Computer Modeling of Automatic Extrusion Die Response, 1997 Polymers, Laminations & Coatings Conference Proceedings

In Automatic Profile Control (APC), a scanning thickness gauge is used to register cross web graphical data. This data is processed by computer algorithms which generate an array of power levels. Each power level is transmitted to a thermally expanding diebolt on an extrusion die. Each diebolt is in contact with the extruding lip, and so can influence the extruded thickness at the point of contact. The objective is to achieve a flat product across the web, although in some cases, bumps are programmed into the material to tighten the edges of rolls which are to be split. Gauging systems with APC have been offered by several gauging companies for about 20 years. Most APC systems are installed on flat film extruders, although with reducing prices for gauging systems, it is now economically feasible to install APC systems on blown film lines. These can use thermal dies or, in some cases, an air ring system is used to adjust the profile of the product.