Wear of zirconia edge guides for conveyance of plastic webs

A laboratory investigation was conducted to determine the cause of less than expected service life of zirconia edge guides used in the conveyance of polyester sheet. Worn guides generate wear debris that can contaminate the web product. A “zero” wear system was the goal in installing the zirconia to replace hardened stainless steel.Zirconia guides from different manufacturing lots were examined for defects that might contribute to the unsatisfactory service life. None were identified.Loop abrasion tests (ASTM G174 using 30 μm alumina lapping film) were conducted on the problem zirconias as well as other ceramics and some cemented carbides. These tests indicated that the zirconia that “failed” in service had at least 10 times the abrasion resistance of the hardened stainless steel guides previously used as guide material, but the cemented carbides tested had better abrasion resistance than the zirconias and other ceramics tested (silicon carbide and silicon nitride). The conclusion of the test program was that goal of a “zero-war” edge guides could best be met with diamond-coated cemented carbide.