b'BLADE WEAR: CAUSE & EFFECTCrepe blade wear modelling: a statistical approach based on process data analysisBy Ian Padley, Manager Global Solution Team -Tissue, BTG Eclpens S.A and Dr James Litchwark, Global Solutions Team -Tissue Engineer, BTG Sweden A.B ABSTRACTThe wear mechanics of the crepe blade are of critical importance in determining the quality of tissue output, the productivity of the tissue machine and the protection of the Yankee.In this paper we briefly review the main blade/Yankee/paper wearing mechanisms and their effects. We then see how this can be measured, but the main body of the paper is concerned with what conclusions we can draw from an analysis of the wear and process factors for overFigure 1. Location of sliding and impact wear on blade tip.800 high performance creping blade analyses compiled by BTG.We review the effect on blade wear of furnish,INTRODUCTION HOW DOES THE BLADE WEAR?coating classification by chemistry orWhy are we interested in the wear ofThe crepe blade wears in two different appearance, add-on rates of base,the crepe blade?The primary concernways:release, phosphate and modifier,might be one of tissue quality, as for cleaning blade impact, Yankee surfaceexample, the all-important handfeelIn adhesive wear two chemically similar type, blade material type and more. of the tissue may deteriorate as theand ductile materials moving against The paper concludes with someblade wears.Or we might have issueseach other in the right conditions recommendations for the tissuemakerwith machine runnability; the wornwill undergo material transfer from to help them set up the optimum safeblade is poor at refreshing the Yankeeone substrate to the other.This is running time for high performancecoating layer-and we can get pinholes,commonly (but slightly misleadingly) crepe blades: sheet breaks or poor crepe ratio as areferred to as microwelding in our Run an uncompromised coatingresult of unrefreshed coating. Finally,industry and is of primary concern layer: use a higher add-on andwe need to consider asset protection. with steel crepe blades and metallized premium base products. High blade wear may indicate aor cast-iron Yankee surfaces. 1Control the wet end for an evencompromised coating layer, and translucent coating layer. thus compromised Yankee surfaceIn abrasive wear, one material is harder Use only high-performanceprotection. Or the coating layerthat the other, and has a higherCrepe blade blades on a thermally sprayedunrefreshed by a worn blade may startmaterial toughness to impart a cuttingwear should (metallized) Yankee surface. to harden, a potential Yankee chatteraction, literally removing particles frombe a subject Run a continuous cleaning blade;initiator.Yes, crepe blade wearthe other substrate. This is how a highof some ceramic is best for low sliding wearshould be a subject of some interestperformance, typically ceramic, bladesinterest to the at the crepe blade. to the tissue maker. wears.Although relatively hard, thesetissue maker!38 TISSUE TECHNOLOGY INTERNATIONAL'