White Papers & Presentations Impact of Extruder Barrel Wear in a Glass Filled Application -- Why Worry? Download PDF here (1480 KB)      Brief Overview   ASTM Dry Sand Abrasion tests reveal that infiltration brazed tungsten carbide cladding provides superior abrasion resistance, compared to other materials commonly used to protect twin-screw elements and barrels. This presentation will discuss these laboratory tests and the results of field data demonstrating the value of protecting processing components with tungsten carbide cladding. Polymer Quality Impact Potential for melt freeze out on cooling barrel ID - results in an insulating barrier that negatively impacts heat transfer Increased product shear/melt temperature due to ineffective heat transfer (cooling) to melt Pellet density negatively impacted due to high melt temperature and potential for out specification/control product Customer is paying for compounded polymer by weight Maintenance Impact High level of unplanned emergency break in  work Replacement decisions can not be based upon measurement - but by “gut” decisions If improper material selection - very high life cycle costing No ownership in the process Operations Impact Start up time  to achieve “lined out” condition are extended/higher yield loss Rates have to be reduced to bring process in specification Extended disruptions to production required to clean barrel ID/pull screws/hot brush barrel ID Additional extended time (24-36 hrs) to cool down and replace a worn barrel at a significant maintenance cost Variable wear of barrels/elements together results in operator adjustments to “work around” Work around requires operators to set machine barrel temperatures beyond their normal conditions/can result in other problems Once normal extruder set up conditions are compromised, the process can easily go “out of control” Establishing Extruder Barrel Measurements / Proactive PM Standard Practices Know your process/define “the cliff”/ go and no go tolerances for different barrel sections Set up proactive barrel measurement schedule for the extruder Clean the barrels to get accurate measurements/hot brushing and pressure washing Get properly applied/calibrated measurement equipment Flite Technology telescopic ID bore measuring device allows for in position barrel ID measurements to reduce downtime Map measurement points /barrel section to ensure repeatability Record measurements and plot wear trend/time to replacement tolerance (See Appendix) Do not forget about measuring elements/the softer sacrificial parts that are easier to replace Maintain spare pre-built shaft set if process is prone to erosive wear to reduce downtime Material Selection — Life Cycle Costing Materials available for extruder barrel erosive wear that were used at Solvay Augusta, Ga. plant  for an 7 year period pre-2000 included: Nitrided - 0.020” surface hardness to 50 Rockwell C D2 — surface hardness to 54 Rockwell C CPM 10 V — surface hardness to 58 Rockwell C scale WPR 29 — surface hardness  to 72 Rockwell C scale (after 2001) CM-410 Extruder Barrel Wear Comparison, Alternate Metallurgy Material Selection — Life Cycle Costing Solvay Augusta Plant standardized on WPR 29 barrels for new extruders purchased after 2001, and upgraded to WPR 29 for replacement barrels on existing equipment. Cost of initial upgrade averaged 30% higher cost for WPR 29 barrels versus others options CM-3410 WPR 29 Wear Rate, 2003-Present Proactive Extruder Barrel PM/Proper Material Selection Results Operator / mechanic ownership in measurement process Replacement decisions made based upon knowing wear impact on the process , “defining the cliff” Maintenance budgeting requirements can be better projected Wear versus process impact can be defined •Product quality improved/no out of specification PD in 3 years on Line A  (see Chart III) Barrel temperature set up profile will be repeatable CM-410 Pellet Density QRB’s, 1996-Present Proactive Extruder Barrel PM/Proper Material Selection Results Work around operation significantly reduced Process capabilities and control will be improved Reduced unplanned downtime by 8% annually Reduced barrels maintenance cost/line by $40,000 annually WPR 29 barrels demonstrated in the cooling section for over 4.5 years with out replacement / 5X previous life Improved life cycle barrel costing in melt/mix and cooling sections Practice will grow to extruder element maintenance Written By: Ken Bowles, Solvay Advanced Polymers