Polymethyl methacrylate, commonly known as Acetal resin, Polyoxymethylene, Polyacetal, or POM, is also referred to as "Sai Gang." It is produced by polymerizing formaldehyde trioxide through solution, bulk, radiation, or vapor phase polymerization, followed by esterification or etherification to cap the ends and granulate. POM is categorized into homopolymer POM and copolymer POM. Homopolymer POM is derived from the polymerization of anhydrous POM, while copolymer POM is a copolymer of formaldehyde trioxide with a small amount of dioxane. POM has a water absorption rate greater than 0.2%, and should be pre-dried before molding. The melting and decomposition temperatures of POM are similar, with poor molding properties. It can be processed through injection molding, extrusion, blow molding, rotational molding, welding, bonding, coating, printing, electroplating, machining, with injection molding being the most important method. It has a high shrinkage rate during molding, so higher mold temperatures are recommended, or annealing treatment can be applied, or reinforcing materials can be added.POM boasts high strength and light weight, often used as a substitute for copper, zinc, tin, lead, and other non-ferrous metals. It is widely employed in various industries such as industrial machinery, automobiles, electronic appliances, daily necessities, pipelines and accessories, precision instruments, and building materials.