--- title: Bridging in the Feed Throat description: Prevent feed throat bridging by understanding how resin melts too early, and learn the ideal temperature settings to avoid costly machine downtime. image: https://www.asaclean.com/hubfs/cleaning-hot-runner-systems.jpg.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 - [All](https://www.asaclean.com/blog/page/1) - More - [aerospace](https://www.asaclean.com/blog/topic/aerospace) - [asaclean](https://www.asaclean.com/blog/topic/asaclean) - [asaclean news](https://www.asaclean.com/blog/topic/asaclean-news) - [Asaclean® benefits](https://www.asaclean.com/blog/topic/asaclean-benefits) - [asahi kasei](https://www.asaclean.com/blog/topic/asahi-kasei) - [automotive](https://www.asaclean.com/blog/topic/automotive) - [Best Practices](https://www.asaclean.com/blog/topic/best-practices) - [black specks](https://www.asaclean.com/blog/topic/black-specks) - [blisters](https://www.asaclean.com/blog/topic/blisters) - [blow molding](https://www.asaclean.com/blog/topic/blow-molding) - [blown-film extrusion](https://www.asaclean.com/blog/topic/blown-film-extrusion) - [buyers](https://www.asaclean.com/blog/topic/buyers) - [caps and closures](https://www.asaclean.com/blog/topic/caps-and-closures) - [carbon contamination](https://www.asaclean.com/blog/topic/carbon-contamination) - [cast-film extrusion](https://www.asaclean.com/blog/topic/cast-film-extrusion) - [Chemical Purging Compounds](https://www.asaclean.com/blog/topic/chemical-purging-compounds) - [clear applications](https://www.asaclean.com/blog/topic/clear-applications) - [Color Changeovers](https://www.asaclean.com/blog/topic/color-changeovers) - [Company News](https://www.asaclean.com/blog/topic/company-news) - [compounding](https://www.asaclean.com/blog/topic/compounding) - [consumer products](https://www.asaclean.com/blog/topic/consumer-products) - [contamination](https://www.asaclean.com/blog/topic/contamination) - [Cost savings](https://www.asaclean.com/blog/topic/cost-savings) - [custom molders](https://www.asaclean.com/blog/topic/custom-molders) - [Customer Success Story](https://www.asaclean.com/blog/topic/customer-success-story) - [decreasing scrap](https://www.asaclean.com/blog/topic/decreasing-scrap) - [defects](https://www.asaclean.com/blog/topic/defects) - [electronics](https://www.asaclean.com/blog/topic/electronics) - [Energy Efficiency](https://www.asaclean.com/blog/topic/energy-efficiency) - [EX Grade](https://www.asaclean.com/blog/topic/ex-grade) - [extruder cleaning](https://www.asaclean.com/blog/topic/extruder-cleaning) - [Extrusion](https://www.asaclean.com/blog/topic/extrusion) - [fillament](https://www.asaclean.com/blog/topic/fillament) - [glass filled](https://www.asaclean.com/blog/topic/glass-filled) - [Glitter](https://www.asaclean.com/blog/topic/glitter) - [Grade Selection](https://www.asaclean.com/blog/topic/grade-selection) - [HDPE](https://www.asaclean.com/blog/topic/hdpe) - [High and Low Temp Changeovers](https://www.asaclean.com/blog/topic/high-and-low-temp-changeovers) - [hold a bubble](https://www.asaclean.com/blog/topic/hold-a-bubble) - [Hot Runners](https://www.asaclean.com/blog/topic/hot-runners) - [Injection Molding](https://www.asaclean.com/blog/topic/injection-molding) - [Injection Molding Tips](https://www.asaclean.com/blog/topic/injection-molding-tips) - [LDPE](https://www.asaclean.com/blog/topic/ldpe) - [Lightweight automotive components](https://www.asaclean.com/blog/topic/lightweight-automotive-components) - [LLDPE](https://www.asaclean.com/blog/topic/lldpe) - [low residue](https://www.asaclean.com/blog/topic/low-residue) - [maintenance](https://www.asaclean.com/blog/topic/maintenance) - [Material Changeovers](https://www.asaclean.com/blog/topic/material-changeovers) - [Mechanical Purging Compounds](https://www.asaclean.com/blog/topic/mechanical-purging-compounds) - [medical](https://www.asaclean.com/blog/topic/medical) - [Melt Flow Index](https://www.asaclean.com/blog/topic/melt-flow-index) - [NPE 24](https://www.asaclean.com/blog/topic/npe-24) - [nylons](https://www.asaclean.com/blog/topic/nylons) - [on the fly](https://www.asaclean.com/blog/topic/on-the-fly) - [packaging](https://www.asaclean.com/blog/topic/packaging) - [PCR](https://www.asaclean.com/blog/topic/pcr) - [PEEK](https://www.asaclean.com/blog/topic/peek) - [Polypropylene](https://www.asaclean.com/blog/topic/polypropylene) - [Post Consumer Resins](https://www.asaclean.com/blog/topic/post-consumer-resins) - [preventative](https://www.asaclean.com/blog/topic/preventative) - [preventative purging](https://www.asaclean.com/blog/topic/preventative-purging) - [processing tips](https://www.asaclean.com/blog/topic/processing-tips) - [profile extrusion](https://www.asaclean.com/blog/topic/profile-extrusion) - [Purge Program](https://www.asaclean.com/blog/topic/purge-program) - [purge programs](https://www.asaclean.com/blog/topic/purge-programs) - [Purge Training](https://www.asaclean.com/blog/topic/purge-training) - [Purge Trial](https://www.asaclean.com/blog/topic/purge-trial) - [purging](https://www.asaclean.com/blog/topic/purging) - [purging compounds](https://www.asaclean.com/blog/topic/purging-compounds) - [purging concentrates](https://www.asaclean.com/blog/topic/purging-concentrates) - [purging procedures](https://www.asaclean.com/blog/topic/purging-procedures) - [Purging Tips](https://www.asaclean.com/blog/topic/purging-tips) - [quality](https://www.asaclean.com/blog/topic/quality) - [recycled resins](https://www.asaclean.com/blog/topic/recycled-resins) - [residue issues](https://www.asaclean.com/blog/topic/residue-issues) - [scrap reduction](https://www.asaclean.com/blog/topic/scrap-reduction) - [Screw Pulls](https://www.asaclean.com/blog/topic/screw-pulls) - [sheet extrusion](https://www.asaclean.com/blog/topic/sheet-extrusion) - [shutdown and sealing](https://www.asaclean.com/blog/topic/shutdown-and-sealing) - [start-up](https://www.asaclean.com/blog/topic/start-up) - [super engineering resins](https://www.asaclean.com/blog/topic/super-engineering-resins) - [Sustainability](https://www.asaclean.com/blog/topic/sustainability) - [Tech Day](https://www.asaclean.com/blog/topic/tech-day) - [technical support](https://www.asaclean.com/blog/topic/technical-support) - [training](https://www.asaclean.com/blog/topic/training) - [trials](https://www.asaclean.com/blog/topic/trials) - [Troubleshooting](https://www.asaclean.com/blog/topic/troubleshooting) - [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/bridging-in-the-feed-throat#subscribe-modal) ### Suscribirse Troubleshooting / 3 min read / June 27, 2017 # Bridging in the Feed Throat - [Facebook Share ](https://www.facebook.com/sharer/sharer.php?u=https%3A%2F%2Fwww.asaclean.com%2Fblog%2Fbridging-in-the-feed-throat) - [Twitter Tweet ](https://twitter.com/intent/tweet?url=https%3A%2F%2Fwww.asaclean.com%2Fblog%2Fbridging-in-the-feed-throat&text=Bridging+in+the+Feed+Throat) - [LinkedIn Share ](https://www.linkedin.com/shareArticle?mini=true&url=https%3A%2F%2Fwww.asaclean.com%2Fblog%2Fbridging-in-the-feed-throat&title=Bridging%20in%20the%20Feed%20Throat&summary=Prevent+feed+throat+bridging+by+understanding+how+resin+melts+too+early%2C+and+learn+the+ideal+temperature+settings+to+avoid+costly+machine+downtime.&source=) - [Pinterest Pin ](https://pinterest.com/pin/create/button/?url=https%3A%2F%2Fwww.asaclean.com%2Fblog%2Fbridging-in-the-feed-throat) - [Email Email ](mailto:?subject=Bridging%20in%20the%20Feed%20Throat&body=https%3A%2F%2Fwww.asaclean.com%2Fblog%2Fbridging-in-the-feed-throat) ![Bridging in the Feed Throat](https://www.asaclean.com/hs-fs/hubfs/cleaning-hot-runner-systems.jpg.jpg?width=640&height=500&name=cleaning-hot-runner-systems.jpg.jpg) ![Three tips for cleaning your hot runner systems.](https://www.asaclean.com/hs-fs/hubfs/cleaning-hot-runner-systems.jpg.jpg?width=307&name=cleaning-hot-runner-systems.jpg.jpg "Three tips for cleaning your hot runner systems.") The [feed throat](http://www.ptonline.com/columns/feed-throat-temperature-control) is one of the most often overlooked parts of injection and extrusion processes. The feed throat is the area at the rear of the screw and barrel where the plastic pellets feed into the plasticating screw.  This is also the area where gases from the molten material are vented out.  The hopper or magnet box sits directly on the feed throat.   As would be expected, this area can be very hot.  Its proximity to the rear zone of heater bands can drive the temperature up to levels that soften and begin melting the pellets a little too early in the process.  This can result in the “bridging” of the feed throat.  Due to the excessive temperatures, the pellets travelling down the throat will start to melt and clump up.  This can completely block the flow of resin into the screw and barrel and essentially run the machine out of material, while also blocking much of the flow of gas out of the machine.  Removing the partially melted clump of material that blocks a feed throat can be both difficult and dangerous. As is usually the case, prevention is the best corrective action.  Most (if not all) modern equipment have a separate water channel that flows around the feed throat to help maintain an acceptable temperature.  There will be a set point option which is normally located on the same page as the barrel temperature zones.  The desired temperature is achieved by the controller opening and closing a flow control valve.  The optimum temperature setting can vary depending on the material you are running, but resist the urge to set it any lower than 130°F.  Colder is not always better.  Too low of a feed throat set point can result in additional cycling of the rear barrel zones as well as the possibility of condensation introducing water into the material as it feeds into the screw. A good rule of thumb for materials that are dried prior to processing is to set the feed throat temp at 20°F less than the drying temp.  If you dry at 175°F set it at 155°F.  Most materials will do fine at 130-150°F. **Learn how to reduce machine downtime with five quick purging compound tips for your injection molding application.** **** ** [![](https://no-cache.hubspot.com/cta/default/468726/interactive-161630774182.png) ](https://www.asaclean.com/hs/cta/wi/redirect?encryptedPayload=AVxigLI527BmiRBBW8bm%2F24NhHUIfIdzK6VwkTjoTfsXkyi18rnPjEcSCqOy8JGq4imAG4jPES9uy32TqUCzzmi5%2BgRJO%2Fvve7lcnEeQPGXmYEawhmvx5CblZCwYIABSmeceFIwmhtRfz5ZES4Ao8UCzADwA6Amf4nLZ1WCGg4OS4IurHliRvtMDvRXitSmb0G6pYBYSHqLvULA2JzcUUxtJ1RYsfbEghC%2FAUQu3oxFW3bsKMOTvL%2FxHQ7Fr&webInteractiveContentId=161630774182&portalId=468726) ** ** ** ![Jerry Weddell](https://www.asaclean.com/hs-fs/hubfs/1713568728231.jpg?width=150&name=1713568728231.jpg) #### [ Jerry Weddell ](https://www.asaclean.com/blog/author/jerry-weddell) With over 30 years in the field, Jerry Weddell is a Technical Sales Representative with a wealth of knowledge in mold-making and purging compounds. While his expertise spans injection molding, extrusion, and blow molding, he is particularly distinguished in injection molding. Jerry's profound understanding of these processes enables him to offer targeted, practical solutions, especially in the nuanced aspects of injection molding. His commitment to providing exceptional guidance and support to clients has made him a respected and trusted figure in the industry. - [Share On LinkedIn ](https://www.linkedin.com/in/jerry-weddell-b0747538) ## Related Posts [![20170413_134825.jpg](https://www.asaclean.com/hs-fs/hubfs/20170413_134825.jpg?width=450&height=250&name=20170413_134825.jpg) Focus on These 3 Things for a Successful Color Change Injection... / 2 min read / September 20, 2017 ](https://www.asaclean.com/blog/focus-on-these-3-things-for-a-successful-color-change) [![The_Best_Purging_Compound_For_Your_Injection_Molding_Machine_.jpg](https://www.asaclean.com/hs-fs/hubfs/The_Best_Purging_Compound_For_Your_Injection_Molding_Machine_.jpg?width=450&height=250&name=The_Best_Purging_Compound_For_Your_Injection_Molding_Machine_.jpg) Easy on the Grease, Injection Molders Troubleshooting / 3 min read / March 07, 2017 ](https://www.asaclean.com/blog/injection-molders-easy-on-the-grease) ## Comments Get Started ## Ready to start improving your efficiency and increasing your profitability? - [Request a Consultation](https://www.asaclean.com/blog/bridging-in-the-feed-throat#) - [Contact Sales](https://www.asaclean.com/blog/bridging-in-the-feed-throat#) ![](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. [Request your free sample](https://offers.asaclean.com/en/free-sample?hsLang=en) ![](https://www.asaclean.com/hubfs/assets/images/icons/icon-calculator.svg) #### Cost Savings Calculator Use our free calculator to see how much you could be saving with Asaclean® Purging Compounds. [See your savings](https://www.asaclean.com/cost-savings-calculator) [ Back to Top ](https://www.asaclean.com/blog/bridging-in-the-feed-throat#top) ```json { "@context" : "https://schema.org", "@type" : "BlogPosting", "author" : { "@type" : "Person", "name" : "Jerry Weddell", "url" : "https://www.asaclean.com/blog/author/jerry-weddell" }, "dateModified" : "2025-05-06T13:19:29.184Z", "datePublished" : "2017-06-27T12:48:00.000Z", "headline" : "Bridging in the Feed Throat", "image" : [ "https://www.asaclean.com/hubfs/cleaning-hot-runner-systems.jpg.jpg" ], "mainEntityOfPage" : { "@id" : "https://www.asaclean.com/blog/bridging-in-the-feed-throat", "@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" : "The feed throat is one of the most often overlooked parts of injection and extrusion processes. The feed throat is the area at the rear of the screw and barrel where the plastic pellets feed into the plasticating screw. This is also the area where gases from the molten material are vented out. The hopper or magnet box sits directly on the feed throat. As would be expected, this area can be very hot. Its proximity to the rear zone of heater bands can drive the temperature up to levels that soften and begin melting the pellets a little too early in the process. This can result in the “bridging” of the feed throat.", "author" : { "@type" : "Person", "name" : "Jerry Weddell" }, "datePublished" : "June 27, 2017", "headline" : "Bridging in the Feed Throat", "image" : "http://cdn2.hubspot.net/hubfs/468726/cleaning-hot-runner-systems.jpg.jpg", "name" : "Bridging in the Feed Throat", "url" : "https://www.asaclean.com/blog/bridging-in-the-feed-throat" } ```