Primary focus areas - Primary focus areas - 20012001

Materials – composition and strength

Die coatings & surface treatments Heat treatmentResidual stress

H-13

March 14, 2001 Residual Stress ReportMarch 14, 2001 Residual Stress Report

Residual stress taskforceResidual stress taskforceMar 14, 2001 reportMar 14, 2001 report

participantsparticipants

Dave Thomason – Pace Mo Jim berry – pace mo Curt kyonka – pace mo Bob ehrman – ast Dr. David Schwam – Case Western Jerry Skoff – badger metal Tech

Goals of theGoals of the

Develop means to predict and reduce the softening effect during production cycling to improve die life

Develop means to predict and Reduce build-up of residual stresses that we now believer contribute to premature failure of die tooling

Residual stress taskforce Residual stress taskforce Facilitators & participantsFacilitators & participants

Case western reserve university Ast – American stress technologies Pace industries General motors powertrain ? Badger Metal Tech, Inc.

idealistic Residual stress task idealistic Residual stress task force force approachapproach

Develop baseline lab stress data Test on Production diesMeasure using x-ray diffraction

and possibly Barkhausen readings

Determine threshold values to indicate when die maintenance or corrective action is needed

Realistic Residual stress task Realistic Residual stress task commentscomments

No baseline lab stress data that can be confirmed in the field

2 Tests on Production dies (MN and MO) that did not support expectations

Scattered inconsistent x-ray and bna readings

Unsuccessful in determining failure threshold on any production dies

Historical data II Historical data II Pace Industries Pace Industries

MOMOgm – cav 9,10gm – cav 9,10

high volume runner multiple cavities flat surface prone to h/c history of rapid h/c flexible production schedule smaller size inserts for handling reasonable time frame for results approval of end user

satisfied attributes and criteria

FOURTH final Measurementrecap

Die has 86,209 shots 08/15/2000 Measurements taken and returned to Pace on

08-25-2000.

Trend indicator averages moving more toward zero for Xrd – More compressive

Mixed readings for bna measurements

Not what was expected

DIEs NOW SHOW signs of upset in RUNNER AREA

Testing stopped

Part Cav #9 KSI 0 degrees 45 degrees 90 degrees 0 - BNA 45 - BNA 90 - BNAFIRST READ 02/17/2000 350 +33.3 +/- 2.6 +34.8 +/- 1.8 +41.2 +/- 1.6 80.1 97.6 173.3

SECOND 03/14/2000 20,523 +29.3 +/- 1.8 +38.7 +/- 2.1 +50.7 +/- 1.4 52.9* 54.9* 98.4*THIRD 05/02/2000 41,209 + 8.1 +/- 1.9 +17.3 +/- 2.6 +22.7 +/- 2.3 41 40 56

FOURTH 08/15/2000 86,209 +9.7 +/-1.8 +15.5 +/-1.0 +24.4 +/-1.9 40 38 62TREND TENSILE STRESS

Part Cav #10FIRST READ 02/17/2000 350 +35.7 +/- 1.6 +40.1 +/- 1.6 +41.0 +/_ 1.2 44.5 81.4 80

SECOND 03/14/2000 20,523 +38.9 +/- 1.8 +59.8 +/- 1.1 +63.9 +/- 1.5 32.4* 64.8* 69*THIRD 05/02/2000 41,209 +28.0 +/- 1.7 +41.7 +/- 1.8 +53.7 +/-1.5 22 40 48

*FOURTH 08/15/2000 86,209 +22.5 +/-1.5 +39.5 +/- 1.9 +48.4 +/- 1.9 33 58 61TREND TENSILE STRESS

DIE HAS NOW VISIBLY UPSET - OCCURRED SOMEWHERE BETWEEN 41K-86K shotsThe calibration area selected on the dies during run 1 of testing was aggressively ground when the dies .arrived for round #2. A separate calibration piece (not H-13) was created during round 2 that will be kept at AST.Sensor Units for Barkhausen were same as first time.(Round #2 dies were ground in area where we took reference barkhausen readings)[Barkhausen measures changes - ie: Residual Stresss, Hardness, Micro-structureand outputs it as a numerical value.

all readingsall readings

No definitive trend with someIncreasing & decreasing tensile stress

hypothesis ihypothesis iTensile stresses build until they

are relieved by development of small micro-cracking

Tensile readings drop after this and then stress BUILDS again.

Once again cracking develops and TENSILE again dropS in value. (CONTINUE UNTIL VISIBLE CRACKING)

Appearance from READINGS show a decrease in tensile stress because of the above phenomenon.

hypothesis iIhypothesis iITHE NORMAL CYCLING OF THE

DIE PUTS THE DIE THROUGH TENSION AND COMPRESSION

The acceptable and followed current assumption is that tensile stress causes cracking and failure

THIS CYCLING, EVEN THOUGH NOT MAXIMIZED EVENTUALLY CAUSEs THE DIE TO UPSET

Where do we go from here?Where do we go from here?

Dip tank testing? X-ray diffraction Prescribed cycles Measure corners Or measure flats Take micro hardness

before and after Photograph x-ray

MEASURED surface area

H-13Dip TankSpecimen

2”eachside

7”

All corners square +.003” to -.003”All corners have .010” radius

Future testing & Future testing & studiesstudies

Should we wait on “big 3” findings through national labs ? (if data is made available to us)

Is it valuable to have case western utilize the dip tank test to: Measure stress changes ? Measure with x-ray and/or bna ? Measure micro hardness ? Historical photomology study ?

How do we test in the lab to obtain data we can use ?

Some Criteria to consider for future Production dies

No polishing or other modifications to tooling during test cycles

Micro-hardness readings prior to and after all shot intervals

Micro-analysis of surface for cracks Shorter measurement cycles Last shot castings should accompany

dies and be retained for comparison at case western

General Committee consensus at this time

sabbatical on future production die tests until we have more data or a definitive course of action based on future available data from other organizations

Same for proposed lab testing until we can Develop some type of base line criteria and format based on above data