Copyright © 2008 Badger Metal Tech, Inc DMC – Feb 13 2008 Die Casting Die Failure Cavitation Effect & Correction Castings with breakout areas shown as

Copyright © 2008 Badger Metal Tech, Inc

DMC – Feb 13 2008DMC – Feb 13 2008Die Casting Die FailureDie Casting Die Failure

Cavitation Effect & CorrectionCavitation Effect & Correction

DMC – Feb 13 2008DMC – Feb 13 2008Die Casting Die FailureDie Casting Die Failure

Cavitation Effect & CorrectionCavitation Effect & Correction

Castings with breakout areasshown as risers

Die with breakout areasshown as pitting


Could this lead to Could this lead to a New Chaptera New Chapterin the study of in the study of

High Pressure Die High Pressure Die failure?failure?


Construction Equipment – Excavators, Crawler Tractors, Loaders

High Impact Machines – Hammers, Crushers, Etc.

Construction Equipment – Excavators, Crawler Tractors, Loaders

High Impact Machines – Hammers, Crushers, Etc.

Correlation to Die Casting Dies? Correlation to Die Casting Dies? Steel Failure – Hydraulic MachinerySteel Failure – Hydraulic Machinery


Steel Failure – Fast Fill Nitrogen Charge AreasPistonCylinders

Cause and CorrectionContamination of steel - UnsuccessfulDesign changes- UnsuccessfulFailure of other related components

Steel Failure – Fast Fill Nitrogen Charge AreasPistonCylinders

Cause and CorrectionContamination of steel - UnsuccessfulDesign changes- UnsuccessfulFailure of other related components

Correlation to Die Casting Dies? Correlation to Die Casting Dies? Steel Failure – Hydraulic MachinerySteel Failure – Hydraulic Machinery


High Speed Photography

Special pressure transducers

High Speed Photography

Special pressure transducers

Joint Research ProgramJoint Research Program with Caterpillar with Caterpillar


Previously mistaken for:Bad steelErosionHeat Treatment

None of the Above

Previously mistaken for:Bad steelErosionHeat Treatment

None of the Above

Failure Mode - CavitationFailure Mode - Cavitation

Does this look familiar?


Fatigue by Fluid entrained gases

Tiny bubbles imploding on surface of the member on which or over which the fluid is flowing

Resulting in high cycle fatigue failure

Fatigue by Fluid entrained gases

Tiny bubbles imploding on surface of the member on which or over which the fluid is flowing

Resulting in high cycle fatigue failure

What is Cavitation – Really?What is Cavitation – Really?

Image source:Dr. Joe Evans Ph.Dwww.pumped101.comwww.caltech.edu


Breaking down the BubbleBreaking down the BubbleA tiny Jack HammerA tiny Jack Hammer

Vapor bubble in various stages ofcollapse.

Solid lines predictedby model.

Dotted lines obtainedthrough experiment.

Stages 1-3 sphericalStage 4 small depression

Depression more toroidalin its 3D shape.

Upon implosion, there-entrant micro jetwould form at the bottomof the bubble with itsenergy directed towardsthe solid surface.



Bubble Stage CollapseBubble Stage CollapseBELOW a Solid BoundaryBELOW a Solid Boundary

1-18 shows a bubble collapsingAt stage 7, small dot at bottom of bubbleGrows in size in following stages then appears to penetrate the upper boundary in Stage 14.

Stage 18 is just prior to total collapse and shock wave generation.



Cavitation EffectCavitation Effect

Cavitation patternduring flow

Bubbles formed at leftresult in damage at right

Source:Dr. Joe Evans Ph.Dwww.pumped101.comwww.caltech.edu


Gear Pump:suction side of pumpnegative pressures at entrypositive pressures at first gear tooth

How to accelerate?Increase air entrainmentcavitation failure was acceleratedcavitation failure more pronounced

Gear Pump:suction side of pumpnegative pressures at entrypositive pressures at first gear tooth

How to accelerate?Increase air entrainmentcavitation failure was acceleratedcavitation failure more pronounced

Where does Cavitation Show Up?Where does Cavitation Show Up?

Photo at right shows damage at lowpressure side of leading edge ofimpeller


Propellers, Pumps, Cylinders,

High Pressure Die Casting

Propellers, Pumps, Cylinders,

High Pressure Die Casting

Collapsing Bubble DamageCollapsing Bubble Damage


Each operational cycle:millions of low pressure cyclescycles go from void to positive pressuresthousands – translates to billions

Billions of cyclescause extremely high cycle fatigueinitially microscopic particles removedas more removed – visible to naked eye

Each operational cycle:millions of low pressure cyclescycles go from void to positive pressuresthousands – translates to billions

Billions of cyclescause extremely high cycle fatigueinitially microscopic particles removedas more removed – visible to naked eye

How do little bubbles do so much damage?How do little bubbles do so much damage?


Fact - Trapped gases in molten metal:collapse - billions of void to positive pressurescause loss of fatigue strength of metalinitially microscopic

Jack hammer effectsmall microscopic particles grow in sizevisible chucks of metal from diepreviously attributed to thermal fatigue

Fact - Trapped gases in molten metal:collapse - billions of void to positive pressurescause loss of fatigue strength of metalinitially microscopic

Jack hammer effectsmall microscopic particles grow in sizevisible chucks of metal from diepreviously attributed to thermal fatigue

How about Die Casting Dies?How about Die Casting Dies?


Die Steel Ejector Insert

Die Steel Cover Insert

Die Cast Trapped Gas – Phase 1Die Cast Trapped Gas – Phase 1

More Infoon our web


Die surface begins to fatigue

Die particles begin to be removed

Die Cast Trapped Gas – Phase 2Die Cast Trapped Gas – Phase 2

More Infoon our web


Die break out and/or heat check starts

More die particles removed

Visible Break Out & Heat CheckingVisible Break Out & Heat Checking

More Infoon our web


Over past 25 YearsOver past 25 Years100,000+ die casting dies100,000+ die casting dies

Over past 25 YearsOver past 25 Years100,000+ die casting dies100,000+ die casting dies

In the USA, Canada In the USA, Canada & Mexico& Mexico

In the USA, Canada In the USA, Canada & Mexico& Mexico


Historical EvidenceHistorical Evidence

100,000+ Dies in 25 yearsNo Die Caster, Tool Shop –sees more

Castings tell the bubble storybreakout prevalent at gate area of castingbreakout prevalent at flow direction change

Everyday we see damage caused by cavitationdamage attributed to bad steel, heat treat, erosion

100,000+ Dies in 25 yearsNo Die Caster, Tool Shop –sees more

Castings tell the bubble storybreakout prevalent at gate area of castingbreakout prevalent at flow direction change

Everyday we see damage caused by cavitationdamage attributed to bad steel, heat treat, erosion


Mistaken IdentityMistaken Identity

Asked to repair heat checks in diemajority of time these are breakout conditions

NOT HEAT CHECKING

Usually close to gate areacan feel with eyes closed the pittingalso evident in flow change areas

Asked to repair heat checks in diemajority of time these are breakout conditions

NOT HEAT CHECKING

Usually close to gate areacan feel with eyes closed the pittingalso evident in flow change areas


How to Counter Die Cast DieHow to Counter Die Cast DieCavitation Effect?Cavitation Effect?

Remove all trapped gases - Impossible

Get rid of bubbles – Break them up

Increase fatigue resistance of steel

Place surface in compression

Increase surface hardness

Remove all trapped gases - Impossible

Get rid of bubbles – Break them up

Increase fatigue resistance of steel

Place surface in compression

Increase surface hardness


How does helpHow does helpreduce cavitation effect?reduce cavitation effect?

Breaks up trapped gas bubbles

High compression to counter fatigue

Micro-texture improves flow

Breaks up trapped gas bubbles

High compression to counter fatigue

Micro-texture improves flow


Compressive Textured Surface

Removes damaging gas bubbles

Compressive Texturing EffectCompressive Texturing Effect


-185

-175

-165

-155-145

-135

-125

-115

-105

-95

-85-75

-65

-55

-45

-35

-25

-15

-55

15

25

35

0.0 2.0 4.0 6.0 8.0 10.0 12.0 14.0 16.0 18.0 20.0 22.0 24.0

Depth (x 10-3 in)

Re

sid

ua

l S

tre

ss

KS

I V

alu

e V

alu

T-21

T-41

T-61

T-71

T-41H

Residual Stress CurvesResidual Stress Curves

High Compressive Values help counter metal fatigue failure

X-RayDiffractionCurves

T-41HHigh Surface CompressionShallow KneeMaximized Depth


TOOLING CIRCLE OF LIFE

TOOLING CYCLE OF

LIFE

anti-solderinganti-solderingpermanent flow permanent flow

effecteffect

““resistance to resistance to thermal fatigue thermal fatigue

cracking & breakout cracking & breakout from cavitation effectfrom cavitation effect

Badger Metal Tech, Inc.FAX 262-252-3956

Toll Free 800-366-1973


Additional BenefitsAdditional BenefitsAdditional BenefitsAdditional Benefits Reduced cavitation breakout and pittingReduced cavitation breakout and pitting Eliminate lamination porosityEliminate lamination porosity Better heat dissipationBetter heat dissipation Increased lubricity and improved metal flowIncreased lubricity and improved metal flow Compressive stress after weld repairCompressive stress after weld repair Better paint adherence – especially powderBetter paint adherence – especially powder

Reduced cavitation breakout and pittingReduced cavitation breakout and pitting Eliminate lamination porosityEliminate lamination porosity Better heat dissipationBetter heat dissipation Increased lubricity and improved metal flowIncreased lubricity and improved metal flow Compressive stress after weld repairCompressive stress after weld repair Better paint adherence – especially powderBetter paint adherence – especially powder

Why apparent less porosity?


Casting SurfaceLamination with trapped gas



Lamination of Casting SkinLamination of Casting Skin


Casting SurfaceCasting Surface



Problem SolvedProblem Solved


To make effect permanentTo make effect permanent Where a need exists for an anti-soldering, Where a need exists for an anti-soldering,

anti-galling or washoutanti-galling or washout

To make effect permanentTo make effect permanent Where a need exists for an anti-soldering, Where a need exists for an anti-soldering,

anti-galling or washoutanti-galling or washout

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Doesn’t this Doesn’t this warrant further warrant further

study by the study by the DMC?DMC?

Documents

Copyright © 2008 Badger Metal Tech, Inc DMC – Feb 13 2008 Die Casting Die Failure Cavitation Effect & Correction Castings with breakout areas shown as