Compression moulding is used for the precision moulding of parts made from plastic and rubber. The preheated material is placed into an open mould cavity, which itself is also heated to soften the material further. The upper mould half is then pressed down to meet the bottom mould half, compressing the material to fill the entire cavity.
Once the material has cooled and solidified, the mould tool is opened and the components retrieved. Parts produced by compression moulding will often have 'flashes' - excess material that will need to be removed post-production. However, despite higher levels of material waste, the associated tooling costs are less for compression moulding than other moulding methods, which makes it a good option for low-volume requirements.
Compared to injection moulding, compression moulding is a slower process, which is compounded by the frequent need for secondary operations. It is also generally unsuitable for more complex shapes. Nonetheless, it remains a popular choice for producing simpler components from rubber and plastics such as PEEK, HDPE, silicone and PTFE.
Used to produce
Simple moulded shapes in low or high volumes.
Various grades of rubber and plastic such as PEEK, HDPE, silicone and PTFE.
Lower tooling costs make it suitable for low-volume production.
Migration of material is hard to control, resulting in 'flashing' and more material wastage.
Unsuitable for complex components.
Slower production process than other moulding techniques.