CNC machine tool is a complex system, which generally includes base, table, column, head-stock and other components. Lightweight is a trend in CNC machine tool development to reduce machine weight without decreasing its machining performance. Furthermore, it is important for improving machining accuracy by increasing the static stiffness. However, it is insufficient only consider weight reduction and static stiffness for the CNC machine tool. Dynamic characteristics must also be considered to maximize its natural frequency in order to avoid resonance. Thus, the optimization design of CNC machine tool is a typical multidisciplinary problem under synthesis considering mass, static stiffness, and dynamic characteristics.
Static stiffness can be measured by using maximum deformation under certain load where maximum stiffness means minimum deformation. The dynamic characteristics are mostly influenced by the first-order, second-order and third-order natural frequencies through infinite element analysis. A new integrated MDO method is then proposed for mechanical structure development of the CNC machine tool. Design variables are chosen effectively for establishing design space. The parametric model is then established and the samples with their responses can be obtained by using Latin hyper-cube sampling and parametric model simulation. The multidisciplinary approximate model is established by using the Kriging method. The optimized design results can be identified through solving the multidisciplinary optimization problem by using the multi-objective GA.