Monday - October 17, 2016

K 2016: Covestro exhibits automotive interior component fabricated by physical foam molding

Cost-efficient production of lightweight decorative components

High surface quality thanks to dynamic temperature control
more imagesdownload
Covestro has developed an integrated polycarbonate-based material and process concept suitable for a cost-effective production of lightweight decorative components for the automotive interior. The concept is based on polycarbonate and enables customized design and styling elements. An example is this glove box cover made from the polycarbonate ABS blend Bayblend®. Its surface shows high-gloss and structured areas.

Covestro supports the trend in the automotive industry towards lightweight components with customizable Class A surfaces that can be fabricated economically in a single step.

At the K 2016 plastics trade fair (Stand A 75, Hall 6), the company is showing prototypes of a glove compartment cover to demonstrate the technology. They were manufactured in an injection mold with dynamic temperature control by means of physical foam molding, from Bayblend® grades (PC/ABS) surface-optimized for use in automotive interiors.

Visitors can also watch the part being manufactured via the ProFoam® method at the stand of injection molding machine specialist Arburg (Stand A13, Hall 13). In this case, the company selected Makrolon® SF800Z, a glass fiber-reinforced polycarbonate from Covestro specifically developed for physical foam molding. It already is in use today for printer housings and other non-automotive applications. It has a UL94 listing for flame retardance.

Even lighter components
“In addition to the lightweight strategy of physical foam molding, which reduces density and thus component weight, we also deliberately took advantage of the opportunity to make process-related design modifications,” said Rainer Protte, head of Special Injection Molding Processes at Covestro’s Polycarbonates business unit. “Increasing nitrogen concentration in the material reduces the viscosity of the melt and improves flow.” This enables mold wall thickness to be reduced without exceeding the permissible injection pressure. The combination of the two effects – reducing density and wall thickness – enabled the weight of this prototype to be reduced by about 30 percent. Polycarbonate and its blends display good mechanical properties, meaning that this material class is also suitable for components subject to high mechanical stress.

Thanks to the process conditions and material, premium surfaces with high-gloss and textured areas can be achieved even with physical foam molding. An additional coating step is unnecessary.

“Mirror-smooth” surface
This is made possible by dynamic temperature control, where superheated water is used to heat the surface of the mold cavity to the glass transition temperature or higher prior to injection. Once the melt has been injected, it is allowed to cool to demolding temperature. The high mold temperature makes the surface of the molded part virtually “mirror-smooth.” Structures can also be rendered very effectively using this method.

The ProFoam® process in operation at the trade fair is a physical foam molding method developed by Arburg, which is based in Lossburg, Germany. The plastic granulate is already enriched with liquid propellant in a granulate lock upstream of the injection unit. During the plasticizing process, the blowing agent dissolves in the melt and is not released again until the pressure increases during injection, when it is then emitted in the form of microcellular “bubbles” that “freeze” during solidification of the melt. Fiber-reinforced plastics can likewise be processed by this method without any additional shearing.

In addition to Arburg, Covestro also worked closely on this project with gwk Gesellschaft Wärme Kältetechnik in Meinerzhagen (temperature control processes), Hiddenhausen-based mold manufacturer Krallmann, and J. & F. Krüth in Solingen, which specializes in mold texturing, the focus in this case being on 3D laser texturing.

Visit us at the K 2016 plastics trade fair from October 19 to 26 in Düsseldorf, Germany, Hall 6, Stand A 75. Find more information at

Visit us also in Hall 13, Stand A 13. Find more information at

About Covestro:
With 2015 sales of EUR 12.1 billion, Covestro is among the world’s largest polymer companies. Business activities are focused on the manufacture of high-tech polymer materials and the development of innovative solutions for products used in many areas of daily life. The main segments served are the automotive, electrical and electronics, construction and the sports and leisure industries. Covestro, formerly Bayer MaterialScience, has 30 production sites around the globe and as of the end of 2015 employed approximately 15,800 people (full-time equivalents).

Find more information at and

Forward-looking statements
This press release may contain forward-looking statements based on current assumptions and forecasts made by Covestro AG. Various known and unknown risks, uncertainties and other factors could lead to material differences between the actual future results, financial situation, development or performance of the company and the estimates given here. These factors include those discussed in Covestro’s public reports which are available on the Covestro website at Covestro assumes no liability whatsoever to update these forward-looking statements or to conform them to future events or developments.