M. Ravi Sankar

Nano-Cutting Fluid for Enhancement of Metal Cutting Performance

Nano-cutting fluids are the mixtures of conventional cutting fluid and nanoparticles. Addition of the nanoparticles can alter wettability, lubricating properties, and convective heat transfer coefficient (cooling properties) of nano-cutting fluids. In the present work, nano-cutting fluid is made by adding 1% Al2O3 nanoparticles to conventional cutting fluid. The wettability characteristic of this nano-cutting fluid on a carbide tool tip is measured using the macroscopic contact angle method. Comparative study of tool wear, cutting force, workpiece surface roughness, and chip thickness among dry machining, machining with conventional cutting fluid as well as nano-cutting fluid has been undertaken. This study clearly reveals that the cutting force, workpiece surface roughness, tool wear, and chip thickness are reduced by the using nano-cutting fluid compared to dry machining and machining with conventional cutting fluid.

Rheological characterisation and performance evaluation of a new medium developed for abrasive flow finishing

Abrasive action in abrasive flow finishing (AFF) mainly depends on medium formulation and machine settings. Medium composition decides the viscosity and it has significant effect on the process performance. In the present work, a new AFF medium is developed, and experiments are carried out to evaluate its rheological flow properties. Later, AFF experiments are carried-out to finish Al alloy and Al alloy/SiC metal matrix composites with a wide range of input parameters to find-out an appropriate input parameters range to get the best surface finish. Then complete experimental study is planned using central composite rotatable design. The finishing results are correlated with rheological properties of the medium. A change in surface roughness is found to be more in Al alloy/SiCp (10%) as compared to Al alloy and Al alloy/SiCp (15%). Justification for the same has been discussed in the paper.

Laser Surface Alloying of Copper, Manganese, and Magnesium with Pure Aluminum Substrate

Laser surface alloying is one of the recent technologies used in the manufacturing sector for improving the surface properties of the metals. Light weight materials like aluminum alloys, titanium alloys, and magnesium alloys are used in the locomotive, aerospace, and structural applications. In the present work, an experimental study was conducted to improve the surface hardness of commercially pure aluminum plate. CO2 laser is used to melt pre-placed powders of pure copper, manganese, and magnesium. Microstructure of alloyed surface was analyzed using optical microscope. The best surface alloying was obtained at the optimum values of laser parameters, viz., laser power, scan speed, and laser beam diameter. In the alloyed region, microhardness increased from 30 HV0.5 to 430 HV0.5, while it was 60 HV0.5 in the heat-affected region. Tensile tests revealed some reduction in the strength and total elongation due to alloying. On the other hand, corrosion resistance improved.

Experimental comparative study of conventional, micro-textured and coated micro-textured tools during machining of hardened AISI 1040 alloy steel

To minimise harmful effects of cutting fluids in machining, researchers have shown interest in the field of dry machining. Surface texturing has capacity to affect tribological conditions. Few researchers have tried to apply controlled surface texturing on cutting tools. In the current research work, micro-textures were fabricated on the rake face of cutting tool using mechanical indentation method. The experimental study explains about advantages of micro-textured and micro-textured with MoS2 coated tools compared to conventional tools. To find out the effect of micro-textures on the strength and rigidity of cutting tool, structural analysis was carried out. Negligible differences over generated von Mises stresses and strains were noticed due to presence of micro-textures on cutting tools. Dry cutting tests were performed and results show significant reduction of cutting forces, feed forces and friction coefficient by micro-textured and coated micro-textured cutting tools compared to conventional tool. Chip morphology with different tools is also studied.

Effect of Abrasive Medium Ingredients on Finishing of Al Alloy and Al Alloy/SiC Metal Matrix Composites Using Rotational Abrasive Flow Finishing

Al alloy/SiC composites possess better mechanical and physical properties thus finding applications in automotive, sports, and aerospace. In some cases, these components require nanolevel finished surface. But, traditional abrasive finishing processes are labor intensive, time consuming and confined to only simple geometries. Abrasive flow finishing (AFF) is one of the advanced finishing processes that can be used to finish complex surfaces by flowing polymer based abrasive medium but its finishing rate is low. In the present work, Rotational-AFF (R-AFF) process is developed where in workpiece rotates about its axis. This rotation provides the dynamic motion (additional force and velocity components) to the workpiece. By cumulative effect of workpiece rotation and medium reciprocation, the active abrasive particles try to abrade the workpiece in a helical path. Thus, finishing length and finishing rate both increase. In AFF process, because of more finishing time medium undergoes chemical change or degradation (loses its viscosity) because of continuous shearing and rise in temperature. Therefore the effect of medium shear viscosity variation with the temperature is studied to understand how the viscosity reduces with the temperature. Later complete experiments are conducted on R-AFF process by varying plasticizer to polymer volume ratio and polymer to abrasive ratio. The finishing from micron surface topography to nanosurface topography is studied using atomic force microscopy.

Experimental study and empirical modelling of magnetic abrasive finishing on ferromagnetic and non–ferromagnetic materials

Magnetic abrasive finishing is one of the advanced finishing processes where in the iron (Fe) particles form a flexible matrix in which the abrasives are trapped when magnetic field is applied. In the present paper, the magnetic flux densities (MFD) are measured at various distances from the outer surface to centre on ferromagnetic and non–ferromagnetic materials with approximately same hardness. MFD is about three times higher on ferromagnetic compared to non–ferromagnetic workpiece. Complete experimental study is carried out and empirically modelled. Best final Ra value about 20 nm and 60 nm is achieved on ferromagnetic and non–ferromagnetic stainless steel, respectively. With increase in abrasive mesh size and decrease in working gap, percentage change in Ra (%ΔRa) increases. Online measurement of forces is done using indigenously developed ring type dynamometer. Normal magnetic force is much higher in case of ferromagnetic than non–ferromagnetic workpiece material but no significant change is found in tangential cutting force.

Machining of Metal Matrix Composites with Minimum Quantity Cutting Fluid and Flood Cooling

In the present work, minimum quantity cutting fluid (MQCF) technology was developed and applied for enhancing the machining performance by maintaining eco-friendly conditions. Machining experiments were carried on Al alloy/SiC metal matrix composite using cemented carbide tool with both MQCF and flood cooling. MQCF was effective in bringing down the forces, surface roughness, flank wear by ~17 %, ~5 %, ~12.5 % respectively compared to flood cooling. In MQCF, the consumption of cutting fluid is extremely low (10ml/min) compared to flood cooling (~ 400-600 ml/min). So, emission produced in MQCF are very less, which is eco-friendly.