• Name of the Staff Members : P. Ramulu• Designation : Work Shop Supdt., • Branch : Mechanical Engineering• Institute : Govt. Polytechnic for women,

Medak.• Year/semester : I year • Subject : Work shop Technology• Subject Code : M-105• Topic : Foundry(2/2.14)• Duration : 100 Minutes • Sub. Topic : Moulding procedure and methods• Teaching Aids : Animation Clips & Images

DEPARTMENT OF TECHNICAL EDUCATION ANDHRA PRADESH

1M105.87 TO 88

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Recap

In the previous class we have covered

Construction of patterns

Colour Code

Core

Advantages & Properties of Cores

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Recap

Type of metal, number of castings, moulding method,

etc will decide the making of pattern

Pattern layout, shaping the pattern are the key steps in

pattern making

Core is meant for providing internal features in castings

Horizontal, vertical, hanging, kiss etc are the types of

cores.

In the previous class , you have learnt …

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Objectives

On completion of this period, you would be

able to know about:

Moulding procedure

Types of Moulding processes.

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Moulding Procedure

The Moulding Box consists of Cope and Drag

The Pattern is kept inside the Molding Box on

Moulding Board.

Parting Sand is dusted on Pattern surface.

Facing Sand is poured up to a depth of 25 mm

Backing Sand is filled.

Ramming is done.

Excess sand is cut off with Strike off Bar.

Contd…

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Moulding Procedure

Fig 55. Moulding Procedure

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Moulding procedure

• Drag is turned over.

• Cope is placed on Drag.

• Parting Sand is sprinkled over Pattern.

• Sprue &Risers are placed in position .

• Moulding Sand is filled in the Cope

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Moulding Procedure

• Sand is rammed

• Excess sand is removed.

• Sprue & Riser pins are withdrawn.

• Cope is lifted off and set aside.

• Pattern is withdrawn from Drag.

9

Moulding Procedure

• Finally Cope &Drag clamped together.

• Metal is melted separately in Electric arc Furnace.

• This molten Metal is poured into the Mould.

• When molten metal cools down the Mould is broken.

• Casting is separated.

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Classification of Moulding Processes

1) According to the Method used

Bench Moulding.

Floor Moulding,

Pit Moulding.

Machine Moulding.

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Bench Moulding

Moulding is done on Bench.

The Flasks are kept on Bench.

Convenient height of Bench is selected.

Employed for small Castings.

Fig 56. Bench Moulding

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Floor Moulding

Moulding is done on Foundry Floor

Used for medium to large Castings.

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Pit Moulding

Moulding is performed in Pit.

Pit is dug on Foundry Floor

It acts as Mould (drag).

A separate Cope may be Used.

Adopted for Large Castings.

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Machine Moulding

Employed for mass production &batch

production. Enables higher accuracy. Enables higher output. Various operations are performed by

Machines,like

a) Ramming.

b) Removal of Pattern.

c) Gate cutting.

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Classification according to Moulding Materials

Green sand Moulding.

Dry sand Moulding.

Skin-dry sand Moulding.

Loam Moulding.

Cement bonded Moulding.

Ceramic Moulding.

Shell Moulding.

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Green sand Moulding

In this moulding moist sand with clay is used.

Used for small & medium Castings.

Drying of the Mould is not necessary.

Molten is poured immediately.

Green refers to moisture not colour of Sand.

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Advantages

Least expensive.

Consumes less time .

Flasks can be reused

Less distortion problem.

Less danger of Hot tear.

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Disadvantages

Sand control is critical

Moisture in sand may cause defects.

Surface finish is poor.

Mould lacks strength.

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Applications

Ferrous and Non –Ferrous Alloys can be casted

Used for small & medium Castings.

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Dry sand Moulding

Synthetic Sand is mixed with binder & Water.

Synthetic Sand does not contain Clay.

Mould prepared is baked in Oven at 240 degrees temp.

Mould becomes Stronger.

Used for medium to large Castings.

Metals like Cast Iron & Mild steel are casted.

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Advantages

Stronger than green Sand Moulds.

Defects are avoided due to baking.

Better surface finish.

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Disadvantages

Cost of production is high.

Slow production rate.

Mould distortion.

Susceptible to hot tear.

Not suitable for light & intricate parts.

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Skin dry Sand moulding.

Synthetic sand with bentonite binder & water is used.

The surface of Mould is dried up to a depth of 15 mm.

Drying is done by Carbon dioxide or hot air.

Adopted for Ferrous & non-Ferrous alloys of large size.

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Advantages

Less expensive.

Requires less time.

Stronger than Green Sand Mould.

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Disadvantages

More Expensive.

Mould weaker than Dry sand mould.

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Loam sand Moulding

Mould made with loam sand.

Sweep pattern is used to prepare mould.

It is rotated in loam Sand to make mould.

Mould is dried to provide strength.

Used for large castings of symmetrical shape.

Large cylindrical, paper mill rolls etc. are casted.

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Loam sand Moulding

Fig 57. Loam Sand Moulding

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Advantages

Large Castings can be casted cheaply.

Symmetrical Castings are made.

Disadvantages

It is slow process and laborious.

Skilled moulders are required.

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Summary

Moulding procedure

Types of Moulding processes like

• Green sand moulding

• Dry sand moulding

• Skin dried moulding

• Loam sand moulding

In this class , you have learnt …

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Frequently Asked Questions

1. Explain The Moulding Process?

2. What are the various types of Moulding processes

depending upon type Mould materials?

3. What are the various type of Moulding processes

depending upon Method of Moulding?

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Quiz

1. Sprue is used for -------------------------

(Gate)

2. Top part of Moulding Box is called--------------

(Cope )

3. Pit moulding is used for------------------------sized castings

(Large)