This topic mainly collects manual materials on plastics. Engineering plastics can be divided into general engineering plastics and special engineering plastics. Engineering plastics can be used as engineering materials and plastics instead of metal manufacturing machine parts. Engineering plastics have excellent comprehensive properties, high rigidity, small creep, high mechanical strength, good heat resistance, and good electrical insulation. They can be used for a long time in harsh chemical and physical environments, and can replace metals as engineering structural materials .