The Rotational Moulding ProcessThe typical rotomoulding process explained
The Rotational Moulding Process
The rotational moulding process, or rotomoulding process, consists of 4 separate operations:
Loading the mould
The process begins with filling a hollow mould with a pre-determined quantity of polymer powder. The oven is preheated. Temperature ranges from 260 °C – 370 °C, depending on the polymer used. Once the powder is loaded, the mould is closed using over centre clamps, and loaded into the oven.
Depending on the oven size, several moulds can be moulded at the same time.
Inside the oven the mould is rotated, as the polymer melts and coats the inside of the mould. The rotation speed is slow. During this phase of the rotational moulding process timing is critical. Real skill is involved in the cook time, shielding mould areas from over cooking or preheating areas to prevent polymer thinning.
Once the heating cycle has ended, the mould is removed from the oven and the cooling cycle begins. Generally moulds are air cooled.
Once the mould is cool enough the mould is opened and the plastic product removed. The product (moulding) will continue to cool.
The whole process now starts again.