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.

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.  

Extrusion: Essential Reading

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.

How Screw Design Can Boost Output of Single-Screw Extruders

Optimizing screw design for a lower discharge temperature has been shown to significantly increase output rate.

Troubleshooting Vent Flow Problems in Single-Screw Extruders

Vent flow can be a costly problem and a housekeeping nuisance. Here is some advice on how to eliminate it.  

The Right Way to Design Vents in Single-Screw Extruders

Designing vents for single-screw extruders requires understanding of polymer flow in the screw channels. Some designs are more effective than others. Here are some guidelines.

Extruder Alignment: Important, but Only Half the Equation

The other half? Aligning and supporting downstream equipment. Here are best practices.

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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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Extrusion Suppliers