their Applications



POLYSTYRENE (PS)

Polystyrene can be transparent or can be made to take on various colors. It is

economical and is used for producing plastic model assembly kits such as

cell phones frames, CD "jewel" cases, and many other objects where a fairly

rigid, economical plastic is desired. However, its major application is in the

food packaging industries.

WORKSHOP ACTIVITY #3—Materials and Their Applications



Polystyrenes are classified into two types.

1. GPPS - General Purpose Polystyrene

• Main characteristics: transparent, stiff, and brittle

• GPPS is very stiff but brittle, and highly transparent (clear) glassy

material. Due to high gloss and sparkling appearance, it is widely

used in thermoforming process to produce cups and trays with glossy

surface.

• GPPS is used as surface layer for multi-layer sheet combined with

HIPS.

2. HIPS - High Impact Polystyrene

• Main characteristics: high impact, opaque

• HIPS is produced by physically adding rubber during polymerization

process of GPPS to make it more impact-resistant.

• High Impact Polystyrene is rubber–modified GPPS.

• HIPS is particularly suitable for thermoforming because of its rigidity

and high impact strength which means that it can be formed,

punched, and sawn without difficulty.

Typical raw materials for PS sheet produced by SABIC:

Typical PS sheet which can be used for Practice training:

Three layer PS sheets: GPPS / HIPS / GPPS

GPPS / (HIPS + Regrind) / GPPS


GPPS PS125 HI-PS PS330

Transparent Opaque

Melt flow index 7.0 g/10min 4.0 g/10min

Izod Impact Strength 12.0 J/M 110.0 J/M



POLYPROPYLENE (PP)

• The second important material for thermoforming is polypropylene, a

plastic material synthesized by stereo-regular polymerization of

propylene using Ziegler-Natta catalyst.

• It is the highest volume polymer in the world

• Main characteristics: lightweight, transparent, heat resistant, chemical/

oil resistant, low in cost.

Types of PP used in Thermoforming:

• Isotactic polypropylene

- Crystalline plastics

• Isotactic PP has three kinds:

1. PP Homopolymer

- Transparent, brittle at low temperature

2. Block copolymer with ethylene

- Opaque, High impact at low temperature

3. Random copolymer with ethylene

- More transparent, less stiff

Key Properties of PP Used in Thermoforming:

1. Higher melt viscosity to avoid excess sagging in the Heating Station.

- PP grade with lower melt flow rate is selected.

2. Depend on customer’s need.

- for transparent & glossy need: homopolymer or random

copolymer is selected.

- for high impact at low temperature without transparency need:

block copolymer is selected.




Typical PP sheet used for Practice Training

Raw material for PP sheet

• SABIC PP 83EK10

Melt flow rate :1.2g/10min.

Izod Impact :No break

• PP sheet

Monolayer PP sheet

Three layer PP sheet: PP/PP +Regrind/PP

Importance of Recycling in Thermoforming

In thermoforming process, about 20 to 50% of plastic is generated as waste

after the cutting process depending on product design, such as Cup or Bowl.

The residual sheet after cutting called skeleton is processed in a recycling

machine to crush and pelletize.

The pellets from the recycling machine is fed back into the sheet extruder to

make a sheet.

Summary

The two kinds of plastics used in Thermoforming process are PS and PP.

Recycling is very important in Thermoforming.

PS—Amorphous structure gives easier formability. Majority among plastics

used in Thermoforming is PS.

PP—Crystalline structure gives superior characteristics such as higher heat

resistance and oil resistance. However, some difficulties in thermoforming

include sagging in the heating station and higher shrinkage rate in the

forming station.




1. To give a brief review of the characteristics of plastics.

2. To discuss the two major types of plastics and their characteristics that is

commonly used for the plastics manufacturing sector.

3. To know the importance of each material and their applications to the

Thermoforming Industry.

PROCEDURE

1. In the classroom, bring two pieces of water cups, one PP and one PS.

Try to observe the difference in characteristics between polypropylene

(PP) and polystyrene (PS).

2. In the Machine site, observe behavior of each material (PS and PP)

during processing and try to note the differences.

3. In your Data sheet, write your observations for each material (PP and

PS). Define their characteristics when it is being use in thermoforming

application.


DATA SHEET

Observations on Thermoforming Materials

ACTIVITY #3—Materials and Their Applications


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POLYPROPYLENE (PP)

POLYSTYRENE (PS)

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Choose the correct answer.

1. What are the (2) two major categories of Thermoplastic Materials?

a. (Semi-) Crystalline & Amorphous

b. Polystyrene & PVC

c. Polystyrene

d. Thermoset & (Semi-) Crystalline

2. To which thermoplastics category does polypropylene and polyethylene

belong?

a. Amorphous

b. Thermoplastic Elastomer

c. (Semi-) Crystalline

d. None of the Above

3. A commonly used plastics material for thermoforming.

a. polyacetal

b. teflon

c. PET

d. nylon

4. Which material is recyclable?

a. Polystyrene

b. Epoxy resin

c. Phenolic resin

d. Polyester

5. What material is characterized to be translucent crystalline polymer that

exhibits high stiffness?

a. Epoxy resin

b. Polypropylene

c. Phenolic resin

d. Thermosets

6. What are the 3 types of polystyrene?

a. GPPS, HIPS, Expandable PS

b. Epoxy, Polyester, Polypropylene

c. Polyimides, Polypropylene, Polyvinyl Chloride

d. Polyacetate, Polycarbonate, Polypropylene


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7. What is the general term for a wide range of synthetic or semi-synthetic

polymerization products?

a. Plastic

b. Polypropylene

c. Scrap

d. Recycling Process

8. Higher melt viscosity leads to excessive sagging in the Heating Station.

Hence, PP grade with lower melt flow rate is selected for thermoforming.

a. True

b. False

9. High Impact Polystyrene is rubber–modified GPPS.

a. True

b. False

10. Thermoformed products are also used in automotive sector.

a. True

b. False


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___________________________________________________________

___________________________________________________________

___________________________________________________________

___________________________________________________________

___________________________________________________________

___________________________________________________________

___________________________________________________________

___________________________________________________________

___________________________________________________________

___________________________________________________________

___________________________________________________________

___________________________________________________________

TRAINEE’S GRADE

FOR THIS ACTIVITY

________________________


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DATE: __________________

DATE: __________________

________________________




The Components of a Thermoforming Machine - Illig RV53b

Thermoforming Machine is a device use to make or transform a

thermoplastic sheet into any desired shape using a mold by applying heat and

pressure.

THERMOFORMING MACHINE PARTS & FUNCTION


The Thermoforming Machine and Mold

The Main control panel system is a device

that regulates the Machine Operation proc-

ess of each part connecting to each other.

Main Control Panel



WORKSHOP ACTIVITY #4—The Thermoforming Machine and Mold

To introduce the sheet into the Feed zone up

to Heating station, the following procedures

must be followed:

• Rolled sheet must be properly inserted

into the shaft.

• Using the Lever arm loader, rolled sheet

must be firmly positioned in the unwind-

ing stand and the exact tension should

be applied.

Unreeling/Unwinding Station

Thermoplastic sheet is heated and softened

in this station. The guidelines for heating the

sheet are the following:

• Temperature should be properly con-

trolled to prevent excessive sag.

Heating Station

In this station, the thermoplastic sheet is

formed into its desired shape, with the re-

quired thermoforming process.

Parts of Forming Station:

• Clamping Frames—used to guide and

hold the sheet during machine operation.

• Tool (Mold)—a devise used to form the

plastic sheet into the desired shape.

• Plug-assist—A mechanical device used

in thermoforming to help distribute the

heated plastic sheet more uniformly be-

fore it actually seats on the mold.

Forming Station




In this station, the molded products are cut

and separated from the sheet/runner.

Parts of Cutting Station:

• Knife Core—aluminum block that sup-

ports the knife.

• Cutting Knife—sharp edged metal part

used to cut and separate the formed

products from the sheet .

Cutting Station

In this station, the finished products are col-

lected to the desired amount using the

pusher.

Parts of Stacking Station:

• Stacking Cage—part of stacking station

where molded parts are collected and

stacked at the desired quantity.

• Pusher—used to put the molded parts

into the stacking cage.

• Ejector Plate—a plate located on top of

the stacking station used to push the

products on top of the conveyor.

Stacking Station

In this station, the runner is rolled or col-

lected. Skeleton sheet or runner should be

properly positioned at the winding roller.

Winding Station



THERMOFORMING MOLDS

Thermoforming mold is a device used to form the plastic sheet into the

desired shape. There are two types of thermoforming molds:

• Prototype (Low Volume Production), and

• Aluminum (High Speed - High Production)

Prototype Mold

This is the mold that is used to make a part that will be evaluated for fit and

function. It is used for low-volume production runs.

Different Kinds of Prototype Mold

• Plaster/3D Print—Plaster molds are cast directly from the model and

used for prototyping. Other casting method is by the use of special

3D printing device to form a mold that is precisely to what is needed.

• Wood—A wooden mold is used mainly for a customer required

prototype or a very low volume production run.

• Epoxy/Polyurethane—A thermosetting plastic mold used for short

production runs that may last at 100 up to 300 parts (shots).

Aluminum Mold

This is a kind of mold made of cast (or machine) aluminum that is prepared

by casting or by layering. Their surfaces can be textured or polished to a

high gloss. Aluminum is an excellent heat conductor and permits rapid

heating and cooling for fast cycles.

Different Kinds of Aluminum Mold

• Porous Aluminum—An aluminum material used for products that

require high optical quality or other cosmetic applications.

• Cast Aluminum—Cast aluminum material is commonly used for thin

gauge applications and having difficult shapes.

• Solid Aluminum—Dedicated for technical/engineered trays.




TWO TYPES OF MOLD DESIGNS

• Male Mold—A male mold or convex mold that has one or more

protrusions over which the heated sheet is drawn to form a shape.

• Female Mold—Female mold or concave mold that has one or more

cavities into which the heated sheet is drawn to form a shape.

THREE (3) KINDS OF MOLD COOLING SYSTEMS

• Ambient Air / Air Spray—most commonly used in vacuum forming

applications.

• In-direct Cooling—the cooling is done thru a cooling block.

• Direct Cooling—mold with integrated cooling channels.

Mold Cooling Table


Type of production Ambient air, air

spray Indirect cooling Direct cooling

Prototypes max 100 trays PU, Plaster, wood

Medium production 100 to 5000str/m Al tool With PU tool

High vol. Production >5000 str/m



VENTING/VACUUM HOLES

Vacuum holes are mold features where the negative air (vacuum air) is

allowed to pass upon forcing the softened plastic sheet against the mold.

Standard Drilled Holes Dimension:

Ø 0.3mm, Ø 0.5mm, Ø 3mm, Ø 5mm




1. To be able to know the different kinds of thermoforming machines, the

parts and function of an ILLIG thermoforming machine and their

specifications.

2. To be able to learn the importance of thermoforming mold, its parts and

the different methods applied.

3. To have a total knowledge about mold assembly and mold parts.

PROCEDURE

Part I—The Basic Parts of Thermoforming Machine

1. Go to the machine site and try to know the different parts of the

Thermoforming Machine.

2. Observe the motion of the different moving parts of the machine and how

the plastics products are formed.

3. In your data sheet, give the names of the parts that are shown on the page

and explain the functions of each of the parts.

Part II—Thermoforming Mold

1. Familiarize yourself with the different mold materials used for

thermoforming mold and try to identify the parts and methods applied in

the mold.

2. In your data sheet, match the word that identify each category or word

that related to each other and to its application


DATA SHEET

Part I—The Basic Parts of Thermoforming Machine

ACTIVITY #4—The Thermoforming Machine and Mold


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1. Part:

Function:

2. Part:

Function:

3. Part:

Function:

4. Part:

Function:

DATA SHEET

Part I—The Basic Parts of Thermoforming Machine … continued



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5. Part:

Function:

6. Part:

Function:

7. Part:

Function:

DATA SHEET

Part II—Thermoforming Mold



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TYPES OF THERMOFORMING MOLDS

1. Low volume production mold

2. Prototype mold made of wood

3. High volume production mold

4. Thermosetting plastic mold

5. Mold that has convex surface

6. Mold used for technical trays

7. Mold that has concave surface

8. Mold for high optical quality product

Answer: (Pick the Answer and Match the word)

Porous Aluminum Mold, Male Mold, Aluminum Mold, Prototype Mold, Female Mold, Solid Aluminum Mold, Epoxy/Polyurethane Mold, Wooden Mold.

MOLD’S COOLING SYSTEM

1. Cooling thru cooling block

2. Mold w/ integrated cooling channels

3. Ambient air / air spray

4. Vacuum holes

Answer: (Pick the Answer and Match the word)

In-direct cooling, Drilled holes under the mold, Direct cooling, Vacuum

forming conventional cooling




1. ____________ is a device having parts that perform or assist in

performing any type of work. Devices with no rigid moving parts can

be considered as tools.

a. Machine

b. Mold

c. Method

d. Material

2. ____________is a device used to make or transform a thermoplastic

sheet into any desired shape using a mold by applying heat and

pressure.

a. Recycling machine

b. Sheet extrusion machine

c. Thermoforming machine

d. Injection molding machine

3. Maximum cycle rate of Illig RV53b thermoforming machine is

____________ cycles per minute.

a. 20

b. 22

c. 24

d. 42

4. What are the main functions of the thermoforming mold?

a. Receive and distribute the material to the surface of the mold

b. Cool the material after forming (water or oil as coolant)

c. Eject the molded product out of the mold

d. All of the above

5. This is a device used to form the plastic sheet into its desired shape.

a. Mold

b. Plug-Assist

c. Knife

d. Pressure


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6. Identify the thermoforming machine work station shown in the picture.

a. Winding station

b. Unreeling station

c. Heating station

d. Forming station


a. Winding station

b. Heating station

c. Unreeling station

d. Forming station


a. Forming station

b. Unreeling station

c. Heating station

d. Winding station

9. Identify the thermoforming machine part shown in the picture.

a. Plug Assist

b. Thermoforming Mold

c. Clamping frames

d. Knife-core Assembly

10. Identify the thermoforming machine part shown in the picture.

a. Mold

b. Clamping Frame

c. Plug-Assist

d. Knife-core Assembly


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___________________________________________________________

___________________________________________________________

___________________________________________________________

___________________________________________________________

___________________________________________________________

___________________________________________________________

___________________________________________________________

___________________________________________________________

___________________________________________________________

___________________________________________________________

___________________________________________________________

___________________________________________________________

TRAINEE’S GRADE

FOR THIS ACTIVITY

________________________


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DATE: __________________

DATE: __________________

________________________




Thermoforming is a simple process: a sheet of thermoplastic is heated and

formed into a designed shape by applying heat and pressure. The sheet is

stretched into a larger shape, which reduces the sheet’s original thickness and

results in a bigger surface area.

THERMOFORMING METHODS & PROCESSES

1. Vacuum Forming Method

Vacuum forming is a process that involves forming thermoplastic sheets into

three-dimensional shapes through the application of heat and pressure.

Advantages:

• Economical for small to medium production runs

• Low tooling costs

• Quick startup

• High strength to weight ratio

• Efficient prototyping

• No need for painting; the color and texture are formed in.

Vacuum Forming Schematic Diagram


Thermoforming Methods & Processes

Page 53

HeaterHeaterHeaterHeater Heated SheetHeated SheetHeated SheetHeated Sheet

Female MoldFemale MoldFemale MoldFemale Mold Vacuum AirVacuum AirVacuum AirVacuum Air

Formed ProductFormed ProductFormed ProductFormed Product


2. Pressure Forming Method

A thermoforming technique whereby vacuum and pressure is used to force

the hot plastic sheet against a mold surface to get a very crisp impression of

that surface.

Pressure Forming Schematic Diagram

3. Plug Assist Forming Method

This is basically the same as straight vacuum forming. But, the heated and

softened sheet is pressed down into the mold by a plug.

After the plug reaches a predefined depth, a vacuum is created inside the

mold so that the sheet is drawn down and forms the shape of the container.

Advantages:

• Economical for small to medium production runs

• Low tooling costs

• Quick startup

• High strength to weight ratio

• Efficient prototyping

• No need for painting; the color and texture are formed in.


WORKSHOP ACTIVITY #5—Thermoforming Methods & Processes

Mold

Pressure Box Pressure Box

Heated Sheet

Pressurized Air

Vacuum Air



Plug Assist Forming Schematic Diagram

4. Other Thermoforming Processes

• Straight Vacuum Thermoforming

• Drape Thermoforming

• Free Draw Thermoforming

• Matched-Mold Thermoforming

• Snap-back Thermoforming

• Billow Forming

• Twin-Sheet Forming


Plug Assist

Heated

Sheet

Mold Vent



1. To give trainees an in-depth knowledge on the three (3) kinds of

thermoforming processes, and the advantages and disadvantages of each

method.

2. To give trainees an introduction to all the processes of an ILLIG RV 53b

thermoforming machine.

PROCEDURE

Part I—Thermoforming Methods/Processes

1. Go to the machine site and try to observe the process that is being used to

get a good product.

2. In your data sheet, explain each given Thermoforming process and draw

a simple schematic diagram of each.

Part II—Thermoforming Machine (ILLIG RV53b) Processes

1. Familiarize yourself with the thermoforming processes of an ILLIG

RV53b thermoforming machine.

2. In your data sheet, explain the whole process of the basic Thermoforming

Machine (iLLig RV53b) and its methods of process.


DATA SHEET

Part I—Thermoforming Methods/Processes

1. Vacuum Forming Process

ACTIVITY #5—Thermoforming Methods & Processes


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Explain the process:

_______________________________________________________________________

_______________________________________________________________________

________________________________________________________________________

_______________________________________________________________________

_______________________________________________________________________

_______________________________________________________________________

Draw the schematic diagram.

DATA SHEET ACTIVITY #5—Thermoforming Methods & Processes


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Part I—Thermoforming Methods/Processes … continued

2. Pressure Forming Process


_______________________________________________________________________

_______________________________________________________________________

________________________________________________________________________

_______________________________________________________________________

_______________________________________________________________________

_______________________________________________________________________




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Part I—Thermoforming Methods/Processes … continued

3. Plug-Assist Forming Process


_______________________________________________________________________

_______________________________________________________________________

________________________________________________________________________

_______________________________________________________________________

_______________________________________________________________________

_______________________________________________________________________




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Part II—Thermoforming Machine (ILLIG RV53b) Processes

Explain each process:

Station 1

Station 2

Station 3

Station 4

Station 5

Station 6




1. Heating is done by top and bottom infrared ceramic heaters with built in

thermocouple. Heating allows sheet to ____________ without any

physical contact.

a. melt b. soften c. burn d. crush

2. Upon switching the machine on, the screen page ____________ appears

on the display screen of control panel.

a. main menu b. temperature menu c. production menu d. clear menu

3. In automatic mode the cutting and stacking station ____________ after

starting production.

a. do not run b. run c. simultaneously run d. intermittent run

4. We can select the operation mode by selecting the symbols in

OPERATION MODES. To run the machine in auto mode which symbol

do we need to select. (Please put tick mark on correct symbol in

following picture).

5. Forming station has ____________ mold to form the sheet into the

desired shape. This is done by application of either air and/or vacuum.

a. top and bottom b. top c. bottom d. sides


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6. The function of the unreeling device is to ____________ the rolled sheet

into the machine thru the feeder zone using a sensor to activate the

loading automatically.

a. unload b. hold c. load d. remove

7. What process of thermoforming is being applied when heated and

softened plastic sheet from extrusion is placed at the top of a female mold

and formed by vacuum only?

a. Straight vacuum forming c. Match mold forming

b. Pressure d. Billow forming


softened plastics sheet is placed at top of a female mold and formed by

pressure and vacuum?

a. Straight vacuum forming c. Thermoforming

b. Pressure forming d. Billow forming


softened plastics sheet is placed at the top of a female mold and formed

and pressed by plug and with application of vacuum?

a. Plug-assist forming c. Billow forming

b. Pressure forming d. Vacuum forming





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___________________________________________________________

___________________________________________________________

___________________________________________________________

___________________________________________________________

___________________________________________________________

___________________________________________________________

___________________________________________________________

___________________________________________________________

___________________________________________________________

___________________________________________________________

___________________________________________________________

___________________________________________________________

TRAINEE’S GRADE

FOR THIS ACTIVITY

________________________


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DATE: __________________

DATE: __________________

________________________




Take note that Standard Operating Procedures and Policies can be effective

catalysts to drive performance improvement and improving the desired

results.

Manpower is either an abstract term for human labor effort (as opposed to

machines, animals etc.) or the number of available/needed for professional

or other tasks.

In plastic fabrication, manpower is referred to as the operator of the machine.

Included in the manpower lists are anybody (overhead) from the supervisory

level up to the highest position working in the company.

Standard Operating Procedure

for iLLiG RV 53b Thermoforming Machine

OPERATOR’S ROLE:

1. Step by step approach on how to operate the RV 53b Thermoforming

machine and its auxiliaries from start-up to shutting down operation

including safety, product quality (checking procedures).

2. How to apply 3 “S” in the Standard Operating Procedures.

Summary of SOP are the following :

1.0 Observe the Safety signs

1.1 Important Safety Reminders

1.2 Additional Important Reminder

2.0 Switch on the air compressor.

3.0 Switch on the water chiller as shown and set the recommended water

temperature (normally at 10°C)

4.0 Open the main air and water supply line by turning on valve.

5.0 General Machine check-up


Manpower and Standard Operating Procedures



6.0 When checklist has been complied and everything have been ful-

filled, switch on the main power supply and the light switch on.

7.0 To ensure absolute safety, the lead Operator must double check.

8.0 Machine Switching-on Procedure

9.0 Overview of Control Panel Screen

10.0 Follow the procedure to star the machine and run the machine.

11.0 Doing quality checks and production segregation.

12.0 Follow the procedure to shut down the machine.

13.0 Do the last ‘S’.

14.0 Reporting system

Following is the example of how SOP explains the parts, Functions and the

detail pictures and video procedures for operating individual part of each

work station. (Note: - For detail SOP please refer the Hand outs of day 6.)

Sample of SOP: 1

WORKSHOP ACTIVITY #6—Manpower and Standard Operating Procedures

Push the main heater button switch.



Sample of SOP: 2

FUNCTION—The function of the Unreeling Device is to load the rolled

sheet into the machine thru the feeder zone using a sensor to activate the

loading automatically.

1. Control panel—used to activate the loading/unloading of rolled sheet

materials

2. Tension adjuster—used to regulate the movement of the loaded rolled

sheet

3. Lever arm loader—used to load/unload rolled sheet using the control

panel

4. Shaft for roll sheets—used to hold and unwind the rolled sheet

5. Pneumatic cylinder of lever arm—used to activate movement of the lever

arm loader

6. Sheet feed roller—used to guide the sheet into the feeder zone

7. Feeder zone—used to guide the sheet into the chain conveyor


1

3

5

6

4

2

7



Sample of SOP: 3—Reporting:

Production Data:

Cycles per minute—is determined from the cycle time.

Cycle time—Time required for one cycle.

Sheet unwind to the forming machine—Length of the sheet web in mm up to

behind the forming station, if a roller preheater or unwind device is used.

Production cycles—Quantity of cycles run in the current operation program.

Production time—Time required for production.

Reading Production Data From Control Panel




1. To learn the importance of manpower in the plastics industry, specially

the role of an Machine Operator

2. To understand the importance of the Standard Operating Procedure and

its application in machine operations

PROCEDURE

Part I - Thermoforming Methods/Processes

1. Proceed to the Machine site and follow the Standard Operating Procedure

(Machine Start-up and Machine Shutdown) in operating the

Thermoforming machine.

2. Put a check in the box in your data sheet to indicate that you have

properly done the step.


SOP for Machine StartupSOP for Machine StartupSOP for Machine StartupSOP for Machine Startup

1. Follow Safety Instructions.

2. Switch on the air compressor.

3. Switch on the water chiller and set the recommended water

temperature (normally at 10°C).

4. Open the main air and water supply line by turning ON valve.

5. Do General Machine Check-up.

6. When checklist has been complied and everything have been

fulfilled, switch on the main power supply and the light switch.

7. To ensure absolute safety, the lead Operator must double

check.

8. Do Machine Cycle/Production Procedure.

9. Do quality checks and production segregation.


Procedure … continued


SOP for Machine ShutdownSOP for Machine ShutdownSOP for Machine ShutdownSOP for Machine Shutdown

1. Push the button to turn-off machine cycle.

2. Push the button to turn off the heating.

3. Check the machine and take-out the products/ skeleton/

runner inside of the machine.

4. Push button to turn-off the control voltage.

5. Check the temperature. When the heating temperature de-

creases and reached 300ºC, switch off the chiller.

6. Switch off the main power of Thermoforming machine.

7. Switch off the compressor.

8. Do the “5S”.

9. Follow the reporting system.

DATA SHEET


1. Machine Startup

ACTIVITY #6—Manpower and Standard Operating Procedures


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Steps Check


• Important Safety Reminders

• Additional Safety Reminders

(Advise by Instructors)


3. Switch on the water chiller and set the recommended

water temperature (normally at 10°C).

4. Open the main air and water supply line by turning

ON valve.


6. When checklist has been complied and everything have been fulfilled, switch on the main power supply

and the light switch.

7. To ensure absolute safety, the lead Operator must

double check.



DATA SHEET


2. Machine Shutdown

ACTIVITY #6—Manpower and Standard Operating Procedures


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Steps Check



3. Check the machine and take-out the products/ skele-

ton/ runner inside of the machine.


5. Check the temperature. When the heating tempera-ture decreases and reached 300ºC, switch off the

chiller.

6. Switch off the main power of Thermoforming ma-

chine.


8. Do the “5S”.





1. Actuation of ___________ is necessary if an unwanted thing happens

during machine operations.

a. Emergency Button b. Switch Button c. Switch Valves d. Control

2. Upon switching on the machine, the screen page ____________ appears

on the display screen of control panel.

a. main menu b. temperature menu c. production menu d. clear menu

3. In automatic mode, the cutting and stacking station ____________ after

starting production.

a. do not run b. run c. simultaneously run d. intermittently run

4. We can select the operation mode by selecting the symbols in

OPERATION MODES. To run the machine in auto mode, which

symbol do we need to select? (Please put tick mark on correct symbol in

following picture).





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___________________________________________________________

___________________________________________________________

___________________________________________________________

___________________________________________________________

___________________________________________________________

___________________________________________________________

___________________________________________________________

___________________________________________________________

___________________________________________________________

___________________________________________________________

___________________________________________________________

___________________________________________________________

TRAINEE’S GRADE

FOR THIS ACTIVITY

________________________


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DATE: __________________

DATE: __________________

________________________




Quality is defined in everyday life and in business, engineering and

manufacturing as the non-inferiority, superiority or usefulness of plastic

products.

As an operator, you must always know the different defects and their impact

on quality of the products from the users point of view.

You must know how to overcome and fix the various problems during

production by making use of process parameters.

The meaning of quality has developed over time with various interpretations

below:

1. ISO 9000—"Degree to which a set of inherent characteristic fulfills

requirements"

2. Six Sigma—"Uniformity around a target value"

3. Philip B. Crosby—"Conformance to requirements". Crosby treats

customer expectations as a separate problem.

4. Genichi Taguchi—Taguchi's definition of quality is based on a more

comprehensive view of the production system: Quality as "The loss a

product imposes on society after it is shipped".

Different Quality Concepts

Many different techniques and concepts have evolved to improve product or

service quality, namely; SPC, Zero Defects, Six Sigma, Quality Circles,

TQM, Quality Management Systems (ISO 9000 & others) and

Continuous Improvement.

The quality of a product or service refers to the perception of the degree to

which the product or service meets the customer's expectations.


Product Quality, Defects and Troubleshooting



Quality Drives Productivity

Quality has no specific meaning unless related to a specific function and/or

object. Quality is a perceptual, conditional and somewhat subjective attrib-

ute.

In plastic fabrication industry, it is commonly stated that “Quality drives pro-

ductivity.” Inspection, which is what Quality Assurance usually means, is

historical, since the work is done.

The best way to think about quality is in process control. If the process is

under control, inspection is not necessary.

Factors Influencing Product Quality

Processing Parameters

1. Time

2. Temperature

3. Pressure

4. Speed

Processing Components

• Raw Material Quality

• Sheet Quality

Environmental Factors

Climatic conditions—Any change in climatic conditions can change the

process and, accordingly, the quality of the product changes.

WORKSHOP ACTIVITY #7—Product Quality, Defects and Troubleshooting



Achieving Quality

To achieve good quality in the end product, the sheet thickness, the layer

thickness and the surface area of sheet must be of good quality.

All service conditions and the majority of end use applications involve some

degree of mechanical loading.

In general, thermoforming is possible with the sheet ranging in thickness

from 0.5 to 15 mm.

TROUBLESHOOTING

Troubleshooting is not an exact science and often involves juggling a dozen

or more variables in a single sheet. The best way to look at and solve these

components are in three stages, namely:

1. The "Symptom": What is it that you see, feel, or measure? What is the

viewed problem with the formed part?

2. The "Root Cause" or "Disease" Issue: There may be a number of these

that could cause a similar "symptom."

3. The "Cure": What are the options that we have to get at the root cause

of the problem?




Common Forming Defects

• Uneven wall thickness

• Wrinkles

• Warped parts

• Incomplete forming of parts

• Poor surface finish

• Blushing or loss of color

• Chill marks or mark-off

• Nipple on mold side of formed part

• Poor wall thickness distribution and excessive thinking in some

areas

• Shrink marks

• Voids or bubbles in formed parts

• Tearing of sheet during forming

• Crazed or brittle parts

SUMMARY

The most progressive view of quality is that it is defined entirely by the cus-

tomer or end user and is based upon that person's evaluation of the entire

customer experience.




1. To learn the basics of Quality checking and its importance to the

production.

2. To identify different kinds of product defects and perform

troubleshooting.

PROCEDURE

1. Operate the RV53b Thermoforming Machine and collect product

samples.

2. Segregate the good products and the rejected (bad) products.

3. Identify the kind of defect that the rejected (bad) products have.

4. Suggest a solution to eliminate the defects and do troubleshooting.

5. In your data sheet, write down the defects and explain what solution/s

were made to correct the problem.


DATA SHEET ACTIVITY #7—Product Quality, Defects and Troubleshooting


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Troubleshooting: What did you do

to correct the problem?

1

2

3

4

Description of Defects

Found on Products

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1. _________ is a degree to which a set of inherent characteristic fulfills

requirements.

a. ISO 9000

b. Quality Form

c. Quality Data

d. Fishbone Diagram

2. ___________ is one of the 4 factors that influence product quality.

a. Temperature

b. People

c. Animals

d. Food

3. ___________ is the process of recovering scrap or waste plastics

products and reprocessing it again.

a. Recycling

b. Cycling

c. Production

d. Troubleshooting

4. When we get marks at the bottom of the thermoformed part, we need to

increase the dimensions / numbers of ____________ holes.

a. venting / vacuum

b. cooling holes

c. tube pipe

d. PVC pipe

5. When the sheet is overheated, operator must reduce the heater

temperature and decrease ________ time.

a. cycle

b. cutting

c. speed

d. clearance


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6. If pressure and/or vacuum timing is not optimized, then we get very good

parts.

a. True

b. False

7. Sagging of material (when material touches the mold) results in folds on

thermoformed part.

a. True

b. False

8. Besides traditional applications and the use of pressure forming method,

thermoforming has conquered an important market share in the

packaging industry.

a. True

b. False

9. Choose three (3) factors influencing product quality.

a. Processing Parameters

b. Processing Components

c. Manpower

d. Environmental Factors

e. Machine Capacity

f. Environmental Factors

10. Choose two (2) processing components.

a. Raw Material Quality

b. Temperature

c. Manpower

d. Pressure

e. Sheet Quality

f. Management

g. Machine


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TRAINEE’S GRADE

FOR THIS ACTIVITY

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DATE: __________________

DATE: __________________

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After successfully completing all the topics from session 1-7, it is now time

to apply all the principles, theories and actual machine practices that you

have learned so that you will develop your skills (machine operation

proficiency). However, since we have only one machine, you will be divided

into 8 groups at 4-5 trainees per group.

You are advised to review from time all the hand outs given to you aside

from the classroom review class to be conducted by your Senior and Junior

Instructions while you are waiting for your turn to operate the machine.

You will also be taught on how to fill up the machine parameters, production

report and activity report forms.

PRACTICE YOUR OPERATIONS SKILLS!

1. Now that you have learned the basics of the thermoforming process, it

is time to practice your skills in running the plant and producing

acceptable products.

2. Strictly follow the Standard Operating Procedures (SOP) for each plant

operations that you are going to perform.

3. Use the worksheet tables and forms in the next pages to record your

data.

4. After each practice operations, write your general comment on the how

well you have done your practice in the Conclusion &

Recommendations page.

5. Write down what you have done well, and what you should improve

for the next practice.

6. Enjoy practicing while being safe!


Hands-on and Practical Training (1)


STANDARD OPERATING PROCEDURES

WORKSHOP ACTIVITY #8—Hands-on and Practical Training (1)




3. Switch on the water chiller and set the recommended water tem-

perature (normally at 10°C).



6. When checklist has been complied and everything have been ful-

filled, switch on the main power supply and the light switch.

7. To ensure absolute safety, the lead Operator must double check.






3. Check the machine and take-out the products/ skeleton/runner in-

side of the machine.


5. Check the temperature. When the heating temperature decreases

and reached 300ºC, switch off the chiller.



8. Do the “5S”.


DATA SHEET ACTIVITY #8—Hands-on and Practical Training (1)


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MACHINE PARAMETER FORM

Checked by : Thermoforming Senior Instructors

Prepared by :

Illig Thermoforming Machine

RV 53b

Parameter Setting Record



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PRODUCTION REPORT FORM


Prepared by :


RV 53b

Production Report



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ACTIVITY REPORT FORM


Prepared by :


RV 53b

Date: Time:





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FOR THIS ACTIVITY

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data.


































8. Do the “5S”.


DATA SHEET

ACTIVITY #9—Hands-on and Practical Training (2)


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Prepared by :


RV 53b


DATA SHEET



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Prepared by :


RV 53b

Production Report

DATA SHEET



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Prepared by :


RV 53b

Date: Time:





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FOR THIS ACTIVITY

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DATE: __________________

DATE: __________________

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data.


































8. Do the “5S”.


DATA SHEET



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Prepared by :


RV 53b


DATA SHEET



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Prepared by :


RV 53b

Production Report

DATA SHEET



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Prepared by :


RV 53b

Date: Time:





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FOR THIS ACTIVITY

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DATE: __________________

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Glossary of Technical Terms for Thermoforming

ABS Acrylonitrile-Butadiene-Styrene terpolymer

Absorption Is the process of radiant energy being absorbed in the

plastic as it is being heated up.

Air convection Heat energy transferred to a plastic via the movement

of hot air about its surface area.

Air convection oven The chamber or structure used to deliver hot air to the

surface of a plastic.

AES A saturated olefinic rubber modified styrene-

acrylonitrile terpolymer generally used in outdoor

exposure applications.

Alkali Acid-neutralizing chemical substance: a water-soluble

chemical that reacts with acids to form salts, has a pH

above 7, and turns red litmus paper blue.

Alloy A combination of blended polymers or copolymers

that result in unique physical properties not available

in the single polymer. An example is Polyvinyl

Chloride combined with Acrylonitrile-butadiene-

styrene.

Amorphous polymers Polymers devoid of orderly molecular

structures. They exhibit a broad melting range as

opposed to crystalline structures.

ASA An acrylic rubber modified styrene-acrylonitrile

terpolymer generally used in outdoor exposure

applications.

Atmospheric pressure The pressure that is applied to the earth’s

surface due to the weight of the air surrounding the

surface of the earth. At sea level it is 14.7 pounds per

square inch.

Banbury mixing A system of mixing materials together using a pair of

contra-rotating rotors that force the materials together (Continued on page 102)


into a homogeneous blend through friction and

pressure. This is an excellent mixing system and

probably the best one available for compounding

plastic alloys.

Bank A group of heating elements that are connected

together with a common electric circuit.

Billow Pre-stretching a heated plastic sheet by injecting air

into a chamber that has the plastic sheet sealed over

the edges of the chamber.

Black body A body that emits the maximum amount of radiant

energy at a given wavelength.

Black panel heaters (solar panels) Heaters with resistance wires imbedded

in a routed out ceramic fiber refractory board and

covered with a black panel quartz or glass plate.

Bleed off The act of letting air out of a mold chamber to allow a

billow to stretch uniformly over a mold so the bubble

does not burst during the forming operation.

Blisters A depression on the surface of a heated plastic sheet or

part caused by the rupturing of the surface of the

plastic as the trapped gases are expanding very rapidly

and escaping as the plastic is softening and allowing

the rupture.

Bridging This is a condition whereby the plastic stretching

across a mold cavity during the forming operation

does not pull down tightly against the mold surface.

Bubble A pre-stretched piece of plastic that is obtained by

sealing the plastic over a vacuum or pressure box and

applying a vacuum or air pressure to this box causing

it to develop a concave or convex hemisphere.

Calrod A resistance wire packed in magnesium inside a

stainless steel tube. When sending electricity through

this wire, the tube will heat up and give off radiant and

convective energy.

(Continued from page 101)

(Continued on page 103)


Catalytic gas heater An enclosed panel in which natural or propane gas

enters into it and is dispersed throughout the panel and

ignited. This causes the panel to give off heat through

radiant and convective energy.

Cavity mold A female mold in which a part is drawn into it via

vacuum or pressure.

Ceramic heater A resistance wire trapped within a ceramic shell that

will heat up when an electric current is passed through

the wire. It is very efficient at given off radiant and

convective energy.

Chain drive A system of raising or lowering the platens on a

thermoforming machine. Chain drives can also be

used to shuttle the plastic into and out of the oven.

Chemical reactor The vessel that is used to polymerize a monomer

through the use of heat and pressure in the presence of

a catalyst.

Chemical resistance The ability of a material to resist having its properties

changed when being exposed to a substance that could

potentially chemically attack it.

Chill marks A wavy surface imperfection that is caused by contact

of the hot plastic to the mold surface before other parts

of the hot plastic contact it.

Clamping frame (mechanism) A mechanical means of holding the

edges of a plastic sheet while it is being heated in an

oven. After the sheet is heated it provides a method of

sealing the plastic to the mold edge to make it possible

to draw a vacuum.

Coefficient of thermal expansion The fractional change in length of a

material in response to a change in temperature. For

plastics this value is somewhere in the range of ten to

the minus fifth, times the temperature change, times

the length or thickness of the part in inches.




Commodity materials Materials that generally are similar and can be

bought and sold based on current market conditions.

For instance, benzene is a commodity. What

difference does it make where or who you buy it

from?

Conduction A method of transferring energy to a material or body

through direct contact.

Conductive plastics Plastics that can actually conduct an electric current,

albeit very weakly and slowly, that will dissipate an

electric charge.

Contoured box – snapback This is a box that has roughly the same shape

as the mold you are trying to form the plastic over. It

has calculated amounts of clearances that prevent the

plastic from being pulled into the vacuum box too

deeply so webbing and thinning do not occur.

Convection A method of transferring energy to a material or body

via the use of fluids or air flowing about that body.

Cooling The process of removing heat from a formed plastic

part as it is drawn onto the mold.

Cooling lines Tubes running through a mold that carry the fluid that

either heats up or cools off the temperature of a mold

to keep it consistent.

Cooling fixture A device that is used to hold the shape of a part after it

is removed from the mold and is cooling off. Typically

it is used to maintain dimensional stability.

Crystalline polymers Polymers that have sharp melting points.

Crystallinity A state whereby the molecular structure of a resin

arranges itself in a symmetrical, geometrical, three-

dimensional pattern forming a polymer.

Cycles – cycle time A complete sequence of events that occur in making a

plastic part from the loading of the sheet to the loading

of the next sheet to make a second part. A time lapse




between identical spots within a repeatable sequence

of events.

Depth of draw The distance that the mold protrudes out of the mold

base or the depth the cavity extends within the mold

from the mold base surface.

Die cutting A system of trimming plastic parts that takes a steel

rule die and applies enough pressure to cut through the

desired areas of the plastic an stopping against a

support plate. A second system is taking two

sharpened edges and sliding them past each other

through the plane of a plastic part.

Die lines Linear grooves or depressions in the back of an

extruded sheet that parallel the machine direction of

the plastic sheet. They are usually caused by hang-ups

in the die or nicks on the die lips.

Dimple A depression in the surface of the plastic sheet or

formed part. The dimple can be caused by a void

within the plastic sheet or moisture within the surface

of the sheet that ruptures when the sheet is heated.

Discoloration The process of a plastic changing color through

exposure of sunlight or applying a substance to the

plastic that chemically attacks it.

Draft The slope of the vertical edges of a mold that is used

to facilitate the removal of the part from the mold.

Drape The process of pulling a hot piece of plastic over a

mold creating a seal along the mold edges.

Draw ratio (stretch ratio) The ratio of the starting thickness of the plastic

sheet to the final thickness of the plastic on the formed

part. Calculating this ratio depends on the geometry of

the part.

Elongation The amount in length a material can increase without

breaking when put under stressed tension.




Emissivity The ratio of radiation intensity from a surface to the

radiation intensity at the same wavelength from a

blackbody at the same temperature.

Entropy The tendency of an energy system or organized entity

to break down.

EPDM Ethylene Propylene Diene Monomer that is used as a

rubber impact modifier in weatherable plastics.

Epoxy resin A thermosetting plastic used for making molds or

tooling fixtures.

Excessive moisture The amount of water that is absorbed in the surface of

a plastic sheet or resin that will keep you from

processing it.

Female mold A cavity used to stretch a piece of plastic over.

Fiberglass Fine strands of glass usually encapsulated within a

resin matrix. It can be used to make molds or

structural parts.

Flammability A measure of the extent to which a material will

support combustion.

Flow characteristics The ability of a heated plastic to pass through a die,

through an orifice, or over a mold in a smooth and

uniform way to allow you to make a sheet or formed

part.

Foam core materials Materials that have gas expanded or air occupied

structures between their solid exterior surfaces.

Expanded vinyl or polyethylenes are good examples.

Forming temperature The temperature at which a plastic will shape

into the geometry you are attempting to attain.

Forming temperature range The high and low points at which a

plastic will be successfully shaped with the detail and

dimensional tolerances required for an acceptable part.




Forming technique A regimented process of steps that allow you to form a

flat sheet into a desired shape. There are numerous

processes that will accomplish this depending on how

complex a shape you are trying to make.

Gas flame heating A heating system that employs an open gas flame to

heat up a plastic sheet. This system gives off both,

convective and radiant heat energy.

Gas regulator A device that controls the amount of gas that enters a

gas heating system thereby controlling the heat output.

Gels Hard particles of resin that are similar to the plastic

matrix they are in but because of their molecular or

cross-linked nature, will not blend in with the other

plastic and will leave a tiny blip on the surface of the

plastic sheet or part. If they are large enough they will

show in the surface of the plastic part as the sheet is

thinned out to form the part.

Glass transition temperature The temperature at which a rigid plastic

softens enough to become somewhat rubbery.

Hardness The property of a material that determines how rigid

or resistant to denting a substance is. In rigid plastics

this is measured by a Rockwell hardness test.

Heat distortion temperature This is the temperature at which a

plastic will begin to distort as measured with test bars

using a standard ASTM test method.

Heating oven The device used to heat up a plastic sheet to forming

temperature. Usually this type of oven is tightly zone-

controlled to distribute heat to the desired areas.

Heating profile The pattern of heat being applied to a plastic sheet

while it is enclosed within an oven so that the heat will

be localized within the sheet and allow certain areas to

stretch more than others during the forming process.

Heater types These are the various types of elements that are used

to heat up plastic sheet. General types listed in this




manual are: ceramic, solar panel, calrod, quartz,

catalytic gas, open flame gas, nichrome wire, and air

convection.

High impact polystyrene This is a resin composed of numerous styrene

monomer molecules polymerized into long polymer

chains and dispersed with soft rubber particles

throughout the rigid polystyrene matrix.

Hot strength The resistance of a heated plastic sheet to being

stretched into the shape of a mold.

Hydraulic A system of putting fluids under compression to move

the platens on a thermoforming machine up and down.

Usually used in conjunction with pressure-forming to

allow maximum clamping pressure.

Hygroscopic The characteristic within a plastic that gives it an

affinity to pick up and retain moisture.

Impact strength The ability of a material to undergo a sudden shock

without breaking. This can be tested in plastics via a

notched izod or falling dart impact test through

standard ASTM test methods.

KORAD An acrylic film used to hold color stability and UV

degradation when laminated to plastic sheet.

Louvers Air or lighting vents designed into a plastic part.

Male mold A protrusion extending out of a flat plane that is used

to form hot plastic over.

Materials Plastic compounds used to construct useful shapes.

Material distribution The process of stretching hot plastic over a

mold and maintaining desired thicknesses in specific

areas of the part.

Melt temperature (point) The temperature at which a polymer changes

from a solid to a viscous liquid.




Micro-switch A device used to electrically stop a moving part on a

machine in the same place consistently.

Moat A groove in a mold used to provide a good sealing

point to prevent a plastic from breaking its vacuum

bond with the mold as the plastic is shrinking during

the cooling cycle.

Mold (v) To shape a heated plastic sheet via heat and

vacuum (pressure) into a desired geometry. (n) The

cavity or protrusion used to shape a heated plastic

sheet into a desired shape.

Mold base The plane that a mold cavity or mold protrusion is

mounted to that is used to seal off the hot plastic sheet

during the vacuum part of the forming cycle.

Mold shrinkage The amount that the plastic part shrinks in relation to

the actual mold size after the part is removed from the

mold and has reached ambient air temperature. This

value is usually expressed in inches per inch. The

typical shrinkage for ABS is .006” Z.001”.

Nichrome-wire heaters A type of heater unit that resembles a wire in a

toaster. It typically heats up to its maximum or cools

off fairly quickly.

Notch sensitive Most plastics exhibit a tendency to crack or break

along a notch or scratch in the surface if an excessive

bending stress is applied to that surface.

Ohms per square The resistance to an electrical charge flowing across

the same surface of a piece of plastic.

Olefins A group of unsaturated hydrocarbons of the general

formula CnH2n. Examples are polyethylene or

polypropylene.

Orientation The alignment of polymer chains to create stress in a

given direction. With thermoplastic materials this

condition causes the molecular structure of the plastic

to be stressed more in one direction than the other.




Percentage timer A timing device that has a total amount of set time,

say 15 seconds as 100%. This timer can then be set at

a certain percent, such as 50%, in which case it would

be allowing a current to flow through a heating

element for 7.5 seconds and not allowing it to flow for

7.5 seconds.

PETG A clear, amorphous, glycol-modified polyester which

is polymerized from dimethyl ester or terephthalic acid

and ethylene glycol. This gives it a better forming

window than PET.

Physical properties Those characteristics that define the physical

parameters of a material, such as stiffness, hardness,

impact resistance, chemical resistance, etc. These

properties can be tested and compared to other

materials.

Physical testing The process of measuring the characteristics of a

material based on standard test methods.

Pimple A raised area on a sheet of plastic or plastic part

caused by a hardened particle or contaminant within

the matrix of the plastic substrate.

Plastic sheet A flat piece of plastic having a specific length, width,

thickness and texture.

Plasticizer A material that can be added to plastics that allow

them to be processed more easily and can change

certain of their physical characteristics such as

toughness or flexibility.

Platen A movable support mechanism that a plug or mold is

attached to that assists in forming a plastic part.

Plug assist A mechanical device used in thermoforming to help

distribute the heated plastic sheet more uniformly

before it actually seats on the mold.

Pneumatic A system where a device is operated via the use of

compressed air.




Polycarbonate polyester of carbonic acid produced by using an

interfacial reaction between dihydric or polyhydric

phenols and a suitable carbonate precursor such as

dichlorocarbonate. It is a clear, amorphous material

with good impact strength and a high heat distortion.

Polycarbonate/ABS An alloy of the two different resins that will provide

some unique physical properties depending on the mix

of the two materials.

Polyester A resin made via the reaction of a dibasic acid and a

dihydroxy alcohol. It is used as a resin base to make

structural parts.

Polyethylene A thermoplastic material made by polymerization of

ethylene molecules. A large range of polyethylene’s

can be made by varying the chain length and additives

to the polymer.

Polymer A organic substance obtained by joining the same type

of monomers into long chains. For example ethylene is

polymerized into polyethylene through heat, pressure

and catalyzation.

Polymerize The process of joining numerous like monomers into a

long chain.

Polypropylene A thermoplastic material made by polymerization of

propylene molecules.

Polystyrene A clear, amorphous, themoplastic material made by

the polymerization of the sytrene monomer.

Pressure box The reinforced box that is draped over the mold in the

pressure forming system to provide the added force

required to get good detail from the mold surface.

Pressure forming A thermoforming technique whereby vacuum and

pressure is used to force the hot plastic sheet against a

mold surface to get a very crisp impression of that

surface.




Processing The act of converting a plastic resin or sheet into a

useful form or shape.

Processor The entity that converts a plastic resin or sheet into a

useful form or shape.

Prototype mold The mold that is used to make a part that will be

evaluated for fit and function.

Punch press stamping The process of trimming a formed part by

using a metal die clamped to a movable platen in a

mechanical press. Forcing the platen against a fixed

base pinches the desired surface of the plastic part and

removes the unwanted excess.

PVC An amorphous thermoplastic material made up of

vinyl chloride polymers. It is widely used in wire

covering and where a chemically resistant plastic is

needed.

PVC/ABS An alloy of polyvinyl chloride and acrylonitrile

butadiene styrene combined to maximize certain

physical properties.

PVC/Acrylic An alloy of polyvinyl chloride and acrylic combined

to maximize specific physical properties.

Quartz heaters A type of heater with about a one-half to three-quarter

inch diameter tube with a resistance wire inside of it

that is backed up by an internal reflector.

Radiant heat An electromagnetic transfer of energy from a heating

emitter to a material or body one would wish to raise

the temperature of.

Radii The rounded edges or curvature of the shape being

dealt with. Typically these radii are designed into the

part.

Reflected off energy The small amount of radiant energy directed at a

plastic sheet that is left over from the energy that




penetrates through the sheet and is absorbed by the

sheet.

Regrind The plastic materials that are reprocessed into plastic

sheet or finished parts more than once.

Ribs A raised or depressed area of a formed part that is

designed into it to increase its structural integrity.

Robotic trimming A mechanized method of performing a secondary

operation on a formed part to enable it to comply with

dimensional specifications.

Router A high speed air or electrically operated cutting tool

used to trim materials to dimensional specifications.

Sag The amount of spherical deflection a flat plastic sheet

experiences as it is heated to its forming temperature.

Sag bands The supporting system that is attached to the clamping

frame to obtain multiple minor sags when using a

multiple cavity mold.

Sandblast The process of forcefully blowing sand against an

object to clean it or put a fine suede-looking surface

on it.

Screening The process of blocking out some radiant energy from

reaching the plastic sheet suspended in an oven by

putting in metal window screening between the plastic

sheet and the heating elements used to heat the plastic.

Seal The edge of a mold base that a hot piece of plastic is

forced against to keep the vacuum enclosed within the

mold chamber while a part is being formed.

Secondary draw ratio After the initial thickness of plastic is

determined on a formed part, the thickness of any

secondary pockets or protrusions will be determined

by the difference in thickness of the material now

available divided by the area left over on the

secondary area of the part.




Secondary operations Those processes that are performed after the

initial forming operation is completed, such as

trimming and assembly.

Shrinkage The phenomenon whereby a plastic decreases in size

linearly and volumetrically as it is cooled. This term

also refers to the inherent stress put into the extruded

sheet during the manufacturing process.

Snapback A thermoforming technique that first pre-forms a

bubble into a pre-draw box, then plunges a male mold

into the inside of the bubble, and as a final step,

vacuums the bubble onto the mold.

Stiffness A measure of the flexibility or rigidity of a material.

This value is usually expressed in terms of flexural

strength or flexural modulus.

Stress Pressure applied to a given body to deform or fracture

it.

Strength the ability to withstand force, pressure, or stress. Also

the ability to resist attack.

Symmetrical An object having a mirror image of itself with respect

to its centerline. One side of the part is identical to the

other side.

Syntactic foam A combination of inorganic foam spheres in a plastic

foam matrix. This material is used for making

insulative plugs to prevent chill marks.

Temperature controlled aluminum tooling Molds made with

enclosed tubes buried within their surfaces that allow

cooled or heated water or some other fluid to flow

through them to control the temperature of the mold to

within a few degrees Fahrenheit.

Tensile strength The pulling force required to stretch or break a given

material. This value is usually expressed in pounds per

square inch.




Texture (grain) The pattern embedded into the surface area of a sheet

or part.

Transmitted through The condition where radiant energy given off

an emitter goes through the object it is hitting rather

than being absorbed or reflected off of that object.

Thermal conductivity The amount of heat in BTUs which can be

conducted through one square foot of any material one

inch in thickness, in one hour, with one degree

Fahrenheit temperature differential across the

thickness (Btu/hr/ft2/F/in.).

Thermal expansion (Coefficient of) The fractional change in length (or

volume) a one inch object will expanded or contract

with a one degree Fahrenheit change in temperature.

In ABS this value is approximately 5 x 10-5 per inch

per one degree Fahrenheit change in temperature.

Thermoforming A system of changing a flat sheet of plastic into a

desired shape.

Thermolator system A mechanical device that is used to regulate that

temperature of a fluid that is subsequently pumped

through heating or cooling lines embedded in a mold

to control the mold temperature.

Thinning The process of taking a finite area of a hot sheet of

plastic and stretching it over a protrusion or cavity of a

larger area and distributing the plastic over this larger

area as best as possible.

Tolerances The maximum and minimum dimensions that are

required to allow a formed part to be functional.

TPO Thermoplastic olefin. Essentially it is a polypropylene

blended with and EPDM rubber.

Trim The excess material around a formed part that is not

part of the finished product. This material is used for

clamping or sealing purposes during the forming

process.




Undercuts Those indentations or extensions from a formed part

that prevent the part from being removed from the

mold without providing some type of movable

mechanism on the mold itself.

Unistrut A U-shaped channel with a clamping bar inside of it

that can be adjusted very quickly by sliding the

clamping bar in either direction of the channel.

UV resistant The condition whereby a material, in this case plastic,

will resist loosing its physical properties when

exposed to the ultra-violet rays of the sun.

Vacuum The absence of atmospheric gas within some given

system.

Vacuum box A five-sided structure on which a heated plastic sheet

can be draped over the sixth side and a partial vacuum

drawn within the box to form an inverted bubble.

Vacuum forming A method of using vacuum to force heated plastic

against a mold surface.

Vacuum forming techniques The various sequence of procedures

one can use to shape a heated sheet of plastic to the

configuration of a mold.

Vacuum holes The holes in a mold which air can pass through to

allow the atmospheric pressure to force the hot plastic

sheet against the mold.

Vacuum seal The edge around a mold base that the heated plastic

sheet is pressed against to allow a vacuum to be drawn

and force the heated sheet against the mold.

Vacuum system The mechanism whereby air is removed from an

enclosed chamber to create a vacuum.

Vacuum volume The size of the enclosed system in which the vacuum

is employed. It also refers to the level of vacuum that

is maintained within the system. Generally a large




vacuum holding tank is employed to keep the inches

of vacuum from being drawn down to low.

Voids Small areas within a plastic matrix that have gas

pockets instead of the solid plastic material that should

be there.

Volume resistivity The resistance of an electrical charge flowing through

the solid structure of the material, in this case plastic.

Warping The condition whereby a part is dimensionally

distorted from its originally formed shape.

Wavelength The distance measured from a point on an

electromagnetic wave to the same point on the wave as

it repeats its phase.

Wavelength of energy A measure of the type of energy given from

various wavelengths of the electromagnetic spectrum.

In plastics we are concerned with the infrared

wavelength band of about .7 microns to about 100

microns.

Weatherable plastics Those plastics that are resistant to physical degrading

when exposed to the ultra-violet rays of the sun.

Weatherability The ability of a material to resist loosing its physical

properties when exposed to sunlight.

Webs Excess plastic material that is doubled up on itself and

does not flow uniformly against a mold. It usually

occurs on the corners of parts with small radii.

Wood tooling Molds made of wood that are usually used to make

prototype parts.

Yield point That point of stress or strain which if reached will not

allow the material to recover to its original shape. Its

elasticity has been exceeded.

Zones Those areas in a heating oven that the temperature is

controlled independently from other areas.



REFERENCES

1. ILLIG Thermoforming - A practical Guide by: Günter Kiefer/Peter

Schwarzmann

2. Operating Manual for ILLIG RV 53b Machine- no. 593 EN/04.04-2

edition

3. Textbooks from SPDC

4. Various Thermoforming & Vacuum Forming websites from the

internet

Thermoforming Workbook Draft

Documents

Transcript of Thermoforming Workbook Draft