Finishing nonuniformity for electrical discharge machined closed complicated flow channels by abrasive flow machining

Abstract

Abrasive flow machining (AFM) is increasingly preferred to finish closed complicated flow channels machined by electrical discharge machining (EDM) owing to its high machining accessibility, surface integrity, and efficiency. The machining accuracy of closed complicated flow channels by AFM is dependent on the uniformity of material removal distribution (named as finishing nonuniformity here), but few studies on the finishing nonuniformity have been done so far. Firstly the finishing nonuniformity for EDM machined complicated flow channel by AFM was modeled and analyzed theoretically. Then three blisk with EDM surface roughness of Ra 1.5 μm, Ra 2.0 μm, and Ra 3.0 μm were finished by AFM to Ra 0.8 μm, and their finishing nonuniformity was compared. Finally, AFM flow simulation was carried out, and the simulation results were compared with that from the experiments. Theoretical results showed that finishing nonuniformity is resulted from the non-uniform flow field of the abrasive medium, and it increases with increasing EDM surface roughness and decreasing AFM surface roughness. This is verified by the AFM experiments and flow simulations. On this basis, the guideline for parameter optimization in the combined EDM + AFM process was discussed.