A study on ultrasonic assisted creep feed grinding of nickel based superalloys

The paper initially reviews research relating to ultrasonic (US) assisted grinding of various workpiece materials. Results from experimental trials to evaluate the influence of applying US vibration when creep feed grinding Inconel 718 with an open structured, alumina based grinding wheel (POROS 2) are then presented. A full factorial experimental array comprising 18 runs was conducted involving variation in wheel speed (30, 35 and 40m/s), table speed (200, 250 and 300mm/min) and grinding condition (with and without vibration). For tests with US vibration, the workpiece was actuated at a constant frequency (similar to 20kHz) via a specially designed block sonotrode attached to a 1kW piezoelectric transducer-generator system. Reductions in vertical (F-V) and horizontal (F-H) grinding force components of up to 23% and 43% for F-V and F-H respectively and surface roughness (S-a) of the ground slots by up to 45% were observed in the majority of tests when utilising US assisted operation. In terms of surface quality, SEM micrographs revealed greater side flow/ploughing and overlapping grit marks in slots machined with the workpiece vibrated in comparison to standard creep feed ground specimens. Three dimensional topographic measurement of grinding wheel surface replicas indicated that US vibration led to an increase in the number of active cutting points on the wheel. (C) 2012 The Authors. Published by Elsevier B. V. Selection and/or peer-review under responsibility of Professor Konrad Wegener