This paper describes the development of an ultra-high speed grinding (UHSG) machine which is capable of 400m/s wheel speed. UHSG is one of the high efficiency machining methods. It has reached the stage where it can complete well with respects to machining efficiency even in comparison with a cutting method. Concept of the UHSG is not new, however a practical application of the UHSG was difficult due to the manufacturing problems of a grinding wheel and a wheel spindle unit in the ultra-high speed rotation. In the previous work, an ultra-high speed spindle unit (30000 rpm, 22kW, 2×106 dn-value) was developed. In this paper, a UHSG machine using the spindle unit was designed and manufactured. Vibration, noise and coolant friction loss of the machine were measured and compared with the conventional grinding results. The UHSG tests were performed under the 300m/s wheel speed using the developed machine and a vitrified bonded CBN wheel. The CBN wheel having a CFRP core was specially designed. However, coolant supply was not enough in the region of the UHSG, therefore the development of a low friction supplying method is needed.
