Technological Advances in Fine Abrasive Processes

Fine abrasives, be they loose or fixed, are invariably used in the production of components of the highest quality in terms of form and finish accuracy, and surface integrity. While optical, mechanical, and electronic applications of advanced ceramics, glasses, and semiconductors may require high form and finish accuracies (e.g., roughnesses in the angstrom range), the depth and nature of the subsurface damage resultant from processing may be equally important. For economic manufacture and for improved reliability of brittle materials, an understanding of the mechanisms of material removal in fine abrasive processes, as well as the nature of damage imparted, are essential prerequisites. Knowledge of the removal mechanisms and nature of damage can enable process improvement and minimize, if not altogether eliminate, surface and subsurface damage. This paper focuses on fine abrasive processes with emphasis on material removal in brittle workmaterials. Generally, indentation models are used to simulate abrasion and polishing. An attempt is made to rationalize various models by linking conventional machining, grinding, ultraprecision machining, and indentation sliding as a cognate transition for material removal operations. Whereas chemical mechanical polishing (CMP) has become the process of choice for finishing semiconductors, the various models developed thus far, although very significant, have addressed isolated aspects of the process and/or neglected certain issues. To use analytical models as predictive tools for finishing of brittle materials, it is necessary to integrate existing understanding into a comprehensive model of the process. This paper reports on some significant technological advances in fine abrasive processes which have been made.