Through the expansion of product seriation, three volute product diagrams were introduced. The process optimization on the three types of volute plate process machining diagrams was carried out to replace the group holes of original product with economical and regular group holes. In order to solve the stamping process problem of ultra-wide and multi-shaped holes for the volute plate after seriation expansion, the hydraulic bending machine was systematically improved to become a usable electro-hydraulic servo bending machine, which provides the processing equipment guarantee. After analyzing the stamping process of three types of volute plate, an electro-hydraulic servo bending machine was proposed to match a set of combined punching die controlled by slide row position and with mobile skip step for the maching of group holes. Group hole machining can be realized through the of deduction group hole list. It is proved that the processing of ultra-wide hole spacing and multi-shaped hole for volute plate after optimization meets the requirements and the quality is improved. Compared with the original manual machining, the efficiency of machining can be significantly improved with the combined punching die and the improved bending machine. It is shown that the equipment improvement combined with die optimization is a good way to achieve “cost reduction and efficiency increase”.