Canadian Plastics

Vented molding eliminates drying

Using a specially-designed barrel and screw just 22 mm in diameter, a U.S. molding plant is molding gears from filled polycarbonate around the clock with excellent results and no pre-drying. The vente...

October 1, 2000   Canadian Plastics



Using a specially-designed barrel and screw just 22 mm in diameter, a U.S. molding plant is molding gears from filled polycarbonate around the clock with excellent results and no pre-drying. The vented screw, designed and built by Xaloy, is installed in a 30-ton all-electric Ferromatik injection molding machine at a Nypro Inc. facility in North Carolina. It runs a PC compound containing PTFE and carbon fillers in high-volume production of gears using a two-cavity tool with a 28 gram shot. Nypro had earlier tried to make the part using vented molding with other suppliers’ equipment but experienced problems with drooling and vent flooding, notes Jay Needham, molding group leader for Nypro Carolina.

The elimination of drying will save Nypro $7,000 a year on energy costs per machine. The use of the vented system also enhances the company’s ability to make quick changeovers of material, avoiding four to five hours of pre-drying.

The plant has ordered two more complete Xaloy vented screw/barrel sets and plans to evaluate the technology for processing other hygroscopic materials. Nypro has 24 molding plants in 11 countries with a total of more than 800 injection molding machines.


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