Mark Jones
Compression moulding has been a commonly used approach to manufacturing rubber mouldings for many years. The process is simple, with raw rubber compound being placed into a heated moulding tool, with the mould then closed and pressure applied until the raw rubber material is compressed into the intended shape.
As with any manufacturing process, there are a number of pros and cons to compression moulding:
Compared with some other moulding processions, compression moulding is often less expensive as the tooling is cheaper and less complicated than in injection or extrusion moulding. Tools for compression moulding can usually be made from lower cost metals, for example, aluminium or lower grade steel, providing that they can withstand the pressure required for the process to be successful.
In order to reach the required level of pressure, the heated mould cavity needs to be overfilled. As a result, this does lead to waste material.
It doesn’t make sense to manufacture expensive tooling for small production requirements, so compression moulding is ideal. Whilst other moulding processes may achieve the same results, they are just not as cost effective as compression moulding.
Compression moulding is not a quick process – rubber is a poor thermal conductor so it takes some time for raw rubber compounds to reach the temperature required for the process to work. When moulding large parts where larger quantities of raw material is inevitably required, the time taken to complete a moulded rubber product is much longer. When a production run is only small, the time taken to complete the process is less of a problem.
There’s no limitation to the weight of raw materials that can be used for compression moulding, providing the tooling is big enough. In contrast, in injection moulding, the mass of rubber materials is much more limited as it depends on the volume of the injection barrel that is used to fill the mould.
If you need complex rubber mouldings, compression moulding is probably not the best suited process. As there is a limited flow of material inside the moulding cavity, air traps in rubber materials are more difficult to get rid of when attempting to produce more complicated moulding designs. On the contrary, compression moulding is ideal for larger, simpler rubber mouldings.
To learn more about which moulding process is best for your specifications, call CB Frost today on +44 (0)121 773 8494.
C B Frost & Co is an innovative and highly experienced rubber and plastics manufacturer and converter. Established in 1921 we have earned a reputation for our extensive product range, comprehensive...
