How to Control Loss in the UPVC Extrusion Process

Purging Material

You can detect many defects like surging; melt fracture, degradation, voids, gels and specks in the profile extrusion process leading to the maximum amount of waste. Using purging material from reputed manufacturers can help to control loss in the UPVC extrusion process.

If you look at the UPVC profile manufacturing industries, you will notice a substantial amount of waste during the manufacturing process. There are different noticeable defects like surging, melt fracture, degradation, voids, gels and specks etc. Some of the causes can have a link to the raw material used. It happens when the raw material is not up to the required specification. Even if all the extrusion parameters have ideal maintenance, you can notice that the manufactured products have a different look, bend, colour or texture. Though it may seem unscientific such problems happen on the production floor. As extrusion is a high-volume manufacturing process, such defects can lead to substantial scrap and time-consuming shutdown.

If you desire to reduce escape and time-consuming shutdowns, it is wise to use purging material purchased from reputed manufacturers.

The way to avoid significant flaws using purging compounds

As told earlier, you can notice surging, melt fracture, degradation, voids, gels and specks etc. Each of these defects can have avoidance using purging material for injection moulding. Let us see how it is possible.


We call it surging if we notice a cyclical variation in product thickness in the extrusion direction. The surge cycle can typically last 30 seconds to 3 minutes, and the cause can be internal or external. It is easier to notice the external causes and rectify those. However, the defect is due to internal components if you do not see any such symptoms leading to external causes. It is sometimes possible to cure such defects by raising the temperature of the feed to promote earlier melting. However, raising the temperature may sometimes tend the pallets to stick to the walls and increase the rejection rate. Instead, if you use purging compounds made by reputed manufacturers, it will be possible to pull out the break-down UPVC material fractions and have a clean frictionless surface.

Melt fracture

Melt fractures are the fine ridges or rough surfaces noticed when the melt comes out fast from the narrow die. It commonly happens when the material happens to experience excessive shear of friction at the die lip. Using mechanical grades from reputed manufacturers can pull out the hard layer developed due to the raw material shear and molecular degradation.


Overheating may limit the rate or produce degradation making dimensional control and sizing difficult. If, in such conditions, you use purging material of reputed make, possible to operate at a low processing temperature will help in eliminating burnt materials without raising the temperature, which may cause costly rejections.

About the author

If you desire to have such purging compound and purging material for injection mouldingit is wise to contact UNICLEANPLUS. You can contact them at +91 9021232809 for free samples or have the latest information on effective purging compounds.