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Some unexpected product quality problems often occur during the processing of PE pipes, usually caused by problems with machinery, equipment or raw materials.
1. The surface of the pipe is corrugated
Reasons: 1. Insufficient refrigeration; 2. The seal ring specifications are not suitable, causing vibration.
Solution: Increase the amount of water in the sizing sleeve or the distance between the mouth touch and the sizing sleeve. Check whether the vacuum groove sealing ring specification is small. If it is small, replace it or reduce the vacuum degree of the vacuum groove appropriately to increase the vacuum degree of the second vacuum groove.
2. Surface pitting (mainly internal cavity)
Reasons: 1. There are impurities in the raw materials; 2. The cavity between the mouth and the core is not cleaned; 3. The temperature of some parts is too high, causing aging.
Solutions: 1. Inspect the raw materials; 2. Clean up or transition for a while; 3. Inspect the temperature sensor
3. Surface dents
Reasons: 1. The raw material is wet and the bubbles are cracked; 2. The water volume of the sizing sleeve is uneven.
Solutions: 1. Drying of raw materials; 2. Adjust water volume or replace the sizing sleeve
4. Surface bright spots
Reason: insufficient water in the sizing sleeve.
Solution: Increase the water volume of the sizing sleeve or remove and replace the sizing sleeve with a large amount of water
5. The inner and outer walls are not smooth in the axial direction
Reason: The moisture content of the raw material is too high.
Solution: raw material drying solution
6. The surface is not bright
Reason: the melt temperature is not suitable or the raw materials are not good
Solution: adjust melt temperature or dismantle and replace raw materials
7. Scratches on the outer surface
Reason: There is sand and gravel on the sizing sleeve, support plate or sealing ring
Solution: Clear the sizing sleeve, support plate or sealing ring
8. Outer waterline
Reason: Some water eyes of the sizing sleeve are blocked, causing some water eyes to have too much water.
Solution: Clear the sizing sleeve
9. The inner cavity groove (occurs in the wall-thickness pipe)
Reason: The wall thickness is too thick, the melt cannot be cooled, resulting in fluidity.
Solution: Try the cooling system to reduce the temperature of the mouth and core.
10. Uneven pipe wall thickness
Reasons: 1. The bolts of the mouth touch or core touch are loose, and the gap adjustment of the mouth touch is not suitable; 2. The temperature of the mouth touch or core touch is uneven, resulting in inconsistent material flow; 3. The sizing sleeve and the mouth touch are not centered, and the spiral separation Shuttle or screen is clogged.
Solution: 1. Tighten bolts or adjust the gap between the mouth and touch; 2. Check the heating ring and temperature sensor; 3. Adjust the sizing sleeve and the mouth and touch the centering and fold the separation shuttle or screen.
11. Low elongation at break
Reasons: 1. The raw materials are not so good; 2. The trend is increasing, and the cleanliness level is improved
Solutions: 1. Adjust the process temperature to improve the actual effect of plasticization; 2. Increase the distance between the die and the sizing sleeve.
12. Large ovality
Reason: gravity effect
Solution: Upgrade calibration equipment
PE pipe manufacturers can only manage the quality of pipes and effectively reduce product costs if they create strict safety operating procedures and process regulations and improve the process and manipulation strength.
