Several casting processes are widely being used in the manufacturing industry for bulk production of a product. Casting processes have the advantage of the elimination of some steps in certain castings such as welding, machining, and forging. Casting is the only technique for some metals due to their unique properties.

Basics Of Casting

Casting is one of the important and useful techniques of the manufacturing technology that is normally utilized for the bulk manufacture of components. The materials are poured in a molten state in a mold where their solidification occurs. This technology is highly useful for economic and rapid manufacture of parts that would require a lot of time if produced by other manufacturing processes like cutting or shaping. Casting processes are utilized for manufacture of a huge range of components that are utilized in various engineering concerns, including small toys and huge turbine blades.

Choosing A Casting Process

A large variety of casting processes have been developed that are designed according to several engineering factors that must be taken into consideration, including the following:

• Number of castings required

• Material to be used for the component

• Cost of production

• Precision of manufacture desired

• Requirement of surface finish

• Processes Of Casting

Over a period of time several casting processes have been introduced in the manufacturing industry that are utilized by taking into consideration the engineering factors already mentioned. The processes normally used for the manufacture of parts are:

Sand Casting

The technique of sand casting is old and generally utilized for the manufacture of huge components by pouring a metal in molten state into the cavity of mold that has been formed from synthetic or natural sand. The creation of cavity is an important function of sand casting process, and accomplished by the use of a pattern that is normally made of metal or wood with dimensions and shape similar to the real part. The dimensions of the pattern are slightly oversize, and therefore the cavity is also larger to balance the reduction of the molten metal while it cools. Sand castings produce components with a rough surface finish including impurities, due to which an allowance for machining of the part is included.

Die Casting

Die casting is used for the manufacture of components that are identical and possess a high degree of accuracy in dimensions. The surface finish of parts produced by die casting is so good that some parts may even not need machining after casting or may involve only slight machining to attain the desired dimensions. However, porosity defects in die casting are more if the size is large because of the air that is entrapped, and secondly since the melt solidifies before it can reach the cavity boundaries. Parts that have an equal thickness of wall can be produced with an increased accuracy by die casting. Molds used for die casting are expensive because these are manufactured from hardened steel, and speed of production is slow.