Swell and Shrinkage During Extrusion
Swell (or die swell, extrudate swell and Barus effect) is a common phenomenon in polymer manufacturing. It occurs due to the material attempting to return to its original shape after having been compressed by entrance into the die. Factors that affect the swell of the material are:
- Rheological characteristics of the material.
- Shape of head and extrudate.
- Pressure in the head.
- The head and compound temperatures.