Ejot GmbH & Co. KG has introduced its first plastic screw.
The Bad Laasphe, Germany-based company showed a plastic version of its established Delta PT metal screw series at K 2010, held Oct. 27-Nov. 3 in Dusseldorf.
The new Delta PT self-tapping plastic screw, which has significantly lower strength than steel, is designed for direct assembly into thermoplastic materials, such as nylon 6, polypropylene, ABS, acrylic or polyoxymethylene, the firm said.
The screw is injection molded of EMS Grivory HTV-5H1, a 50 percent glass-fiber-reinforced polyphthalamide based on a semi-crystalline, semi-aromatic co- polyamide.
A major advantage of the plastic is weight savings, with a typical Delta PT plastic screw weighing 1.1 grams, vs. 1.83 grams for aluminum and 5.27 grams for steel-screw equivalents.
Other advantages include ease of producing screws in variable lengths, high insulation properties and a coefficient of thermal expansion close to that of the plastic parts being fixed by the plastic screw.
A particular design feature involves combining the screw thread on one side with a central spanner-tightening head section and an integrated snap-fitting hinge on the other, all molded as one part in the same material.
At K, the screws were being molded on a Babyplast micro injection molding machine at Barlog Plastics GmbH's stand. Barlog, of Engelskirchen, Germany, is a plastics materials distributor and compounder of engineering plastics with in-house product development, prototyping and pre-production at its BaHsys subsidiary.
The Ejot screw is the latest of numerous metal-replacement parts developed by Barlog and Bahsys. Others include sanitary fittings, water meters and castors for hospital beds.