4 Quick Purging Tips for Sheet Extrusion
1. Don’t Run to Failure
When we visit sheet extrusion plants, we usually see one of two scenarios. Engineers either skip purge during changeovers and instead use regrind, a DIY-purge, or their next production resin. This ends up leading to contamination since regrind and virgin can’t clean out your extruder or die and just layer over time. Or they run until failure because they aren’t changing material/color or have a tight deadline. In both cases, processors look at the price of the production resin and tell us that they’re okay taking a little longer on changeovers because the cost of resin is cheap. Over time you will have contamination issues that will bring production to a screeching halt. Production resins are not designed to clean machines and are not a substitute for commercial purging compounds. Purging in-between production runs will extend the time between teardowns. You should try to avoid teardowns at all costs. Although purging might take some time in the short term, it will dramatically improve your product quality and output in the long term.
2. Only Increase Heats for Contamination
Many processors worry about using purging compounds because they think they’ll have to increase heats to activate the purging power. We know that increasing your heats takes time, and this can be a deterrent. You might be pleasantly surprised to hear that in most cases, you do not need to increase heats for normal changeovers. We typically only recommend you increase heats when you’re dealing with contamination issues. If this was an objection that kept you from embracing purging, we want to put your mind at ease. Our products were created and perfected to be easy-to-use high-quality products. If they were difficult to use or made your life harder, it would defeat the purpose of our products.
3. For Tricky Applications, Consider Asaclean® PrePurge
When working with HDPE, LDPE, & LLDPE, it’s common to experience streaking and gels. In low pressure spots like the edges of the die, material tends to hang up. In situations where you struggle to displace your purge, we recommend using our Asaclean® PrePurge to expedite the process. PrePurge is offered in both high and low flow formulations. Contact an Asaclean® Purging Expert for a free consultation on this application.
4. If You Have to Push Screws, Use EX Grade to Reduce Downtime
Removing your screw from your machine without a purge requires great effort, and the cleaning itself takes hours of manual, tedious scrubbing. You must remove the layers of resins or contaminants that have accumulated around the screw. This excessive downtime is certainly affecting your company’s bottom line.
If you’re running until failure or running until you experience severe contamination, EX Grade is a solution that can make your life much easier in a hurry.