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Introduction to Die Casting(VEDCME600)
DaimlerChrysler Corporation
Chassis & Powertrain Materials Engineering
Presented by
Cast Metals Engineering & Prototyping
Larry Kopka - Sr. Specialist Materials Eng.
Ph: 776 - 7473, E-mail: lk7@dcx.com
Randy Beals - Materials Eng.
Ph: 776 - 7478, E-mail: rsb19@dcx.com
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DIE CASTING - DIE ALLOYS
QUALITIES REQUIRED FOR DIE STEELS:
EXHIBIT GOOD TOUGHNESSRESISTANCE TO CRACKING
RESISTANCE TO WEAR I EROSION
RESISTANCE TO HEAT CHECKING
HIGH THERMAL CONDUCTIVITY
LOW THERMAL EXPANSION
RESISTANCE TO OXIDATIONGOOD THERMAL SHOCK RESISTANCE
REASONABLE COST
MOST POPULAR DIE STEELS USED FOR PRODUCTION
CHROMIUM BASED - USED FOR ALUM & MAG DIE CASTING:
H-13 / OTHERS: H-11, H-12, CROMO-N, QRO 80M, &ORVAR M SUPREME
LOW CARBON STEEL - USED FOR ZINC, LEAD, &
TIN DIE CASTING:
P-20, P-21, SAE 1020 & MARAGING STEELS
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Introduction to Die Casting
Larry KopkaDCX Materials Engineering
Agenda Die Casting Process
Equipment, Operation, Process Parameters
Die Casting Defects/ Trouble Shooting
DaimlerChrysler Materials Engineering
Process Control Requirements for Die Cast
Structural Components
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Die Casting Design Considerations
Case Studies of DCX Die Cast Components
Problems, Failure Analysis Die Casting Supplier - Process Control
Introduction to Die Casting
Larry KopkaDCX Materials Engineering
Agenda
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MOST POPULAR DIE STEELS USED FOR PROTOTYPING
P-20, P-21, & SAE 1020
DIE HEAT TREATMENTS
AUSTENITIZE / QUENCH / TRIPLE TEMPER TO Rc 45-52STRESS RELIEF
DIE SURFACE HARDENING HEAT TREATMENTS
CARBURIZING, CARBO-NITRIDING, NITRIDING,
TUFFTRIDING, & IONITRIDING
DIE CASTING - DIE ALLOYS
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Curve of Plunger Travel vs. Time
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Curve of Plunger Pressure vs. Time
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SLOW SHOT SPEED SYSTEM (1 ST. EVENT)
SLOW SHOT PHASE INITIATES THE MOVEMENT OF THE
LIQUID ALLOY METAL BY THE PLUNGER.SLOW SHOT CYCLE IS COMPLETED WHEN PLUNGER
HAS COVERED POUR HOLE & SHOT SLEEVE IS FILLED.
SLOW SHOT SPEED IS "CRITICAL" - PROPER SLOW SHOT
INSURES MINIMUM AIR ENTRAPMENT IN LIQUID METAL.
FAST SHOT SPEED SYSTEM (2ND. EVENT)FAST SHOT PHASE COMPLETELY FILLS DIE CAVITY
RAPIDLY TO INSURE LIQUID METAL DOES NOT SOLIDIFY
BEFORE FILLING DIE CAVITY.
INTENSIFICATION SPEED SYSTEM (3RD. EVENT)
PLUNGER TIP CONTINUOUSLY APPLIES INCREASED
PRESSURE TO MINIMIZE POROSITY - STUDIES SHOW
ONLY MARGINAL RETURNS.
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DIE CASTING DEFECTS
POROSITY (GAS):
ENTRAPPED SPHERICAL INTERNAL VOIDS / PORES CONTAINING GAS (HYDROGEN). GASPOROSITY IS CAUSED BY THE ENTRAPMENT OF AIR FROM TURBULENCE DURING CAVITY
FILL, THE SOLUTION OF HYDROGEN GAS IN THE MOLTEN ALLOY (ABSORPTION FROM HIGH
HUMIDITY, MOISTURE IN LUBRICANTS, LACK OF DEGASSING OF MOLTEN ALLOY, MOISTURE
ON ALLOY INGOTS, ETC.). GAS POROSITY MAY BE ELIMINATED BY PRE-HEATING (DRYING)
INGOTS, DEGASSING THE MOLTEN ALLOY, CONTROL OF LUBRICANT APPLICATION /
DRYING, USE OF COVER GAS, VENTING DIE CAVITY, GATING CHANGES, OR IMPLEMENTINGVACUUM SYSTEMS TO REMOVE AIR FROM DIE CAVITY PRIOR TO FILL.
POROSITY (SHRINKAGE):
IRREGULAR SHAPED INTERNAL VOIDS / PORES WHICH DO NOT CONTAIN GAS AND FORM
IN HEAVY SECTIONS DURING SOLDIFICATION. SHRINKAGE IS CAUSED BY THERMAL
CONTRACTION AND INADEQUATE FEEDING OF MOLTEN METAL DURING SOLIDIFICATION.SHRINKAGE POROSITY MAY BE ELIMINATED BY REDESIGN TO ELIMINATE THICK WALL /
BOSS SECTIONS, ETC., PROVIDING BETTER FEEDING OF MOLTEN METAL (VIA GATES, RIBS ),
PROVIDING GREATER ALLOY FLUIDITY (HIGHER ALLOY TEMPERATURE), INCREASING
INJECTION / INTENSIFICATION PRESSURE AND ADJUSTING CASTING PARAMETERS.
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DIE CASTING DEFECTS
COLD SHUTS:
COLD SHUTS ARE "CRACK - LIKE " NON - FUSED OR LAPPED AREAS THAT APPEAR ON THE
SURFACE OF A CASTING. COLD SHUTS ARE THE RESULT OF TWO STREAMS OF LIQUID
MOLTEN METAL MEETING AND FAILING TO UNITE OR METALLURGICALLY BOND. COLD
SHUTS MAY BE
CAUSED BY COLD DIES, LOW POURING TEMPERATURE (SUPER HEAT), SLOW SHOT SPEED,
INADEQUATE FEEDING/GATING, LOW CASTING INJECTION PRESSURE, ETC. COLD SHUTSMAY BE ELIMINATED BY INCREASING INJECTION PRESSURE, INCREASING THE POURING
TEMPERATURE, INCREASING DIE TEMPERATURES, PROVIDING BETTER DIE DESIGN
(LARGER GATES, ADDITION OF RIBS FOR FEEDING, ETC.)
MISRUNS / NON-FILL:
A IRREGULARITY OF THE CASTING SURFACE CAUSED BY INCOMPLETE FILLING OF THEMOLD CAVITY DUE TO LOW POURING TEMPERATURE, GAS BACK PRESSURE FROM
INADEQUATE VENTING OF DIE CAVITY, INADEQUATE GATING, COLD DIE CAVITY, ETC.
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DIE CASTING DEFECTS
CRACKS / HOT TEARS:
A CRACK IS A FLAT INTERNAL FREE SURFACE (FRACTURE) OR OPENING. CRACKS MAY BE
CAUSED BY INTERNAL STRESS DEVELOPED AFTER SOLIDIFICATION (HOT CRACK) OR BY
STRESSES DUE TO SHRINKAGE - RESTRAINT (HOT TEARS) AS THE METAL CONTRACTS AND
THE HOT STRENGTH IS EXCEEDED DURING SOLIDIFICATION. HOT TEARS MAY BE
ELIMINATED BY MINIMIZING RESTRAINT VIA ADDING RIBS TO DISTRIBUTE STRESSES,PROVIDING GENEROUS RADII (LOWER STRESS CONCENTRATION Kt), DECREASING
HOLDING TIME TO EJECT CASTING FROM DIE, CHANGE DIE CASTING PARAMETERS, SUCH
AS, DIE TEMPERATURE, DIRECTION OF METAL FLOW AND MOST IMPORTANTLY CHANGING
DIE CASTING DESIGN. DESIGN CHANGES RELATED TO MULTIPLE / COMPLEX RIB
JUNCTIONS AND THICK BOSS / THIN RIB - WALL TRANSITIONS ARE VERY EFFECTIVE IN
ELIMINATING RESTRAINT CRACKING.
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INCLUSIONS ("DIRT") / DROSS:
INCLUSIONS ARE PARTICLES OF FOREIGN MATERIAL (DROSS, SLAG, MOLD
MATERIAL, REFRACTORIES) TERMED "EXOGENOUS" OR INHERENT INCLUSIONS
TERMED "INDIGENOUS" (OXIDES, SILICATES, SULFIDES, ETC.) IN A METALLIC
MATRIX. INCLUSIONS MAY BE INHERENT IN THE CAST ALLOY INGOT, ORPRESENT DUE TO INADEQUATE ALLOY REFINING PROCESSES, INTRODUCED
DURING RECYCLING, OR DURING THE CASTING PROCESS (INADEQUATE
DROSSING, DEGASSING, ETC.).
DIE CASTING DEFECTS
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CHRYSLER MATERIALS ENGINEERING REOUIREMENTS FOR
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CHRYSLER MATERIALS ENGINEERING REOUIREMENTS FOR
PROCESS CONTROL OF DIE CAST STRUCTURAL COMPONENTS
SPECIFICATION/ENGINEERING DRAWING REOUIREMENTS:
THE APPROPRIATE CHRYSLER MATERIAL (MS) & PROCESSING (PS)
SPECIFICATIONS FOR THE SPECIFIC MAGNESIUM, ALUMINUM, OROTHER DIE CASTING ALLOYS MUST BE DESIGNATED ON THE
ENGINEERING DRAWING. A LISTING OF SOME FOLLOWS:
MAGNESIUM SPECIFICATIONS:
MS-9231 (HIGH DUCTILITY MAGNESIUM DIE CASTING ALLOYS)
MS-2413 (MAGNESIUM DIE CASTING ALLOYS)MS-10675 (MAGNESIUM ALLOY INGOT FOR DIE CASTING)
ALUMINUM SPECIFICATIONS:
MS-2410 (ALUMINUM DIE CASTING ALLOYS)
MS-3495 (ALUMINUM ALLOY INGOT FOR DIE CASTING)
PROCESS SPECIFICATIONS:
PS-I0ll (RADIOGRAPIC INSPECTION OF CASTINGS)PS-8335 (PENTAGON-CRITICAL VERIFICATION SYMBOL)
PS-5190 (DIE CASTING PROCESS CONTROL)
THE ENGINEERING DRAWING WILL DESIGNATE THE CRITICALLY
STRESSED ZONES OF THE COMPONENT AS DESIGNATED BY PS-8335
AND DETERMINED BY FEA, ENDURANCE TESTS, STATIC & DYNAMIC
(SLED, DROP TOWER, ETC.) LOAD TESTS.
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STANDARD CASTING / REFERENCE RADIOGRAPHIC FILMS:
AFTER OPTIMIZATION OF DIE CASTING PROCESS PARAMETERS,
CHRYSLER MATERIALS ENGINEERING WILL X-RAY A MINIMUM OF
TWELVE (12) CASTINGS TO ESTABLISH A "STANDARD CASTING". THE
"STANDARD CASTING" WILL BE SELECTED AND AGREED TO BY
CHRYSLER PRODUCT / PLATFORM ENG., MAT'LS ENG., QUALITY
ASSURANCE, PURCHASING & THE DIE CASTING / 1ST TIER SUPPLIER.
THE "STANDARD CASTING" AND RELATED RADIOGRAPHIC FILM
STANDARDS WITH DESIGNATED CRITICAL ZONES, WILL BE USED FOR
X-RAY / FLUOROSCOPIC INSPECTION OF PRODUCTION CASTINGS BY
THE DIE CASTING SUPPLIER. THE QUANTITY AND FREQUENCY OF
CASTINGS INSPECTED FOR PRODUCTION CONTROL WILL BE
ESTABLISHED BY CHRYSLER ENG & QUALITY ASSURANCE, BASED ON
CRITICALITY AND SAFETY RELATED REQUIREMENTS.
PRE-PRODUCTION VALIDATION:A DESIGNATED QUANTITY OF INITIAL PRODUCTION CASTINGS
(USUALLY 100-300 PCS) DEPENDING ON COMPONENT CRITICALITY &
SAFETY RELATED REQUIREMENTS WILL BE X-RAYED AND COMPARED
TO THE "STANDARD CASTING" / FILM STANDARDS AGREED UPON.
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