Abstract
The paper details the effects of depth of cut and vibration amplitude when ultrasonic assisted (US) creep feed grinding Inconel 718 with an open structured alumina based wheel. The workpiece was actuated at a constant frequency (∼20.5kHz) via a block sonotrode attached to a 1kW piezoelectric transducer-generator system. A full factorial experimental array comprising 12 tests was conducted involving variation in depth of cut (0.1, 0.5 and 1.0mm), amplitude of vibration (high and low) and grinding condition (with and without vibration). Wheel speed and table feed were fixed at 30m/s and 600mm/min respectively for all tests. Application of ultrasonic vibration resulted in reductions in vertical (Fv) and horizontal (Fh) force components by up to 28% and 37% respectively, however greater wheel wear (30-60% lower G-ratio) occurred under hybrid operation due to increased grit/bond fracture. SEM micrographs of the slots machined with US assistance revealed higher levels of side flow/ploughing in comparison to standard creep feed ground specimens. Additionally, more overlapping grit marks were visible on surfaces subject to ultrasonic assisted grinding. Increasing amplitude of vibration produced lower grinding forces (up to 30% for Fv and 43% for Fh) but higher workpiece surface roughness (up to 24%). Topographic maps of grinding wheel surface replicas indicated that use of US vibration generally led to an increase in the number of active cutting points on the wheel.
Highlights
Nickel based superalloys are used extensively in the hotter sections of gas turbine engines, as they are able to maintain their strength and corrosion resistance better than other metallic alloys
The majority of tests showed lowering of both vertical (Fv) and horizontal (Fh) grinding forces by up to 28% and 37% respectively, when grinding was employed with vibration
As outlined in the literature, this was probably due to a reduction of thermal load on the abrasive grits, caused by intermittent cutting action of the grains under ultrasonic actuation [16]
Summary
Nickel based superalloys are used extensively in the hotter sections of gas turbine engines, as they are able to maintain their strength and corrosion resistance (at temperatures above ~700oC) better than other metallic alloys. The majority of published papers on UAG report significant reductions in normal and tangential grinding forces (~30-50%) [10,11,12], together with a reduction in thermal damage/grinding burn and improvement in workpiece surface finish [10,11,12,13,14]. The majority of published work over the past ~20 years has largely involved vibration applied to the workpiece as opposed to the grinding wheel, primarily due to the comparatively simpler experimental setup. This approach has been adopted in the present research involving the creep feed grinding of Inconel 718 workpieces with an open structured alumina wheel. The objective of the work was to investigate the effects of depth of cut (ae) and amplitude of US vibration on grinding forces (vertical and horizontal), wheel wear (G-ratio), workpiece surface roughness/quality (2D and 3D parameters) as well as wheel surface topography
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
