Plastic Molding Tutorial
- Author:tony
- Source:sinotech
- Release on :2015-06-04
Injection molding is a process in which a polymer is heated to a highly plastic state and forced to flow under high pressure into a mold cavity, where it solidifies. The molded part, called a molding, is then removed from the cavity. The process produces discrete components that are almost always net shape. The production cycle time is typically in the range 10 to 30 seconds, although cycles of one minute or longer are not uncommon. Also, the mold may contain more than one cavity; so that multiple moldings are produced each cycle.
Process and Equipment
Equipment for injection molding evolved from metal die casting. An injection molding machine consists of two principal components: (1) the plastic injection unit and (2) the mold clamping unit. The injection unit is much like an extruder. It consists of a barrel that is fed from one end by a hopper containing a supply of plastic pellets. Inside the barrel is a screw whose operation surpasses that of an extruder screw in the following respect: in addition to turning for mixing and heating the polymer, it also acts as a ram which rapidly moves forward to inject molten plastic into the mold. A nonreturn valve mounted near the tip of the screw prevents the melt from flowing backward along the screw threads. Later in the molding cycle the ram retracts to its former position. Because of its dual action, it is called a reciprocating screw, which name also identifies the machine type. Older injection molding machines used a simple ram (without screw flights), but the superiority of the reciprocating screw design has led to its widespread adoption in today's molding plants. To summarize, the functions of the injection unit are to melt and homogenize the polymer, and then inject it into the mold cavity
Equipment for injection molding evolved from metal die casting. An injection molding machine consists of two principal components: (1) the plastic injection unit and (2) the mold clamping unit. The injection unit is much like an extruder. It consists of a barrel that is fed from one end by a hopper containing a supply of plastic pellets. Inside the barrel is a screw whose operation surpasses that of an extruder screw in the following respect: in addition to turning for mixing and heating the polymer, it also acts as a ram which rapidly moves forward to inject molten plastic into the mold. A nonreturn valve mounted near the tip of the screw prevents the melt from flowing backward along the screw threads. Later in the molding cycle the ram retracts to its former position. Because of its dual action, it is called a reciprocating screw, which name also identifies the machine type. Older injection molding machines used a simple ram (without screw flights), but the superiority of the reciprocating screw design has led to its widespread adoption in today's molding plants. To summarize, the functions of the injection unit are to melt and homogenize the polymer, and then inject it into the mold cavity
Shenzhen GAINSHINE Plastic Technology Co.,Ltd.CHINA TPE/TPRsupplier.was founded in 2002. Our main products are thermoplastic elastomer (TPE, TPR, TPU, TPV), while we are dedicated on studying and developing new macromolecule material. We are a professional enterprises on researching, developing, producing and selling customer-oriented plastic products.
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