By Bob Lebeaux, President, The Plastics Group of America
October 13, 2009 in Polypropylene
Myth: Using glass-filled materials will rapidly wear out molds and molding machines.
Fact: Once the resin is melted, the wear is not much higher than for mineral-filled materials. However, wear will be higher in material handling systems where pellets abrade the lines and hoppers. Thicker transfer lines and gentle radii on all bends will minimize this issue.
Myth: Using glass-filled regrind from sprues, runners and bad parts will ruin the properties of the parts.
Fact: While regrind materials will have slightly lower properties, the molder can normally recycle all of the regrind if certain steps are taken. Regrind should be added back in evenly throughout the run, and, molds should be designed with no more than 20% of the weight in sprues and runners.