Sanding and grinding
Sanding can either be done by hand, or mechanically on an endless belt or with
a disc sander. The heat conductivity of plastics is low making them easily
susceptible to softening. The sanding speed should therefore be low and wet
sanding can be considered, as this reduces the chances of gumming.
Abrasive discs rotating at high-speeds on a hand grinder, can also be used to
remove material fast.
Polishing and buffing
Engineering plastics which are rigid (
Stanyl PA46, Arnite PET and PBT,
Akulon PA6 and PA66, and Xantar PC) can be buffed
on standard buffing equipment, in order to bring the surface to a desired
roughness level and give parts an appearance that may vary from a dull satin
finish to a highly polished look. Buffing is done on a rotating wheel made of
layers of cotton or muslin, that are dressed with a buffing compound.
A slurry of pumice and water can be applied to remove the surface
irregularities and provide a satin finish. Special polishing compounds give
parts a high gloss. Polishing is done in several steps, the last treatment
being wiping off the polishing compound with a dry, soft wheel.