While there are many similarities between purging compounds, some of the compounds have unique characteristics or uses.
• Ultra System's FDA-approved Ultra Plast chemical compound softens color, encrustations, black spots, rust and other impurities. It has a new expanding-foam formula that does not require wait time. If used frequently, it protects steel from oxidation, making cleaning easier and faster.
• Dyna-Purge's mechanical compounds are available in a variety of formulations to match specific processes and temperatures. The company's D2 products are good at flowing to boundary areas and purging through system components that have a minimum clearance of 0.025 inch. They are effective at temperatures of 350 to 625 degrees Fahrenheit.
• Sun Plastech has both chemical and mechanical options. Its strongest purging compound is its Asaclean EX grade, which is glass-filled to scrub carbon and/or color deposits while leaving behind less purging compound residue. A screw-pull test was conducted, using LDPE on one screw and Asaclean's EX styrenic product on another. The screw "purged" with LDPE had to be heavily hammered from the other end for removal, while the screw on which the EX styrenic was used pulled loose with just a couple of hammer taps.
• Using all-natural ingredients, iD Additives offers both concentrated and ready-to-use purging compounds, all of which are FDA-compliant. Its SP (chemical), M (mechanical) and LQ (liquid) purges are all concentrated without polymer carriers so they can be used with any resin. This eliminates the need to buy four or five different grades.
• Moulds Plus has an extensive line of chemical purging products, along with some chemical/mechanical hybrids. Its Ultra Purge compounds are FDA-approved, food-grade safe and hot-runner safe, so you can purge the machine and hot runners at the same time. Additionally, the compounds have a concentrated formulation that enables operators to use an in-house resin as a carrier.
• Neutrex makes Purgex-brand chemical purging compounds. The complete line is manufactured in the U.S. from quality raw materials and virgin resin and can be used for material and color changes, as well as for removing residual contamination in injection molding, extrusion or blow molding machines. Neutrex says using the product reduces material costs and scrap, increases the production of good parts and improves machine utilization.
• Slide Products' NPT purging compound eliminates the need for multiple purging products since it effectively operates at temperature ranges from 160 degrees Fahrenheit to 600 degrees, removing all traces of barrel residue and solving the problem of removing stubborn residue between color or resin changes. NPT consists of concentrated purge pellets that react chemically to heat, quickly and effectively cleaning machinery without extra soak time, excess downtime or lost productivity. NPT requires no mixing or preparation time, and it is nonhazardous, FDA compliant and free of harsh odors.
Lisa Jo Lupo, correspondent
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