Purging Dies in Blown Film Extrusion

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In some cases, purging a blown film line with a commercial purge compound to help with a difficult color change, resin change or carbon removal will lose the bubble. I’ve often been asked how the machine can be cleaned with a purge material without making a mess.

I recently visited a plant to support the testing of one of our chemical purges. Chemical purges typically sit and soak once the system is full or run at a minimum rpm for a brief period of time. In this case, we ran the purge for 15 minutes at 20 rpm’s.

As the purge exits the die, it needs to be removed relatively quickly so it does not flow over the edges of the die. If the die is relatively small, this shouldn’t be a problem. If the die’s diameter is large, the purge exiting the die can be difficult to keep up with. When purge patties become larger, they grow more difficult to handle and the technician is forced to rush.

A simple remedy is to have two technicians at the die during the purge process. If they are stationed at the 12 and 6 o’clock positions, each tech is responsible to clean half of the purge exiting the die making the extrudate much more manageable. The whole process becomes easier, safer, and without the mess.

The technicians and Production Manger were very pleased with the results and ease of use of our chemical purge. The die was free of contamination (black specks) and did not have to be manually torn down and cleaned. 

Ready to reduce your production downtime to protect your profits? Learn more about how purging compounds and process efficiency work in tandem.

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Topics: Troubleshooting, Plastics Processing, color contamination, color contaminants, Extrusion, Plastics Production, reduce downtime, Blown Film Extrusion, extrusion troubleshooting, plastics manufacturing, Sheet Extrusion, Screw Pulls, Blown Film Purging, Reduce Scrap-rate, preventative purging, color dispersion, cleaning extrusion die

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