Plastic plasticizing screws are divided into three sect […]
Plastic plasticizing screws are divided into three sections according to their geometric appearance:
1. Feed zone This zone is the ditch depth of the fixed screw ditch. Its function is to be responsible for preheating and plastic solids conveying and pushing. It must be ensured that the plastic begins to melt at the end of the feed section (that is, it is preheated to the melting point). The length of this segment is divided into crystalline (POM, PA ??, etc.)> non-crystalline (PS, PU, ABS, etc.)> thermal sensitivity (PVC, etc.). Generally: Amorphous: about 48 ~ 58% L ...... (AS, ABS, PS, etc.) Crystallinity: about 48 ~ 58% L ... (PA, POM, PE, PP, CA, etc.) About 45 ~ 55% L
2, compression zone (compression zone) This zone is the tapered screw sulcus tooth depth, its function is the plastic raw material melting, mixing, shear compression and pressurized exhaust. The plastic will completely dissolve and the volume will shrink in this section, so the design of the compression degree (compression ratio) is important. The general length is: Non-crystalline: about 25 ~ 35% L ... (AS, ABS, PS, etc.) Crystallinity: about 22 ~ 32% L ... (PA, POM, PE, PP, CA, etc.) : About 28 ~ 40% L PVC: 100% L
3, metering zone (metering zone) This zone is the screw groove groove fixed groove depth, its main function mixing, melt glue conveyance, metering, must also provide sufficient pressure to maintain the uniform temperature of the melt and stabilize the molten plastic flow.
The general length is: Non-crystalline: about 15 ~ 58% L ...... (AS, ABS, PS, etc.) Crystallinity: about 48 ~ 58% L ... (PA, POM, PE, PP, CA, etc.) : About 45 ~ 55% L Although the plasticizing screw can be distinguished according to its function or geometric appearance, in the actual plasticizing process, the functions of each section overlap, and it is difficult to distinguish the interval.