External Gas Moulding is a process often used for parts designed and manufactured by SPM. This process calls for a gas to be introduced in an external surface of the injected thermoplastic material, in order to compress it and to eliminate surface defects due to shrinkage.
The external gas moulding process can be summarized in the following steps:
- Closing mould
- Plastic injection
- High-pressure gas injection against the internal surface of the part
- The gas injected remains under pressure in order to compress the plastic until it is cooled
- The gas is released and then the mould is opened
The benefits of External Gas Moulding are multiple:
- Reduction in deformation
- Elimination of suction
- Reduction of injection pressure and therefore of the press tonnage
- Materials savings
- Energy savings
