Within the plastics manufacturing industry, there are plenty of manufacturing processes for the production of plastic products. The most important techniques in this market are additionally to rotational moulding; blow moulding, vacuum moulding and injection moulding.
Rotational moulding in short
Rotational moulding is the pressure-free heating of plastic powder in a mould into a shaped plastic product. In the production process a mould of aluminium or a sheet-form part is filled with thermoplastic powder (usually PE or PP), and then closed. The mould is heated in a large oven. By rotating, in two mutually perpendicular axes, the molten material is pressed against the mould wall and takes its shape. The product is then cooled and taken out of the mould. Through the process of pressure-free thermoplastic an impact resistant product is created, that is available in almost any shape. Production series range from 100 to 5,000 products per mould per year and have a weight between 0.5 KG to 300 KG
Rotational moulding vs. blow moulding
Blow moulding or blow moulding is another very popular method of production. Molten plastic is extruded into a preform. Pressurized gas – usually air – then presses the molten plastic into the mould until it cools and hardens. After cooling, it can be removed from the mould.
| Rotational moulding | Blow moulding | ||
| + | Pression-free product | + | Short cycle times |
| + | low investment costs | + | More materials types possible |
| + | Freedom of design | + | High level of detail |
Rotational molding vs. vacuum forming
In the vacuum forming, plastic foil is heated to the deformation temperature, for example, via an infra-red oven. The heated foil is stretched in or around a mould. A vacuum is created between the surface of the mould and plastic so that the plastic in the form of the mould is sucked out, the product is then force cooled.
| Rotational molding | Vacuum forming | ||
| + | Pression-free product | + | Short cycle times |
| + | Low investment costs | + | More materials types possible |
| + | Freedom of design | + | High level of detail |
Rotational moulding vs. Injection moulding
With injection moulding, molten plastic is injected under high pressure into a mould. By cooling the plastic solidifies, which obtains the plastic product. With injection moulding it is possible to produce complex parts. Because of the high cost of the injection moulding it is especially suitable for larger production quantities.
| Rotational moulding | Injection moulding | ||
| + | Low investment costs | + | Short cycle times |
| + | Thick walls possible | + | More types of materials possible |
| + | Easy to produce hollow products |
