Compression Molding

Compression molding is a high-volume thermoset molding process that employs expensive but very durable metal dies. It is an appropriate choice when production quantities exceed 10,000 parts. As many as 200,000 parts can be turned out on a set of forged steel dies, using sheet molding compound (SMC), a composite sheet material made by sandwiching chopped fiberglass between two layers of thick resin paste. To form the sheet, the resin paste transfers from a metering device onto a moving film carrier. Chopped glass fibers drop onto the paste and a second film carrier places another layer of resin on top of the glass. Rollers compact the sheet to saturate the glass with resin and squeeze out entrapped air. The resin paste initially is the consistency of molasses (between 20,000 cps and 40,000 cps); over the next three to five days, its viscosity increases and the sheet becomes leather-like (about 25 million cps), ideal for molding.
SourceBook 2020
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SourceBook 2020

Welcome to the online SourceBook, the counterpart to CompositesWorld's annually published print SourceBook composites industry buyer's guide.
Article

Innovation in SMC: A long history and great potential

Manufacturer’s representative Steve Brown reflects on the history of sheet molding compound (SMC) development and lessons he has learned from working with companies through the process.
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CAMX 2019 exhibit preview: Macrodyne Technologies

Macrodyne Technologies Inc. (Concord, Ont., Canada) is featuring its compression molding, shuttle, single- and multi-opening heated platen presses.