POLYMER PROCESSING

Most injection moulding processes use a reciprocating screw injection moulding machine.
The reciprocating screw injection moulding machine uses a large screw inside a heated barrel to melt the plastics pellets, and convey the polymer melt. The screw typically turns counterclockwise, and the friction created by the screw pushing the material down the barrel causes shear heating.
Shear heating is responsible for most of the heat required to melt the plastics pellets. The rest of the heat is provided by the barrel heaters which enclose the barrel.
During injection, the reciprocating screw forces the polymer melt into the injection mould. As the melt is injected into the mould, the flow characteristics are dependent on the material’s viscosity.