Análise da qualidade superficial no fresamento em raio com ferramenta de ponta esférica

Abstract

Cutting and strategies parameters, when well defined in a ball nose milling process, can allow good surface quality. The mold and die industry, is a big requester of components with complex geometries and have been searched advances in quality of these surfaces in order to obtain reduction of finishing processes after machining. The surface quality after the machining operation is not sufficient for the entry of these molds and die into productive lines in the industry. The improvement of manufacturing times, costs, superficial quality and dimensional accuracy are always searched for mold and die. In order to improve the surface quality of molds and dies, the present study presents a bibliographical review from the principles of machining to machining in complex surfaces, tool-piece contact and contributions of other works for this theme. The objective of this experiment was characterize the machined surface as the influence of ball nose milling in the longitudinal and transverse direction in a complex geometry when the RPM and the feed rate are variable according to the maximum effective contact diameter between tool and part. For the experiment, a ball nose milling with interchangeable insert was used. Four samples of AISI H13 material were used, where two of them with longitudinal milling and the other two with transverse milling were considered. It was identified for all strategies, that the points which the tool acts perpendicular to the part, in other words, mainly using the center for cutting, the surface quality is impacted and the parameters Ra, Rz and Rmax increase considerably. An improvement in the roughness results is observed while the cutting parameters are increased. For the transverse direction machining it was possible to conclude that the proper calculation of the cutting parameters allows to equalize differences in the surface quality identified in the machining with usual parameters. Analyzing the behavior between test samples for transverse machining, of the ten points evaluated, was identified gain in surface quality in five points, in another four points the quality remained at similar levels and only in one point there was a drop in surface quality . The texture images allowed to complement qualitatively the surface with the roughness results obtained. In addition to the gain in surface quality, for machining in the transverse direction with parameters calculated according to the maximum effective contact diameter, the gain in time of approximately 29% in the machining process was identified.(sic)