What is a purging compound?

A purging compound is a resin-based product designed to clean thermoplastic molding machines of many types; injection molding machines, blow molding machines, and extruders which are used to manufacture plastic parts for a wide range of industries, including automotive, consumer, medical and many others.

Purging Compounds Explained

When a resin is introduced into a machine to produce a plastic component, the barrel, screw, nozzle and mold or die must be free of any residue or contaminants to produce acceptable parts. For example, when a molder completes a run of black parts and needs to begin producing white parts, the black plastic resin must be completely removed from the machine before white parts can be produced. Also, if the processor needs to change tooling and/or material, the previous material and any contamination (such as black specks), must also be purged out before satisfactory parts can be manufactured.

Advantages of Using Purging Compounds

Without a thorough purge between a color change and/or material change, defects such as black specks or streaking will cause newly manufactured parts to be rejected. Reject parts and machine downtime add up to costly waste for the manufacturer. An ideal commercial purging compound (CPC) is comprised of resin pellets blended with proprietary materials and is designed to work with various manufacturing processes and temperatures.

Commercial Purging Compounds Applications

Commercial purging compounds are available to purge commodity materials such as acrylic, polypropylene, polyethylene, polystyrene, polyvinyl chloride, as well as engineering resins such as ABS, polycarbonate, PET, PBT, nylon, TPO, TPE, and many more commonly processed resins.

Commercial purging compounds are utilized to clean nozzles, screws, barrels, and extrusion dies. As well, some CPCs have been designed to clean hot runner systems/manifolds. Purging thermoplastic process equipment on a regular basis with a quality commercial purging compound can eliminate the need to pull a screw for manual cleaning. Should pulling the screw be part of a maintenance program, the use of a high quality purging compound prior to pulling the screw can make the process easier.

In addition, many commercial purging compounds are recommended for use before and/or after machine shutdown. This practice often prevents the formation of contamination during machine cool down, leading to improved startup, including the reduction of scrap material and parts.

Different types of commercial purging compounds are available in the marketplace, including mechanical, chemical, and combination mechanical/chemical. It is important to note that there is no equivalency between CPCs manufactured by different companies, and the amount needed and results obtained with one purging compound are not necessarily the same for other CPCs.

Order Our Newest Purging Compounds Today

Purgex is thrilled to announce that we have released a new purging compound specifically for automotive applications. Or visit our helpful purging compound comparison tool to see how all our products stack up.