PPS material: PPS plastic injection molding process

Although the hygroscopicity of PPS plastic is weak, 140 ℃ is still required to improve the appearance of molded products and prevent salivation × 3 hours or 120 ℃ × 5 hours of pre drying.

In order to prevent bridging during drying, 105 ℃ is recommended according to the specific conditions of the grade × 5 hours of pre drying.

Due to the strong moisture absorption of carbon fiber, the carbon fiber reinforcement grade (2130A1, 7140A4, etc.) especially needs to be pre dried.

As far as natural color is concerned, in order to obtain a more stable hue, the drying conditions should be kept uniform.

Precautions when setting forming conditions

(1) Barrel temperature

When the temperature of the barrel under the hopper is excessively reduced, the friction between the barrel and the screw will tend to increase.

If there is no problem with liquidity, a small drop in temperature will help reduce residual discoloration. In particular, the zui should be set at 300-320 ℃ when forming non black molded products.

(2) Mold temperature

Mold temperature has a great influence on the characteristics.

From the appearance of molded products, dimensional stability, heat resistance and creep resistance when using at high temperature, the mold temperature zui should be higher than 130 ℃ but not lower than 120 ℃.

(3) Injection pressure

Generally, the injection pressure of 30~100MPa is preferred for zui. In order to reduce flash, low pressure forming is recommended.

(4) Injection speed

In order to obtain a good appearance, high-speed injection should be carried out. However, high-speed injection is easy to lead to warping and charring of molded products, so as long as the appearance is good, it is unnecessary to overuse high-speed injection. Zhenghao Special Engineering Plastics specializes in the production and sales of PPS plastic raw materials with complete models and favorable prices. Welcome to call us for discussion. Fortune Hotline: 13656263509, Contact: Mr. Yan.

(5) Back pressure

In order to keep the metering stable, it is recommended to set the back pressure as 2~5MPa. When the metering is unstable, the back pressure can be slightly increased to 8~10MPa.

(6) Screw speed

Generally, 40~100rpm is appropriate. The rotating speed zui should not exceed 200rpm, otherwise the glass fiber will be cut off and the resin will heat up.

(7) Detention in barrel

Even if PPS plastic is retained in the barrel for a long time, its viscosity will not increase significantly. This shows that the use of hot runner is effective.

Cleaning after forming

It is recommended that in general, under the condition of maintaining the barrel temperature during PPS plastic molding, first use polycarbonate containing glass fiber for cleaning, then use polyethylene for cleaning, and then use the two for repeated cleaning alternately. The efficiency will be higher if the cleaning materials in the barrel are completely discharged and then loaded into the next cleaning material. Commercial acrylic cleaning materials can also be used to replace polycarbonate containing glass fiber.

The following describes the stopping and starting of the molding machine and the method of material switching.

(1) When forming stops

It is recommended to clean DURAFIDE under the condition of maintaining the barrel temperature during DURAFIDE molding, and then use resins with good thermal stability (high-density polyethylene, commercially available acrylic cleaning materials, etc.) under the same molding temperature as DURAFIDE. If you want to continue the DURAFIDE molding, you can also use only DURAFIDE for cleaning.

(2) At the beginning of forming

If the resin in the barrel is stable within the PPS plastic molding temperature range, it can be heated to the PPS plastic molding temperature intact, and then cleaned with PPS plastic.

If the molding temperature range of the resin is different from that of PPS plastic, it is recommended to adjust the barrel temperature to the molding temperature of the residual resin in the barrel, and then clean it with the resin (high-density polyethylene, polycarbonate (as appropriate), etc.) that can be used at the molding temperature of both PPS plastic and residual resin and has good thermal stability, and then set the molding temperature of PPS plastic and clean it.

If the resin in the barrel is PPS plastic, it can be heated to the molding temperature of PPS plastic intact and cleaned.

(3) During resin switching

If it is a resin that can be switched with PPS plastic intact, refer to the above molding stop and start methods, and clean it intact while maintaining the barrel temperature.

If it is a resin that cannot be switched with PPS plastic intact, it is recommended to clean it with a resin with good thermal stability (high-density polyethylene, etc.) at the molding temperature of both PPS plastic and the resin to be switched, and then set it to the molding temperature.

(4) Other

If it remains in the barrel for a long time, the natural color of PPS plastic will sometimes change color, so it should be fully cleaned.