1. The twin screw should be able to scan the entire i […]
1. The twin screw should be able to scan the entire inner surface of the screw closely to obtain good heat conduction, mixing effect and narrow residence distribution time.
2. The radial gap between the screw and the barrel (barrel) should be less than 0.003 times the screw diameter.
3. Streamlined design is adopted to avoid dead ends.
4. When the plastic contains solid filler particles that need to be crushed under high stress, a dispersing and mixing unit must be selected. The dispersing and mixing unit can also ensure that the unmelted plastic particles are not transported to the end of the screw. Therefore, even if there are no solid filler particles in the plastic, the dispersive mixing unit is very useful.
5. The configuration of the distributed mixing section should be comprehensively considered to reduce the difference in consistency and the uneven melt temperature. The preferred position of the mixing section is at the end of the screw.
6. When the plastic is mixed with corrosive fillers, such as corrosion dioxide, glass, etc., the screw and barrel (barrel) should be made of wear-resistant materials.
7. When extruding PVC, fluoroplastics or other plastics that can corrode the surface of exposed gold chips, the screw, barrel (barrel) and head should be made of corrosion-resistant materials.
8. The mixing section should have low pressure drop and excellent forward pumping ability.
9. In order to improve the conveying performance of materials and reduce the hanging material, the radius of the fillet at the bottom of the thread groove should be larger, and the use of multiple threads and small pitches should be avoided to reduce screw friction and improve conveying capacity.
10. When the screw uses a coating, the coating with low friction should be given priority. This will improve the conveying performance of the screw, resulting in higher output and better stability, and the screw is easier to clean.
The ten methods mentioned above are necessary for a qualified screw and can be used for reference.