Effective corner machining via a constant feed rate looping tool path

In the finish machining of a pocket corner, varying radial depth of cut is generally encountered by the end milling tool during the entry into and exit from the corner. This leads to substantial variability of the machining process. This paper presents the generation and application of a multiple looping tool path for corner machining with the objective to reduce the machining variability and improve the machining efficiency. Material removal rate is selected as the measure for the machining variability. To reduce the material removal rate for a straightforward corner machining tool path, feed rate needs to be decreased as the end mill approaches the corner apex and increased as it exits the corner. Instantaneous changes of feed rate are not possible in practice due to practical limitations on the servo drive system of common machine tools. A tool path of constant feed rate is thus preferred for effective corner machining. The looping tool path proposed in this work is composed of a series of smoothly connected linear and circular segments to ensure its applicability for all machine tools. For a given corner geometry, a single-cutter as well as a double-cutter strategy have been introduced to maximise the machining efficiency. Various case studies were carried out to examine the resulting material removal rate and total machining time for different machining operations.