H.D.Plastics is a reliable factory and supplier for custom flexible and rigid plastic pipes and other square or round plastic tubings made by plastic extrusion processing with great features of superior Longevity and high flexibility.

Multiple engineering thermal plastics can be extruded into custom-built plastic tubing or personalized pipes in our H.D. extrusion workshop. such as HDPE (High-density polyethylene), ABS,PVC or uPVC, PP (polypropylene), PE (polyethylene), PC (Polycarbonate), PMMA (Acrylic).

During our 10 years of plastic extrusion manufacturing,we have accumulated a lot of practical knowledge on material and extrusion techniques to make sure the superior quality of plastic pipe extrusion.

two color PC tube
Extruded fiberglass Profiles

Single-screw extruders often use plasticized pellets to form plastic pipes. So the quality of hard pipe products is largely determined by the degree of plasticization and uniformity of the semi-finished pellets.

There are two kinds of plasticizing processes for pellets: one is to plasticize the powdered material in the extruder after kneading and uniformity. And then release the round material on the head while cutting the pellets into round pieces by the rotating throwing knife;

Another is plasticizing the raw material by the dense refining and rolling machine. The material is made to a certain thickness, just like a certain width of the sheet material, rolled into a roll, and then cut into square granules.

First : Extruded plasticized pelletizing

There are several advantages to this type of pelletizing. Such as continuous sealing, a small investment in equipment, low labor intensity, and low noise. So it is the current main trend for the granulation process.

Especially for twin-screw pelletizing extruder, due to its good mixing degree and plasticization uniformity, it has been generally attached importance.

However, we should pay more attention to the following points during production:

  1. Keep the raw materials sufficient fineness to ensure uniform mixing in the kneader. Otherwise, the particles will appear trisodium lead sulfate white spots, carbon black spots, and filler clumping points in the extrusion granulation process.
  2. Keep resin loose type (i.e. cotton ball type) resin so as not to affect the continuous burst of granulation.
  3. Control the extruder body temperature less than 170 ℃ so as to avoid the discolor of the outside of the granules with the internal microporous. Such pellets are unstable and easily decomposed in the pipeline production.
  4. Often change the filters as not to mix in the garbage.

Second: Roller pelletizing by Dense refining

High temperature is not suitable for both dense plasticizing and roller plasticizing. The dense plasticizing material temperature should be no more than 175-180 ℃, and roller plasticizing spacing no more than 3 mm. multi-turning process in low-temperature is more reasonable. At the same time, each batch of granules is required to plasticize evenly.

It is divided as follows: The raw materials must be mixed evenly in the mixing process, otherwise, the trisodium lead sulfate and barium stearate are easily precipitated during the extrusion, and the granules are less stable and easy to decompose.

In the dense plasticizing process, if the material temperature is too high, the plastic pipe extrusion process is easy to hairy, blistering.

Without the use of the refining machine, but with the second roll plasticization production granules, we should pay attention to the plasticization temperature not be too low, otherwise, the tube is easy to brittle, and the flat test can not meet the quality requirements.