Many polymer-forming processes are essentially two-stage; the first stage with polymers being the production of the polymer in a powder, granule or sheet form and the second stage being the shaping of this material into the required shape. The first stage can involve the mixing with the polymer of suitable additives and other polymers in order that the finished material should have the Laundry basket mould required properties. Second-stage processes for thermoplastics forming generally involve heating the powder, granule or sheet material until it softens, shaping the softened material to the required shape and then cooling it. For thermosets the second-stage processes involve forming the thermosetting materials to the required shape and then heating them so that they undergo a chemical change to cross-link polymer chains into a highly linked polymer. The main second-stage processes used for forming polymers are:
Plastics Moulding
This includes injection moulding, reaction compression moulding and transfer moulding.
Plastics Forming
This includes such processes as extrusion, plastic vacuum forming, plastic blow moulding and calendering.
Plastics Cutting
Injection moulding,
In addition, products may be formed by polymer joining. The processes are:
Adhesives, Plastic Welding,Fastening systems such as riveting, press and snap fits and screws.
The choice of process will depend on a number of factors, such as:
The quantity of items required The size of the items
The rate at which the items are to be produced, i.e. cycle time The requirements for holes, inserts, enclosed volumes, threads Whether the material is thermoplastic or thermoset
Plastic Injection moulding
Moulding uses a hollow mould to form the product. The main processes are injection moulding, reaction injection moulding, compression moulding and transfer moulding