Bauser, an injection molding company specialized in precision parts located in Wehingen, Germany, has successfully introduced a production process for automotive gears, using DSM Engineering Plastics Stanyl PA46 annealing technology. The company was the first plastic gear supplier in Germany to jointly commercially introduce the technology, almost 2 years ago. Annealing is a high temperature after-treatment of an injection molded part, during which significant morphological changes occur. Stanyl is annealed when heat treated above its glass transition temperature [Tg80°C], but below its melting temperature [Tm295°C], preferably at temperatures around 220°C for 2 - 4 hours. The effects obtained through annealing are irreversible. At the indicated annealing temperatures (>210°C), a nitrogen atmosphere is recommended to avoid any thermal oxidation of the material.
The process is especially applied when aspects like performance, durability and safety has to be boosted. Hans Wennekes, Business Development Manager Stanyl, explains: "After annealing, the parts generally have up to 35% higher mechanical properties above Tg, as well as increased wear and creep performance. A positive side effect is the reduction of moisture uptake by 35%." Key applications for annealed Stanyl gears are those with high demands on load or safety performance and where polyacetal cannot be used. These include wiper systems, sliding doors, roof systems using worm gear actuators. In non-automotive, the process can be used for general applications such as sliding, folding and roll-up door openers.