Polyphenylene sulfide (PPS) Injection Molding Process

Date：2010/1/9 10:30:07

Polyphenylene sulfide (PPS) Injection Molding Process
 
Polyphenylene sulfide is a stable crystalline resin. Requirements for rigidity, durability, mechanical products, requiring heat, flame electrical products can also be used to require corrosion resistance of chemical devices, etc..
Molding process:
① polyphenylene sulfide absorption is small, the high melt temperature, low viscosity, generally do not need to be dried before molding process. There are special requirements, it is recommended drying temperature is 150 ○ C ~ 160 ○ C, a period of 2 to 3 hours.
② often forming large, each longer cycle time, resin in the barrel along with the residence time increased. And stay too long in the heat, the resin was more the color will be black and the phenomenon of liquidity decreased slightly, but the characteristics of the resin is not significantly affected. Often forming large barrel for low temperature applications, the molding temperature of 290 ○ C ~ 360 ○ C optimum molding temperature 315 ~ 330 ○ C.
③ shot at different speeds, the product of the surface brightness is not the case, the faster injection, surface gloss, the better, but is susceptible to product warping, burning, which should pay attention to, typically use medium injection speed, high pressure injection molding conditions . Injection pressure of 500 ~ 2000kg/cm2, optimum injection pressure of 900 ~ 1500 kg/cm2. To prevent the weight of each change in shape of different products, plus a number of back pressure (5kg/cm2 so) can be stable moldings.
④ PPS is a crystalline resin, molding shrinkage increase or decrease in impact strength, heat distortion temperature of the long-term, surface hardness, creep resistance, heat resistance and weather resistance and other water features governed by crystallinity. Therefore, molding, the mold should be properly controlled temperature, mold temperature requirements of 50 ○ C ~ 180 ○ C, suitable for 120 ○ C ~ 160 ○ C between. Molding surface state is not good, dull or poor dimensional stability when the temperature used, rigid enough, you can consider increasing the mold temperature to 140 ○ C or more.
⑤ materials mouth: Use open mouth enough material can be molded, but in order to prevent the materials mouth overflow, recommend the use of closed material mouth, while the material is able to separate the mouth of the heater control, more convenient for molding. Feed nozzle tip of the mouth with 2 ~ 3 ○ inverted cone with a diameter of φ3 ~ 6 is appropriate.

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