Plastics Extrusion

Extrusion is a continuous process through which parts of a fixed cross-sectional profile are made. Material is fed through a hopper into an extruder, essentially a rotating screw surrounded by a heated barrel, where it is mixed, melted and pumped through a die. The die gives the part its shape. Types include film extrusion, sheet extrusion, pipe, profile and tubing extrusion.

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ESSENTIAL READING

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How to Select the Right Tooling for Pipe Extrusion

In pipe extrusion, selecting or building a complementary set of tooling often poses challenges due to a range of qualitative factors. Here’s some guidance to help you out.  

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Extrusion

The Importance of Barrel Heat and Melt Temperature

Barrel temperature may impact melting in the case of very small extruders running very slowly. Otherwise, melting is mainly the result of shear heating of the polymer.

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Extrusion

Single vs. Twin-Screw Extruders: Why Mixing is Different

There have been many attempts to provide twin-screw-like mixing in singles, but except at very limited outputs none have been adequate. The odds of future success are long due to the inherent differences in the equipment types.

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Extrusion

Troubleshooting Screw and Barrel Wear in Extrusion

Extruder screws and barrels will wear over time. If you are seeing a  reduction in specific rate and higher discharge temperatures, wear is the likely culprit.   

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Postconsumer

Looking to Run PCR on a Single Screw? Here’s What to Keep in Mind

Just drop it in and mix it up? Sorry, there’s a lot more to it than that. Here is some of what you need to consider.  

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Extrusion

What to Know About Your Materials When Choosing a Feeder

Feeder performance is crucial to operating extrusion and compounding lines. And consistent, reliable feeding depends in large part on selecting a feeder compatible with the materials and additives you intend to process. Follow these tips to analyze your feeder requirements.

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Latest Extrusion News And Updates

Downstream Line for High-Precision Profiles

NPE2024: System features calibration and cooling tables, haul-offs, cutting units and tilting tables.  

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Cutting-Edge Measurement and Control Devices for Extrusion

NPE2024: Sikora showcasing a range of cutting-edge equipment designed to meet the high standards of the hose, tube and pipe market.

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Automation

Coiling System Features Automated Spool Removal

NPE2024: Designed for wire and cable and tubing, system is equipped with a Yaskawa cobot for automated spool removal.  

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Enhanced Dry-Ice Cleaning Systems for Screws, Tooling

NPE2024: Cold Jet will be displaying four new dry-ice cleaning solutions for screw and tooling, and will also offer booth visitors a chance to win one of them.  

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NPE

Extruder Controls Make for More Energy Efficiency

NPE2024: Twin-screw extruders packed with features to optimize energy consumption.  

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NPE

Single-Inlet Plenum Air Ring Improves Gauge Control

NPE2024: New design also eliminates multiple hoses to clean up production area.

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Featured Posts

Extrusion

Screw Design Tips to Boost Productivity

In this collection of articles, two of the industry’s foremost authorities on screw design — Jim Frankland and Mark Spalding — offer their sage advice on screw design...what works, what doesn’t, and what to look for when things start going wrong.

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Processing Megatrends Drive New Product Developments at NPE2024

It’s all about sustainability and the circular economy, and it will be on display in Orlando across all the major processes. But there will be plenty to see in automation, AI and machine learning as well.

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Extrusion

What You Need to Know About the Design and Operation of Maddock Mixers

Designed properly, all entering solid polymer fragments and certain types of PE gels entering the Maddock mixer can be trapped and dispersed into the matrix resin. But many are not properly designed. Here’s what to look out for.  

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New Blown-Film Cooling Technologies Set to Debut at NPE2024

Cooling specialist Addex to roll out new auto-profiling air ring for rotating dies, and new single-plenum air ring.

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Maximize the Cooling Capacity of Your Extrusion Line

Maximizing output in extrusion requires a thorough understanding of not only the cooling requirements of the extruder but of the extrudate as well.  

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How Polymer Melts in Single-Screw Extruders

Understanding how polymer melts in a single-screw extruder could help you optimize your screw design to eliminate defect-causing solid polymer fragments.  

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FAQ: Extrusion

However, there are actual limits on increasing output as L/D is increased. Usually these limits are due to the inability of the feed section to deliver more polymer. On smaller-diameter screws, that limit often is determined by screw strength. On small screws you can only go so deep in screw channels before the screw is over torqued and fails. On larger extruders, the efficiency of feeding decreases as the channels get deeper until there is no further increase in output.

There are four main things to consider in selecting the correct stack for your application: the overall cooling capacity, the products to be processed, the mechanical capability, and the rolls’ internal design. Considering just the cooling capacity, the top roll is there to set the sheet thickness as well as its uniformity.

One of the most useful evaluations is the relatively simple calculation of drag flow. Drag flow is simply half the volume of one turn of the metering section per second at a specific screw rpm, which, when multiplied by a units conversion and the melt specific gravity of the polymer, is a very accurate approximation of the output in lb/hr at no head pressure.

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