CNC milling strategy of EVA foam with varying hardness to provide a high degree of surface roughness of orthotic shoe insoles is presented in this work. Machining parameters (tool path strategy, spindle speed, feed rate, and step over) in addition to hardness material and wide tolerance insoles were optimized using a hybrid approach of Taguchi-Response Surface Methodology (TM-RSM). The aim of this research was to develop mathematical models and determine the optimum machining parameters which could be applied for the CNC milling of EVA foam as the insoles. Experiments were performed on a CNC milling machine with a standard milling cutter and run under dry coolants. The effects of the six parameters on the average values of surface roughness were initially analyzed by an S/N ratio of TM. Optimal conditions were established from the TM and then used to determine the optimum values in RSM modeling. The final results indicate the significant improvement of percentages (0.24% and 4.13%) in the surface roughness of the insoles obtained with TM-RSM as compared to the TM analysis. It is envisaged the present study would add to the understanding of production for orthotic shoe insoles through CNC milling.

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Club foot is one of the foot deformities caused by genetic factors. Patients with this characteristic have abnormal foot shape. Daily activities cannot be carried out by patients properly. The most important difficulty is finding shoes as the right footwear, precision and comfortable to use. The number of patients who are not small in Indonesia is an important topic discussed in this paper. Semi-Reverse innovative design (RID) is a Reverse Engineering application with 3D mesh data and able to get the precise and accurate surface contours of the club foot patient. Computer Aided Design (CAD) PowerShape 2019 was used in this paper to get a variation of the design of an orthotic ankle foot insole that fits the club foot patient's foot. The resulting output is in the form of three types of insole designs with geometric error tolerance of 0.08 mm.

In this study, ethylene-vinyl acetate (EVA) foam orthotic shoe insoles with different surface roughnesses (Ra) are investigated in terms of CNC milling strategy. Based on a hybrid Taguchi-response surface methodology (TM-RSM) approach, machining parameters, including tool path strategy, spindle speed, feed rate, and step over, as well as material hardness, are of particular interest. The main aim of this work is to develop mathematical models and determine the optimum machining parameters. Experiments are conducted on a CNC milling machine with a standard milling cutter and run under dry coolants. The optimal conditions are established based on TM and then used to determine the optimum values in the RSM modeling. The main finding of the present work is that there are significant improvements in the Ra, by up 0.24% and 4.13%, and machining time, by up 0.43% and 0.41%, obtained with TM-RSM in comparison to TM analysis.