An examination of worn paper slitting blades from various paper mills showed that the predominant wear mechanism is abrasion with fatigue damage as a minor factor. A laboratory wear rig was designed and constructed to simulate an industrial paper slitting machine and which incorporated an instrument designed to measure accurately the change in profile of slitter blades during wear. Blades manufactured from BS 970 535A99 steel were worn with and without additions of paper dust and it is shown conclusively that three-body abrasion by hard particles in paper dust is the principal wear mechanism.
An analysis was developed to give open cut distance at the point of slitting as a function of wear. A critical open cut distance was found when shear slitting changed to tensile slitting and an unsatisfactory cut was obtained; the critical open cut distance for various grades of paper was determined. A mill trial was performed which supported the validity of open cut distance as a measure of useful life of blades. The results were analysed using conventional wear theory and a linear relation between volumetric wear and running distance was obtained.
The wear resistance was assessed of blades coated by the following surface treatments: boridising, carburising, cermet plating and plasma arc spraying. A cermet plating comprising diamond particles dispersed in an electroless nickel matrix produced the best wear resistance. Comparisons of the coated blades with the conventional steel blades lead to conclusions about surface structure and properties required to give good wear resistance in paper slitting blades.
|Date of Award||1979|