Reverse innovative design and manufacturing strategy for optimizing production time of customized orthotic insoles with CNC milling

Reverse innovative design (RID) of insole shoe orthotics for patients with diabetes and the manufacturing strategy in optimizing the production time of the insole were examined in the present work. The plantar surface of the feet from two female patients was scanned using a 3D scanner yielding a 3D mesh foot for each patient resulting in an STL file format. The geometric shapes of the 3D models of the feet were fitted very well using curve based surface modeling (CBS-modeling) for insole orthotics design and integrated with CAM (computer-aided manufacturing). Optimization of the manufacturing time was simulated in CNC milling with the Taguchi approach. The manufacture of the optimal insole design was achieved at the optimum machining parameters such as toolpath strategy (A) with raster machining, spindle speed (B) of 15000 rpm, feed rate (C) of 900 mm/minutes, and step over (D) about 0.30 mm. The optimal design of the orthotic insole has the geometric tolerance (D) of 0.75 mm for patient 1 and 1.50mm for patient 2. The optimal machining time for the insole of patient 1 is 3.79 and 4.02 hours for patient 2. The optimal machining time for the insole of patient 1 is 227.48 minutes and 241.65 minutes for patient 2. These valuable data are needed for the real manufacturing process of insole material in CNC millin