die casting gravity semi permanent mould or permanent mould cold chamber hot chamber (heating...

DIE CASTING

GRAVITY SEMI PERMANENT MOULDOR PERMANENT MOULD

COLD CHAMBER HOT CHAMBER

(HEATING CHAMBER) OUTSIDE THE MACHINE

INTEGRAL WITH THE MACHINE

PERMANENT MOULD OR GRAVITY DIE CASTING 

*METALLIC MOULDS USED *TWO HALVES OF DIES- ONE FIXED, ONE MOVABLE

•VERY CLOSE TOLERANCE CASTINGS, MORE STRENGTH, LESS POROUS

•-BETTER SURFACE FINISH COMPARED TO SAND CASTING

•-SURFACE FREE FROM SAND & DENSITY HEAVY

ONLY FOR SMALL AND MEDIUM SIZE CASTINGS

FOR NON FERROUS, MAINLY

LARGE QUANTITY, BUT IDENTICAL PIECES ONLY

SEMIPERMANENT DIECASTING• DIE PRESSURE AT 20 TO 20,000 ATM

• PRESSURE FILL SOLIDIFICATION

• FOR NONFERROUS METALS

• FOR INTRICATE SHAPES

• CLOSE TOLERANCES POSSIBLE

• FOR MASS PRODUCTION, >10,000

1.     A GOOD DIE SET MECHANISM2.      MEANS FOR FORCING METAL3.      DEVICE TO KEEP DIE HALFS PRESSED4.      ARRANGEMENT FOR AUTOMATIC REMOVAL OF CORES- IF ANY5.      EJECTOR PINS

TWO TYPES OF PRESSURE DIE CASTING COLD CHAMBER-

HEATING CHAMBER OUTSIDE THE MACHINE

- FOR Al, Mg, Cu, AND HIGH MELTING ALLOYS

HOT CHAMBER-

HEATING INTEGRAL WITH THE HANDLING

GOOSE NECK MECHANISMS WIDELY USED

FOR LOW MELTING ALLOYS- Zn, Pb, Etc.

ALSO VACUUM DIE CASTING MACHINES- SPACE BETWEEN THE DIES AND PASSAGE VACUUMISED BEFOR POURING-

SUBMERGED PLUNGE TYPE, DIRECT AIR DIE CASTING MACHINES

2

3

1

12

3

D.A.D.C. MACHINE – showing two positions of pot

ANOTHER TYPE OF D.A.D.C. MACHINE

A TYPICAL DIE

ECCENTRIC CLAMPING

MOULD / DIE HALFVENT HOLE POURING

BASIN

MOULD CAVITY

CENTRIFUGAL CASTINGTRUE- C.I. PIPES, LINERS, BUSHES, CYLINDER BARRELS ETC.SEMI- CENTRE CORE FOR INNER SURFACE- SHAPE BY MOULD AND CORE, MAINLY NOT BY CENRTRIFUGAL ACTION- Eg:FLYWHEELSPRESSURE OR CENTRIFUGAL CASTING- ALSO TERMED AS CENTRIFUGINGFOR NON SYMMETRICAL SHAPES MOULD WITH ANY SHAPE PLACED AT CERTAIN DISTANCE FROM AXIS

CENTRIFUGING PROPERTIES OF CASTING DEPEND ON

DISTANCE FROM AXIS

SQUEEZE CASTINGDIE, PUNCH, EJECTOR PIN

PARTS OF NEAR-NET SHAPE MADE, COMPLEX AND FINE

SURFACE DETAILS OBTAINED

FOR FERROUS & NON FERROUS

CENTRIFUGING PROPERTIES OF CASTING DEPEND ON

DISTANCE FROM AXIS

SQUEEZE CASTINGDIE, PUNCH, EJECTOR PIN

PARTS OF NEAR-NET SHAPE MADE, COMPLEX AND FINE

SURFACE DETAILS OBTAINED

FOR FERROUS & NON FERROUS

SQUEEZE CASTING• DEVELOPED IN 1960’S (also called liquid forging)• SOLIDIFICATION OF MOLTEN METAL UNDER HIGH

PRESSURE (pressure application when liquid partially solidifies 70 to 140 MPa)

• A COMBINATION OF CASTING & FORGING• DIE, PUNCH, EJECTOR PIN • PUNCH KEEPS ENTRAPPED GASES IN SOLUTION,

RAPID COOLING DUE TO HIGH PRESSURE DIE- METAL INTERFACE

• PARTS OF NEAR-NET SHAPE MADE, COMPLEX AND FINE SURFACE DETAILS OBTAINED. No riser needed

• FOR FERROUS & NON FERROUS• AUTOMOTIVE WHEELS, SHORT BARRELED CANNONS

ETC.

SINGLE CRYSTAL GROWING (S.C.G.)• FOR SEMICONDUCTOR INDUSTRY

• CRYSTAL PULLING METHOD-

CZOCHRALSKI PROCESSCZOCHRALSKI PROCESS• SEED CRYSTAL DIPPED INTO THE MOLTEN

METAL, PULLED SLOWLY, (AT 10 m/ s), WITH ROTATION

• LIQUID METAL SOLIDIFIES ON THE SEED AND CRYSTAL STRUCTURE CONTINUED THROUGHOUT

CASTING TECHNIQUES FOR SINGLE CRYSTAL GROWING (S.C.G.)

CONVENTIONAL USE OF CERAMIC MOULD

GRAINS WITH THE ABSENCE OF THERMAL GRADIENT

DIRECTIONAL SOLIDIFICATION PROCESS

CERAMIC MOULD PREHEATED.

MOULD SUPPORTED BY WATER COOLED CHILL PLATES.

AFTER POURING, ASSEMBLY LOWERED

CRYSTALS GROW AT CHILL PLATE SURFACE UPWARD. COLUMNAR GRAINS FORM

CASTING TECHNIQUES FOR SINGLE CRYSTAL GROWING (S.C.G.)

• POLYCRYSTALLINE- ANISOTROPY• SINGLE CRYSTAL- PROPERTIES SAME IN

ALL DIRECTIONS• CASTING OF GAS TURBINE BLADES BY

S.C.G.

CONVENTIONAL

• USE OF CERAMIC MOULD

GRAINS- AS WITH THE ABSENCE OF THERMAL GRADIENT

PRESENCE OF GRAIN BOUNDARIES- MAKES STRUCTURE SUSCEPTIBLE TO CREEP AND CRACKING ALONG BOUNDARIES

DIRECTIONAL SOLIDIFICATION PROCESS, (1960’s)

CERAMIC MOULD PREHEATED. MOULD SUPPORTED BY WATER COOLED CHILL

PLATES.AFTER POURING, ASSEMBLY LOWERED CRYSTALS GROW AT CHILL PLATE SURFACE

UPWARD. COLUMNAR GRAINS FORMBLADE DIRECTIONALLY SOLIDIFIED WITH

LONGITUDINAL- NOT TRANSVERSE- GRAIN BOUNDARIES. THUS STRONGER

SINGLE CRYSTAL BLADES, (1967),MOULD HAS CONSTRICTION IN THE SHAPE OF

CORK SCREWTHIS CROSS SECTION ALLOWS ONLY ONE

CRYSTAL TO FIT THROUGHWITH THE LOWERING, SINGLE CRYSTAL GROWS

UPWARD THROUGH CONSTRICTIONSTRICT CONTROL OF MOVEMENT NEEDEDTHERE IS LACK OF GRAIN BOUNDARIES, MAKES

RESISTANT TO CREEP AND THERMAL SHOCK.--EXPENSIVE

FLOATING –ZONE METHOD

• POLYCRYSTALLINE ROD (SILICON)- ALLOWED ALLOWED TO REST ON A SINGLE CRYSTALTO REST ON A SINGLE CRYSTAL

• INDUCTION COIL HEATS THE PIECES

• COIL MOVED UPWARD SLOWLY (20 m/ s)

• SINGLE CRYSTAL GROWS UPWARD WITH ORIENTATION MAINTAINED

• THIN WAFERS CUT FROM ROD, CLEANED, POLISHED

• USE IN MICROELECTRONIC DEVICES