Quality Problems and Solutions in PE Pipe Production
The unexpected quality problems often occur in the production of PE pipes, which are generally caused by the problems of equipment or raw materials. Following will introduce the common PE pipe quality problems and their causes and solutions based on the experience of PE pipe production over the years.
1. Ripples appear on the surface of pipes. Reasons: 1. insufficient cooling and 2. improper sealing ring size, resulting in vibration.
Solution: Increase the water intake of the calibration sleeve or increase the distance between the calibration sleeve and the calibration sleeve. Check whether the size of vacuum groove seal ring is small. If it is small, replace or reduce the vacuum degree of the first vacuum groove appropriately, and increase the vacuum degree of the second vacuum groove.
2. Surface pitting (mainly inner wall). Reasons: 1. There are impurities in the raw material. The cleaning of the inner wall between the two mouths and the core moulds is not clean. 3. The local temperature is too high, which leads to aging.
Solution: 1 Check raw material 2 clean or transition period 3 Check temperature sensor
3. Surface pits. Reasons: 1. The moisture content of raw material and bubble burst are not uniform.
Solution: 1 raw material drying 2 adjusting water volume or replacing sizing sleeve
4. Bright spots on the surface. Reason: The water quantity of sizing sleeve is insufficient.
Solution: Increase the water content of the sizing sleeve or replace the sizing sleeve with large water content
5. Axial roughness of inner and outer walls. Reason: Water content of raw materials is too high.
Solution: raw material drying treatment
6. Reasons for surface dullness: inappropriate melt temperature or material problems
Solution: adjust melt temperature or replace raw material
7. Causes of scratches on the outer surface: sand and stone attached to the sizing sleeve, supporting plate or sealing ring
Solution: Clean calibration sleeve, supporting plate or sealing ring
8. Reasons for external surface water line: local water hole blockage of calibration sleeve, resulting in excessive water volume of individual water eyes.
Solution: Clean calibration sleeve
9. Reasons for inner wall grooves (mostly in wall-thickness pipes): the wall thickness is too thick, the melt is difficult to cool, and flow occurs.
Solution: Trial use of central cooling system to reduce the temperature of mouth touch and core touch.
10. Causes of uneven wall thickness of pipes: 1) Mouth touch or core touch bolt loosening, inappropriate adjustment of mouth touch clearance. 2) Non-uniform temperature of mouthfeel or core-feel results in inconsistent material flow. 3) The calibration sleeve is out of alignment with the mouth, the spiral shunt shuttle or the screen is blocked.
Solutions: 1) Fastening bolts or adjusting the gap between mouths 2) Checking the heating ring and temperature sensor 3) Adjusting the sizing sleeve and mouthfeel to fold the shunt or screen.
11. Reasons for the low elongation at break: 1. The raw material is not well shrunk, 2. The orientation increases, and the cleanliness increases.
Solution: 1. Adjust process temperature, strengthen plasticizing effect 2. Increase the distance between mouthfeel and sizing sleeve.
12. Great ellipticity: Cause: gravity
Solution: To increase the calibration device, PE pipe manufacturers must establish strict raw material supplier evaluation procedures, select the appropriate raw materials and deal with them properly according to the testing situation of raw materials. The production of high quality polyethylene pressure pipe depends strongly on the comprehensive output ability of the equipment. When selecting the equipment, the pipe manufacturer must make full investigation and demonstration in order to select the equipment with high cost performance. Tube manufacturers should establish strict operating and technological regulations and strengthen process and control efforts, in order to achieve the goal of both controlling the quality of pipe and reasonably reducing production costs. The process setting of pressure pipes and the solution of quality problems in production process need a lot of production experience, which requires manufacturers to accumulate a large amount of raw data, analyze and summarize, and guide production, in order to achieve the steady improvement of product quality.
