Plastic injection molding, also known as injection molding, its principle is to add granular or powdery raw materials into the hopper of the injector, the raw material is heated and melted into a flow state, under the injection machine screw or piston driven, through the nozzle and mold gating system into the mold cavity, Plastic Injection Molding in the mold cavity hardening stereotypes.
Plastic Injection Molding Advantages:
1. Short molding cycle, high production efficiency, easy to realize automation
2, can shape complex, precise size, with metal or non-metallic inserts plastic parts
3. Stable product quality
4. Wide range of adaptation
In industrial products, plastic injection molding products are: Kitchen supplies (garbage cans, bowls, buckets, pots, tableware and various containers), electrical equipment shell (hair dryer, vacuum cleaners, food mixers, etc.), toys and games, the automotive industry, a variety of products, Plastic Injection Molding and many other parts of the product.
Plastic injection molding is mainly used to enhance pet molding. Pet in general can only choose screw injection molding machine molding. It is best to select a mutant screw with a stop-reverse ring at the top, the surface hardness is large and abrasion-resistant, the length-diameter ratio is not l/d= ($number): 1 compression ratio is about 3:1. D too large material in the barrel stay time too long, excessive heat easily cause degradation, Plastic Injection Molding affecting product performance. Compression ratio too small shear heat less, easy plasticizing, poor product performance. Conversely, the glass fiber will be more broken, the mechanical properties decline. Processing glass fiber reinforced pet, the material cylinder wall wear more severe, the material cylinder using wear-resistant materials manufacturing or lining with wear-resistant materials. The nozzle is short, Plastic Injection Molding the inner wall requires polishing and the aperture is as large as possible. The hydraulic brake valve type nozzle is good. Nozzle should be insulated and temperature control measures to ensure that the nozzle will not freeze blockage. However, the nozzle temperature should not be too high, otherwise it will cause the drooling. Before starting the molding must use the low pressure PP material, the barrel clean.
Plastic Injection Molding conditions:
1. Barrel Temperature: Pet Molding temperature range is narrow, the temperature will directly affect the performance of products. If the temperature is too low, then plastic is not good, so that plastic parts appear sunken, lack of material and other defects; Conversely, the temperature is too high, will cause overflow, nozzle casting, color depth, mechanical strength drop, and even cause degradation. Usually, Plastic Injection Molding the barrel temperature control in the 240~280℃, glass fiber reinforced pet barrel temperature of 250~290℃, not more than 300 ℃, nozzle temperature is generally lower than the barrel temperature 10~20℃.
2. Mold Temperature: Mold temperature directly affect the cooling rate and crystallinity of the melt, the crystallinity is different, then the plastic parts performance is different. Usually, the mold temperature control in the 100~140℃, when forming thin-walled plastic parts, desirable small value, forming thick-walled plastic parts, it is desirable to large value.
3. Injection pressure: Pet melt fluidity is good, easy to shape, Plastic Injection Molding usually using medium pressure, pressure for 80~140mpa, glass fiber reinforced pet injection pressure for 90~150mpa. The determination of injection pressure should consider the viscosity of pet, the type and quantity of filler, the position and size of the gate, the shape and size of the plastic parts, the mold temperature and the type of injection moulding machine.