ATLANTA - Using polymers as carriers for molding metal parts is not a new process, but Endex Polymer Additives Inc. has added what it claims is a new way to make metal parts on traditional plastic injection molding machines. Gerry Mooney, president of the Ajax, Ontario-based additives and metal molding firm, said using Endex's metal-plastic injection molding compounds enables metal fabricators to avoid the costly, slow and painstaking work of molten metal casting, machining and finishing by creating finished parts on plastic molding equipment.
``The people who do metal casting seem excited about this,'' Mooney said in an interview at the Society of the Plastics Industry Inc.'s Structural plastics Division conference in Atlanta. ``Suddenly there is no need to burn off the plastic, shrink the metal part, to do sintering, or any post-mold work.''
Endex is offering three compounds that combine nylon with 93 percent copper, nylon with 90 percent stainless steel, and plastic with a 75 percent metal blend. The firm manufactures powdered metal products, including alloys, brass, copper, iron and stainless steel. Polymers used in the compounds include acetal, ethylene vinyl alcohol, high and linear low density polyethylene, nylon, elastomers and polypropylene.
``From those contents, you can see that the compound is essentially metal,'' Mooney said. ``Our metal powders are mixed with the plastic, and the metal is never heated enough to melt. Unlike other plastic-metal techniques, the plastic is never burned off, and serves as part of the finished part.''
The benefits are many, Mooney claims, including much shorter cycle times, multicavity production and huge volume, compared with conventional cast or molded metal production.
``We started out by developing this for bullets for the Canadian Army,'' Mooney said. ``The process worked, but the whole program of producing ammunition was unpopular and was eventually scrapped. We kept on and developed other applications.''
He said the company has made gears, bushings and internal parts for electronic and office equipment, aquarium heaters, electromagnetic shielding, buckles, trophies, cosmetics containers, urns, sprockets and self-lubricating bearings, among other items.
Endex's compounds come in pelletized form.
``We have found that the high metal loadings don't bother the molds,'' Mooney said. ``And in the past, even when you molded or cast plastic with metal, there would be sintering, or machining, or shrinking of the part that had to be done. Our compounds produce a finished part.''
