Compression moulding is a very popular method of producing plastic products as it provides many advantages over other methods of plastic manufacture. Plastics that, once heated cannot be reformed (also known as thermosetting plastics), are typically used for this type of production.

The raw thermosetting plastic, either in the form of small granules also known as resin or putty, are heated and poured into an open cast or mould.  Once the cast has been filled with the heated plastic it is closed and placed in an oven. A high pressure is applied until the plastic hardens and sets. It is then left to cool, sometimes in a cooling water bath or by blowing cool air across the plastic, until it completely solidifies. The plastic is then careful removed from the cast and ready for the final touches e.g. painting, waxing, etc.

There are many advantages to utilising the compression moulding process over other methods, for example, less material is wasgted. As the raw plastic is poured into the cast in a partially solidified state rather than a liquid state, it allows the manufacturer to measure the exact quantity of raw plastic required which reduces the amount of plastic that gets lost during the process. Another advantage to the manufacturer is that compression moulding is considered a relatively easy and quick method and does not require the use of heavy machinery and constant monitoring by a large number of staff. Again, this reduces the overhead costs for the business and the amount of waste during production as there are less spillages and leaks as the material moves from one machine to another ensuring that all the raw resin is used.

This process of producing plastics is used when very strong materials are required. Compression moulding of plastics was first developed as a way to produce materials that could be used as a substitute for metals. Due to the strength of the resultant plastics, they are usually produced to form parts for automobiles such as hoods, casings and bumpers as well as sports equipment and electric insulators. To increase the strength even further, metal inserts can be melted with the plastic and moulded together to produce an extra strong plastic / metal product. As with other casting methods, these can also be used to produce quite intricate details.  

Plastic companies utilise a wide range of production methods to create plastic products, each with a very different set of characteristics. You can find more information at Ensinger’s website, one of the leading plastic companies in Europe.