Annealing

Annealing is a high temperature after-treatment of an injection molded part.

Annealing Stanyl
Important morphological changes occur in Stanyl during annealing.

Stanyl is annealed when heat treated above its glass transition temperature [Tg80°C], but below its melting temperature [Tm295°C], preferably at temperatures between 210 and 240°C for 4 - 12 hours. The effects obtained through annealing are irreversible. Annealing can be carried out in standard industrial ovens. At the indicated annealing temperatures(>210°C), a nitrogen atmosphere is recommended to avoid any thermal oxidation of the material. Stanyl parts will anneal at lower temperatures - e.g. when operating at continuous temperatures around 150°C,but the process will take longer. As a planned heat treatment in a production process, the higher temperatures mentioned above should be used.

An important practical aspect of these mechanical property improvements is that annealed Stanyl parts can carry and transmit higher loads. For instance, smaller gears can be designed to transmit the same torque as current larger designs: annealing allows for miniaturization.

Unfilled Stanyl annealing conditions giving water uptake levels similar to PA66 or cast PA6

Annealing Xantar

Parts made of Xantar PC can be annealed to relieve the internal material stresses that are introduced during injection molding or machining, in order to prevent environmental stress cracking.

This can be done by heating the parts for approximately half an hour at a temperature 20°C (36°F) below the Vicat softening temperature. For most Xantar PC grades this means that the annealing temperature should be around 128°C (262°F). Mechanical properties may be affected by the heat treatment. Impact strength may be especially reduced. This negative effect is less after annealing at lower temperatures: e.g. at 80 - 95°C (176 - 203°F) for at least 12 hours.

If necessary, parts must be well supported during the heat treatment, to prevent deformation due to gravitational forces acting on the part.