POM （polyoxymethylene resin） definition: polyoxymethylene is a kind of linear polymer without side chain, high density and high crystallinity. According to the different chemical structure of its molecular chain, it can be divided into Homo POM and co POM. The important difference between the two is that the density, crystallinity and melting point of POM are high, but the thermal stability is poor, the processing temperature range is narrow （about 10 ℃）， and the stability to acid and alkali is slightly low; while the density, crystallinity, melting point and strength of POM are low, but the thermal stability is good, it is difficult to be resolved, the processing temperature range is wide （about 50 ℃）， and the stability to acid and alkali is good. It is an engineering plastic with excellent comprehensive properties. It has good physical, mechanical and chemical properties, especially excellent friction resistance. Commonly known as saigang or tougang, it is the third largest general engineering plastics Suitable for making wear-resistant parts, transmission parts, chemical, instrument and other parts.