Technical Problems & Causes about the Production of PPR Pipes


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”.

In the production of PPR pipes, some problems may appear, and the followings are some common problems and their causes.





Unevenness in the inner wall of the pipe.

1. Screw temperature is too high. 2. Screw rotation speed is too fast.


Black stripes on the surface of the pipes.

1. Die head temperature is too high.

2. The filter is not clean.


Air bubbles on the inside of the pipe.

The raw materials are damp.


Suddenly slow material discharge

1. High temperature in the screw heating zones

2. Water in the extruder; low pressure in the head.

3. Low pressure of the nose solution.


The inner wall of the pipe is rough.

1. Mandrel temperature is low.

2. The machine's body temperature is too low.

3. The screw temperature is too high.


Dull surface of the pipe.

The die mouth temperature is too low or too high.


The surface of the pipe has wrinkles

1. The temperature around the die mouth is  not well-distributed;

2. The cooling water is too hot.

3. Hauling speed is too slow.


The inner wall of the pipe is cracked.

1. Material has impurities.

2. The temperature of the mandrel is too low.

3. The machine's body temperature is low.

4. Hauling speed is too fast.


There are coke marks on the surface of the pipe.

1. Machine body or die temperature is too high.

2. The die head and filter are not cleaned.

3.  There are impurities in the grain.

4.  The thermal stability of raw materials is poor or the thermal stability dose is too little.

5. Control temperature meter failed.


The pipe has large longitudinal or transverse shrinkage.

1. The radial difference between the inner diameter of the sizing sleeve and the die is large (transverse).

2. Fast hauling speed (longitudinal).


Uneven wall thickness

1. Die mouth and mandrel are not aligned.

2. Uuneven head temperature.

3. Unstable traction.

4. Unstable compressed air.

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.

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