Optimisation of cutting parameters of new material orthotic insole using a Taguchi and response surface methodology approach

Abstract The milling process on a computer numerical control (CNC) machine is a crucial operation in the development of the modern manufacturing industry. Milling is the operation of peeling workpieces on machine tools that are often used in the manufacturing industry. The quality of the machining result is generally based on the surface roughness (Ra). The two main factors that have a significant effect on Ra are the cutting conditions and the irregularity of the machining process. A good surface quality is necessary to determine the optimal machining parameter settings for the resulting Ra to be truly low and as optimal as possible. Engineers can obtain this condition through a fair and correct optimisation technique. Optimisation techniques can be used to obtain the best results under certain scenarios. A statistical method approach such as the design of experiment by combining the Taguchi method and the response surface methodology (RSM) is an efficient method of obtaining optimal responses. An orthogonal array L18 2 × 34 was used in this study to select the optimal cutting parameters to manufacture an insole using a CNC milling machine. The Taguchi method was used to obtain a combination of cutting parameters, while the RSM was used as an optimisation technique to obtain the optimal Ra value through the formation of a second-order regression model. The research results indicate that the optimal cutting parameter conditions in the insole manufacturing process in a CNC milling machine with OA L18 2 × 34 are the spindle speed 12,500 rpm, step over 0.15 mm, feed rate 850 mm/min, and the Raster 90 toolpath strategy using the material type X. The optimal conditions were determined to obtain an Ra value of 5.328 μm.