Feasibility of single -step superfinish hard machining and its effect on surface integrity
Abstract
The potential benefits derived by bearing manufacturers from the introduction of hard turning as an alternative to grinding are diluted by the gross inefficiency of the subsequent, hitherto indispensable, abrasion-based superfinishing process. Advances in the machine tool and cutting tool technologies have made it conceivable to generate turned surface geometrically similar to those superfinished. The manufacturers ability to take a hardened stock and turn and superfinish it all in one step would facilitate significant enhancements such as increased Return on Assets and improved Customer Service. Previous research has proved that it is feasible to turn hardened steel to the same surface finish as grinding. Research has also indicated that compressive residual stresses are induced in the surface during turning, that may be beneficial to fatigue life. This research introduces the concept of precision hard turning that would enable that single step superfinishing of hardened steel. The research explores experimentally the cutting conditions that could be used to attain the same surface finish as abrasion-based (AB) superfinishing. Based on these experiments, an experimental model is developed that can be used to identify a range of cutting conditions that would produce a specified surface finish. Furthermore, this research presents results of experiments that measured residual stress profiles induced by precision hard turning. The residual stress profiles were observed to be primarily compressive. A discussion is presented to explain the formation of compressive residual stresses in hard turning. An experimental model is developed to represent the effect of precision hard turning parameters on residual stresses. Finally, the research suggests a new optimization criteria that can be used to select machining parameters to meet surface finish requirements and maximize fatigue performance.
Degree
Ph.D.
Advisors
Liu, Purdue University.
Subject Area
Industrial engineering|Metallurgy|Mechanical engineering
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