PURGING COMPOUNDS | PROCESSING Keeping the process clean
Purpose-designed purging compounds carry an additional cost over using in-house resin. However, that premium can be repaid through savings in downtime and product wastage, reports Mark Holmes
Short production runs and rapid changeovers are increasingly the norm in most compounding opera- tions. As a consequence, the need to minimise the amount of waste or off-spec material during production is now a top priority. The use of commercial purging compounds can help achieve these goals and can also help in keeping valuable compounding extruders in first-class condition. Routine purging with commercial purging compounds is environmentally conscious and can help reduce both waste and cost, according to Dyna-Purge. “In order to understand how purging fits into a sustainability programme, it is necessary to understand the numerous features and benefits of CPCs (commercial purging compounds)”, says Kelli Ropach, International Business Manager. “Purging compounds improve part quality. Consist- ent and programmatic purging can clean and remove deposits and contamination, which may cause defects.”
Any contaminants that make their way into a compound will eventually find their way into finished injection moulded or extruded parts. “The market demands quality and is typically qualified by a third party organisation, in addition to a corpo- rate quality directive. This is most common in automotive, medical, and food and drug packag-
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ing applications. If parts contain black (carbon) specks, pit marks, delamination due to contamina- tion, resin or colour streaks, the market will con- sider the part as sub-quality or rejected and the part becomes waste or scrap,” Ropach says. In addition, growing demand along the supply chain for cost reduction means suppliers have to look for new cost saving strategies. With resin and additive prices, utility costs, and labour rates all rising, one way to cut cost is to make sure all money is spent on production of saleable quality product, Ropach argues. “Consistent and program- matic use of a CPC will help prevent problems or defects. It will also help to reduce the time it takes to purge and the amount of material wasted or spent. Speeding resin or colour transitions increas- es the availability of production time.” Reduction of scrap and waste are priority targets
for all processors. “These two concerns rank high in company management,” says Ropach. “When scrap and waste is reduced, there is an increase in the output of acceptable quality parts and more usable and saleable yield from the resin investment. The result of lower scrap and waste therefore allows the processor a better overall yield on performance due to the reduction of lost time or recovered opportunity, energy and hourly productivity.”
Main image: Purpose- designed purging
compounds can speed up can save time and reduce waste during product
changeovers
� September 2020 | COMPOUNDING WORLD 61
IMAGE: ASACLEAN
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