The framenhofer Institute for Mechanics of Materials IWM in Freiburg.

　　A micrometer-thin layer

　　Electrical insulation is provided by a ceramic layer that shields the conductive heating layer from the steel tool underneath. The layer that actually gets heated is made of a specially designed conductive hard material. In this case, the challenge of sputtering lies not only in producing a perfect insulating layer so as to avoid any short circuits, but also in integrating a sensor into the thin-film heating layer. A sensor placed here can measure the temperature of the tool wall and be used to regulate the manufacturing process.

　　To achieve this, the researchers set about integrating incredibly fine thermocouples, made from nickel or nickel-chrome alloy and each just a few hundred nanometers thick. Thermo- couples can be produced using thin-film technology and incorporated into the insulation layer. Due to their extremely low mass, thermocouples react incredibly fast to temperature changes and make it possible to directly measure the temperature of the tool wall. Through a series of laboratory experiments, the researchers were able to demonstrate that thin-film heating can be used to achieve the desired tool wall temperature very quickly indeed. The researchers are now looking for injection molded parts industry partners to help prepare the process for injection molded parts use in series manufacture.