A new nozzle system which consists of a discharge nozzle and supply equipment has developed for environmental friendly metalworking fluid, called oil-on-water droplet metalworking fluid. This system provides excellent cutting performances in terms of roughness on finished surfaces, burr dimensions and cutting force in both aluminum alloy and stainless steel milling. As its application to practical use, the system has been employed for grooving process in the production line of engine main bearings which was conventionally machined under dry condition. It has been shown that the developed system can improved the machining performances in terms of machining error and tool life. The improvement for the machining error leads to significant reduction in the rejection of defective parts in the production line and more than twofold increase in tool life is obtained.