Rotational molding

Rotational molding, also called as rotomolding or rotocasting, is a plastic moulding process to produce hollow parts. This molding process is carried out without pressure and the mould is slowly rotated, usually around two perpendicular axes, are the basic principles of the process.

This operation consist on four stages:

1. Charging

Plastic material, normally in powder form, is placed into a mould. Then the mould is closed and rotated slowly on two axis.

2. Heating

The mould is then heated while rotating, until all the polymer has melted and adhered to the mold wall.

3. Cooling

Usually with air and sometimes a fine mist of water.

4. Demolding

When the material has cooled sufficiently, the process is stopped and the product is taken out of the mould.

The main advantages of this process are:

• Low tooling costs. As this is a casting process there is no pressure. This means moulds are inexpensive and low volume can be economic.
• It’s easy to make complicated shapes. Rotomoulding readily accommodates production complexities such as stiffening ribs, moulded inserts and different surface textures.
• Uniform wall thickness. Rotomoulding achieves consistent wall thickness with corners tending to be thicker. This increases product strength and integrity.
• Rotational moulding machine costs are low compared to other processes and the investment required is small.