Desenvolvimento de uma metodologia para degradação de graxas lubrificantes em laboratório

Abstract

A new process for grease mechanical aging in laboratory was developed, in order to allow a better study of its rheological properties and their alterations during the grease’s life. A device was developed and, as a case study, it was chosen the grease used in rolling bearings applied to ore transportation conveyor belt rolls. Rheological oscillatory tests and deformation ramp tests were carried on a rheometer in order to measure the sample’s dynamic viscosity and to plot their flow curves. It was noted a reduction on the grease’s dynamic viscosity due to aging process, especially when measured on lower deformation rates. A ball bearing supplier’s model for determination of the frictional moment was then used in order to evaluate frictional momentum and energy loss for both new and laboratory aged greases, where it was noticed changes on its energy efficiency. For the average deformation rate at which the studied rolling bearings work, it is noticed a reduction on energy loss due to mechanical ageing process.