METAL CASTING: PREPARATION OF MOULD, Terminology of Casting, Pattern, Drag, Cope, Check, Parting Line, Bottom Board, Facing Sand, Coal Dust, Backing Sand, Runner, Ingate, Riser, Moulding Procedure

METAL CASTING

PREPARATION OF MOULD

Aim: To prepare a mould for a given single piece pattern

Material Required:

Moulding sand, Facing sand, Baking sand, Parting sand, core, pattern, cope box, Drug box, Bottom board.

Tools Required:

Sprue, Riser, Chaplets, Gate cutter, Trowel, Vent rod, sleek, Bellow.

METAL CASTING: PREPARATION OF MOULD, Terminology of Casting, Pattern, Drag, Cope, Check, Parting Line, Bottom Board, Facing Sand, Coal Dust, Backing Sand, Runner, Ingate, Riser, Moulding Procedure


Terminology of Casting:

Flask: 

A moulding flask is one which holds the sand mould intact. Depending upon the position of the flask, in the mould structure it is referred to by various names as drag cope and check. It is made up of wood for temporary applications or more generally of metal for long term use.

Drag: 

lower moulding flask.

Cope: 

Upper moulding flask.

Check: 

Intermediate moulding flask used in three moulding

Pattern: 

Pattern is a replica of the final object to be made with some modifications. The mould casting is made with the help of the pattern.

Parting Line: 

This is the dividing line between the two moulding flasks that makes up the sand mould. In split pattern it is also the diving line between the two halves of the pattern.

Bottom Board: 

This is a board normally made of wood which is used at the start of the mould making. The pattern is first kept on the bottom board sand is poured on it and then the ramming is done in the drag.

Facing Sand: 

It is a specially prepared sand which is placed around the pattern which has superior properties with regards to refractoriness permeability etc. this will ensure better surface on the castings.

Coal Dust: 

The small amount of carbonaceous materials sprinkled on the inner surface of the moulding cavity to give better finish to castings.

Moulding Sand: 

It is a mixture of sicila, clay and moisture in appropriate proportions to get the desired results and it surrounds the pattern facing sand while making the mould. The moulding sand is the mixture.

Backing Sand: 

It is chat constitutes most of the refractory material found in the mould. This is made up of used and burnt sand.

Core: 

It is used for making hellow cavities in castings.

Sprue: 

The passage through which the molten metal from the pouring basin reaches the mould cavity. In many cases it control the flow of metal into the mould.

Runner: 

The passageways in parting plane through which molten metal flow is regulated before they reach the mould cavity through the In – Gate.

Ingate: 

The actual entry point through which molten metal enter mould cavity.

Riser: 

It is a reservoir of molten metal provided in the casting so that hot metal can flow into the casting when there is a reduction in volume of metal due to solidification.

Chill: 

Chill are metallic objects which are placed in the mould to increase the cooling rate of molten metal.

Moulding Procedure:

1. First a bottom board is placed either on the moulding platform or the floor making surface ever.

2. The drag-moulding flask is kept upside down on the bottom board along with the drag part of the platform at the center of the flask on the board.

3. Dry facing sand is spri

Precautions:

1. There should be enough clearance between the pattern and the walls of the flask.

2. The ramming of the sand should be done properly so as not to compact it too hard, which makes the escape of gases difficult.

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