High-density polyethylene(HDPE) water supply pipe is a commonly used water supply pipe. Due to its good flexibility and high pressure resistance, it has become the best choice for modern water supply and drainage. Moreover, high-density polyethylene(HDPE) water supply pipes are made of white, non-toxic, and flexible PE raw materials, which are used in many engineering projects.
However, sometimes it is found that the surface of high-density polyethylene(HDPE) water supply pipe is rough and fails to meet the qualified standard. If the surface of the PE water supply pipe is not smooth and unqualified during the acceptance of the project, the acceptance will fail. There are many reasons for the rough surface of the pipe. Therefore, only when the cause is clear, can we take a targeted solution to make the high-density polyethylene(HDPE) water supply pipe have a high-quality surface. The following are several common reasons, for reference only, Please contact us for specific information to analyze and answer for you.
1.If the high-density polyethylene(HDPE) water supply pipe is made of new materials, removing the moisture in the raw material will cause the surface of the pipe to be not smooth; if it is not smooth, only a thin layer on the surface is produced, indicating that it is likely to be caused in the die section, in order to make the surface smoother, the molecules on the surface of the melt must achieve the necessary level of relaxation before entering and exiting the mold.
2.The surface roughness of the high-density polyethylene(HDPE) water supply pipe is caused by the friction between the melt and the mold surface, and has nothing to do with the mold surface roughness.
3.For high-viscosity polyethylene, due to the strong entanglement between the molecular chains, the surface of the high-density polyethylene(HDPE) water supply pipe is very rough, which is not easy to separate from the melt and cannot form effective lubrication. So, if you want the pipe surface to be smooth, you must add another lubricant.
4.The friction between the melt and the die leads to the accumulation of material on the die, which leads to non-smoothness.
5.The uneven cooling water output of the sizing sleeve causes the surface of the pipe to be not smooth. The reason is that with the expansion of the diameter, the more the sizing sleeve is affected by the circulation of cooling water and the greater the damage caused by gravity, the greater the cooling water output required, the greater the difficulty of cooling. The water output of each water inlet pipe should be adjusted, and the water output at the upper part should be appropriately expanded or the water output at the location where the actual effect of cooling is poor.
6.Because the heating time of the raw materials in the engine or barrel is too long, the engine and the screw barrel are not cleaned, the production and processing temperature is too high, or the screw is damaged. When adding recycled materials, this kind of situation should stop adding crushed materials up and down within 1.5 hours of shutdown. If it does not start 4 hours after shutdown, the temperature should be quickly reduced to 150-200°C to minimize the decomposition level of raw materials. Attention should be paid to check whether the production processing temperature is included in the extrusion regulations.
7.When the raw material is wet, if it is not fully dried, the surface of the PE pipe will cause air bubbles to cause pitting. Observe that such pits have a tail caused by stretching on the reverse of the extrusion. At this time, the raw material needs to be dried and could be solved.
8.When there are impurities that cannot be plasticized in the raw materials, pits can also be caused. When such pits are large, the impurities can been seen and identified. At this time, the production and processing temperature must be increased or the raw materials must be replaced.
9.The surface of the PE pipe is not smooth due to the excessive cooling water output. This kind of situation is mainly caused on the hole-type sizing sleeve, because the internal flow channel of the sizing sleeve is not partitioned, and part of the water is under heavy pressure under the action of gravity, and the water output is large. The upper part of the water output is small, and the surface of the pipe is soft, causing pitting in places with high pressure.
The above reasons are only a few common in production. If you encounter similar or production problems, please contact us. Our production engineers will conduct specific analysis according to the specific situation and find out a solution to the problem.
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