Large-size polyurethane molding gives designers greater scope
The cladding sections of a computer tomograph, for which Siemens AG in Forchheim have come up with a fresh new design, have been produced using Baydur® 110 polyurethane.
The manufacturer of the polyurethane parts, Thieme GmbH & Co. KG of Teningen, have literally set high standards in this project –both the front, molded in one shot, and the rear wall of the high-tech piece of medical equipment measure almost two by two meters with a wall thickness of just five millimeters.
The attractive casing of the new machine is made of Baydur® 110. The front and the rear wall of the machine. Both measure 1,880 x 1,820 millimeters, and the front also has a 300 millimeter high cone. In order to produce a projected surface area of this size, a mold carrier and a mold had to be developed that can maintain a locking force of over 500 tons at an internal pressure of 15 bar. This was possibilities with Baydur® 110.
The amount of polyurethane processed in one shot in the multi-cavity mold cores – around 25 kilograms –is not unusual nowadays, but the ratio of wall thickness to flow length that proved possible with Baydur® 110 would not have been feasible with thermoplastics. Despite the thin walls, both the large sections and the smaller side elements are rigid enough to give good stability over the entire housing in combination with metal reinforcements. With thermoplastic materials, accurately positioned apertures, slits, ribs and domes would have to be created at a later stage; with Baydur® it was possible to mold them in, making design work easier. This polyurethane is also extremely high-impact and gives the complex internal workings of the tomograph –around 700 kilograms of metal and electronics moved once around the patient in half a second – optimum protection. Added to this, the high-quality Baydur® polyurethane surface gives the machine a very aesthetic appearance.