ELECTROTRIBOLOGY IN METAL CUTTING (WEAR, CARBIDES, STEEL, TITANIUM)
Abstract
Electrotribology is a phenomenon which was extensively explored for three decades, mostly in the USSR. It involves altering the naturally occurring thermoelectric current flow, between cutting tool and workpiece in metal cutting, as an independent parameter. Until the mid 1970's, when the work described herein commenced, virtually all published reports claimed that forcing changes to this cutting current caused variations in cutting tool life or wear, and surface finish of the machined workpiece, as dependent parameters. In reality, the phenomenon is negligible to the point of non-existence. It is conceivable that it did exist and has disappeared due to changes in purity or microstructure of materials since the 1950's, when the phenomenon was discovered and was apparently very pronounced in Europe and the USSR. Such salient differences in materials could be either in the workpiece or the tool, if not both. In the course of the present studies, an effort was made to approximate post-war European materials by obtaining custom non-deoxydized steels, but the effect was not found in these materials. A meticulous procedure for comparative wear testing under varied cutting conditions was developed with the use of a continuously variable speed lathe, and resulted in dramatically uniform tool wear under differing cutting current conditions. This procedure, the "balanced cut", alleviates a general problem in comparing such parameters, that a variability of a factor of three or more is commonplace. Another published contention, that drilling in titanium showed a dramatic electrotribology effect, was exhaustively tested and found, both via tool life and drilling torque, to have no statistical validity. Historically, the greater care and more replications employed in later experiments have resulted in a decreasing trend for the effect to be manifested. This thesis is in agreement with the most recent publications, which claim no statistical validity for electrotribology in cutting tool wear.
Degree
Ph.D.
Subject Area
Mechanical engineering
Off-Campus Purdue Users:
To access this dissertation, please log in to our
proxy server.