Casting Processing

1.Preheating

Preheat prepolymer and curative to the suitable temperature. Make sure that the moisture of the curative is qualified.

Preheat mold to the suitable temperature. It should be noted that mold release should be spray on the mold before preheating.

Usually, TDS will give the recommend temperature.

2.Degassing

This process is to remove air bubbles from prepolymer and curative.

3.Mixing

The two components(prepolymer and curative) are mixed in a certain proportion.

4.Casting

Once the prepolymer and curative are mixed, a chemical reaction commences. In very hard materials the time available is very short.

5.Curing and Post Curing

The mold containing the polyurethane should be placed in an oven that is set to a temperature 5 to 10℃ higher than the casting temperature. The ideal temperature is the maximum the molding will reach. This will reduce the shrinkage in the mold.

The casting is kept in the oven long enough to develop sufficient strength to allow the part to be successfully demolded without any damage or distortion. The curing time varies depending on the chemistry of the system.