Author: haroonkhan

Sometime, it is impossible to use core print to support the core. In this case, a metallic support is used which is known as chaplet. Chaplet is made of same material as the material of casting. It gets fused with molten metal. Chaplets are placed in a mould between the mould face and the core…

Chills are used to improve the directional solidification with faster heat conduction by metallic chills; solidification is initiated and accelerated at desired locations. The thinner section of a casting solidifies earlier in comparison to thicker section, which results in distortion, internal stress set up, crack etc. Chills increase the solidification rate in thicker section and…

A network of passage of molten metal from pouring basin to mould cavity is known as gating system. It consists of pouring basin, downsprue, skim bob, runner, gate, riser, etc. A good gating system should have the following properties: Types of Gates Figure 20.16 Types of Gating Systems Risers Risers are provided in mould to feed…

At first, pattern is placed on moulding board, which fits the flask being used. The lower moulding box is placed on the board with the pin down as shown in Figure 20.15 (a). Moulding sand, which has previously been tempered, is filled over the pattern. The sand should be pressed around the pattern with the fingers…

Bellows: This is used to blow out loose sand from the cavities and surface of the mould. Slick: Slick is used for repairing moulds. It is a small double-ended tool having a flat on one end and a spoon on the other. It is also available in various shapes. Lifters: Lifters are used for smoothing and cleaning out…

Refractoriness: Refractoriness is a property of moulding sand due to which it can withstand high temperature of molten metal without fusing and burning. Permeability: Permeability is ability of moulding sand to escape vapour and gases formed during pouring the molten metal into the mould cavity. Due to lack of permeability there may be casting defects like blowhole,…

Mould making is a process of creating a replica of casting with the help of patterns and moulding sand. The cavity, produced in sand body, facilitates the molten metal to solidify and to take the shape of the cavity. Various types of moulding sands used in a foundry are classified as follows: Green Sand: Green sand…

Solid Pattern/Single Piece Pattern: A single piece pattern is used for a simple casting. In this pattern, no joint or partition is used. It can be moulded in a single moulding box as shown in Figure 20.4. Figure 20.4 Single Piece Pattern Split Pattern: If design of the pattern is not simple, it is difficult to withdraw as a…

The surface finish of the casting product may not be as good as required, therefore, extra dimensions in the pattern are provided. The extra dimensions or extra materials provided for the pattern are known as allowances. The following allowances are provided for pattern making: Draft Allowance: To exit out the pattern from the mould easily, the…

Pattern is a replica of the product, which is to be manufactured through casting. It is used to make a mould cavity of required shape and size. Various types of pattern materials such as wood, aluminium, steel, plastic, and cast iron are used in sand casting. The selection of pattern materials is based on their…