machinery | Wear protection
wear-resistant powder metallurgy,” the company says. With 20 years of experience in the sector, Lesun
offers a wide range of steels, including SKD11, K110 and W6Mo5Cr4V2 tool as well as SuS18 stainless grades, and alternative heat treatment options. “Appropriate accessories can effectively extend the uptime of the ba- sic machines and meanwhile reduce the production cost for customers,” the company says.
FliteGuard coating technology is claimed to reduce abrasive wear without risking barrel damage Source: Extreme Coatings
compromise solution to achieve enhanced wear resistance against abrasion, but also reasonable corrosion resistance. For the majority of our clients, this is a welcome solution to cover a wide variety of different process tasks and recipes,” says Dieter Gross, Managing Director. “In addition to our high abrasion resistant PM
Right: Xaloy MPX incorpo- rates small spherical tungsten carbide
particles to
create a dense, abrasion resistant surface
68
(powder metallurgical) steel elements – solid steel – or our high corrosion resistant bi-metallic PM steel elements, we have now a special PM steel alloy as a compromise. This material offers good abrasion, as well as corrosion resistance. These elements are produced from solid steel and are not bi-metallic,” he says. “For our HIP (hot isostatic pressing) barrels we often use a PM steel alloy, which has got very good abrasion resistance as well as reasonable corrosion resistance. The barrels are coated with this PM steel, with the coated layer usually having a thickness of 3-5mm. The advantages of the coated layer include the ability to have an entirely seamless layer on the inside of the barrel, including side feeder opening or venting/ degassing opening. This results in abrasion and corrosion resistance throughout the inside of the barrel. The coated layer also provides improved thermal conductivity,” Gross says. Chinese screw and barrel element maker Nanjing Lesun Screw points out that conveying and kneading blocks are the two main functional elements in a co-rotating twin screw extruder so it is important to select the most appropriate design, material and finish for each application. “We intend to provide our custom- ers with the most appropriate solution based on the properties of their own products. For instance, nitriding steel, chrome-vanadium steel, stainless steel and
COMPOUNDING WORLD | August 2017
Coatings According to Tom Kvinge, Managing Director of Extreme Coatings, high fill percentages of abrasive fillers, higher output rates and corrosive by-products from degraded resins all now require improved surface treatments/ alloy materials for extruder screws and barrels. “Adhesive wear is the reason 99% of extrusion screws are repaired or replaced. Extrusion screws operate nearly continuously and incidental contact with the barrel wall is inevitable,” he says. “Every processor knows that a new screw and barrel
system operates at the peak of productivity. From that peak of output, even a small amount of wear begins to negatively affect melt rate and overall production. Screw design and proper process settings are always the first line of defence in reducing extrusion feed screw wear. After design and process settings are optimised, selecting high quality materials of construction is the next consideration that offers a high return on invest- ment,” says Kvinge. Over the past 20 years Extreme Coatings says that it
has protected more than 35,000 feed screws. “We have learned a lot about what causes screw and barrel wear,” Kvinge says. “We have enhanced our FliteGuard process to protect standard feed screws, making them super bi-metallic feed screws. FliteGuard specifically addresses the persistent consistent problem of adhesive wear. Just 0.5 mm of FliteGuard CarbideX can be the equivalent of 2.5 mm of lesser alloy materials in wear resistance. In addition, FliteGuard is compatible with any barrel liner.”
www.compoundingworld.com
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PHOTO: NORDSON CORPORATION
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