Infrared welding redesigned
As a contactless process, infrared welding offers undoubted advantages over heated tool welding. The contactless heat transfer enables the processing of materials that otherwise tend to stick. The method is particularly useful when processing fiber-filled materials. The principles common on the market, such as quartz glass and metal foil emitters, reach their limits when processing three-dimensional components - "There must be something to be done," they thought at PolyMerge GmbH, a manufacturer of machines for plastic welding in Geretsried in Upper Bavaria.
The development agenda included properties such as high performance, durability and free geometric design. In order to achieve these objectives, a 3D printing process was used and modified. This enables the production of a ceramic emitter in almost any desired geometry. Of course, ceramic is not a good electrical conductor. This necessary property could ultimately be achieved through a special doping. In contrast to metallic materials, the material can withstand very high temperatures without oxidizing in the oxygen in the air and thus has an enormous service life. The operating temperature is well above the usual 800°C and ensures a significant increase in performance compared to a metal foil emitter. In theory, doubling the temperature means 16 times the optical power output. This power reserve may be used to reduce the cycle time. However, it also enables a heating process with significantly increased distances between the component surface and the emitter. This distance in turn helps to ensure a constant temperature even when processing components with tolerances. Another positive side effect of the novel emitter material is its rigidity. This enables the emitter to be freely positioned in the room with just a few connection points. This makes it possible to guide the emitter in such a way that its emitted light reaches the upper and lower joining partners. The otherwise usual use of two emitters per device and a massive carrier plate can be dispensed with. This saves money and energy; the lack of a carrier plate means that it does not have to be heated in an energy-intensive manner. Due to the reduced mass, the changeover time is also significantly reduced.
The result is nothing less than a small revolution. The process is always attractive whenever large-format three-dimensional components are to be joined. The fields of application include applications in the automotive area of the interior, exterior and drive train. In addition to the positive process-side properties, the use of a 3D printing process offers another advantage: In the unlikely event of a defective emitter, a tailor-made replacement is available at short notice.