Glass fiber manufacturing methods

Glass-mat reinforced thermoplastic (GMT) is similar to SMC and is available in sheet form, reinforced with random oriented fibers that may be continuous or discontinuous. It is manufactured on a double belt press where the glass fiber mats are sandwiched between layers of extruded molten polymer before it enters the press. The thermoplastic is usually about a few millimeters thick and thus stiff, and hence stored as fiat sheets. Another method involves deposition of a molten mixture of resin, chopped fibers, and additives over a moving belt where the water is driven off. The fiber volume fraction in this compound is usually 0.1-0.3 and fiber lengths are in the range of 10-30 mm, unless the reinforcement is continuous. 

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