Surface finishing: Combining design with functionality
Multifunctional kitchen appliances that weigh, chop, and cook within a single device are now hugely popular; the top brand Thermomix is flying off shelves all over the world. Just 10 months after the current model, the TM5, came on to the market, the millionth such appliance rolled off Vorwerk’s production line. “Many of our customers have been loyal Thermomix fans for years, because they know they can rely on our quality,” says Dr. Thorsten Gläser, head of Materials Engineering at Vorwerk. The appliance has been designed so as to perform the various functions without elaborate changeover procedures, and is also easy to clean. “For this we rely on the highest engineering skills and first-class materials,” says Gläser.
For the curved white housing of the device Vorwerk decided on a high-gloss surface finish with PLEXIGLAS®, or, to give it its correct chemical name, polymethyl methacrylate. PLEXIGLAS® molding compounds allow production of components for many different applications that have long proven themselves in, for example, automotive construction and the lighting industry. And they are always inspiring new ideas. As overmolded or co-extruded finishes, they lend their excellent properties also to the underlying material. And it isn’t just the functionality that impresses: In the Thermomix housing, for example, the excellent transparence of PLEXIGLAS® results in a seamless and particularly high-gloss surface with a brilliant depth effect. “This gives the housing a distinguished appearance and also a pleasant feel,” says Siamak Djafarian, head of the Molding Compounds Product Line at Evonik. “After all, Thermomix isn’t just practical, it also looks very good. And our PLEXIGLAS® molding compounds contribute to that.”
Good looking as well as tough
For the Thermomix, Vorwerk has, moreover, chosen materials that can stand up to long-term use. “PLEXIGLAS® has the highest surface hardness of all thermoplastics,” explains Andreas König of Technical Service at Ter Hell, a long-standing trading partner of Evonik, “and so makes surfaces more robust.” A knock from a bowl leaves the material unaffected, as does hot food dripping on to the housing or the detergent used in cleaning the appliance after cooking. “PLEXIGLAS® has excellent chemical resistance,” says König, “and is therefore robust and easy to clean.” Not even direct sunlight can damage the housing: While other transparent plastics yellow with time as a result of UV radiation, PMMA looks just as it did on the first day, even after long use. “For us that was an important consideration, because we set store by the long service life of our appliances,” says Dr. Gläser of Vorwerk.