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Ultrasonic vibration-assisted dry grinding is a sustainable hybrid manufacturing technology that decreases the negative environmental impact of coolant, reduces manufacturing costs, and improves surface integrity. The present investigation analyses the mechanisms associated with ultrasonic vibration-assisted dry grinding of AISI D2 tool steel with an alumina grinding wheel. It also compares the influence of traditional dry grinding and traditional wet grinding modes with the ultrasonic vibration-assisted dry grinding mode at different ultrasonic vibration amplitudes. Ultrasonic vibration was applied to the sample in the longitudinal feed direction. Further, kinematics of the abrasive grit path during the traditional grinding and ultrasonic vibration-assisted dry grinding is presented schematically. In this research, the impacts of ultrasonic vibration amplitude as well as the depth of cut on the process yields such as ground surface topography, grinding force, specific grinding energy, force ratio, surface finish, microstructure, and hardness were investigated experimentally. Experimental results revealed that the highest decline in tangential and normal grinding forces in ultrasonic vibration-assisted dry grinding at ultrasonic vibration amplitude 10 µm and the reduction in surface roughness parameter ( Ra, Rq, and Rz) in ultrasonic vibration-assisted dry grinding was 43.23%, 42.59%, and 33.69%, respectively, in comparison to those in traditional dry grinding and 26.35%, 26.94%, and 27.48%, respectively, in comparison to those in traditional wet grinding. It was observed that ultrasonic vibration-assisted dry grinding is beneficial as the profile produced by ultrasonic vibration-assisted dry grinding has a comparatively flat tip, and profile points are shifted to the bottom of the mean line. This study is expected to assist ultrasonic vibration-assisted dry grinding of hard materials.

In the precision fabrication industries, ultrasonic vibration-assisted grinding is widely utilized for the finishing of “difficult-to-cut” materials due to its intermittent cutting mechanism and brittle-to-ductile mode machining. In this study, a two-dimensional finite element model (FEM) of single grit ultrasonic vibration-assisted dry grinding (UVADG) and conventional dry grinding (CDG) of AISI D2 steel has been developed, which taken into account the influence of longitudinal ultrasonic vibration on the workpiece with variable downfeed. The effects of ultrasonic vibration and downfeed on the chip formation mechanism, temperature field, grinding force, and equivalent stress and strain were evaluated by analytical and simulation methods. The results show that the formation of the grinding chips under UVADG is much shorter and straighter than CDG mode at all respective downfeed. The validation experiment compared the simulated and experimental grinding force in both grinding modes to verify the reliability of the FEM results. The validation results demonstrate that the FEM model can accurately describe the single grit UVADG and CDG grinding. At each downfeed, the CDG mode has generated a larger equivalent plastic strain than the UVADG mode, resulting in a higher thermomechanical load on the workpiece. According to the findings, UVADG mode has the least plastic damage on the ground surface, which may improve the surface integrity of the ground component.

Nowadays, precision manufacturing industries are required faster surface inspection tools for the achievement of high productivity. In this context, the Barkhausen noise (BN) technique is adopted as a quick response technique in the grinding for qualitative evaluation of surface integrity of AISI D2 tool steel. Present work investigates the effect of eco-friendly coolant, i.e., cryogenic, on surface integrity of ground sample in the plunge grinding mode at different downfeed and compared with dry and wet environments. Surface integrity was assessed in respect of surface roughness, microstructure, and microhardness. Magnetic response of ground surface was reported by Barkhausen noise analyzer in the form of root mean square (rms), peak, and number of pulses. From the outcomes, it was perceived that no significant variations were found in the microstructure and microhardness of the ground surface and subsurface after cryo-grinding owing to lower thermo-mechanical loading. Besides, lower surface roughness was obtained in the case of cryo-grinding because of thermal softening effect. A linear correlation between BN input parameters, i.e., magnetic field intensity and BN responses at different magnetizing frequency could be achieved. Finally, better BN responses, including higher rms, peak, and number of pulses, were found under the cryogenic environment.

In this work, three actual impeller geometries of identical size, with backward, radial, and forward flow passages in the same volute casing, are experimentally analysed and numerically simulated to understand the flow physics characteristics and the performance mapping under different flowrate conditions. A grid independence test is carried out for the whole computational domain to capture complex flow behaviour inside blades. The three-dimensional numerical analysis is performed under steady flow conditions, and for a rotational domain, a moving reference frame approach (frozen rotor method) is used. The results obtained from experimental and simulated cases for backward, radial, and forward curved centrifugal fans with varying mass flowrates shows that static pressure and total pressure are increased with an increase in rotation speed and the static pressure gradient is higher in forward curved blades than in backward and radial bladed centrifugal fans. A blade’s low and high-pressure regions along the suction and pressure sides are visualised by numerical analysis. The degree of recirculation within blade passages, flow reversal and vortex formation in volute and tongue regions is observed to be different in all three types of flow passages, which clearly describes its influence on the performance characteristics of centrifugal fans.

Grinding generates a lot of heat in the grinding zone area during operation. Therefore, it is important to keep the temperature under control by using various cutting fluids to get a good ground surface quality. The existence of a stiff air layer surrounding the abrasive wheel is known to waste most of the cutting fluid supply in the interface area between the abrasive wheel and workpiece. Due to the high grinding speed, stiff air layers prevent cutting fluids from entering the interface area. Hence, to enhance the grinding performance, cryogenic cooling has been introduced to improve the penetration into the stiff air layer. The current work investigates the grindability of the ground surface of AISI D2 tool steel under different environments: dry, wet, and cryogenic, regarding grinding forces (i.e. tangential and normal force), specific grinding energy, and surface characterisation. This paper also proposed a method to evaluate image-based Abbott–Firestone curve (bearing area curve) parameters to characterise the ground surface topography. Significant reductions in grinding forces (64%–67% and 44%–50% in Ft, 54%–58% and 34%–39% in Fn), low specific grinding energy (64%–67% and 44%–50%), decrease in surface roughness (46%–51% and 30%–36% in Ra, 37%–41% and 31%–35% in Rz), improved 2D and 3D roughness profiles and higher bearing area ratio (89.54%) were observed at 40 µm downfeed in cryogenic cooling environments compared to dry and wet environments, respectively. Thus, observations show the importance of cryogenic cooling across the experimental domain.

The surface roughness of austenitic (304), martensitic (410) and ferritic (430) grades of stainless steels have been measured after fine emery paper grinding. The surface integrity of the ground samples were further examined in SEM. Metal removal during emery paper grinding occurred by rubbing, ploughing, micro cracking and gouging out of metal grains. The rate of corrosion/year, as determined through potentiostat test in 0.9 N NaCl solution, increased with surface roughness but it was insignificant in case of the metallographically polished samples of all the stainless steels. Corrosion progressed fast from the grinding pits on the stainless steel sample surfaces.

According to tooling industries, grinding is the most effective and economical machining for AISI D2 tool steel owing to its low thermal conductivity. The first objective is to investigate the effect of grinding environments on surface integrity of AISI D2 tool steel. Grinding performance like force ratio and grinding temperature was investigated under wet and dry environments. The second objective is to qualitatively assess the thermal damage of ground surface using non-destructive hysteresis loop (HL) technique. The result shows that higher force ratio and surface roughness were obtained under flood grinding. Maximum thermal damage in terms of drastic variation in microstructure and microhardness were observed under dry grinding owing to serious plastic deformation at higher grinding temperature. HL outcomes like lower average permeability, higher coercivity and remanence were obtained with higher thermal damage on ground surface. Finally, linear correction was obtained between HL outcomes and microhardness of ground samples.

An as cast Al-33%Cu eutectic alloy has been processed by semisolid heat treatment, with the ultimate objective of developing a ductile and strong eutectic composite material for probable application as bearing materials and other sliding wear components. In this phase of work only microstructural characterises has been attempted. The as cast sample of Al–Cu alloy is subjected to isothermal heat treatment at a temperature of 560 °C for varying periods of time and followed by water quenched. The microstructures of the semisolid heat treated (SSH) samples are analysed using an optical microscope and scanning electron microscopy (SEM). The microstructures of the quenched Al-33%Cu alloy samples show lamellar to lamellar + dendritic transition after SSH treatment. The quenched microstructure after 20 min of holding time primarily consists of copper aluminide dendrites + supersaturated α–Al grains. A massive copper-aluminide (>80%Cu) intermediate phase is observed after 3 to 6 min SSH. The sample configuration did not change after semisolid heat treatment and water quenching. This suggest that complete remelting and overburning did not occur during the semisolid heat treatment. The SSH sample shows maximum hardness, after 10 min holding time compared to solution treated (at 560 °C) and aged (at 150 °C) sample of a standard Al-4.5%Cu cast alloy. The Transmission electron microscopy (TEM) micrograph of the as quenched 10 min. SSH sample shows rod shaped CuAl2 (θ) precipitates, a dislocation network, cellular subgrains and an extremely fine lamellar eutectic. Solute cluster probably Guinier–Preston (GP) zones, precipitates and fine α –Al grains was observed in the peak aged sample. The x-ray diffraction (XRD) analysis of aged SSH treated sample shows several intermetallic copper-aluminide phases in each sample.

Grinding is the final process in the manufacturing of precise components with adequate surface integrity. Surface integrity has significant effect on the working life of component. The aim of the present work is to experimentally investigate the effect of eco-friendly grinding i.e. dry, belt and pedestal grinding on the surface integrity of different stainless steels (SS) like austenitic AISI 304SS, martensitic AISI 410SS, and ferritic AISI 430SS. Surface integrity was assessed by surface topography, surface roughness, microchip morphology, metallographic of microchip and thermal damage of ground surface. The surface topography of microchip and ground samples was observed by scanning electron microscope (SEM) and energy dispersive X-ray spectroscopy (EDX). Grinding performance was investigated in terms of grinding force. Further, corrosion performance of different grade SS was measured using potentiodynamic corrosion test in 0.9N NaCl solution under different grinding condition. The result shows that excellent ground surface quality with lowest surface roughness was obtained in AISI 304SS under all grinding modes. Spherical and ribbon microchips were observed during belt and pedestal grinding. SEM-EDX analysis indicated that iron-chromium oxide nodules were formed on ground surface and microchip. Lower grinding force was obtained during dry grinding of AISI 430SS. Finally, maximum corrosion rate was found in all grades of stainless steel during pedestal grinding owing to rupture of Cr2O3 protective layer.