BMC thermosetting material mold design point of attention
Since the flow behavior of hot plastic melts is very different from that of thermoplastic melts, the corresponding molds are also different. The flow of the thermosetting plastic melt is similar to the Bing flow. The casting system requires a small flow resistance, and in order to accelerate the curing speed in the cavity, the molding cycle is shortened, and the temperature needs to be raised appropriately during the flow. The difference between thermoset plastics and thermoplastic injection molds is mainly manifested in:
a) The design of the flow channel is different in terms of main channel, runner, cavity position, gate location, gate size and shape design.
b) The thermosetting plastic injection mold must be equipped with a heating device and a temperature control system to facilitate the smooth chemical change of the material in the mold.
The molding temperature is the type of material, molding pressure used, complexity of the product, wall thickness, control of shrinkage, flow conditions, And presence or absence of preheating.
The temperature is high, the curing speed is fast, and the production efficiency is high; and in order to obtain a good surface quality, a lower temperature is used, especially for molded products that require slow closing of the mold. However, the low Temperature and long material flow time will slow down the press forming process. In order to prevent the appearance of cracks on the surface of the product, for some deep cavity, complex shape and thin walled products, low temperature molding conditions are needed.
In general, the upper and lower molds usually need the same temperature, but sometimes the temperature of the mold halves should be different in order to facilitate the removal of the products or to selective make the molds appear to be needed for the mold release. In General, it is desirable that the temperature of the mold half on which the product can be held should be about 5-15°C lower.