Bulk molding compounds variations

In larger-volume production, preimpregnated sheet compounds are used. The fabricator forms the sheet compound to shape and initiates the cure. These compounds are known as prepregs (preimpregnated materials), SMCs (sheet molding compounds), and BMC (bulk molding compounds). There are many variations within each group (Chapter 4). 

Complex reflectors within new vehicle headlamp assemblies typically must withstand temperatures of up to 400°F. Appropriate thermoplastic materials must be selected not only for the lamp backcan and lens, but also for the electronic/electrical connectors. Variations on filled polyester, poly(imides), bulk molding compound (a sheet molding compound [SMC] analogue), and nylon/poly(phenylene oxide) alloys are typically utilized in these applications. Poly(carbonate) (PC) or impact-modified PC is typically used in the lens applications where high heat is required. Acrylic plastics can and are most typically utilized in lens apphcations that do not require high heat, such as rear stop mount designs. 

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