What is Rotational Moulding?
Rotational moulding is a unique plastic moulding process used primarily to create seamless, stress-free, hollow one-piece items. Also called rotomoulding, it is a high temperature, low pressure manufacturing method that combines heat and bi-axial rotation. Typical moulded parts can include parts such as containers, canoes, tanks, children's toys, medical and industrial equipment, and automobile parts.
Proponents of the rotational moulding process point to its low production cost and unlimited design possibilities. Offering designers the opportunity to manufacture stress-free parts with uniform wall thickness and complex shapes, rotational moulding is a competitive alternative to blow moulding, thermoforming and plastic injection moulding. It produces little waste since the required weight of plastic to produce the part is placed inside the mould. Yet some critics point to its longer cycle times, where only one or two cycles per hour occur, and prefer faster manufacturing processes.
The Process of Rotational Moulding
The process of rotational moulding begins with filling a hollow mould with a quantity of powder resin (polymer). More often than not this powdered resin is polyethylene although other compounds such as polypropylene, PVC, and nylons can also be used. The mould is then heated at high temperatures in an oven and bi-axially rotated as the polymer melts and coats the inside of the mould.Learn More
The History of Rotomoulding
The development history of Rotomoulding is a long one, dating back to the Egyptians who used rotational casting processes for creating ceramics. Moulding processes were used hundreds of years ago by the Swiss to make hollow chocolate eggs. In modern times, somewhere between 1940 and 1950 in the USA, the rotational moulding process was developed for a small number of plastics but its popularity did not take off because it was regarded as a slow process.Learn More