DESIGN AND MANUFACTURING ORTHOTICS SHOE INSOLE WITH OPTIMUM SURFACE ROUGHNESS USING THE CNC MILLING

This experimental study shows the designing of orthotics shoe insole for diabetic patients (ISO-diabetes) and determines the optimal machining parameters in CNC milling of the insole made with EVA rubber foam. The CAD model of ISOdiabetes and mathematical modelling of the average surface roughness for the insole were explored. Firstly, 3D models of ISO-diabetes was brought from the digitized scanned data, then four cutting parameters such as: tool path strategy, spindle speed, feed rate and step over were optimized using the Taguchi method according to L934 orthogonal array. The optimum surface roughness as a function of cutting parameters was predicted using the response surface methods. Lastly, the mathematical model of surface roughness was validated using the ANOVA. Based on the S/N and ANOVA, the optimal cutting parameters yielded the optimum Ra, which corresponds to the tool path strategy with raster 45O, spindle speed of 1300 rpm, the feed rate of 800 mm/minutes and step over about 0.2 mm, of which, is the most influential parameter. And these optimized conditions provided important input data for application of the low-cost milling of ISO-diabetes