Best Structures Of Extruder Screws For Plastics

Date:2022-4-28 Author:hcscrew

huachen screws for plastics

We have seen many screws for plastics. The structure of a plastic extruder single screw may look simple, but it contains a lot of learning. A conventional extruder single screw hass 3 zones.

01 Plastic extruder feed zone

Fixed the screw groove depth, its function is responsible for preheating and plastic solids transport and pushing. At the end of the feed section, the plastic must begin melting. To do this, it must be preheated to the melting point of plastics.

Generally, the feed zone is 48 ~ 58% L for non-crystalline plastics (ABS, PS), 48 ~ 58% L for crystalline plastics (PA, POM, PE, PP), and 45 ~ 55% L for plastics with glass fiber.

02 Plastic extruder compression zone.

Tapering screw groove teeth deep, its function for plastic raw materials melting, mixing, shear compression, and pressurized exhaust. In this section, the plastic will dissolve completely; the volume will be reduced, so the degree of compression is important.

The length of the compression zone is generally 25 ~ 35% for non-crystalline plastics (ABS, PS), 22 ~ 32% for crystalline plastics (PA, POM, PE, PP), and 28 ~ 40% for heat-sensitive plastics (PVC).

03 Plastic extruder metering area.

Screw groove fixed groove depth, its main function mixing, melt transport, metering in addition, must also provide sufficient pressure to maintain a uniform temperature of the melt and stable flow of molten plastic.

The general length of the metering area is about 15 ~ 58% L for non-crystalline plastics (ABS, PS) and 48 ~ 58% L for crystalline plastics (PA, POM, PE, PP, etc.) as well as 45 ~ 55% for glass fiber.

04 Summary

The actual plasticization process and the function of each segment are difficult to distinguish because they overlap, despite the fact that extruder screws for plastics can be distinguished by function or geometric appearance.

We are studying extruder screws for plastics to improve the shear mixing effect, the uniform mixing, the plasticizing ability, and the temperature uniformity of the melt. According to the different processing materials, we combine the most optimal screw structure.

When the feed section teeth deeper the more conveying volume, but the screw requires a larger torque; the feed section teeth are too shallow, the conveying volume is not enough, and the compression ratio is not enough.

When the metering section tooth depth is too deep, the compression ratio is insufficient, the required feeding force is higher. Too shallow when easy to overcook and burn. General tooth depth of about 0.03 ~ 0.07 times the diameter of the screw. The plasticizing screw, therefore, has the functions of conveying, melting, mixing, compression, and metering, which play a very important role in the process of plasticizing.

Quote or contact us at HUACHEN Screw Barrel, for more screw barrel engineering support for your new screw barrel.


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