Is vacuum calibration tooling something new?
Vacuum calibration tooling has been used in the manufacture of plastics since the 1950s, however, many improvements in tooling have been introduced in recent years. The tooling is built with channels to create a path for air (vacuum) and a series of ducts to allow for the flow of coolant. PVC, Polyethylene and most thermoplastic resins are assisted by a vacuum that is applied to the external surface of the extruded profile while it is drawn through a calibrating tool. During this step, the profile is formed and the surface of the extrusion is cooled indirectly by water flowing through channels in a calibrating tool. This process is most often used for tubular extrusion, where the key issue is the assurance of roundness. It is also used when a true 90 degree angle must be maintained. This entire process is often referred to as vacuum calibration.
