Rubber moulding is a method of adding heat and pressure to uncured rubber in order to produce a useable rubber product.
There are basically 5 elements in the moulding process:
- Uncured rubber
- Cure time
Heat and pressure force the uncured rubber into the mould to make it conform to a specific size and shape. The curing of rubber is a process called vulcanization.
Vulcanization is necessary to convert natural rubber into a more durable material. The combination of heat and certain curatives (like sulphur) make natural rubber stronger and more elastic.
The two methods of rubber moulding are:
- Compression moulding is the original production method. Rubber preforms are placed manually into a preheated open cavity. Then hydraulic pressure is used to close the mould allowing the preforms to cure inside. Once the curing time is up, the moulds are opened, and the cured rubber removed. Compression moulding is cost-effective for low quantities and when bonding rubber to metal.
- Injection moulding for rubber is based on the method invented for the moulding of plastics. Instead of preforms, pre mixed rubber strips are fed automatically into the machine. Production volumes are much higher and the quality is more consistent.
Rubber types used at Timbren:
- NATURAL - usually in the range of 45 to 85 durometer.
- SBR (Styrene Butadiene Rubber) - ranging from 50 to 60 durometer.