What is cold press moulding?

Fibres in the form of mats are placed on the mould and overlap at the pinch-off area of the mould. The resin used consists of two batches mixed together, one batch contains the catalyst and the other contains the accelerator. The resin is poured into the mould and the press lowered and the mould closed. The resin is forced to the edges of the mould but cannot escape due to the overlap of fibre at the pinch-off area. Over this area the fibre is compressed more than over the rest of the mould. The effect is that the resin is contained in the mould but air can escape, hence creating a back pressure that ensures the resin flows into all parts of the mould. A cold cure process is used (although some increase in temperature is common) with an accelerator in place to achieve cure within a reasonable time scale (e.g. ~15 minutes). The curing process is exothermic so that care must be taken not to degrade either the mould or the product.

The release method is the same as for hand lay up except that a high temperature release material may be required due to the exothermic nature of the cure process.

Continuous glass filament mat are generally used although woven roving and multi-axial reinforcements of both glass and carbon fibres are suitable materials for this manufacturing method. The resin are typically, polyester, epoxy and phenolic, the latter being used for more demanding applications

As the manufacturing pressures and temperatures are low, the tooling is relatively light duty and hence low cost. This method also allows for moderate production rates and can be considered for high volume production.

Some of the key points of this method include: