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DIE CASTING

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die casting gravity semi permanent mould or permanent mould cold chamber hot chamber (heating chamber) outside the machine – PowerPoint PPT presentation

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Provided by: RAMACHANDRAN
Learn more at: http://www.dss.nitc.ac.in
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Title: DIE CASTING


1
DIE CASTING
  • GRAVITY SEMI PERMANENT MOULD
  • OR PERMANENT MOULD

  • COLD CHAMBER HOT CHAMBER

  • (HEATING CHAMBER)
  • OUTSIDE THE
    MACHINE


  • INTEGRAL WITH THE MACHINE

2
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
3
  • 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, gt10,000

1.     A GOOD DIE SET MECHANISM 2.      MEANS FOR
FORCING METAL 3.      DEVICE TO KEEP DIE HALFS
PRESSED 4.      ARRANGEMENT FOR
AUTOMATIC REMOVAL OF CORES- IF ANY 5.     
EJECTOR PINS
4
  • 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

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1
1
2
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3
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14
D.A.D.C. MACHINE showing two positions of pot
15
ANOTHER TYPE OF D.A.D.C. MACHINE
16
A TYPICAL DIE
VENT HOLE
MOULD / DIE HALF
POURING BASIN
MOULD CAVITY
ECCENTRIC CLAMPING
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19
CENTRIFUGAL CASTING TRUE- C.I. PIPES,
LINERS, BUSHES, CYLINDER BARRELS ETC. SEMI-
CENTRE CORE FOR INNER SURFACE- SHAPE BY
MOULD AND CORE, MAINLY NOT BY
CENRTRIFUGAL ACTION-
EgFLYWHEELS PRESSURE OR CENTRIFUGAL CASTING-
ALSO TERMED AS CENTRIFUGING FOR NON
SYMMETRICAL SHAPES
MOULD WITH ANY SHAPE PLACED
AT CERTAIN DISTANCE FROM AXIS
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CENTRIFUGING PROPERTIES OF CASTING DEPEND ON
DISTANCE FROM AXIS
SQUEEZE CASTING
DIE, PUNCH, EJECTOR PIN
PARTS OF NEAR-NET SHAPE MADE, COMPLEX AND FINE
SURFACE DETAILS OBTAINED
FOR FERROUS NON FERROUS
27
CENTRIFUGING PROPERTIES OF CASTING DEPEND ON
DISTANCE FROM AXIS
SQUEEZE CASTING
DIE, PUNCH, EJECTOR PIN
PARTS OF NEAR-NET SHAPE MADE, COMPLEX AND FINE
SURFACE DETAILS OBTAINED
FOR FERROUS NON FERROUS
28
SQUEEZE CASTING
  • DEVELOPED IN 1960S (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.

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SINGLE CRYSTAL GROWING (S.C.G.)
  • FOR SEMICONDUCTOR INDUSTRY
  • CRYSTAL PULLING METHOD-
  • CZOCHRALSKI 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

31
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
32
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.

33
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

34
  • DIRECTIONAL SOLIDIFICATION PROCESS, (1960s)
  • CERAMIC MOULD PREHEATED.
  • MOULD SUPPORTED BY WATER COOLED CHILL PLATES.
  • AFTER POURING, ASSEMBLY LOWERED
  • CRYSTALS GROW AT CHILL PLATE SURFACE UPWARD.
    COLUMNAR GRAINS FORM
  • BLADE DIRECTIONALLY SOLIDIFIED WITH LONGITUDINAL-
    NOT TRANSVERSE- GRAIN BOUNDARIES. THUS STRONGER

35
  • SINGLE CRYSTAL BLADES, (1967),
  • MOULD HAS CONSTRICTION IN THE SHAPE OF CORK SCREW
  • THIS CROSS SECTION ALLOWS ONLY ONE CRYSTAL TO FIT
    THROUGH
  • WITH THE LOWERING, SINGLE CRYSTAL GROWS UPWARD
    THROUGH CONSTRICTION
  • STRICT CONTROL OF MOVEMENT NEEDED
  • THERE IS LACK OF GRAIN BOUNDARIES, MAKES
    RESISTANT TO CREEP AND THERMAL SHOCK.--EXPENSIVE

36
FLOATING ZONE METHOD
  • POLYCRYSTALLINE ROD (SILICON)- ALLOWED TO 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

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