How to Identify Causes of Extrusion Barrel Wear

Since a single plastic extruder for a plastics manufacturing line costs tens of thousands of dollars or more, it is essential to find the root cause of excessive wear as soon as possible to avoid damaging this expensive equipment. Here are some simple steps to do just that.

things you'll need:
measurement tools that measure to thousandths of an inch or millimeters

1. Measure the surface distance of the screw from the shaft. If the screw is bent, then it will cause plastic to flow at excessive pressure in a direction the equipment is not designed to have, wearing the screw barrel with the fluid flow of molten plastic. Imagine a river carving a canyon, but this is very hot molten plastic wearing out metal.

2. Measure the barrel for straightness. It it was dropped during installation, dropped, rotated and warped by a motor or otherwise bent, the extruder screw itself may be wearing against the plastic extruder barrel.

3. Check the alignment of the extruder shaft and the gear reducer. If the extruder screw is at even a slight angle in any part of the barrel rotation, the barrel gets excessive wear. This will occur whether the screw comes into contact with the barrel or the more narrow gap than designed during plastics extrusion causes extra pressure on the molten plastic to deform the extruder barrel.

4. Measure the pressure inside the screw channel. A rapid pressure rise in screw channel, resulting in a pressure forcing the screw sideways, causing it to deform.

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