Moulding refers to a manufacturing process which involves the shaping of material using a rigid frame called a pattern. Extrusion moulding uses this process to create tube-shaped objects from a variety of materials.
Extrusion moulding extrudes, or forces out, materials through a die to create such products as hoses, drinking straws, rods and pipes. A die is a manufacturing tool used to shape or cut material via a press, or machine that uses pressure to compact or otherwise reshape an object.
Extrusion moulding is done via an extrusion machine. The machine motor turns a screw, which feeds plastic through a heater. The granules in the plastic melt into liquid, which is pushed through the die tool. This forces the material into a tube shape determined based on the specific shape of the die. The material forms a solid tube shape after cooling.
Extrusion Blow Moulding
Extrusion blow moulding refers to a specific extrusion moulding process used to create hollow plastic objects. A hole is cut in one end so that compressed air can pass through the plastic before it is melted down via the standard extrusion process. Pressurized air is forced through the heated, tube-shaped plastic until it cools.
Read more: What Is Extrusion Moulding? | eHow.com