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RocTool, German institute work together on inductive heating

Article-RocTool, German institute work together on inductive heating

One of the more significant developments at the Fakuma tradeshow earlier this month likely fell below most processors' radars as the developers of two technologies for inductive heating of injection molds agreed to partner, a move that could encourage the technologies’ already swift-growing acceptance.

One of the more significant developments at the Fakuma tradeshow earlier this month likely fell below most processors' radars as the developers of two technologies for inductive heating of injection molds agreed to partner, a move that could encourage the technologies’ already swift-growing acceptance.

There was reason for concern as both have interesting but similar technology, similar enough that a patent dispute could have ensued and prevented the processing community from showing interest in either. Instead, the two—RocTool (Le Bourget du Lac, France) and Germany’s plastics institute in Lüdenscheid (German acronym KIMW)—will work together, with RocTool acquiring the KIMW’s patents and the institute agreeing to continue its development work while also promoting both outfits’ products in Germany, Europe’s largest injection molding market and one open to innovation.



Joining KIMW’s Stefan Schmidt (center) and RocTool’s Alex Guichard (right) is Korbinian Kiesl, owner of injection molding machine maker, Billion, which hosted RocTool at its stand at the Fakuma tradeshow.
MPW has reported on both of these and their developments before, including this article. Inductive heating is not new, but both RocTool and the KIMW have advanced it significantly. The gist of induction is that electricity, and not water or oil, is used to rapidly heat an injection mold’s surface. Because only the surface of the mold is heated, cooling also can be done rapidly. The combination of rapid heating and cooling helps prevent warpage and makes for better surface appearance.

The German partner’s Indumold technology involves use of an inductor inside an injection mold, while RocTool’s Cage system forms a cage around a mold’s exterior. Indumold is already in commercial use, says Stefan Schmidt, managing director in Lüdenscheid. RocTool actually only changed focus to injection molding in 2008 but sold 16 licenses in 2008 and expects to sell about 20 this year. Prior to 2008 the company had worked almost exclusively with processors of thermoset composites.
  
On an injection mold, RocTool CEO Alex Guichard says a Cage-equipped mold’s surface can be heated about 100ºC in just 6-10 seconds; Indumold gets you that 100ºC change in temperature in just two seconds, says Schmidt. Injection of the melt is onto this hot surface, with water then used to rapidly cool the mold. Because the inductive heating only affects the mold’s surface, cooling can be focused just on that and not be wasted on the rest of the mold.

Guichard and Schmidt say the path to partnership was forged as both businesses began to compete on some projects. Generally, though, Indumold makes more sense for parts with deep cuts, and the Cage system is better for large panels. Patent concerns also played a part, as did Guichard’s realization that it would take a German partner to be successful in that country.

RocTool acquired the IP, patents, brand name and know-how surrounding Indumold and will now license the process as well as its own. The Lüdenscheid team will demonstrate RocTool’s technology at their facility and help introduce it to Germany; the KIMW also received an ownership stake in RocTool. RocTool, though a small company, has a presence in Japan, the U.S., and soon Taiwan and India, offering opportunity for Indumold to see use far afield from its German roots, says Schmidt. “The next challenge,” he says, “is to get the cooling (on an inductively heated mold) to be as rapid as the heating.”

Inductive heating is not for every molding application as there is a cycle-time penalty. The technology is of interest for system costs reduction in the processing of parts which, after molding, require coating, painting, or other surface enhancement. The rapidly heated mold surface causes parts to form with no weld line and often with a near-mirror surface.

Guichard adds, “So far, most of the emphasis has been on parts with a top surface finish, but the future will be more use of the rapid heating for high-temp materials” such as polyether etherketone (PEEK). Impressive at the Fakuma tradeshow in October was a large (60 cm by 50 cm; 900g) PEEK part, 2.2 mm thick, that RocTool displayed. The panel was molded with a single injection point, demonstrating how the heated (330ºC in this case) mold surface positively affected melt flow. “If you can change the flow, you dramatically change the injection molding business,” said Guichard. Matt Defosse
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