High Speed and High Accuracy Machining of Long Flexible Parts with Combined Face Milling Cutters

Abstract

This paper describes an innovative method to machine the guide rails for elevators in high efficiency and high accuracy. Guide rails are usually machined on a planer. However, the machining time is long because of the useless return motion of the table and low cutting speeds. In order to decrease the machining time, face milling with combined cutters was applied to the machining of guide faces. The trial face milling of guide rails indicated the reduction of the width of guide rails at the tool exit and deterioration of the perpendicularity of guide faces. Thus, in this research, the machining mechanism affecting the accuracy of the machined surfaces was studied. The analytical and experimental results revealed that cutter path deviation from the center of a guide rail affects the width reduction at the exit part of the guide rail, whilst the clamping stiffness of the guide rail has a much greater influence on the perpendicularity of the guide face than the cutter path deviation. It was also found that change in the number of cutting edges engaged in machining simultaneously caused wavy machined surface with a long wave length. Finally, determined based on the above findings were the critical tool path deviation and critical clamping stiffness, which permitted the efficient machining of the guide rails at a high cutting speed of 267m/min and a high feed rate of more than 1000mm/min, decreasing machining time by a factor of six.