Changing your screens in the extruder may cause the melt temperature to drop, which can affect the shape of your product.

This is more commonly the case with flat or irregular profile shapes as opposed to circular dimensions, which are not usually affected by the change.

For example, in a flat die, a cooler melt temperature will cause the product to be thicker around the edges than in the center.

There’s ways around this problem; you can adjust the screw’s RPM or line speed and place a gear pump after the screen changer to help maintain a constant output through the die. This will help regulate your product dimensions. 

Click here to read about other factors that affect your extrusion process.