P. Vamsi Krishna

Nanofluids as a potential solution for Minimum Quantity Lubrication: A review

Several studies are being carried out to curtail the heat generated in machining. Among the various alternatives available, cutting fluids remain to be the choice. However, the various limitations of the cutting fluids restrict their application. Hence, different techniques are being explored to replace the use of cutting fluids, minimum quantity lubrication being one of them. This present article tries to review the available literature and examine nanofluids as potential candidates for minimum quantity lubrication.

Solid lubricants in machining

This article presents a review of solid lubricants application in different machining processes such as grinding, milling, drilling, and turning. Of late, several reasons have led to the increased usage of solid lubricants in machining. The heat generated in the cutting zone during machining is critical in deciding the workpiece quality. Although cutting fluids are widely employed to carry away the heat in machining, their usage poses threat to ecology and the health of workers. Hence, there arises a need to identify eco-friendly and user-friendly alternatives to conventional cutting fluids. Modern tribology has facilitated the use of solid lubricants as an alternative to cutting fluids in machining. Graphite, calcium fluoride, molybdenum disulphide, and boric acid are the general solid lubricants used in machining. Process performance is improved with the application of solid lubricants in machining. By reducing coefficient of friction, cutting forces and tool wear are reduced in machining with solid lubricants. Reduction in cutting forces results in lower specific energy requirement and thus reduces production cost. Surface quality of the machined workpiece is also improved with solid lubricants.

Preparation and characterization of properties of nanographite-based cutting fluid for machining operations:

Soluble oils are the most popularly used oils in metal-cutting industry. However, the regular application strategy, flood cooling, involves the problem related to its disposal. Hence, mist application can be seen as an alternative procedure. Since less amount of cutting fluid is used, its capacity to carry away heat and provide adequate lubrication is limited. Therefore, the heat carrying and lubricating abilities of soluble oil need to be enhanced. Graphite has better lubricating and cooling properties, and hence inclusion of graphite nano particles in cutting fluid may help in formulating a better coolant in machining operation. This paper consists of two parts. The first part consists of preparation of nano cutting fluid by different methods followed by their stability evaluation, and second part consists of characterization of the basic properties of nano cutting fluid.

Experimental investigations on influence of mist cooling using nanofluids on machining parameters in turning AISI 1040 steel

Soluble oils are the largest class of oils used in metal cutting industry. Flood cooling involves problems related to its treatment and disposal. Minimum quantity lubrication in the form of mist application can be used to replace flood cooling. But as less amount of cutting fluid is used in minimum quantity lubrication, its capacity to carry away heat and providing adequate lubrication is limited. Hence, the heat-carrying and lubricating ability of soluble oil has to be enhanced. Graphite has better lubricating and cooling properties and hence inclusion of graphite nanoparticles in cutting fluid may help in formulating a better coolant in machining operation. This article compares the performance of mist application of nanographite-soluble oil with dry lubrication, flood lubrication and mist application of soluble oil without nanographite in turning AISI 1040 steel. Performance is evaluated based on experimental measurement of average chip–tool interface temperature, tool wear and cutting forces. The results showed that use of nanographite-soluble oil in mist application has greatly improved the cutting conditions by lowering the temperature generated, reducing the tool wear and reducing the cutting forces.

Performance assessment of micro and nano solid lubricant suspensions in vegetable oils during machining

The application of conventional cutting fluids as lubricants during machining operations is not user-friendly and eco-friendly. Owing to this reason, new eco-friendly and user-friendly alternatives to these cutting fluids are being extensively researched. In this context, the present work focuses on preparation of vegetable oil–based micro and nano cutting fluids, followed by evaluation of their applicability in machining. The comparative performance of micro and nano cutting fluids is consolidated and presented in this work. Micro and nano solid lubricants, namely, boric acid (H3BO3) and molybdenum disulphide (MoS2), are mixed with coconut and sesame oils separately and sonicated thoroughly. The samples thus prepared are used in machining for the examination of cutting forces, cutting temperatures, tool wear, and surface roughness in order to assess machining performance of the cutting fluid at the specific cutting conditions. It is observed that performance of nanofluids is better than micro fluids in reducing cutting temperatures, cutting forces, tool flank wear, and surface roughness of the machined surface.

The effect of natural rubber particle inclusions on the mechanical and damping properties of epoxy-filled glass fibre composites

Vibration damping is proving important for improved vibration and noise control, dynamic stability, fatigue, and impact resistance in advanced engineering systems. In the present work, the effect of natural rubber particle inclusions on the mechanical and damping properties of epoxy-filled glass fibre composites is investigated. Test specimens are fabricated with inclusion of natural rubber particles of different sizes and tested for tensile strength, tensile modulus, flexural strength, and flexural modulus. These mechanical properties are influenced by the size of the rubber particle inclusions. Vibration tests are carried out and damping ratio is calculated. It is observed that damping ratio varies with inclusion of natural rubber particles and that 0.25mm particle inclusions improve damping better than other selected particle sizes without greatly affecting the stiffness in the case of cantilever beams and fixed free plates.Vibration damping is proving important for improved vibration and noise control, dynamic stability, fatigue, and impact resistance in advanced engineering systems. In the present work, the effect of natural rubber particle inclusions on the mechanical and damping properties of epoxy-filled glass fibre composites is investigated. Test specimens are fabricated with inclusion of natural rubber particles of different sizes and tested for tensile strength, tensile modulus, flexural strength, and flexural modulus. These mechanical properties are influenced by the size of the rubber particle inclusions. Vibration tests are carried out and damping ratio is calculated. It is observed that damping ratio varies with inclusion of natural rubber particles and that 0.25mm particle inclusions improve damping better than other selected particle sizes without greatly affecting the stiffness in the case of cantilever beams and fixed free plates.

Online tool wear prediction in wet machining using modified back propagation neural network

Tool wear monitoring is one of the critical issues in the automated industry. Though use of artificial neural networks for tool wear monitoring is widely reported in the literature, the models are built only for dry machining. In the present work, a neural network model for cutting fluid assisted machining is proposed. Experimentation has been carried out using different cutting fluids and the results were used to build up and test the model. Further, an improvement in the network is proposed using simulated annealing, which can automatically and effectively optimize the network architecture, as opposed to the conventional trial and error method.

Experimental investigation to study the performance of solid lubricants in turning of AISI1040 steel

Abstract Machining is one of the most fundamental and indispensable processes of the manufacturing industry. The heat generated in the cutting zone during machining is critical in deciding the workpiece quality. Though cutting fluids are widely employed to carry away the heat in machining, their usage poses threat to ecology and the health of workers. Hence, there arises a need to identify eco-friendly and user-friendly alternatives to conventional cutting fluids. Modern tribology has facilitated the use of solid lubricants. The present work features a specific study of the application of solid lubricants in turning of AISI1040 steel with carbide tool. Results show considerable improvement in reducing the cutting forces, coefficient of friction between chip and tool interface, average tool flank wear, and the surface roughness of the machined surface with solid lubricants. Among the selected lubricating conditions boric acid performed well compared to graphite. Chip thickness ratio is also evaluated to study the lubricating action of selected solid lubricants during turning.

Experimental evaluation of nano-molybdenum disulphide and nano-boric acid suspensions in vegetable oils as prospective cutting fluids during turning of AISI 1040 steel

The present work focuses on the experimental evaluation of the performance of vegetable oil based nanofluids during turning. Nanofluids are prepared by dispersing suspensions of two types of solid lubricants namely, nano-boric acid (nBA) and nano-molybdenum disulphide (nMoS2) individually in two vegetable oils which are, coconut oil (CC) and sesame oil (SS). After thorough sonication, the formulated nanofluids are applied as lubricants while turning AISI 1040 steel. The fluids with and without nanoparticle inclusions (npi) are tested for basic properties like flash and fire points, kinematic viscosity, and thermal conductivity. To estimate the performance of nanofluids as lubricants, machining parameters namely main cutting force, cutting tool temperatures, surface roughness, and tool flank wear are measured. Viscosity and thermal conductivity of CC-based nanofluids is found to be better when compared to those of SS. Improvement in machining performance is observed by the application of nanofluids. CC + nMoS2 at 0.25% and 0.5% npi has shown reduction in cutting forces, cutting temperatures, tool flank wear, and surface roughness when compared to sesame oil based nanofluids. On an average, nMoS2 suspensions in CC at 0.5% npi have shown 9–13% and 20–25%, reduction in cutting forces, cutting temperatures, tool flank wear, and surface roughness respectively when compared to nBA counterparts in CC and SS at all npi.

Application of nanomaterials as coolants/ lubricants in machining

Machining is one of the most promising techniques used in manufacturing to generate workpiece with good surface finish and quality. High temperatures generated due to friction during machining adversely affect the quality of workpiece in spite of the use of cutting fluids. Application of conventional cutting fluids in machining threatens ecology and health of the workers. In order to combat the negative effects of conventional cutting fluids, ample research is in process to formulate modern cutting fluids endowed with user and eco friendly properties. This paper presents a wide spectrum of past and ongoing research on the formulation and performance of modern nanofluids as alternatives to conventional cutting fluids in machining. It is an attempt to focus on the affirmative effects of nanofluids in machining. The procedures implemented to prepare nanoparticles and nanoparticles are briefly presented. Basic properties of nanofluids, which affect the machining performance are discussed. Performance of nanofluids in terms of cutting forces, tool flank wear, cutting temperatures and surface finish is discussed.