Injection molding, also known as injection molding forming, is a molding method that combines injection and molding. The advantages of the injection molding method are high production speed, high efficiency, automated operation, a wide variety of products, shapes ranging from simple to complex, sizes ranging from large to small, and precise product dimensions. Products are easy to upgrade, and complex-shaped parts can be formed. Injection molding is suitable for mass production and for molding processing of complex-shaped products.
Compared with other molding technologies, it has many distinct characteristics:
1. Advantages of Injection Molding
1) Since the melting and plasticizing of the molding material and the flow forming are carried out separately in the barrel and the mold cavity, the mold can always remain in a state where the melt quickly condenses or crosslinks and solidifies, which helps shorten the molding cycle.
2) During molding, the mold is clamped before the molten material is injected. In addition, the molten material with good flowability causes very little wear to the mold cavity, so one mold can produce large batches of injection-molded products.
3) One operator can often manage two or more injection molding machines. Especially when molded parts can be automatically unloaded, even more machines can be managed, so the labor required is relatively low.
4) The entire molding process—clamping, feeding, plasticizing, injection, mold opening, and demolding—is completed by the action of injection molding, making the injection molding process easy to fully automate and program-control.
5) Because the pressure during molding is very high, plastic parts with complex shapes, clear surface patterns and markings, and high dimensional accuracy can be molded.
6) Through co-injection, more than one material can be molded; materials with a hard skin and a foamed core can be effectively molded; thermosetting plastics and fiber-reinforced plastics can be molded. Because precision molds and precision hydraulic systems can be used in molding, together with microcomputer control, products with very high precision can be obtained, with volume tolerances reaching μm.
8) Production efficiency is high. Two sets of molds can contain dozens or even hundreds of cavities, so dozens or even hundreds of plastic parts can be molded in one molding cycle.
9) Molded plastic parts require only a small amount of trimming before use, and waste generated during the molding process can be reused, so there is very little waste of raw materials in injection molding.
2. Disadvantages of Injection Molding
1) The key equipment for injection molding is the mold, but the cycle for mold design, manufacturing, and trial molding is long, and production start-up is relatively slow.
2) Due to cooling condition limitations, it is relatively difficult to mold plastic parts with thick walls and large variations.
3) Because the cost of injection molding machines and injection molds is relatively high, start-up investment is large, so it is not suitable for small-batch production of plastic parts.
4) The quality of molded products is limited by many factors, so technical requirements are high and mastery is relatively difficult.