sheet extrusion flat die

So it’s time for you to buy a new sheet extrusion flat die. What do you need to know to about current die design technology to make sure you get what you need and want from your supplier?

The purpose of a sheet extrusion flat die, of course, is to deliver a uniform flow of polymer across the exit of the die lip so that the film or sheet product is flat and the gauge is uniform. Because the die is “just a nozzle”—it simply takes what comes in and shapes and discharges it—it’s designed to “leak” uniformly. The ability of a die to deliver a uniform flow rate across the die lips is based on the internal shape and structure of the die. In so-called coat hanger dies, the shape of the triangular dam between the manifold and the exit, and the change in manifold diameter, determine the uniformity of flow. Alternatively, in an inverted preland die, the shape of the preland step determines the uniformity of flow across the die face.