The Reason of Abnormal Production Quality of PE Plastic Pipe and Solution


Ningbo Fangli Technology Co., Ltd. is a mechanical equipment manufacturer with nearly 30 years’ experiences of plastic pipe extrusion equipment, new environmental protection and new materials equipment. Since its establishment Fangli has been developed based on user’s demands. Through continuous improvement, independent R&D on the core technology and digestion & absorption of advanced technology and other means, we have developed PVC pipe extrusion line, PP-R pipe extrusion line, PE water supply / gas pipe extrusion line, which was recommended by the Chinese Ministry of Construction to replace imported products. We have gained the title of “First-class Brand in Zhejiang Province”.


1. The raw material: There are so many grades of PE raw material, the same grade of raw material can produce the PE corrugated pipe but can’t produce PE Water Pipe. The key is to choose the fit raw material.

2. Influence of temperature on PE pipe quality: Temperature is the main factor influencing the pasticization and pipe quality. The lowly temperature will cause cannot reach such good plasticity. The high temperature will cause the material easy to decompose. The temperature should be controlled according to the raw material, extrusion machine, the head of the extruder, screw rotation speed, and so on. By producing the hard PVC pipes, because the heating temperature is close to the decomposing temperature, the temperature of all parts should be controlled strictly. At the same, notice the deviation of the temperature meter and the location of the measurement.

3. Influence of screw rotation speed on the quality: The chosen screw rotation speed influences the capacity and quality directly. On one hand, it depends on the type of extrusion machine, on the other hand, it depends on one the pipe diameter. screw speed up, extrusion output up, the shear force of the material is large, it’s good for plasticization, However, the material stays in the screw for a short time, excessive heat of friction makes the inner wall of pipe getting rougher, hard of pipe getting down. So, the control of the screw rotation speed should be controlled according to capacity, product appearance, and physical and mechanical.

4. Influence of traction speed on the PE pipe quality: The traction speed influences the pipe wall thickness directly. Traction speed should achieve a balance between extrusion speed, usually, traction speed is higher than extrusion speed by about 1% to 10%.

5. Influence of vacuum on the pipe quality: Negative vacuum sets the tube and keeps it round. The pressure is 0.02-0.05mpa.

6. Influence of traction cooling on the pipe quality: Incomplete cooling procedure will cause the extruder material sticker. The best choice is fan cooling combined with water cooling.






Wall thickness

Wall thickness unevenness

Partial wall thickness is too thin

1. the space between medrial and die mouth was unsuitable:dolt of die mouth or medrial were loose,

2. Discharging Speed unstable

3. Traction speed unstable

4. Water mould Lack of cooling water

5. Temperature of Die mouth and medrial were uneven,cause the material flow can not keep the same every parts of temperature are suitable.

6. Cooling of the discharge part were no good

7. Caliber got rusty

8. Caliber was too far away from die mouth

9. Caliber and die mouth wasn’t align,Screw shunt shuttle and screen pluged.


1. fine tune the position of the die head,tighten the bolts or adjust the gap between the die mouth and the mould

2. Adjust the position of the motor ,or replace the belt(tight),replace the carbon brush

3. Check the traction device(chain,mechanical scale,air pressure,etc)

4. Check the wall thickness of the small parts of the spray pipe and spraying head, etc.

5. Check the heating ring and temperature sensor,adjust the temperature of heating coil in each area

6. Unclog the lower section and cooling system

7. Polish the sizing sleeve

8. Close the distance

9. Adjust the sizing sleeve and mouth touch centering split flow shuttle or decorative mesh.

Wall thickness is thin at the top and thick at the bottom

1. material melt flow rate is large viscosity is small(like ME3440)

2. Cooling is not timely

3. Core die and die mouth spacing is not suitable


1. Fully consider the gravity factor to adjust the spacing of the die mouth and medrial

2. Increase the cooling water (consider reducing the water temperature)

3. Micro-predicate the spacing of medrial and die mouthe accordingly

Wall thickness generally exceeds the upper limit

1. Extrusion is too fast

2. Traction is too slow

3. The outer diameter is small

1. Reduce the extrusion speed of the main machine

2. Speed up the traction speed

3. Increase the vacuum degree

Wall thickness is generally insufficient ,wall thickness changes at any time

1. Extrusion is too slow

2. Outside diameter is too large

3. Traction too fast

4. Small viscosity of the material body flow rate,not enough heating in each area

5. The temperature at the lower material mouth is high or encounter large blockage of materials

6. Extrusion degree change

1. Increase the extrusion speed of the host

2. Reduce the vacuum degree

3. Reduce the traction speed

4. Increase the temperature of each area of the main machine

5. Dredge the water temperature of the upper section of water

6. Check the traction

7. Increase the pressure appropriately

8. Sieving or granulating raw materials

Outer diameter

The outer diameter is sometimes large and sometimes small  

1. Unstable vacuum level

2. Traction machine slipping

1. Check whether the vacuum box leakage,vacuum pump operation is normal

2. Adjust the clamping force or change the friction material

Large ellipticality


1. Gravity and cooling is not good

Install the correction device,increase the cooling.

If you need more information, Ningbo Fangli Technology Co., Ltd. welcomes you to contact for a detailed inquiry, we will provide you with professional technical guidance or equipment procurement suggestions.

  • QR
We use cookies to offer you a better browsing experience, analyze site traffic and personalize content. By using this site, you agree to our use of cookies. Privacy Policy