November 15th, 2022
As effective as purging compounds can be in helping to clean the machine barrel assembly, they don’t always do a great job in completely cleansing the screw of baked-on waste and resin. This is a dilemma that we have seen many plastics molders have to contend with on a regular basis.
Many of our molding experts will “pull the screw” after purging to ensure it is void of any unwanted residue. If additional contaminants are found, it might cause a technician to attempt a manual scrape using steel wool, screwdrivers – even hammers and torches – to rid parts of these stubborn impurities. There are times when Slide’s purging compounds cannot get enough initial contact with the backs of the flights/spirals on the screw, or the resin deposit is so intense that it requires supplemental chemical or mechanical cleaning processes to be applied.
The Slide Resin Remover and NEXGEN Mold Cleaner formulations are created to completely break down the most hardened annoying pollutants from the screw flights once the screw is pulled from the barrel.
Here are a couple of stories from the field that demonstrate the importance and value of completely purging the barrel and cleaning the screw.
One of our customers in New York was working with our local distributor on a purge need. The product worked great at cleaning the barrel, but also cleaned a lot of unwanted residue from the screw itself. In fact, so much contaminant was removed that the first few cycles shot so much excess resin into the mold cavity that it ended up all over the mold face. Through the years, the molder had kept making small adjustments, increasing the settings to counteract the buildup so that more and more rotations would be performed for each part cycle to get enough resin into the mold cavity. After a complete purge and screw cleaning, the remedy was to reduce the screw rotation speed and the amount of resin released into the mold after the purging procedure. Both the barrel and the screw were now clean and all reset to desirable stock factory settings.
Some time ago, another of our molder customers came up with the idea to keep the pulled screw hot so the plastic didn’t harden and make it more difficult to remove from the screw. Then he immediately sprayed the Slide mold cleaner on the screw buildup. After a few minutes, the baked-on resin that was wrapped around the heated screw softened and gelled, making it easy to pull off.
Slide’s original Resin Remover product has been around for decades and designed to keep plastic injection molding machinery in production as long as possible. It’s no surprise that one of our creative customers found another use for this formulation to help make their job easier and thus avoid using harsher methods that could damage the screw.
Ideally, a purge product would successfully clean both the barrel and screw, but when the screw is so contaminated that it needs to be pulled and manually cleaned, the Slide Resin Remover or NEXGEN Mold Cleaner are great chemical formulas to easily soften and break down an unwanted polymer.