seminar Seedfunds in PTW and performance …...plastics, due to their insulated corrosion surface...

Darmstadt | 28.10.2010

CSI – seminarSeedfunds in PTW and performance evolvement MPZ

Prof. Dr.-Ing. E. Abele Mario DewaldJakob FischerPatrick Pfeiffer

Research aims and strategic development

Mechanical Engineering | Institute of Production Management, Technology and Machine Tools | Prof. Dr.-Ing. E. Abele | 101019De1 | 1

PTW Research Groups

Technology

Machine tools andcomponents

Productionmanagement

Sustainableproduction

Machining

Focus:

Mechanical ProductionMachine Tool Industry

Batch Production


The PTW emphasises on its practical oriented research

•Approx. 4 Mio. € in third-party funds for research projects per year

•Approx. 2/3 of our projects are realised through a direct cooperation with industry

56 employees supervice:

•6 lectures with approx. 800 students per year

•Approx. 40 current research projects

•More than 100 seminar papers and diplom/master theses per year

Personnel

Financing

Administrative section

Associate lecturers

Research staff

Workshop and technical section

84

33

14

Industrial joint projects

Contract based research for the manufacturing industry

Basic research

State (government) funds

Donations

36

20

30

13 1


PTW‘s Test Bay

Machinery3 3-axis HSC milling center2 5-axis HSC milling center4 3-axis machining center2 5-axis machining center3 3-axis CNC lathes1 Industrial robot with motor spindel

Testbeds• different test beds for motor spindles• Test bed for linear mesurementsystems

• Centrifugal test bed for centrifugalforce measurements

• balancing machines• dynamometers

Measuring tools (selection)• 3D coordinate-measurment too• Surface measurement tool• Travelling microscope


Further education for students and employees from the industry

Teaching Module Machining Teaching Module Montage

• Set-up time reduction/SMED

• Multiple machine assignment

• Pull/Kanban for the assembly

• Autonomous maintenance

• Heijunka/streamlining production

• Ergonomic workplace design

• Just-in-Time Production

• Flexible Taktzeitangleich

5S, Visualisation, Standardisation, Performance Management, KVP

A learning Operation at the TU Darmstadt: Prozesslernfabrik CiP (Center for industrial Produktivity)

Product geared motor Product

Pneumatic-compact-cylinder

Real Products from a real production environment with• Machining

• Manual assembly

• Logistics

• Quality audit


Seed Fund Project within the PTW

Title:

Influence of boundary layer effects on cutting tool wear at Titanium machining

-Heat preadjustment of cutting tools to control process temperature in Titanium

cutting applications-

Goal:

Heat transfer enhancement of the cutting process for maximizing

tool life in machining Titanium alloys

Related research activities within the PTW

• Industry driven research in the field of titanium cutting since 1973

• Development of appropriate tool surfaces for minimalize tool wear in cutting

Titanium in 2003 (Dissertation Sahm)

• Industry working group since 2008

Source: Crosskey 2007 Source: Siemers 2006 Source: PTW 2010


Additive Manufacturing: Research within the PTW

Additive Manudfacturing

- Using Direct Metal Laser Sintering (DMLS) for manufacturing complex

geometries and parts

- Research of machinability of DMLS generated parts and Materials

- Optimization of the process chains of HSC and DMLS

Possible Seed Fund:

Additive Manufacturing of internal cooling structures for

tool holders or cutting tool inserts out of tungsten for real

Ultra High Speed Cutting and very long tool life


• Over 20 years of experience in High Speed Cutting

• Industry driven research machining of hard to machine material with UHSC

Source: CSI 2010 Source : PTW 2010 Source : PTW 2010 Source : IWU2010


Seed Fund Project within the PTW

Title:

Enhanced Heat Conduction for Tool Surfaces in High Speed Cutting

-Using PCD for High Speed Cutting of Cast Iron Materials with

Innovative Cooling Systems-

Goal:

Heat Transfer enhancement by optimizing the cutting tool geometry

for machining cast iron materials with PCD tools


• Over 20 years of experience in cast iron machining (GCI, CGI, SGI, ADI)

• Development of appropriate tool materials (PCD, cBN, Carbides, Coatings)

• Development and implementation of innovative cooling strategies (Cold

Compressed Air, CO2-Snow, Minimum Quantity Lubrication, Dry Machining)

Source: Eisenwerk Brühl, PTW

Mario Dewald

Darmstadt | 28.10.2010

Seed Fund:Influence of boundary layer effects on cutting toolwear

-Using temperature preadjustment for improve tool life in HSC- machining on Titanium alloys-


Agenda

• Classification of Seed Fund Project

• Goal

• Motivation for Titanium alloy machining

• Theory of wear formation

• Theoretical approach

• Temperature Measurement

• Conclusions / Further Steps


Classification of Seed Fund Project within the CSI

Classification of the actual

seed fund project in the area of

CSI - „Heat Transfer Enhancement“

In Cutting processes the heat transfer between cutting tool, emergingchips and the workpiece the main variable for increasing productivity!

Seed Fund: Influence of boundary layereffects on cutting tool wear


Agenda


• Goal







Goal of the Seed Fund Project

Goal: Heat transfer enhancement of the cutting process for maximizing tool life

Why enhance a better heat transfer the tool life in HSC-machining of Titanium?

Thermical incidents

Mechanical properties

Chemical reactions

Chip formation

Highest cutting temperature Chip welding, tribochem. wear

Elastic deformations Chip segmentation

The specific physical characteristics of titanium alloys causes highestcutting temperatures, which produce further problems


Agenda


• Goal







Application range of titanium alloys with specific reasons for implementation

• Medical parts biocompatibility

• Light weight structures high Strength at low weights

• Offshore application corrosion resistance

• Aerospace light weight construction

Motivation for Titanium alloy machining


Motivation for using Titanium alloys in aerospaceapplications

• Conserve ressources in fossil fuel, by avoiding heavy

structures in dynamicaly moved devices

• Can be combined with conductive carbon fibre reinforced

plastics, due to their insulated corrosion surface and is, so

far, better than aluminium alloys

Specific reasons for improving machining applications on

titanium alloys:

• Poor „fly to buy“ ratios of 1:8

• Difficult to cast, inert gas is needed

• Hydrogen embrittlement of near net shape castings

• Major factor for improving cost efficiency in production

Wing belt – machining volume 90%

Motivation for Titanium alloy machining in aerospace

Semi finished parts

Finished part


• Structural components

• Jet engines rotating parts

• Jet engines non rotating parts

• Landing gear and frame joints

Source: RLC Engineering Group Ltd. & MTU



Jet engines rotating parts

• Increase on titanium in Jet engines because of new alloys with high temperature stability

• Due to costintensiv productionstrategies and high technological

process chains, existing component parts can achive production

costs up to 50.000 € [source: Callender (Lancashire) Aeropart Ltd.]

• A huge contingent of these costs are covered in cutting tool

material due to the extensive high amount of wear



Agenda


• Goal







Theory of wear formation

Chip formation process on titanium is depending on the physical properties of Ti-alloy

Temperature caused

softening

Local heating

through

deformation and

friction

Strain Hardening

Quelle: Altmüller

source: Peters, Leyenssource: Breutinger

source: Siemerssource: Hegewald



The physical properties of Titanium are responsible for the production costs:

• Costs are caused by low tool life and high non productive machine time for tool changing

• Reason is highest wear rates in

• This is due to high cutting temperatures TC ≈ 900-1400 °C subject to

• High thermal capacity cp ≈ 520 J/kg·K of the Ti- alloys

• Low heat transmission through low thermal conductivity λ = 4 - 20 W/m·K of the Ti- alloys

Werkstoff C45 St37 HSSE Titan Ti6Al4 Wolfram Hartmetall

Zugfestigkeit Rm

[MPa]580 370 - 345 895 4200 -

Wärmekapazität c

[J/kgK] 440 490 460 526 580 130 -

Wärmeleitfähigkeit *

[W/mK]32 57 19 22 6-18 167

120kobaltarme WC-Co

HM, 20 W/mK HM auf

TiC-Basis

Dichte *

[kg/m³] 7850 7850 8700 4510 4430 - -

In comparisonthermal conductivity

coefficient is 10



Heating zones and wear zones:

Heat by deformation

Heat by friction on toolflank

Heat by friction on rake face

Crater wear

Friction is the main reason for crater wear in HSC machining on Ti- alloysand leads to cutting edge breakage through a loss of stability


Maximum detectable wear is behind the cutting tip and is attended by highest cuttingtemperatures on cutting surface

Static friction

Sliding friction


[source: Hua, Shivpuri]

Crater wear is a result of sliding friction on the rake face because of thehigh friction induced temperatures



Known:

• mainly the whole active energy of the cutting process is turned into heat

Unknown:

• distribution of heat in the cutting process elements

international literature do not give any

significant conclusion in recent 30 years

But:

Two main reasons are mentioned for extremly

crater wear at HSC machining in Ti- alloys

Temperature caused chemical reactions between cemented carbide and Ti- alloysvs.

Tension cracking alongside isothermes in cutting tool material

Distribution of heat in process

tool1 – 80 %

Workpiece7 – 38 %

chips20 – 90 %


Agenda


• Goal







Theoretical approach

Scientific question:

Has the temperature gradient in cemented carbide any influence of on tool wear development

To do:

• Identification of the category groups of cutting speeds vc, feeds f and tool flankwear Vbmax

for characterisation of interesting parameter ranges that produces highest temperatures

• Heating and cooling tool tip on several different preadjustment temperatures about

173°- 673°K in intervals of 50°K

Which methods for heat transfer are feasible for cemented carbides?

1. step Simulation

Can we eliminate the theory of isothermal tension cracking by heating up?

2. step Construction of an prototype tool that allows heating and cooling

Improve the measurement system for detecting absolut temperatures

3. step Measurement method under use of thermographical phosphors


Agenda


• Goal







Test set up for infrared detection

Material:

• Ti 6Al 4V

Temp. Preadjustment:

• Warming

Acetylene&Oxygene

• Cooling

CO2 snow

Tool concept:

• cemented Carbide K10

Parameters:• f = 0.1 – 0.3 mm/r• ap = 0.25 mm• vc = 100 – 350 m/min• 2 test runs per point

Temperature measurement

Cam fixed at turret�� constant view angle

Tool holder & tool

Camera Setup:

• Resolution: 640 x 512 Pixel

at 30 Hz

• Super framed presets:

-10 °C - 350 °C (no filter)

• Emissivity: 0.92

• Software: AT IRControl

l = 100 mm


f [mm/r]vc [m/min]

0.2 0.25 0.3

200 x

250

300



Tool holder & tool

Test without temperature preadjustmet:

LOI1LOI0

POI2

POI1POI0

45

46

47

48

49

50

51

52

53

1 6 11 16 21 26 31 36 41 46 51 56 61 66 71 76 81 86 91

Te

mp

era

tur

Pixel

TemperaturprofileLOI0 LOI1

0

100

200

300

400

1 6 11 16 21 26 31 36 41 46 51 56 61 66 71 76 81 86 91 96 101106111116121

Tem

pera

tur

Bild Nummer

TemperaturprofileMean(POI0) Mean(POI1) Mean(POI2)




Tool holder & tool

Test without temperature preadjustmet:

f [mm/r]vc [m/min]

0.2 0.25 0.3

200

250

300

LOI1LOI0

POI2

POI1POI0

Results:• Temperatures decrease by increasing cutting

speeds

• Temperatures have an optimum by f = 0,25 mm

• Chip welding and fast abrasive wear at higher

cutting speeds


f [mm/r]vc [m/min]

0.2 0.25 0.3

200 x

250

300



Tool holder & tool

Test with acetylene & oxygene warming:

LOI1LOI0

POI2

POI1POI0

0,00

50,00

100,00

150,00

200,00

250,00

1 6 11 16 21 26 31 36 41 46 51 56 61 66 71 76 81 86 91 96

Te

mp

era

tur

Pixel


0

50

100

150

200

250

300

350

400

1 11 21 31 41 51 61 71 81 91 101 111 121

Tem

pera

tur

Bild Nummer





Tool holder & tool

Test with acetylene & oxygene warming:

LOI1LOI0

POI2

POI1POI0

Results:• Peak Temperatures increase by increasing

cutting speeds

• Temperatures increase by increasing feed

• Start temperatures are very unequal (between

100°C – 350°C)

• Unexpected functinality of the prewarming of

the cutting tool

• No chip welding

f [mm/r]vc [m/min]

0.2 0.25 0.3

200

250

300


f [mm/r]vc [m/min]

0.2 0.25 0.3

200 x

250

300



Tool holder & tool

Test with CO2 cooling :

LOI1LOI0

POI2

POI1POI0

0

20

40

60

80

100

120

140

160

1 6 11 16 21 26 31 36 41 46 51 56 61 66 71 76 81 86

Te

mp

era

tur

Pixel


-100

0

100

200

300

400

1 6 11 16 21 26 31 36 41 46 51 56 61 66 71 76 81 86 91 96 101106111116121

Tem

pera

tur

Bild Nummer



f [mm/r]vc [m/min]

0.2 0.25 0.3

200

250

300



Tool holder & tool

Test with CO2 cooling :

LOI1LOI0

POI2

POI1POI0

Results:• Temperatures decrease by increasing cutting

speeds

• Temperatures have an optimum by f = 0,25 mm

• A lot of broken tool tips


Agenda


• Goal







Conclusions

Tool holder & tool

HSC Ti6Al4V, vc = 200 m/min, f = 0.25 mm/r, ap = 0.25 mm

0

100

200

300

400

1 6 11 16 21 26 31 36 41 46 51 56 61 66 71 76 81 86 91 96 101106111116121

Tem

pera

tur

Bild Nummer

Temperature profiles POIs normal machining

Mean(POI0) Mean(POI1) Mean(POI2)

0

100

200

300

400

1 6 11 16 21 26 31 36 41 46 51 56 61 66 71 76 81 86 91 96 101106111116121

Tem

pera

tur

Bild Nummer

Temperature profiles POIs with preheating

-100

0

100

200

300

400

1 6 11 16 21 26 31 36 41 46 51 56 61 66 71 76 81 86 91 96 101106111116121

Tem

pera

tur

Temperature profiles with precooling

LOI1LOI0

POI2

POI1POI0


Further Steps

Tool holder & tool

LOI1LOI0

POI2

POI1POI0conclusion:• For the tested parameter range the combination of

vc = 200 m/min, f = 0.2 mm/r and ap = 0.25 mm leading to the desired

crater wear development

• Huge falsification due to trough flying chips in the infrared detection

Better measurement method for detecting absolut temperatures

Further steps:• LOI analysis has do to be done in the beginning, in the mittle and on the

end of the process

• Finalization of test analysis and finishing the report

• Publication in a scientific paper

• Acquisition of research project allready done at the AIF

• Acquisition of research project at the DFG

seminar Seedfunds in PTW and performance …...plastics, due to their insulated corrosion surface...

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Transcript of seminar Seedfunds in PTW and performance …...plastics, due to their insulated corrosion surface...