Material Selection Requirements
Look carefully at the assembly process for unfriendly chemical exposure to the components. Check the cutting fluid residues and protective coatings on bolts and screws etc. Check the chemical compatibility of O-rings and gaskets materials with your selected plastic. A chemical in thread-locker (a liquid preparation used for securing screw in a boss) that attacked a polycarbonate boss deluded engineers for quite some time before they finally identified the culprit. Also consider contact with other plastics, di-octyl phthalate, a commonly used plasticizer in PVC, chemically attacks polycarbonate. At higher temperatures, more of this additive migrates to the surface of the PVC part. This chemical attack is accelerated by elevated temperature. If used, ensure the compatibility of adhesives, pipe-joint compounds, paints, coatings, printing inks etc. with the material you select. |