Abstract:Horizontal ram is one of the main moving parts of Ngau Tau type EDM machine, which has an important influence on machining accuracy. Based on the sensitivity analysis, the structure design parameters and the stiffened plate structure of the ram with lightweight and bionic design were carried out respectively. Based on the finite element analysis (FEA) method, the ram change rule of mass and stiffness was calculated while different design parameters changed. Results show that the quality of ram is lost by 8031 kg (796%), the largest deformation is reduced by 289 μm (1254%) and efficiency of specific stiffness is improved by 338%, on the whole, which has improved the dynamic and static characteristic of the EDM machine.