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The Plastic Extrusion Process
Custom sheet extrusion is the process of converting plastic pellets into cut-to-size sheets or rolls of plastic through a combination of heat, pressure, and specialized equipment. This plastic sheet can then be further processed into parts via thermoforming, or printed, or die-cut, etc.
Extrusion through a flat die onto highly polished steel chrome rolls (usually positioned in a 3-roll stack) is the most common technique used for making thermoplastic sheet.
The process is fairly simple; resin is fed into an extrusion machine where it is melted. The extruder, consisting of a heated barrel with an internal rotating screw, pumps the melted polymer into a flat sheet die, which "sizes" the sheet to a general thickness and width. Plastic sheet exits the die in a semi-viscous state and travels through a series of rolls to cool and further size the thickness and width. At the end of the machine center the plastic sheet is either cut to a specific length and width or wound into rolls for subsequent use by the customer.
Additional detail is provided as follows:
– General Overview of Extrusion Process
– Four Basic 3-Roll Stack Configurations
