There is a constant search for new manufacturing methods using lighter components made from plastic, especially in the automotive industry. Previous experiments with weight reduction using foaming polymers often failed because the resulting coarse-grained surfaces did not meet the visual requirements of manufacturers or end customers. These components made of particle-foam were also difficult to install, as the material’s porous structure meant fixing points for other components could not be built in.
The Heinze Gruppe GmbH therefore developed a standard assembly and fastening system for particle-foam components, with the K-Fix parts. These parts are encased in expanded polypropylene foam (EPP), and form an inseparable bond with the component. This saves up to 20 percent in weight compared with conventional plastic components. In addition, K-Fix has good insulating properties and even withstands heavy shocks. The K-Fix fasteners will be on show at this year’s K 2019 trade fair in Düsseldorf.
With metal components, attaching other components is complicated and expensive, as insert threads or nuts usually have to be welded in place first. With plastics, however, these parts can be moulded in directly during production, which is why more and more functional parts in the automotive industry are being manufactured using such polymers. Although components made of particle-foam are among the lightest options, attaching additional parts has only been possible to a limited extent, because of the spherical pores. “That’s why we developed the particle-foam composite injection moulding process,” claims Ingo Brexeler, Managing Director of Krallmann Kunststoffverarbeitung GmbH, part of the Heinze Gruppe. “EPP is coated with thermoplastic material made from PP, which creates a composite component, securely bonded together. This element can be attached securely, and is at the same time up to 20 percent lighter than conventional plastic components.”
But not every manufacturer has the equipment needed for these demanding foam and injection moulding processes. This is why the Heinze Gruppe’s K-Fix parts offer a user-friendly assembly and fastening system based on the particle-foam composite injection moulding process. Thanks to specially processed EPP, high thermal conductivity and energy absorption are ensured, as well as an attractive surface.
Standard particle-foam fasteners
Each K-Fix element consists of a black body made of particle-foam, in which the injected fastener is located. Once the K-Fix element is encased in additional EPP foam, it forms an unbreakable and secure bond with the surrounding part. These K-Fix brackets also allow foam interior lining to be attached to any door shell, for instance. “We supply a broad range of K-Fix fasteners – from clips or dust and liquid tight fittings, to snap hooks or latches,” explains Brexeler. “So we are paving the way for assembly tools, as well as cable glands in insulating modules or quick-release fasteners, and can adapt these to the needs of our customers.” K-Fix thus supports automated production, as the elements can be integrated into any process chain.
The Heinze Gruppe uses a specially developed production unit to manufacture K-Fix, with an injection moulding machine, a foaming machine, a six-axis robot and a tool optimised for particle-foam composite injection moulding. “First, the EPP moulded part is encased in foam and inserted into the injection mould by the robot,” explains Brexeler. “In the next step, the K-Fix fastener bracket is moulded securely in place. During this stage, the surface of the insert also melts, causing the two components to become inseparable.” These securely bonded K-Fix elements can be attached anywhere and withstand even high loads and heavy shocks.
Individually locatable lightweight components
Based on many years of practical experience at the Heinze Gruppe in developing components for lightweight design, the plastics experts have put together a design catalogue showing the various most-commonly needed K-Fix configurations. “As a plastics parts supplier, we also help our customers with special requests. We therefore provide comprehensive advice in the early stages,” adds Brexeler. “For instance, individual adjustment and locating for the K-Fix elements are possible at any time, if required.” In addition, K-Fix has its own website, where users can find all the important information and variants. This makes it quick and easy to select the right component.