Cooling plastic pipe and profiles has always been a challenge, and never more so than at today’s extrusion rates, which can be in excess of 1500 lb (682 kg) per hour. When determining how best to cool extruded products, we need to look not only at the material, but also the wall thickness and even the geometry of the extrusion. There is a big difference between cooling a window lineal profile, with wall thicknesses of a few millimeters, and an inch-and-a-half-thick piece of wood composite deckboard.
Today’s high-productivity extrusion operations have come a long way from the days when profiles were cooled in nearly static baths of city or well water, with water being drained to the sewer after extracting as much heat as possible. Water-supply and disposal charges were enough to nearly end this practice, even before productivity issues made a more intelligent approach a necessity. With the help of downstream extrusion system experts like Conair, extruders are calculating exactly how much heat needs to be removed — and how quickly— in order to operate both successfully and profitably. You might think the secret would be found in getting the water as cold as possible. And you might be wrong. In fact, it’s a whole lot more complicated than that.