Dinesh Setti

Influence of nanofluid application on wheel wear, coefficient of friction and redeposition phenomenon in surface grinding of Ti-6Al-4V

Difficulties in the grinding of Ti-6Al-4V originate from the three basic properties: poor thermal conductivity, high chemical reactivity and low volume specific heat of the material. Under severe grinding conditions, all these factors together lead to the accelerated wheel loading and redeposition of chips over the work surface. Redeposition and wheel loading have a significant effect on the surface finish, grinding forces, power consumption and wheel life. In this study, water-based Al2O3 nanofluid as metalworking fluid is applied during the surface grinding of Ti-6Al-4V under minimum quantity lubrication mode after dressing the wheel with different dressing overlap ratios. The severity of the redeposition over the work surface was observed by measuring various surface profiles taken perpendicular to the grinding direction at several locations on the ground surface. The nanofluid application was able to prevent redeposition over work surface that became evident from the measured surface finish parameters that results along the grinding direction. Coefficient of friction was estimated On-Machine using the measured forces for different wheel work speed ratios, depth of cut and dressing overlap ratios. The results showed the effectiveness of nanofluid in reducing friction at high material removal rate (i.e. high depth of cut and high speed ratio) conditions when compared to the dry environment. From the measured forces variation with respect to the number of passes, it became evident that, nanofluid application delayed the frequency of wheel loading and grit fracturing cycle, which leads to the increase in the wheel life.

Grindability improvement of Ti-6Al-4V using cryogenic cooling

Titanium and its alloys are well known for their difficult machinability nature. Because of Ti-6Al-4V alloy’s strong chemical affinity, high temperature and pressure during the grinding process, the formed chips easily weld onto the grinding wheel surface. This phenomenon reduces the wheel life and diminish the surface quality. To control the effect of temperature, most grinding operations today employ cutting fluids. These fluids help in improving the surface quality and increasing the wheel life. However, because of environmental and economic concerns, industries are now looking for sustainable alternative cooling techniques such as cryogenic cooling. The aim of this study is to present the application of liquid nitrogen cryogenic cooling as an alternative cooling technique for grinding Ti-6Al-4V alloys. To compare the effect of cryogenic condition, experiments were conducted under both dry and wet (soluble oil) conditions. Experimental results proved the effectiveness of cryogenic cooling in reducing the grinding force, obtaining better surface finish, and being less damaging to the surface condition. Finally, multiple regression models were developed to predict the normal force and tangential force in cryogenic condition. The developed models have been validated with experimental data, and the maximum prediction error of the model for normal and tangential forces was less than 12% and 9%, respectively.

A modified model for estimating the contact length in surface grinding

The real contact length during the grinding process is considered as an important subject for researchers, mainly because it reflects the intensity of the responses such as grinding forces and temperature generation. In order to measure and assess the real contact length, many experimental techniques and prediction models are available in the literature. Among all these models, the model developed by Rowe and Qi is being used widely by researchers because of its ability to make close predictions with real values. Rowe and Qi coined the term called roughness factor in their model. This factor varies with grinding environments and wheel–work material combinations. To decide it for a new environment, one has to do the laborious experimental work. In this article, the roughness factor has been analysed from the grinding temperature and the heat partition ratio point of view and expressed so that without experimental work prediction of the roughness factor can be done. For this, a new factor called as the thermal factor has been proposed based on the roughness factor modifications. Its good correlation with dimensionless temperature and heat partition ratio under different grinding environments have been presented and discussed in the current communication. It seems that the thermal factor can be helped in an easy and accurate prediction of the contact length during grinding operations.

An investigation into the application of Al2O3nanofluid–based minimum quantity lubrication technique for grinding of Ti–6Al–4V

Nanofluids, suspensions of nanoparticles in base fluid, has shown attractive cooling and lubricating properties. The nano–coolants and nano–lubricants find applications in a wide variety of materials processing technologies. It is anticipated that, if properly employed, nanofluids usage could surpass the conventional cutting fluids in the future. Minimum quantity lubrication (MQL) technique also, has achieved a significant consideration in manufacturing processes to minimise the environmental loads caused by the usage of traditional cutting fluids. The aim of this work is to examine the potential of Al2O3 nanofluid under MQL mode to improve the grinding characteristics of Ti–6Al–4V alloy. 1% Volume concentration of water–based Al2O3 nanofluid was applied during the surface grinding operation using an indigenously developed MQL setup and the results have been compared with those of conventional coolant under both flood cooling and MQL mode.

An alternate method for optimisation of minimum quantity lubrication parameters in surface grinding

Currently, the manufacturing sector is adapting sustainable techniques to minimise the damage to the environment. Minimum quantity lubrication (MQL) is one of the sustainable techniques to address the ecological and economic issues. In MQL atomised mixture of cutting fluid and compressed air is injected into the machining zone. The effectiveness of MQL technique primarily depends on the quality of the mixture which mainly depends upon the droplet quality. In this work, a combination of microscopy and image processing techniques has been used to ascertain the quality of droplets. The raw droplet features captured with a stereo-zoom microscope and analysed by measuring the average droplets size and number of droplets per unit area. To ensure the enhanced effectiveness of MQL parameters like droplets quality, air pressure, flow rate and nozzle positions have been optimised experimentally. Further, obtained optimal MQL parameters have been used in the grindability study of Inconel 718.

A Method to Predict and Visualize the Wheel and Work Surface Topography in Surface Grinding

Visualization of work surface topography through simulations is very challenging task in grinding process due to the complexity of wheel-work interactions with a very high number of cutting points (grits). Kinematic mapping of abrasive grits on a three-dimensional wheel topography enables the evaluation of ground surface topography through simulations. In this paper, a method for generating the ground surface topography based on wheel specifications is presented. Abrasive grits size, abrasives volume percentage and their nature of distribution on the wheel surface are considered in the modeling and visualization of wheel topography. The simulation results of ground surface topographies prove the feasibility of the developed method.