--- title: "Purging for Extrusion: Screw & Barrel vs. Downstream" description: Purging Expert Jeremy Cooley discusses purging compounds for extrusion. Consider screw & barrel vs. purging downstream extrusion equipment. image: https://www.asaclean.com/hubfs/Blog%20Header-extrusions%20screw%20vs%20downstream.jpg --- [ Order Online ](https://asaclean.my.site.com/b2bstore) [ Free Sample ](https://offers.asaclean.com/free-sample) ## [ Asaclean Blog ](https://www.asaclean.com/blog) Browse by Topic " aerospace asaclean asaclean news Asaclean® benefits asahi kasei automotive Best Practices black specks blisters blow molding blown-film extrusion buyers caps and closures carbon contamination cast-film extrusion Chemical Purging Compounds clear applications Color Changeovers Company News compounding consumer products contamination Cost savings custom molders Customer Success Story decreasing scrap defects electronics Energy Efficiency EX Grade extruder cleaning Extrusion fillament glass filled Glitter Grade Selection HDPE High and Low Temp Changeovers hold a bubble Hot Runners Injection Molding Injection Molding Tips LDPE Lightweight automotive components LLDPE low residue maintenance Material Changeovers Mechanical Purging Compounds medical Melt Flow Index NPE 24 nylons on the fly packaging PCR PEEK Polypropylene Post Consumer Resins preventative preventative purging processing tips profile extrusion Purge Program purge programs Purge Training Purge Trial purging purging compounds purging concentrates purging procedures Purging Tips quality recycled resins residue issues scrap reduction Screw Pulls sheet extrusion shutdown and sealing start-up super engineering resins Sustainability Tech Day technical support training trials Troubleshooting Twin Screw twin screw extrusion two step purging U Grade ULTEM venting Viscosity webinars wire extrusion - 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[Twin Screw](https://www.asaclean.com/blog/topic/twin-screw) - [twin screw extrusion](https://www.asaclean.com/blog/topic/twin-screw-extrusion) - [two step purging](https://www.asaclean.com/blog/topic/two-step-purging) - [U Grade](https://www.asaclean.com/blog/topic/u-grade) - [ULTEM](https://www.asaclean.com/blog/topic/ultem) - [venting](https://www.asaclean.com/blog/topic/venting) - [Viscosity](https://www.asaclean.com/blog/topic/viscosity) - [webinars](https://www.asaclean.com/blog/topic/webinars) - [wire extrusion](https://www.asaclean.com/blog/topic/wire-extrusion) [ Subscribe ](https://www.asaclean.com/blog/purging-for-extrusion-screw-barrel-vs.-downstream#subscribe-modal) ### Suscribirse Chemical Purging Compounds / 4 min read / February 01, 2022 # Purging for Extrusion: Screw & Barrel vs. Downstream - [Facebook Share ](https://www.facebook.com/sharer/sharer.php?u=https%3A%2F%2Fwww.asaclean.com%2Fblog%2Fpurging-for-extrusion-screw-barrel-vs.-downstream) - [Twitter Tweet ](https://twitter.com/intent/tweet?url=https%3A%2F%2Fwww.asaclean.com%2Fblog%2Fpurging-for-extrusion-screw-barrel-vs.-downstream&text=Purging+for+Extrusion%3A+Screw+%26amp%3B+Barrel+vs.+Downstream) - [LinkedIn Share ](https://www.linkedin.com/shareArticle?mini=true&url=https%3A%2F%2Fwww.asaclean.com%2Fblog%2Fpurging-for-extrusion-screw-barrel-vs.-downstream&title=Purging%20for%20Extrusion%3A%20Screw%20%26amp%3B%20Barrel%20vs.%20Downstream&summary=Purging+Expert+Jeremy+Cooley+discusses+purging+compounds+for+extrusion.+Consider+screw+%26amp%3B+barrel+vs.+purging+downstream+extrusion+equipment.&source=) - [Pinterest Pin ](https://pinterest.com/pin/create/button/?url=https%3A%2F%2Fwww.asaclean.com%2Fblog%2Fpurging-for-extrusion-screw-barrel-vs.-downstream) - [Email Email ](mailto:?subject=Purging%20for%20Extrusion%3A%20Screw%20%26amp%3B%20Barrel%20vs.%20Downstream&body=https%3A%2F%2Fwww.asaclean.com%2Fblog%2Fpurging-for-extrusion-screw-barrel-vs.-downstream) ![Purging for Extrusion: Screw & Barrel vs. Downstream](https://www.asaclean.com/hs-fs/hubfs/Blog%20Header-extrusions%20screw%20vs%20downstream.jpg?width=640&height=500&name=Blog%20Header-extrusions%20screw%20vs%20downstream.jpg) ![Wire_Tube 4](https://www.asaclean.com/hs-fs/hubfs/Wire_Tube%204.jpg?width=346&height=173&name=Wire_Tube%204.jpg) Extrusion applications vary greatly depending on the application. Wire coating, Compounding, Fiber, Sheet, Profile, Cast Film, and Blown Film are just a few examples of different extrusion processes. The extruder itself can vary as well when you consider screw design, size, twin vs single, etc. but the genesis remains the same. The motor turns the screw at a desired RPM, pulls pelletized resin from the hopper through the feed throat, melts the plastic resin as it passes through the different zones of the screw and a uniform plastic melt exits the end of the screw ready to travel through the downstream equipment. Some processors just need to clean the screw and barrel and that is usually a fairly straight forward process. The specific grade of purging compound depends on several factors including the type of production resin being ran, processing temperatures of the production resin, colorants or other additives, issue that is being addressed, and several others. When a purge is needed for elements that are beyond the screw and barrel that is when design and build of the die and a technical understanding of what is actually happening becomes really important. Beyond the end of the screw we sometimes see screen packs, melt pumps, static mixers, and feed blocks for co-extrusion applications. Beyond that you come to the die and depending which application is being discussed the varied types and styles of extrusion dies are numerous. The same factors that go into the grade recommendation for the screw and barrel still hold true for the die such as production resin, temps, colorants, etc. However, the grade of purging compound recommended to clean the die area includes some other factors to think about. We always want to establish what type of issue is taking place within the system that the correct purge can eliminate. Are we looking at color or material changes, contamination that is building up in the die area, low flow or high pressures, complete cleanout after a run, or shut down and seal for the weekend or extended downtime where black specs at start-up needs to be avoided? The grade selection will depend at least somewhat on how the plastic moves throughout the die. Some questions you should ask yourself: 1. **Are there unique flow channels that can hold previous material or contamination? ** 2. **Does the die have mandrels (pipe & tubing) where previous color or contamination can hide? ** 3. **Are there deckles in place on a hanger die (sheet & cast film) which meter down the width but can also hold back material flow and cause degradation? **On hanger dies we like to remove the deckles so that the entire width of the die can be purged and how difficult it is to get material to the outside edges may make the difference between a chemical or mechanical grade recommendation. 4. ** Are you running a crosshead die (wire coating)?** This is completely different than the other processed since the wire has to be pulled through while the plastic coating is being extruded. Some crosshead dies can have complex flow channels. Keep in mind that there are many grade options for purging compounds. Speaking to your technical sales rep and digging into the specifics of a process can make a huge difference in having the right purge grade for the right application. The factors in play are many, but having the correct purge grade on hand when it is needed will be a game changer for your shop. ** Learn more about how to reduce production downtime and protect your profits with a purging compound.** ![Yoko Tanaka](https://www.asaclean.com/hs-fs/hubfs/Yoko%20Tanaka%20Headshot%203-25-16.jpg?width=150&name=Yoko%20Tanaka%20Headshot%203-25-16.jpg) #### [ Yoko Tanaka ](https://www.asaclean.com/blog/author/yoko-tanaka) Yoko Tanaka is the Marketing Manager at Asaclean. She has been helping molders and extruders learn about Asaclean purging and how to improve their processes for the past eight years. - [Share On LinkedIn ](https://www.linkedin.com/in/yokotanaka/) ## Related Posts [![Extrusion Defects–Pinstriping](https://www.asaclean.com/hs-fs/hubfs/AI-Generated%20Media/Images/This%20image%20shows%20navy%20blue%20vertical%20pinstripes%20on%20a%20white%20background.jpeg?width=450&height=250&name=This%20image%20shows%20navy%20blue%20vertical%20pinstripes%20on%20a%20white%20background.jpeg) Extrusion Defects–Pinstriping Troubleshooting / 2 min read / October 25, 2019 ](https://www.asaclean.com/blog/high-cavitation-injection-molding-0) [![](https://www.asaclean.com/hs-fs/hubfs/Sheet%20Die.png?width=450&height=250&name=Sheet%20Die.png) Purging Extrusion Sheet Applications & the Challenges with Hanger Dies Chemical... / 3 min read / March 23, 2021 ](https://www.asaclean.com/blog/purging-extrusion-sheet-applications-the-challenges-with-hanger-dies) ## Comments Get Started ## Ready to start improving your efficiency and increasing your profitability? - [Request a Consultation](https://www.asaclean.com/blog/purging-for-extrusion-screw-barrel-vs.-downstream#) - [Contact Sales](https://www.asaclean.com/blog/purging-for-extrusion-screw-barrel-vs.-downstream#) ![](https://www.asaclean.com/hubfs/assets/images/icons/icon-layers.svg) #### Free Sample Request a free sample of Asaclean® Purging Compounds for your plant and start saving today. 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[See your savings](https://www.asaclean.com/cost-savings-calculator) [ Back to Top ](https://www.asaclean.com/blog/purging-for-extrusion-screw-barrel-vs.-downstream#top) ```json { "@context" : "https://schema.org", "@type" : "BlogPosting", "author" : { "@type" : "Person", "name" : "Yoko Tanaka", "url" : "https://www.asaclean.com/blog/author/yoko-tanaka" }, "dateModified" : "2022-03-22T23:35:55.047Z", "datePublished" : "2022-02-01T15:46:46.000Z", "headline" : "Purging for Extrusion: Screw & Barrel vs. Downstream", "image" : [ "https://www.asaclean.com/hubfs/Blog%20Header-extrusions%20screw%20vs%20downstream.jpg" ], "mainEntityOfPage" : { "@id" : "https://www.asaclean.com/blog/purging-for-extrusion-screw-barrel-vs.-downstream", "@type" : "WebPage" }, "publisher" : { "@type" : "Organization", "logo" : { "@type" : "ImageObject", "url" : "https://www.asaclean.com/hubfs/Asaclean%20Logo%20TM.jpg" }, "name" : "Asahi Kasei Plastics North America" } } ``` ```json { "@context" : "http://schema.org", "@type" : "Article", "articleBody" : "Extrusion applications vary greatly depending on the application. Wire coating, Compounding, Fiber, Sheet, Profile, Cast Film, and Blown Film are just a few examples of different extrusion processes. The extruder itself can vary as well when you consider screw design, size, twin vs single, etc. but the genesis remains the same. The motor turns the screw at a desired RPM, pulls pelletized resin from the hopper through the feed throat, melts the plastic resin as it passes through the different zones of the screw and a uniform plastic melt exits the end of the screw ready to travel through the downstream equipment. Some processors just need to clean the screw and barrel and that is usually a fairly straight forward process. The specific grade of purging compound depends on several factors including the type of production resin being ran, processing temperatures of the production resin, colorants or other additives, issue that is being addressed, and several others. When a purge is needed for elements that are beyond the screw and barrel that is when design and build of the die and a technical understanding of what is actually happening becomes really important. Beyond the end of the screw we sometimes see screen packs, melt pumps, static mixers, and feed blocks for co-extrusion applications. Beyond that you come to the die and depending which application is being discussed the varied types and styles of extrusion dies are numerous. The same factors that go into the grade recommendation for the screw and barrel still hold true for the die such as production resin, temps, colorants, etc. However, the grade of purging compound recommended to clean the die area includes some other factors to think about.", "author" : { "@type" : "Person", "name" : "Yoko Tanaka" }, "datePublished" : "February 01, 2022", "headline" : "Purging for Extrusion: Screw & Barrel vs. Downstream", "image" : "https://468726.fs1.hubspotusercontent-na1.net/hubfs/468726/Blog%20Header-extrusions%20screw%20vs%20downstream.jpg", "name" : "Purging for Extrusion: Screw & Barrel vs. Downstream", "url" : "https://www.asaclean.com/blog/purging-for-extrusion-screw-barrel-vs.-downstream" } ```