How to Pick the Best Purging Compound For Your Extruder


Different Extrusion processes have different needs from purging compoundsWhen it comes to cleaning different kinds of extrusion equipment, there is no one-size-fits-all process or purging compound solution.

Carbon builds up in your machines’ dead spots – such as their nozzle areas and mixing sections – and without the right purging compound and procedures,  you run the risk of increased reject rates. 

However, determining the proper purging compound grade for is not simply about eliminating color and carbon contamination – it’s also about the impact on your bottom line.

Taking a narrow view may lead you to choose the wrong purging compound, which ultimately wastes resources and affects profitability.

With your efficiency and profitability on the line, you can’t afford to predetermine what purging compound to apply and how much of it to use. You must ask yourself the following questions in order to determine the right product grade for your systems.

5 Questions To Determine The Right Purging Compound

What is the size of your extruder?

The size of your machines, specifically barrel capacity, is a main and obvious determinant of how much product you need to use for an effective clean. Also consider how many lines and layers are involved.The bigger the barrel, the bigger the die, and the more lines and layers you have, the more purging compound you must use. 

What resins are you using?

Determining how to clean your systems is dependent on whether you’re using high-temperature resins such as PEEK, PEI or LCP versus PC, ABS or Acetal. When high-temperature resins sit in the barrel, degradation occurs rather quickly; they tend to cement themselves to your screw, which may require using a glass-filled, high-temperature grade of purging compound. But if you proactively clean your systems, non-glass-filled grades are perfectly acceptable.

What is your range of operating temperatures?

As mentioned above, the temperature at which you process your resins has a big impact on the grade of purging compound you should use. There are different grades for operating temperatures as low as 320 degrees Fahrenheit to as high as 790 degrees Fahrenheit. But it’s not simply temperature alone that’s important; you must also consider whether you’re switching from high- to low-temperature resins, or vice versa.

High-temperature resins often require PF or PX2 Grade purging compounds, whereas low-temperature resins may require E Grade.

What is the intended application(s) of the purging compound?

Purging products can be used for several different cleaning applications, and each of them may require a different grade of purging compound. Different applications may require different temperatures, and may necessitate high-scrubbing action. These applications include:

  • Color changes
  • Material changes
  • Sealing or shutdown
  • Clear and low-residue applications
  • Carbon or color contamination
  • Holding a bubble in blown-film

What issues are you currently experiencing?

There is a wide range of problems your extruder may be experiencing, and the kinds of issues you’re having – such as color streaking, the presence of black specks or trouble removing previous resins – will likely dictate the best solution for your situation.

Using the right purging compound helps you maximize your operational efficiency by effectively eliminating all contamination and increasing up-time and productivity. If you understand the impact of each of these five questions, you are equipped to choose the right solution to effectively clean your extruder. 

Learn how to reduce machine downtime with five quick purging compound tips.

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Topics: Production Efficiency, color contamination, Extrusion, Plastics Production, preventative measures, carbon specs, carbon contamination, Extrusion Lines, reduce downtime, Extrusion Purging, Blown Film Extrusion, Cast Extrusion, extrusion troubleshooting, extrusion die, Film Extrusion, Sheet Extrusion, extrusion blow molding

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