The effect of the flexibility of CNC machines on the precision of orthotic insole manufacturing

Nowadays, CNC machines are also used in the production of custom prosthetic socket molds and customized insoles. High density polyurethane foam and EVA (ethylene vinyl acetate) materials of different densities are used in this sector. It is suitable for high speed manufacturing due to the fact that the materials used have low cutting loads in terms of processing. For this reason, it is desirable to use the highest feed speeds that can be provided by the machine in the manufacture of prosthetic socket molds and customized insoles. The inertia loads caused by higher feed speeds cause vibrations on the structure. Therefore, the weight of the moving parts must be reduced, and at the same time, the machine rigidity must be high. In this study, the vibration analysis of a CNC machine manufactured for this purpose was examined with the finite element method and experimentally. The design of 4 Axis CNC Machine was created in SolidWorks program according to industrial requirement. The analysis model of the machine was created in ANSYS/Workbench program. The assembly model consists of sub-assemblies called members. The members are connected to each other by connectors. The analysis model consists of solid and shell elements. Static and modal analyses were performed by using analysis model and stress, displacement and natural frequencies are obtained. Experimental results and analysis results were compared. New flexible model was designed for the compare effect of flexibility between rigid and flexible design on the milling process. Milling process was performed both design and the results were measured via Coordinate Measure Machine (CMM). Outcomes of milling process were compared and the precision differences between flexible and rigid design was specified.