Many new innovative technologies are now being introduced and re-introduced for foamed injection molding processing. Often called microcellular foaming, the new technologies uitilize a number of approaches to achieve fine cellular structures with double digit weight and cycle time reductions. The key to the innovative technologies is computerized process control, good tool design including counter pressure, static melt mixing and new chemical blowing agents. These technologies have subtle differences, which are very important for optimum part performance. Technologies include a microcellular injection molding process using supercritical gas and polymer mixtures, which reduces part weight while creating a swirled surface finish. If used in conjunction with Textron's IntelliMold technology, a process controls system that decreases part weight and cycle time while eliminating surface irregularities, a Class A surface is obtained. This technology involves the use of a sophisticated closed-loop control technology. Based on the concept that "you can't control what you can't measure" the intelliMold system provides a quantum leap in microcellular injection molding technology. In addition, new compact gas counter pressure (CCP) modules are providing significant improvements in structural foam processing. The new Caropreso designed module, for example, pressurizes the mold using small tailored tooling modifications. The internal gas prevents the gas within the melt from breaking through the surface during processing. This allows a solid surface or outer skin to form as the foamed cellular core expands. Processors are also using new tailored static mixers to create highly uniform melt components at constant temperatures. Static mixers create turbulent melt flows and ensure ideal cross-flow pattens over the entire flow-cross section. New chemical blowing agents (CBA) are also making dramatic strides in achieving reproducible cell distributions and size in micro-cellular foaming. New applications include foam bumpers, fascia, and a variety of other automotive parts. Chemical blowing agents now utilize microencapsulated small particle size components with very narrow distributions to achieve both significant weight reductions and cycle time improvements. Trials have shown these improvements can be achieved on conventional equipment without the need for licensing.
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