S4 MECHANICALSTIST

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MODULE 1

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Sand Muller

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Sand Mullers

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MOULDING METHODS

•Bench moulding

• Floor moulding

•Pit moulding

•Machine moulding

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Types of Moulds• Green Sand Mould

• Dry Sand Mould

• Skin-Dried Sand Mould

• Air-Dried Sand Mould

• Core Sand Mould

• Loam Mould

• Shell Mould

• Cement Bonded Sand Mould

• Ceramic Mould

• Plaster Mould

• Sodium Silicate- CO2 Mould

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Types of Moulding• Green Sand Moulding

• Dry Sand Moulding

• Skin-Dried Sand Moulding

• Core Sand Moulding

• Loam Moulding

• Shell Moulding

• Cement Bonded Sand Moulding

• Ceramic Moulding

• Plaster Moulding

• Sodium Silicate- CO2 Moulding

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Sodium Silicate- CO2 Moulding

Na2 SiO3 + CO2 Na2CO3 + SiO2

Sodium Silicate Silica Gel

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SHELL MOULDING

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Plaster Mould Casting

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Ceramic Slurry

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MOLD MAKING

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HAND MOLDING EQUIPMENTS

1. Bellow

2. Brush

3. Lifter

4. Dust bag

5. Gaggers

6. Peen Rammer

7. Hand Ramer

8. Floor Rammer

9. Hand Riddle

10. Sprue Pin

11. Sprue Cutter

12. Spray- Gun

13. Spirit Level

14. Sprigs and Nails

15. Swab

16. Trowels

17. Shovel

18. Vent Wire

19. Strike off bar

20. Draw Spike

21. Gate Cutter

22. Draw Screws

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CORE

Required Casting

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Pattern

CORE

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Properties of CORE Sand Green Strength

Dry strength

Hardness

Permeability

Refractoriness

Collapsibility

Should generate minimum amount of gases during

pouring of molten metal

Bench life (should be able to retain its properties during

storage.)

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Core Sand Ingredients1. Granular Refractories

1. Silica Sand (Dry, Clean & Pure)

2. Zircon

3. Carbon

2. Core Binders

a) Organic

i. Core oil

ii. Water soluble binders

iii. Synthetic resins, thermosetting

iv. Wood floor

b) Inorganic

i. Fire clay

ii. Silica floor

iii. Iron oxide

c) Other binders

a) Portland cement

b) Sodium silicate

3. Water

4. Special additives

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Core Box 17

CORE BAKINGEQUIPMENTS USED FOR THE BAKING OF CORES

1. Core Ovens

a) Batch type

i. Drawer type

ii. Rack type

b) Continuous type

2. Dielectric Bakers

3. Radiant Bakers

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FINISHING OF CORE

1. Cleaning

a) Trimming

b) Brushing

c) Coating

d) Mudding

2. Sizing

3. Core Assembly

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Core Shifting & Chaplets20

Permanent Mold Casting

(Gravity Die Casting)21

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BLOW HOLES

CASTING DEFECTS

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BLOW HOLES

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MISRUNS

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COLD SHUT

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MISMATCH

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FINS OR FLASH

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SHRINKAGE CAVITY

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METAL PENETRATION & SURFACE ROUGHNESS

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HOT TEAR

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SLAG INCLUSIONS

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SWELL

REQUIRED CASTING DEFECTED CASTING

Swelled section

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INSPECTION & TESTING OF CASTINGS• VISUAL INSPECTION

• DIMENSIONAL INSPECTION

• PRESSURE TESTING• WATER PRESSURE TEST

• AIR PRESSURE TEST

• RADIO-GRAPHICAL TESTING• X-RAY TESTING

• γ-RAY TESTING

• EDDY CURRENT INSPECTION

• ULTRASONIC TESTING

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Radio-Graphical Testing

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LIQUID PENETRANT TEST

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3 4

1. Section of material with a crackthat is not visible to the nakedeye.

2. Penetrant is applied to the surface.3. Excess penetrant is removed.4. Developer is applied, rendering the crack visible.

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EDDY CURRENT INSPECTION

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ULTRASONIC TESTING

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• Pouring Cup• Sprue• Sprue Base/Well• Runner• Gate• Riser

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FUNCTIONS OF A GATING SYSTEM

•Fill the mould cavity before solidification starts

•Reduce the turbulence of molten metal

•Minimize wastage of metal

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ELEMENTS OF GATING SYSTEM• Pouring basin/cup: Funnel shaped cup which forms the top portion of

the sprue.

• Sprue: A vertical passage, usually tapered to minimize turbulence. It connects the poring basin to runner via sprue well

• Sprue well: Deep and enlarged portion beneath the sprue

It absorbs shocks of the molten metal and retainsinclusions

• Runner: Horizontal passage which connects sprue well & Gates

• Gate: Passage that finally leads molten metal from runner in themould cavity

• Riser: A riser is a vertical passage or opening through the cope

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PRINCIPLES OF RISERING• A riser or a feeder head is a passage of sand made in the

mould.

• The molten metal rises in the feeder head after the mouldcavity is filled up.

FUNCTIONS OF RISER:

• Act as a vent for gases

• Helps to confirm that the mould is completely filled

• Act as a reservoir of molten metal to feed and compensatefor shrinkage during solidification of a casting.

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OPEN RISERBLIND RISER

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BLIND RISER

• Advantages:• Smaller in size, less wastage of metal

• Slow solidification of molten metal

• Disadvantages:• Difficult to mould

• Does not indicate the filling of mould cavity

OPEN RISER

• Advantages:• Easy to mould

• Disadvantages:• Larger in size, more wastage of metal

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CHILLS

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• External Chills• Direct chills• Indirect chills

• Internal chills

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GATING RATIOSprue Well area : Runner cross sectional area : Gate cross sectional area

1 : 3 : 3

1: 0.75 : 0.50

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TYPES OF GATING SYSTEM

• Pressurized Gating System• The total cross sectional area decreases towards the mold cavity

• Unpressurized Gating System• The total cross sectional area increases towards the mold cavity

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CENTRIFUGAL CASTING

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•CENTRIFUGAL CASTING•True Centrifugal casting•Semi-Centrifugal Casting•Centrifuged Casting

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TRUE CENTRIFUGAL CASTING

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SEMI CENTRIFUGAL CASTING

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CENTRIFUGED CASTING

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CONTINOUS CASTING

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CONTINOUS CASTING

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