Define Fabrication. List the methods used. Discuss extrusion moulding in detail.
Fabrication of plastic is the technique of giving any desired shape to the plastics by the use of mould. Because of the properties of polymers it is possible to mould them and change their shape using a number of different repetitions manufacturing processes. A proper method is to be selected depending upon the shape and type of resin being used. Before moulding ,it is essential to dry the resin in order to achieve optimum performance of finished products.
The methods used are:
1. compression moulding.
2. transfer moulding.
3. extrusion moulding.
4. injection moulding.
The thermoplastic materials are moulded by this method. They undergo continuous moulding to from articles of uniform cross-section. These articles include tubes, rods, strips, insulated electrical cables, etc. In this method, thermoplastic materials are heated to plastic condition and then pushed by means of a screw conveyor into a die having the required shape of the article to be manufactured. Here the plastic mass gets cooled due to the atmosphere exposure. A long conveyor carriers away the cooled product continuously.