DMC – Feb 13 2008 Die Casting Die Failure Cavitation Effect & Correction
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Transcript of DMC – Feb 13 2008 Die Casting Die Failure Cavitation Effect & Correction
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
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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?
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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
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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
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High Speed Photography
Special pressure transducers
High Speed Photography
Special pressure transducers
Joint Research ProgramJoint Research Program with Caterpillar with Caterpillar
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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?
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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
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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.
Image source:Dr. Joe Evans Ph.Dwww.pumped101.comwww.caltech.edu
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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.
Image source:Dr. Joe Evans Ph.Dwww.pumped101.comwww.caltech.edu
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Cavitation EffectCavitation Effect
Cavitation patternduring flow
Bubbles formed at leftresult in damage at right
Source:Dr. Joe Evans Ph.Dwww.pumped101.comwww.caltech.edu
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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
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Propellers, Pumps, Cylinders,
High Pressure Die Casting
Propellers, Pumps, Cylinders,
High Pressure Die Casting
Collapsing Bubble DamageCollapsing Bubble Damage
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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?
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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?
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Die Steel Ejector Insert
Die Steel Cover Insert
Die Cast Trapped Gas – Phase 1Die Cast Trapped Gas – Phase 1
More Infoon our web
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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
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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
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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
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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
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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
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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
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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
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Compressive Textured Surface
Removes damaging gas bubbles
Compressive Texturing EffectCompressive Texturing Effect
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-185
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-155-145
-135
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-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
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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
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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?
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Casting SurfaceLamination with trapped gas
Die Steel Cover Insert
Die Steel Ejector Insert
Lamination of Casting SkinLamination of Casting Skin
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Casting SurfaceCasting Surface
Die Steel Cover Insert
Die Steel Ejector Insert
Problem SolvedProblem Solved
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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?