The basic requirement that moulding materials must meet are-

• Refractoriness to withstand the pouring temperature
• Cohesiveness to retain the moulded shape.
• Permeability to permit gases to escape
• Collapsibility for easy removal of casting

Pattern and mould-

A pattern is a replica of the desired casting and is used for making the mould cavity. Various types of patterns are used in casting - the choice depending upon the production quality and the casting configuration. Single-piece patterns are obviously least expensive but have limited applications. Split patterns or two piece patterns are most widely used since it can be easily withdrawn from the mould and can be used for intricate shapes.
Patterns are always made somewhat larger than the final casing to allow for shrinkage, distortion and finishing. These are taken care by shrinkage, draft, finish, distortion and shake allowances.

Metal Casting-

Casting is the oldest and perhaps the most popular mean of producing the desired shape. The final product or the casting can be made from any metal that can be melted and have virtually any configuration. Castings have been produced in sizes varying from few millimeters to several meters and can weight from few grams to several tons.
The process basically involves melting and superheating the raw material up to the desire temperature. The molten metal is then allowed to solidifying in the mould cavity and on cooling, the product is taken out to get the casting. Several casting processes have been developed over the years - each having its own characteristics, applications, advantages and limitations.

Casting-

In casting processes the liquid metal is poured into the mould cavity of desired shape which on solidifying takes the shape of the cavity. Sand casting, investment casting, die casting and continuous casting are some of the commonly used casting processes.

1) Process-type manufacturing-

It involves continuous processing, that is the material goes through a series of process steps in a continuous manner which eventually gives the finished product. This type includes production of raw material and chemical products. The fabrication-type manufacturing involves production of discrete components and is achieved by changing the raw material into a final product using manufacturing processes and assembly operations.
The manufacturing processes that are used in fabrication-type manufacturing can be classified into five broad categories-
a) Casting
b) Forming
c) Machining
d) Welding
e) Heat treatement