FAQ - Plastic Recycling and Granulating

FAQ

1、Why are there black spots in the produced plastic granule in the process of plastic recycling?

Reasons	Solutions
The recycled plastics contain many impurities	Strengthen the cleaning and screening processes, increase mesh numbers or layers of filter screen
The feeding bin experiences localized overheating, causing carbonization of the materials.	Reduce the extruding temperature and increase mesh numbers or layers of filter screen
The plastic extruder machine features strong local shearing force, resulting in material carbonization.	Reduce the extruding speed and increase mesh numbers or layers of filter screen
The pressure of die-head is too high and the reflux material is too great, causing material carbonization.	Increase the temperature of the die-head; Change the filter screen and reduce its mesh numbers.
The equipment is aging and the adhesion inner the cylinder increases.	Change equipment or spare parts
The accumulated material in the discharge hole is carbonized and discharged.	Clean the gas exhaust hole regularly.
Discharge hole is not smooth and the accumulated material is carbonized and discharged.	Clean regularly or change spare parts.
The screw thread is damaged and the material in the dead corner is carbonized.	Replace or repair the screw.
Gas exhaust is blocked, leading to materials carbonization.	Clean the exhaust hole and keep it clear.

2、Why do broken plastic strips occur frequently when the materials are extruded?

Reasons	Solutions
Insufficient extrusion amount	Raise the rotating speed of screw, feeding speed or change the filter screen.
The high temperature of the die-head leads to low material viscosity.	Properly reduce the temperature of die head.
Poor plasticizing causes plastic agglomerates	Increase the extruding temperature or speed to promote full plasticizing.
Mixing materials are different in characteristics.	Adjust the temperature or speed based on actual conditions.
Gas exhaust is blocked and the plastic strips have pores.	Ensure smooth exhaust and reduce the extruding temperature properly.

3、Why are many plastic granules coming out hollow?

Reasons	Solutions
High moisture content	Increase the drying temperature or time to ensure clear discharge hole.
The processing temperature is low, causing incomplete plasticization of the materials.	Improves the processing temperature reasonably.
The water temperature is so low that materials shrinks, resulting in a shrinkage cavity.	Reduces the temperature of die-head and improves the temperature of cooling water reasonably.

4、 What is the reason of material leaking in the exhaust port of the extruder during the plastic granulating process?

Reasons	Solutions
Feeding speed and the rotary speed of the main extruder are not matching.	Reduces the feeding speed or improves the rotating speed of the main machine properly.
The temperature in natural exhaust port is low, resulting in poor plasticizing. Under compression of the extruder, the material will leak.	Improve the temperature in the natural exhaust port to boost plasticizing.
The screw is not matched with the natural exhaust port in the feeding barrel.	Choose matching screw and feeding barrel.
No reverse conveying element or reverse kneading block is equipped in the port.	Equip a reverse conveying element or reverse kneading block.

Our factory has over 30 sets of CNC lathes in the production of plastic processing equipment, such as feeding sawing machine, CNC gantry machining center, CNC screw milling machine, CNC deep-hole boring machine, and cylindrical grinder. Meanwhile, with the adoption of more technologies into plastic recycling, CAD/CAM continues to grow in importance. Thus during the whole manufacturing process, our experienced engineers and technicians utilize CAD/CAM engineering approaches to optimize the entire operation. This allows us to supply high quality plastic machinery with optimal performance.