Wear protection | machinery There is an increasing need to protect
extruder screws and barrels from abrasive materials and demanding processing conditions. Mark Holmes finds out more
Protecting your screw and barrel
Wear may not be a new challenge for processors but it is certainly a growing one. The high filler levels and stiff reinforcing fibres required to produce compounds that meet today’s demanding performance requirements place great demands on extruder screws and barrels in terms of both abrasion and corrosion. Many applications simply would not be viable without some form of surface protection. With that in mind, extruder manufacturers and suppliers of specialist cladding and coatings continue to develop new wear management options to extend the service life of twin-screw extruders. KraussMaffei Berstorff says compounders today are
increasingly handling recipes that contain high levels of fibre reinforcement, incorporate special additives such as flame retardants, or utilise high volumes of fillers or recycled material to reduce cost. These all have the potential to damage processing machinery, making wear protection an issue of ever increasing importance. The company recently intro-
duced a new high wear resistant alloy liner for its ZE BluePower twin-screw extruder series. “We have addressed this problem and examined a large variety of metal
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materials available on the market. This is how we have found the perfect complement to our portfolio of materials,” says Andreas Madle, Process Engineer in the Plastics Development division at KraussMaffei Berstorff. The new 72HA material – an iron-based powder-
metallurgical alloy with high carbon and chrome content – is manufactured using hot isostatic pressing (HIP) technology. The company says the chemical composition of the material ensures very good protec- tion against abrasive wear and corrosion and facilitates mechanical processing. “The new material offers optimum wear protection
when it comes to applications with abrasive and corrosive stress, plus an extremely attractive price compared to the high-performance materials used so far,” Madle says. “The liners made of 72HA material are through-hard- ened. We have already manufactured the first liners made of 72HA for an extruder of the ZE BluePower series and
tested them in practical use with excellent results.”
Main image: Component wear is a growing
problem for
compounders handling
increasingly abrasive and corrosive recipes
Left: Barrel liners on KraussMaffei Berstorff’s ZE BluePower compounders use the company’s new 72HA high chrome content alloy
August 2017 | COMPOUNDING WORLD 63
PHOTO: SHUTTERSTOCK
PHOTO: KRAUSSMAFFEI BERSTORFF
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