Improving finishing uniformity using fluid field vibration in abrasive water flow polishing of inclined hole

Micro-inclined holes in nickel-based alloys have important functions in hot-section components of aero-engine. Hole-wall surface defects occur during electrical discharge drilling (EDD) or laser drilling (LD) of these inclined holes. Abrasive water flow polishing (AWFP) is a promising method for finishing inclined holes after EDD or LD processes. However, the abrasives tend to gather at the obtuse edge of the inclined hole during regular AWFP and cause remarkably nonuniform finishing. Fluid field vibration-assisted AWFP has been studied to solve this problem. A comparison between the absence and presence of low-frequency flow field vibrations in AWFP of inclined holes was made. Subsequently, the effects of vibration amplitude and frequency on the polishing results were investigated. The results show that the radial vibration of the fluid field can significantly improve the abrasive dispersion inside the inclined hole and, consequently, enhance the kinetic energy and collision frequency of the abrasives impinging the hole wall. This results in a better material removal uniformity. With the fluid field vibration, the hole-wall finishing nonuniformity inside the target hole can be decreased by 78% under a relatively low amplitude and high frequency. The averaged roughness achieved was Ra 1.3 μm, whereas the original prepolishing hole-wall roughness was Ra 5.5 μm.