A Six Sigma approach for precision machining in milling

Controlling the process variations on the perimeter of a component to the targeted mean in milling is a huge challenge. Several factors such as spindle speed, feed rate, depth of cut, etc. affects this process variation. In this paper, spindle speed and feed rate are considered. Aluminum alloy 6061 widely used materials in aircraft, automobile and helicopter components is selected for this study. A full factorial design of experiment is carried out with five levels. Three different machining conditions: machining 2 mm thickness, machining 3 mm thickness and machining 4 mm thickness are considered. The objectives of the study are: (a) to determine the optimum cutting parameters to minimize the process variations found on the perimeter of the work piece;' (b) to determine which machining condition provides least process variations. To achieve this, 25 different combinations of experiments are conducted under each machining condition. Thus, a total of 75 experiments are carried out. Non-contact laser detection system is used to collect the real-time machining data. Two-way ANOVA is used to analyze the data. The results found that (a) both spindle speed and feed rate are significant over the process variations on the perimeter of a component; (b) feed rate is more significant on the outcome when compared to spindle speed; (c) process variations found on the perimeter of the component size 2 mm thickness are more when compared to a component size 4 mm thickness; and (d) mathematical models are derived for determination of optimum cutting parameters to achieve tighter process variations. © 2014 The Authors. Published by Elsevier Ltd. Selection and peer-review under responsibility of the Organizing Committee of GCMM 2014.