The process is different from thermoplastic injection moulding. In this the injection cylinder is cooled instead of heating. A plunger injects the compound into the mold cavity. The heated mold activates the thermoset cure chemistry.
The advancements and tech improvements are increasing the capability and productivity. This cold runner technology, gate cutters, die electric analysis and transducers holds promise of increasing yield. The parts which are molded, degated, deflashed and packaged automatically, the uses are becoming more frequent. This cold runner manifolds eliminate scrap runners. The wastage is minimized to the extent of 50% and even more of the thermoset shot weight parts produced traditionally.
The traditional designs require finishing after ejection. Only a manual labor is enough to separate the curved runner system and to grind down witness marks. Incorporating in mold gate cutters improves quality. For the large gate designs it gives less glass fiber breakage with high performing parts.
The quality and consistency are optimized with dielectric analysis monitoring the rate and cure of thermosetting materials. Thus precise control of mold pressure can reduce scrap rates, secondary operations eliminating land flash and preserves in mold detail.
Also known to be as bulk molding compounds it persists several properties that are attractive to automotive, electric and appliances markets.
It is heat resistant
It possess dimensional stability
It has the chemical resistance
Possess load bearing capability
Less susceptible to chemical attacks
Thermoset resins can retain their performance at higher temperatures than thermoplastic resins. However, these are reinforced thermoset polyester resins containing a catalyst that have a finite shelf life and even the resins cannot crosslink to the same degree. The resins are brittle comparatively to the thermoplastic materials. Though it is an advantage that thermoset scrap can be recycled but it cannot be reground and reused. Also it requires as milling operation prior to reuse. It requires a special stuffing mechanism on the injection machine for automatic molding.