- The developed equipment has been applied in the machining of spray holes of diesel injector nozzles. The applications show that the holes’ space accuracy being better than ±0.1◦ and the holes’ size accuracy being controlled within ±2 m for the hole-diameter range from ˚140 m to ˚300 m with taper angle 0–1.3◦ (K-factor 0–2.3). Compared with the machining efficiency of straight hole without assisted vibration that of taper hole with assisted vibration was improved by 44%, and the machining-feed efficiency of each hole was up to 1.5 mm/min without including the auxiliary time.