What problems cause the uneven wall thickness of PVC pipes?

01. Problems with molds
One of the key factors for the uneven wall thickness of PVC pipes lies in the molds. The clearance of the molds or the shape of the mold channels can both lead to uneven flow of PVC raw materials during the forming process, which in turn results in inconsistent wall thickness of the pipes. Especially in terms of mold design standards or manufacturing precision, it may cause the flow of raw materials to be blocked during the pipe forming process, resulting in changes in wall thickness at different positions.

Concrete manifestations:
Uneven mold clearance: The asymmetrical clearance on the upper and lower or left and right sides of the mold may lead to a relatively faster flow rate of raw materials in these areas, thus making the wall thickness of the pipes in these parts thinner.
Mold design defects: Unreasonable design of the mold channels will affect the flow of molten PVC, resulting in thicker or thinner wall thickness in some areas.
Another situation is the blockage of the mold channels. Any tiny blockage will lead to poor flow of the molten PVC, which will then affect the uniformity of the wall thickness of the pipes. Finally, mold cleaning is an important step to ensure the normal operation of the mold. Any inadequate cleaning may result in the uneven wall thickness of PVC pipes.

02. Uneven Plasticization and Insufficient Pressure
During the production process, uneven plasticization or insufficient pressure can also lead to uneven wall thickness. Uneven plasticization means that the PVC raw materials fail to melt evenly during the heating process, and the fluidity of some raw materials is poor, which further affects the wall thickness of the pipes. Insufficient pressure means that the molten PVC materials in the mold cannot be fully squeezed into every corner of the mold, resulting in incomplete molding.

Concrete manifestations:
Uneven plasticization: If the temperature control of the plasticizing equipment is unstable or the rotational speed of the screw is inappropriate, it may lead to differences in the physical properties of the molten PVC raw materials during the flow process, thus making the wall thickness of some parts of the pipes thinner.
Insufficient pressure: If the output pressure of the extruder is too low during the production process and cannot send enough molten PVC into the mold, this will also result in uneven pipe molding, especially in the distal or corner parts of the mold.

The reasons for the uneven wall thickness of PVC pipes may involve multiple factors such as mold design, mold blockage, uneven plasticization, and insufficient pressure. Shandong novista Chemicals has performed outstandingly in solving production problems in industries such as PVC, CPVC, and engineering plastics.