Abrasive Wear Causes

1. Improper Component Materials

The failure to use wear resistant materials in barrel linings and screws allows the occurrence of abrasive wear at a much more rapid rate. Give us a call and we will be glad to discuss the different materials available.

2. Inadequate Screw Design

A screw design that is too aggressive, that is, compression ratio too high or transition section too short, can contribute to premature abrasive wear. An overly aggressive screw design can cause excessive shearing of the resin contributing to the scouring effect of abrasive, reinforced resins.

3. Incorrect Heat Profile or Heater Band Failure

Heater band settings that are too low in the feed and transition zones can cause too much shear in melting the resin. The excessive shear causes abrasive wear on the root and flight radii of the screw and on the barrel lining. The same condition can result from heater band failure where inadequate conductive heat is used to melt the resin. Many molders of reinforced material use a “reverse” or “hump” heat profile.

4. Excessive Back Pressure

In some cases, back pressure is used to compensate for an improper screw design in an effort to complete the melting of the resin. Excessive back pressure increases the scouring effect of the materials (especially reinforced resins) against the screw and barrel. It can also break glass fibers, creating parts with less than desired physical properties.

5. Failure to Use Magnets

Another form of abrasive wear occurs when foreign particles enter the barrel. The use of magnets, screens or filters can avoid the gouging and fracturing of components caused by processing nuts, bolts, pens, pencils, screw drivers and the like.

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