Heavy-duty materials for control systems

Professional consulting expertise is essential to ensure proper material selection and processing for highly complex tasks and component requirements, particularly in light of current environmental and recycling regulations. When developing, designing, and selecting a material for a new component, Kieback & Peter, a Berlin-based manufacturer of HVAC systems, relied on the technical expertise of the Application Development team of plastics distributor K.D. Feddersen.

Kieback & Peter is a leading provider of equipment and system solutions for the heating, ventilation and air-conditioning (HVAC) industry and for building management systems. Boasting decades of experience, the company is an established supplier of high-quality, innovative control systems for HVAC applications and computer-aided building management, providing innovative solutions for drive systems in all areas where a high level of control accuracy, reliability and flexibility is required. This includes all aspects of building automation, as well as industrial facilities and classic HVAC applications.

Innovative, reliable raw materials to manufacture these products are a basic requirement for Kieback & Peter, whose production facilities are located exclusively in Germany despite the company's international orientation. During the development of a new miniature servo drive (servo drives are power-operated devices used to actuate armatures/valves), plastics distributor K.D. Feddersen was consulted to assist in the search for a suitable material for parts of the gear housing.

The chosen material had to be capable of being produced in light grey, the signature colour used for all products made by the manufacturer. Flame retardant-compliant to UL 94 V-0, with halogen- and antimony‑free flame protection to boot-this is an essential requirement for marketing the products around the world. Besides flame retardance, this specific application requires optimal mechanical properties for snap fits and for screw bosses in terms of pull-out strength and over-tightening resistance. Likewise, superb electrical characteristics and compliance with RoHS and WEEE played an important part in the material selection.

"Based on the customer's specifications, we opted for a Celanex® XFR® grade with 20% glass-fibre reinforcement, a PBT from Ticona, a leading producer of engineering polymers," says Heinz-Günter Onken, application engineer at plastics distributor K.D. Feddersen.

"In collaboration with the Berlin-based Design Engineering department at Kieback & Peter, we calculated the effective forces such as screw torque and pull-out torque and provided recommendations for optimising the production process, which were then implemented at the plant in Trier," adds Heinz-Günter Onken.

 "All three live parts - the supporting plate, housing and flange - were able to be released for production with the material recommended by the distributor following the optimisation process and subsequent testing," affirms Karsten Krause, Design Engineering team leader at Kieback & Peter.

Celanex® is a semi-crystalline, thermoplastic polyester based upon polybutylene terephthalate (PBT). It is suitable for use in applications up to +140°C. Celanex® is the material of choice for the production of high‑quality, heavy duty engineering moulded-parts, for example, in the electrical, electronics and automotive industries and in household appliances. In precision engineering and machine-building applications, it is used as a material for gears, bearings and other slide elements.

Supporting plate, housing and flange of the Kieback & Peter MD 15 miniature servo drive, made of Celanex® XFR®