Rotation Secrets
Polyethylene is the material mostly used for rotomoulding, with different physical properties for different kind of products, delivered in a fine powder. The grain size is 400 - 600 micron. Often the material is mixed in house with a colouring compound, also in a fine powder. Besides PE other materials are also used in rotomoulding, for example PP, PVC and PA.
The material is weighed carefully and will be placed in one side of the mould. The quantity of raw material determines the wall thickness of the final product, which varies between two and twelve millimetres. The mould is closed and starts to rotate around the horizontal and vertical axes. The rotating arm is placed into the oven, in which the material is heated with a temperature of 240 to 325 degrees Celsius. The raw material starts to flow and attaches itself to the walls of mould. After a while a uniform layer of material will be formed to the wall.
After the heating cycle the mould will be transported to the cooling bay. The mould is cooled by means of blowing air so the product hardens to be taken out of the mould. The rotation is stopped and the product can be demoulded.
