Rotomoulding, or rotational moulding, is a process of manufacturing various components from plastics. The basic advantages of rotomoulding include very low internal stresses in the products and relatively low costs of the tooling: the mould.
Rotomoulding has found a wide variety of practical applications. Rotomoulding is feasible for containers and tanks used for water, fuel or oil, with a capacity ranging from millilitres to thousands of litres; recreational and sports articles, including kayaks, boats; plastic playground furniture, including slides and swing seats; gardening products like pots and decorations; and automotive parts, such as canopies, wheel arches, consoles and boards; as well as machine enclosures, and much, much more.
Advantages of rotomoulding:
- Zero pressure strain (due to zero internal stress from moulding)
- Low mould fabrication costs (in comparison to other plastic moulding processes)
- Feasible for moulding very large components of complex geometry
- Feasible for the production of plastic articles with embedded metal parts (threaded pins, inserts, etc.) for further assembly or outfitting
- Multi-layer moulding
- Cost-effective in large and small production runs
- Quick mould retooling
- Easy colour changeover
- Feasible for production of hollow products without any additional processing required
- Short mould fabrication times
- Zero to minimal material loss during the production process
- Feasible for the production of different products using the same machine
In the rotomoulding process, a defined volume of plastic material (granulated, powdered or liquid) is charged to an empty product mould. The mould is spun around two perpendicular axes.
The mould is heated at the same time, until the molten plastic adheres in a solid layer to the mould walls and takes the shape of the mould. The mould is then spun in a cooling operation. Finally, the mould is opened to remove the finished product.
Rotomoulding is quite demanding at each process step, from mould fabrication to material selection and the correct performance of the rotomoulding operation itself.