An induction process for rapid mold heating, originally designed for composites, is now available for thermoplastic and thermoset injection molding of parts requiring high surface quality, says process developer RocTool of France. (RocTool North America is in Atlanta.) The company patented in 2004 its Cage System, which heats just the surface of a tool "almost instantly" by electromagnetic induction and then cools that surface just as quickly with fluid channels close to the tool surface.

 

The tool is surrounded by a "cage" of inductors, which heat a special alloy that forms the surface of the tool. RocTool says the process helps mold very thin-wall parts with "difficult" materials, produces smooth surfaces without visible weld lines, and allows use of 30% to 50% lower pressures. RocTool works with the toolmaker and molder to coordinate tool design and also runs 2D and 3D simulations to model the electromagnetic field of the cage system.