Auxiliary equipment supplier ACS Group is marketing Eriez Manufacturing Co.'s new PolyMag technology for magnetically separating valuable resins from multimaterial parts - where one resin has a small amount of magnetic additive molded-in.
Headquartered in Erie, Pa., Eriez is known for its separation equipment using magnetic metal detection, vibration feeding and screening, and large magnets to move around hunks of metal. With PolyMag, the company is moving into automated plastics recycling by making the plastic itself magnetic.
John Collins, manager of the PolyMag Division, said the market for the plastics separation equipment is growing right along with the growth of two-shot injection molding, overmolding, coextrusion and suction blow molding. Each process creates parts using two or more types of plastic.
PolyMag can separate out the more-expensive resin - for example, a flexible thermoplastic elastomer molded as a sealing gasket onto a larger part made from a commodity resin, Collins said.
One obvious market is automotive molding, with large-volume production and complex parts that combine several materials, he said. The transportation segment accounts for about half of all TPE sales, Eriez said. But company leaders expect other markets to emerge as PolyMag becomes more well-known.
``We're in the pioneering stage. People aren't aware yet that this technology is there,'' Collins said.
But he said two-shot molders are open to new ideas. ``I see some of the most progressive molders are getting into this [two-shot] first. They know about product design and tooling design,'' he said.
Eriez sells both the PolyMag additive and the separation equipment, which uses a series of disc-shaped rare-earth magnets arranged on a roll.
Eriez officials outlined PolyMag in a Jan. 4 interview at Plastics News' Akron office. The company was awarded U.S. patents on the process in mid-2005.
Collins said the key innovation is metering just a tiny bit of the additive into one of the resins, at the rate of about 1 percent by weight. The amount of material - either iron oxide or magnetic stainless steel, with a wax carrier - is so small that it does not degrade properties of the molded part, he said. Also, PolyMag does not make the plastic electrically conductive.
The additive is blended in using a standard additive feeder located below the material feeder.
During molding, scrap parts are run through a standard grinder, then the material is fed to the PolyMag separator. An Eriez vibratory feeder conveys the material over the magnetic roll. Untreated granules pass over the roll and move on, but the material treated with the additive clings to the magnet, through the Kevlar conveying belt, and passes underneath, where it is removed by a splitter.
The material then can be moved back to the molding press. Plastic parts that use chemically bonded materials may require a second pass over the separator, or a fine-particle grind.
Eriez ships PolyMag additive in 25-pound bags. The portable press-side separator, with a separation capacity of 175-500 pounds an hour, sells for $21,900. Eriez also offers a model with two magnetic rollers that can separate regrind with three components.
The company also recently announced a 24,000-square-foot expansion at its headquarters plant in Erie, which now totals 100,000 square feet. Eriez officials will break ground this spring.
Tim Shuttleworth, president and chief executive officer, said plastics processing has been a fringe market for Eriez. ``But we want with PolyMag to grow in plastics,'' he said.
ACS of Wood Dale, Ill., said PolyMag complements its line of materials-handling equipment and granulators. ACS will sell other Eriez products such as metal detectors, gate and hopper magnets, bin vibrators and vibratory feeders.
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