Injection molding technology adds heating circuits, lights or more to molded parts, in the mold

A series of new injection molding technologies developed by Swiss moldmaker Georg Kaufmann can be used to add even more function to plastic parts, with no secondary work necessary. Parts leave a mold as fully functional systems, to include even having fully integrated heating elements.

At a recent event the moldmaker displayed parts that had decorative plastic and textile surfaces covering sensors that light up at the touch, and parts coated with a semiconductor-filled pigment that turns warm when a current passes through it.  

The functional surface technology was on display at last month's Plastics in Automotive Engineering event in Mannheim, Germany. (See other recent coverage from that event including articles on Dow Automotive's Voraforce material for use in rapid resin transfer molding of carbon fiber reinforced parts, RocTool's advances in inductively heated molds for forming automotive interior parts, and our report on a new synthetic fiber from Milliken that can be used to replace talc as a filler.) According to Markus Haller, director of sales at the moldmaker, who met with PlasticsToday during that event, its new surface functionality molding project has met with great interest among automotive OEMs. The reason won't make many Tier 1 automotive systems suppliers happy as once an OEM is able to make parts with such functionality, it can operate independently of the Tier 1s which, to now, typically have developed high-end multi-material molding technology and sold parts made using this to OEMs. With the Georg Kaufmann model, an OEM could purchase a mold and either do its own captive processing of its systems or install the mold at an injection molders.

Unfortunately but understandably, the people at Kaufmann are not very open as to exactly how these parts are made, but the basic premise is rear injection molding at pressures low enough so that the integrated sensors and surface materials are not damaged. The company long has been a leader in development of injection molds suitable for processing parts with attractive or functional surfaces, such as for molding of car door panels.

There were about eight different examples hanging at the company's small exhibit stand. A typical one was a slightly rounded panel, about half the size of a car door panel, with a capacitor sensor built into it that served as a light switch. Typically a surface material of some sort- a textile, for example- would be used to cover these sensors, and be inserted into an injection mold. The textile or other surface material is then rear injection molded, so that the sensors are encapsulated between the surface material and the thermoplastics backing.

Other panels were hot or cold to the touch. Applications for these could include armrests in car doors, warmed slightly to make them more comfortable for passengers. Unlike the panels with integrated light sensors, the warm ones relied on a coating that is laminated onto a decorative surface, with this surface material then back injection molded to give it structure and support. The coating has conductive pigments in it (graphite and others) that carrier a small electric current; the amount of resistance helps to control the level of heating, but temperatures above 40° C (104° F) can be realized on the part's surface. Georg Kaufmann developed the coating in an exclusive cooperation with an unidentified supplier. Copper braiding or nets are used to conduct electricity.

The moldmaker has also continued the development it showed at last fall's K show in Düsseldorf, Germany, where it displayed (with injection molding machine maker Engel) an injection molding cell molding thin "organic sheets" for automotive front ends in a hybrid technology. The sheets were developed by Bond-Laminates (Brillon, Germany) and are called organic because of the plastic-consist of special fabrics embedded in a defined orientation in a glass-reinforced polyamide 6 matrix. In varying versions of the technology, the sheets can be made with different resins and different fibers: glass, Kevlar, or carbon. The original technology was developed by DuPont and acquired by Bond-Laminates. Kaufmann, Bond-Laminates, Engel and other partners have further developed the processing technology so that now these sheets can be overmolded with films to present parts with attractive surface finishes.

In related news, the moldmaking company Georg Kaufmann has created a new subsidiary called Georg Kaufmann Innovation. Also based in Busslingen, Switzerland, the new company will help processors and others to "develop unconventional ideas and transform them into practical production solutions." The service offered extends from the initial concept and the development and optimization of the manufacturing process through to mass production.

According to Kaufmann officials, the decision to create the new operation was driven by the continuing trend towards production integration in the plastics industry. Processes that were once completely separate are now being integrated into a single complex production sequence. Successful implementation of this integration is tough, and that is where the new company's engineers hope to help.