A Test Method for the Assessment of Tribological Aspects of Abrasive Machining

Abstract

Abrasive machining such as grinding involves simultaneous contacts, between the workpiece and several abrasive grits. Hence, it is difficult to assess the tribological effects (i.e., friction and wear) of individual grits from grinding tests. Therefore, there is a need to develop a laboratory scale test technique based on single-grit tests. In this research, a test method, which employs a pin-on-disk tribometer using single abrasive particles sliding against a workpiece material, is designed. To evaluate the proposed test, alumina and silicon carbide abrasives are used as pins and bearing steel and tool steel are used as disks. Single-grit abrasion tests are conducted with loads similar to those estimated for the individual grits in grinding. To confirm the results, steel specimens are ground in a cylindrical plunge mode using either alumina or silicon carbide grinding wheels. Data, obtained from the two sets of experiments are compared in terms of material removal rate, frictional behavior, wear of abrasives and the mechanisms of material removal. Morphological features of the debris collected for both tests are identified using a scanning electron microscope. The results indicate that the single-grit abrasion test can be used to predict the tribological interactions during abrasive machining. The trends in the material removal rates during single-grit abrasion and grinding are in good agreement. In both cases, alumina abrasives wear faster than silicon carbide when used against either steel under dry condition. The material removal mechanism is identified as "cutting" for bearing steel and as "plowing" for tool steel, consistent with the differences in the mechanical properties of the two steels.