Common Problems and Solutions in Cutting Tools Implementation Practice in the Setting of Automotive Powertrain Plant: System Outlook Viktor P. Astakhov

Common Problems and Solutions in Cutting Tools Implementation Practice in the Setting of Automotive Powertrain Plant: System Outlook

Viktor P. Astakhov

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Viktor P. Astakhov IMTS 2008 2

Intr

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ion

What is a Tool Commodity Management (TCM) Company?

The basic objectives of a TCM company set by the automotive industry are:

1. To keep production lines running while meeting quality requirements.

2. To meet a cost per unit (CPU) target set by the customer.

3. To assure direct tooling cost savings per year as required.


Intr

od

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ion

Virtuality vs. Reality

In the ideal world, these three objectives are the parts or facets of the tool management continuous process, which can be run by business management-type personnel with some engineering training. Any practical tool management process is a discrete process consisting of a great number of “Problem Occurrence-Problem Solving” dyads (couples). A problem occurrence can be thought of as failure, referred as tool failure. The tool management process runs smoothly if and only if each and every dyad “Problem Occurrence-Problem Solving” is completed, i.e. when for each problem that occurs on the daily basis, a proper, timely solution is provided. To accomplish that, a fast-respond problem solution system established by of any modern TCM company.


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Example of the machining system (drilling)


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Right Tool at Right Time at Rite Price

•“Right time” is when the customer needs the tool to keep its production running.

•“Right cost” calculates through CPU for a given application.

•The term “Right tool” is totally illusive.

The “right tool” can be thought of as that one made to the print approved by the customer (an automotive company) and thus posted in the corresponding tooling database system. However, if this tool does not work properly, the blame goes to a TCM company, which has little to do with its design and approval. Moreover, a TCM company is responsible for the investigation of the tool failure.


Intr

od

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Tool Problem

As seen

As it is

Simple questions

1. System coherence who is responsible?

2. What resources has a TCM company to investigate a tool failure?

3. What recourses has a tool manufacturer to investigate a tool failure?

4. Have you ever seen a 5Why analysis that point the root cause for the tool failure problem?


Some Common Problems and Solutions


Vei

ns

Cutting Through the Veins


Vei

ns


A

Ø17+0.013-0.03360°±0.5°

Ø14.48-0.030

O.A.L.

0.005 A

0.010 A

0.02 A

+0.1

4-PLC'S ON 14.48 DIA

0.8

0.15-0.25O.D. RELIF PER SIDE

ENLARGEDSECTION A-A

1+0.2

25°±2°

A

A

±1°0.02 A

DETAIL I

ENLARGED

POINT GRIND AV-1AL

DET. I

Ø20h6

130±1.5

0.8x45°2-PLC'S

56±1.5 (SHANK LEN.)

72.5±1.5 (FLUTE LEN.)

50.72±0.13

c /2=0.6

0.32

0.0025

-0.2

67° 100°±2°

3.3±0.15

cl ct

n

Point angle

Common drill and its geometry A reason for high point angle


Vei

ns


Chisel edge

Aluminum deposit formed on the rake face of the chisel edge due to highly negative rake angle

Feed marks and fractured edges at the exit of each vein.

Sladge


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0

10

20

30

40

50

60

80 100 120 140 160

Point angle (deg)

Chi

sel e

dge

flank

ang

le (d

eg)

8

12

15

18

Secondary flank

angle 25o

2

2.5

3

3.5

4

4.5

5

80 100 120 140 160

Point angle (deg)

Leng

th o

f the

chi

sel e

dge

(mm

)

8

12

15

18Secondary flank

angle 25o

20

25

30

35

40

45

50

55

60

65

70

90 100 110 120 130 140 150 160

Point angle (deg.)

Chi

sel e

dge

angl

e (d

eg.)

8

12

15

18

Secondary flank

angle 25o

-80

-70

-60

-50

-40

-30

80 100 120 140 160Point angle (deg)

Chi

sel e

dge

rake

ang

le (d

eg)

8

12

15

18

140

145

150

155

160

165

170

175

180

80 100 120 140 160

Point angle

Ch

ise

l we

dg

e e

ng

le

8

12

15

18Secondary flank

angle 25o

Improved drill geometry


HS

SHSS Tools

Following tested possibilities to decrease CPU with HSS tools are most feasible:

1. Application of the advanced application-specific tool coatings

2. Optimization of the finish grinding and re-grinding practices3. Use Diffusion process4. Optimization of the tool geometry5. Use the advanced tool materials as REX 121 and ASP

developed for dry applications6. Optimization of the metallurgical properties of the

workpiece prior gear machining to achieve its maximum machinability.


HS

SSharpening flaws

Grinding Burr

Burns


HS

SDiffusion© Process

This process has been developed to improve the basic physical characteristics of metals, alloys and composite materials (including cutting tool materials as high speed steels, sintered carbides, PCBN, PCD etc.). The essence of the Diffusion© process is the healing microdefects and strengthening of interfacial bounds that enhances the physical and mechanical properties of materials. This healing is achieved by introducing a high density energy flux (the rate of transfer of energy through a unit area (J·m2/s)) through the entire cross-section of the material in a strictly controlled fashion. The diffusion© process results in the increased tensile strength by 5 – 25%; wear resistance - by 30 – 300%; fatigue life by 50 – 400% and decreased friction by 30 – 60%. This process does not affect the final dimensions and shape of the parts, as well as it does not create any superficial and in-depth residual stresses. As a result, this process is normally applied as a final operation after any kind of heat treatment or coating, grinding and polishing.

Diffusion© ProcessResults

HS

S


Car

bid

e T

oo

lCarbide Tool

In the author’s opinion, the following tested possibilities to decrease CPU with carbide tools are most feasible:

1. Application of the advanced application-specific tool coatings combined with high polish of substrates and airlapping after the coating.

2. Utilization of the application-specific carbide grades developed for machining aluminum.

3. Optimization of the tool design and geometry.

4. Synchronization and optimization of drill-rougher-finisher operations including the use of combined tools.


Car

bid

e T

oo

lCommon flaws

Improper carbide grade + incorrect geometry

Coarse grind

Improper carbide grade


Car

bid

e T

oo

lExample of Case Studies

Upper Valve Body, aluminum alloy 380Carbide straight flute combined drill –new coating for Al

applications

A regular tool design with a new coating has been tested using the same machining regime, tool material and other machining conditions (2 tools were tested). The analysis of the test results shows:

1. Tool life tripled2. Average tool life – 2,500 cycles3. Tool life of the tested tool – 7,500 cycles4. Tool wear type is normal for the work material5. Both margins do not show any excessive wear as with the regular

tool. No wear marks were found on the additional supporting areas made on the heels. This shows that the tool maintained its working integrity during the whole tool life

6. All the cutting edges (drill, reamer and chamfer) have uniform wear.


PC

DPSD Tool

Some most common flaws found in PCD tools Brazing


PC

DSome most common flaws found in PCD tools

Gap between PCD inserts and the tool body


PC

DSome most common flaws found in PCD tools


PC

DRecommendations

The following is recommended to both tool manufacturers and users to avoid the discussed and many other common and specific problems with PCD tools:

1. Use application-specific PCD grades2. Specify, inspect and maintain surface roughness on the ground surfaces of

PCD inserts3. Specify brazing quality4. Specify and inspect the backtaper5. Use proper re-sharpening/re-tipping strategy6. Use proper machining regimes for PCD tools7. Pay particular attention to carbide grade selection for PCD-tipped drills8. Design and manufacture tools with no gaps between PCD inserts and carbide

bodies, with overhanging of PSD inserts, with coolant holes directed into the machining zone (not before and not after), with 5-10 microns radius of the cutting edge (edge preparation) etc. Note that the diameter of the coolant holes as well as the location of their outlets with respect to the PCD inserts should be specified on the tool drawings.


PC

DImportance of the backtaper


PC

DProper wear pattern of PCD insert


Sta

nd

ard

To

ol

Standard Tool

Standards for indexable inserts:

1. ISO1832: 2004

2. ANSI B212-4

Standard for tool holder

ISO 5608:1995

MTLNR - 1616H-09

Clamping system

Insert shape

Holder style Hand of tool

Shank size Insert size Insert clearance angle

1

2

3

4

5

6 7 8 9


Tools with indexable inserts

Valenite in its catalog in the dimensions of tool holder lists without any explanations two parameters “axial” and “radial” having the angular dimension. Seco Tools in the list of its toolholder parameters provides two angles, namely o and p. no explanations and/or figure are given to explain the meaning of these two angles. According to Bohler turning catalog, practically all of its toolholders are suitable for neutral inserts (N). However, it is not mentioned how the flank angle (relief) is provided by these tool holders. The same can be said about Ingersoll turning tool catalog.

Sta

nd

ard

To

ol

Sandvik

Kennametal (both)


Proper tool geometryS

tan

dar

d T

oo

l

External Internal

ISCAR

Cutting edge inclination angle

Normal flank angle


Consequences of insufficient flank angleS

tan

dar

d T

oo

l


Cracking due to high MRSS

tan

dar

d T

oo

l Boring of the liners


Incomplete Tool DrawingsD

raw

ing

s


Dra

win

gs


Dra

win

gs


Common featuresT

oo

l D

raw

ing

s

1. No tool geometry is shown according to the ISO and/or ANSI standard for tool geometry. No edge preparation conditions vitally important fop PCD tools are mentioned (microgeometry parameters).

2. Although all the shown tools are assemblages, no any bill of material is provided. In other words, no indication of the tool, tool shank and brazing filler materials are mentioned.

3. No shape and location tolerances are indicated including the runout of the working part with respect to HSK holder as probably the most important shape tolerance.

4. No surface finish is mentioned.5. No particular sizes of PCD inserts including its thickness as well as the

thickness of the carbide substrate are shown.6. There is no indication how the cutting inserts are secured in the body.

Technically, a paper glue can be used and this would not violate the drawing requirements.


Importance in-house testing and R&D facilitiesR

&D

• If tool brakes or does not perform adequately first time you try it then you may lose the trust of the customer in your ability to solve their tooling problems. As the old saying goes, “You Never Get a Second Chance to Make a First Impression.”

• Nowadays, many automotive powertrain plants use modern sophisticated equipment with expensive high-speed spindles. A wreck such a spindle due to tool failure cost a lot.

• As a new tool is to produce real parts for real transmissions and engines, the quality procedures require to have a filled out and approved a process change request (PPCR) form before the cutting tool can ever been ordered.

• Real production lines and manufacturing cells are not playgrounds because the production time is expensive and limited.


Thank You

"In theory, there is no difference between theory and practice. But, in practice, there is."

- Jan L.A. van de Snepscheut

Documents

Common Problems and Solutions in Cutting Tools Implementation Practice in the Setting of Automotive Powertrain Plant: System Outlook Viktor P. Astakhov