Injection molded glass fiber/TPs

Table 5.29 Problem/fault vs. solution/correction of injection molded glass fiber/TPs...

Injection molding The RTPs (reinforced thermoplastics) are practically all injection molded with very fast cycles using short glass fiber producing highly automated and high performance products. The TPs used include nylons, acetals, polyethylenes, and polypropylene. Of all the RP materials used, about 55wt% represent these RTPs. 

The process of injection molding (IM) is used principally for processing unreinforced or glass fiber reinforced thermoplastics (TPs) and thermosets (TSs) (Figure 4.1). Up to at least 90wt% of all plastics processed are TPs. There are many different types or designs of IM machines (IMMs) that permit molding many different products based on factors such as quantities, sizes (such as auto bumpers to medical micro products), shapes (simple to complex), product performances, and/or economics.1,150>157,173 176 476... 

Reinforcements usually come in continuous or chopped fiber forms as in woven and nonwoven fabrics. Both thermoplastic (TP) and thermoset (TS) resins are used in RPs (Chapter 3). At least 90 wt% of all RPs use glass fiber (E-type) materials (Chapter 2). At least 55 wt% of all RPs use TPs even with their relatively lower properties compared to reinforced TSs (RTSs). Practically all reinforced TPs (RTPs) with short or long glass fibers are injection molded at very fast processing cycles producing... 

As explained in the previous major section on injection molding, most IM parts are made from TP, and some of TP uses milled glass fibers to improve part performance. Other fibers have seen limited use to date. TS compounds usually include reinforcements. 

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