Extrusion Know How
The Truth About Barrel Heating
The main purposes of the heaters are to melt the polymer that remains in the barrel at cold startup, to assist in forming the initial melt, and to “trim” the barrel temperatures for specific purposes such as improving feed rate.
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Where Does Shear Heating Occur? Here’s How to Find Out
One of the least understood yet most important concepts is viscous dissipation, which is the shearing or stretching of the polymer between the rotating screw and stationary barrel, causing heat to develop in the material.
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Dead Screw Talking
There's a lot you can learn by conducting a post-mortum examination of your screw.
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Screw Surging, Part III: Unfilled Discharge Section
This type of surge happens most frequently with two-stage screws when the second stage has far more capacity than the first stage. It can also happen when a screw is limited in feeding or melting, causing a partially filled metering section.
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Overfeeding Can Cause Surges, Too
Surging can be caused by feed restrictions, as covered in another column, and also by over-feeding or under-melting, discussed here.
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Solving Feed-Related Surging
Understanding the causes of surging can help troubleshoot and correct it.
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Extrusion: A Roll Is a Roll Is a Roll?
Chill rolls may looks simple and shiny, but they play a critical part in cooling and polishing film and sheet and are not all the same.
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Follow This Action Plan to Keep Your Sheet Dies in Line
Getting back into production after maintenance or troubleshooting requires a coordinated effort. Here’s how to get your sheet line up and running as fast as possible.
Read MoreExtrusion: Reducing Energy, Part II: ‘Adiabatic’ Extrusion
The term adiabatic extrusion was very popular in the ’60s and ’70s, but has seemingly disappeared from the processing terminology of today.
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