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Surface appearance, Take One: Piano-black PC/ABS parts with no painting

Article-Surface appearance, Take One: Piano-black PC/ABS parts with no painting

MPW caught up with French company RocTool at December’s Euromold trade show in Frankfurt, where the company came to draw attention to the new trick—injection molding—it has taught its inductive heating system.

MPW caught up with French company RocTool at December’s Euromold trade show in Frankfurt, where the company came to draw attention to the new trick—injection molding—it has taught its inductive heating system.

RocTool emerged almost a decade ago at the JEC composites show in France, and until recently its technology for rapidly heating a mold’s surface to high temperatures using an inductive heating method patented by the firm has seen use only in some composite plastics processing.

But Matt Boulanger, the company’s business development manager, told MPW at Euromold that the company has optimized its technology for the injection molding market, where it sees great potential and in which interest already is high. Indeed, the week after Euromold, Boulanger started a multicity tour of the U.S., visiting potential customers interested specifically in what the technology could mean for injection molding. (For more on the firm, a good start is our June 2004 issue, p. 48, or search our website.)

Top photo: A Cage System is shown attached to the rear of an injection
molding machine.

Above: RocTool bets its mold heating technology will attract processors of parts requiring a great surface finish.

What it could bring to molders, said Boulanger, is the ability to process very high-quality parts of very high-temperature materials with very thin walls with very tight control of temperatures, so that in many cases there is no need for painting or coating parts after molding. The key is that the Cage System, as RocTool’s mold heating technology is known, only heats the surface of a mold, but does it very rapidly. Because only the surface of the mold is heated, cooling also can be done rapidly. The combination of the two helps prevent warpage and makes for better surface appearance. “We’ve molded PEI (polyetherimide, a very viscous thermoplastic) parts at just 1-mm thickness but with good surface appearance,” he said. No mold preheating is necessary, and molding machine pressure typically can be reduced by up to 30%, he added. 

At the firm’s Euromold stand he showed MPW two automotive interior parts, molded on the same mold but with one heated/cooled via RocTool’s Cage and the other using standard technology. Both parts were molded with a single gate. The part formed on a Cage-heated mold more accurately reflected the mold’s surface, with the part matte where it was supposed to be and glossy where it was intended. The other part’s matte-like appearance wasn’t very matte at all. “Tier Ones and OEMs see the chance for better surface quality,” Boulanger said.

“The tool design has to be optimized” to work with the Cage system, Boulanger notes, especially with regard to where cooling lines need to be placed and what sort of steel should be used. The method of attaching a Cage system to an injection mold, so that the mold is inductively heated, also is part of RocTool’s intellectual property. So far there appears to be about a 10-second cycle-time penalty when switching from an established mold to one heated via RocTool’s Cage, so clearly the technology will not see use in swift-cycling packaging applications. Current licensees of the technology include two French molders, Group Dedienne Plasturgie (Dedienne) and Plastivaloire (PVL), Europe’s largest molder of television frames. Automotive parts processor Visteon was the first to show interest in the injection molding technology and had an exclusive license for a short time, as did Didienne, but the exclusivity of both has expired.

Last October RocTool displayed the process on a Billion injection molding machine at Pôle Européen de la Plasturgie (PEP), a French technology center in Oyonnax, the center of the country’s processing industry. Boulanger showed MPW video of the event, attended by 250; presenters included experts from Dow Chemical, DuPont, and PVL. PVL showed attendees large, glossy, ‘piano-black’ PC/ABS frames it molded, and did not need to paint, which met customers’ requirements. He said Dow, DuPont, and other resin suppliers already have shown interest in developing materials specifically for the process. Boulanger added that RocTool is keen this year to find a similar technology center in the U.S. where its technology can be demonstrated, but where its IP is guaranteed protection. The firm also has contacted the Society of the Plastics Industry, asking after space at the association’s NPE 2009 exhibition in Chicago in June. The firm currently is recruiting a sales manager for North America. 
On the business end, RocTool can sell a test license to a processor and help it make a prototype/pre-series mold equipped with the Cage heating system. Once the mold and process are optimized, the processor then can acquire a full production license. “We want to license to good processors,” Boulanger stated.—[email protected]

Click here to read about another outfit who makes the same claim.
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