Browsing by Author "Mathew, Nitin Tom"

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Application and future prospects of additive manufacturing in dermatology
(OUP, 2022-06) Mathew, Nitin Tom
The article discusses the additive manufacturing/3D printing of human skin for advanced applications. Even though this is still in its infancy, additive manufacturing has the potential to revolutionize the field of dermatology and cosmetology.
Delamination and tool wear in drilling of carbon fabric reinforced epoxy composite laminate
(Elsevier, 2022) Mathew, Nitin Tom
In the present work, drilling experiments were performed on carbon fiber reinforced epoxy composites, fabricated by compression molding. The effect of various process parameters on delamination and tool wear during drilling were investigated. The laminate, after fabrication, was tested to find the elastic modulus, fiber volume fraction and tensile strength. A full factorial experiment with process parameters at three levels each were performed initially to find the optimum cutting condition which was used in the second experiment to compare the performance of four different drill bits with varying geometry. Analysis of delamination and tool wear revealed that the tool with point angle 90°, helix angle 35° was the best tool for drilling carbon fiber reinforced epoxy composites as it resulted in the least delamination and showed no significant tool wear. Tool with point angle 140°, helix angle 30° also performed well while TiAlN coated tool performed poorly due to the erosion of the coating at the cutting edges resulting in increased cutting forces and higher delamination. Delamination and tool wear was observed to be the highest in tool with a point angle of 118°and helix angle 30°.
Drilling of titanium aluminide at different aspect ratio under dry and wet conditions
(Elsevier, 2016-10) Mathew, Nitin Tom
To increase the wide use of intermetallic titanium aluminides for various fields of engineering application, a broad understanding of the machinability of these material is essential. The present work is focussed on the drilling of this intermetallic alloy at low and high aspect ratio under dry and wet environments. The machinability in dry and wet conditions were assessed based on the thrust force, torque, burr formation, surface quality, tool condition and chip morphology. The supply of cutting fluid is found to be effective in reducing the thrust force and torque and producing quality surface. Burr, being an important factor in drilling have also been studied, and the findings show the presence of uniform burr with and without roll back in dry and wet condition respectively. Surface defects formed and their intensity during both the machining environments were analysed. Built up edge formation on the drill tool was detected in all cutting conditions. The transformation of chip shape as the depth of hole progresses is also detailed in the present work. Furthermore, the study demonstrates the feasibility of drilling titanium aluminide in dry and wet environment. The overall results indicate that dry environment is not viable for high aspect ratio drilling.
Dry Deep Drilling of Titanium Aluminide
(ASME, 2016-03) Mathew, Nitin Tom
Intermetallic titanium aluminides are recognized as the possibly alloys for high performance aerospace and automobile application. There is an increasing interest of this material due to their extraordinary material properties. The understanding of the machinability of titanium aluminides during various metal cutting processes is very much essential for its wide acceptance over various fields of application. Drilling, with high aspect ratio is a key machining area to be explored because of its complex nature. In the present work, holes were drilled on a titanium aluminide intermetallic alloy with an aspect ratio of 9.37, focusing on the machinability under dry environment using coated and uncoated twist drill. Machinability investigations were evaluated based on the, thrust force, torque, surface integrity, chip morphology, burr formation and performance of the tool. From the results of thrust force and torque, it is revealed that the coated tool doesn’t show any significant advantages over the uncoated tool. The variation of chip shapes was observed as the depth progresses. Small ring shape, uniform and non-uniform roll back burr were observed as the cutting parameters are varied. The adherence of workpiece material on to the tool and various surface defects were observed under all cutting conditions.
Electroplated CBN superabrasive wheel for grinding intermetallic titanium aluminide
(Inder Science, 2019-02) Mathew, Nitin Tom
An experimental investigation is reported on the surface grinding of intermetallic gamma titanium aluminide using electroplated cubic boron nitride grinding wheel. In order to implement the wide acceptability of this material in various fields, the machinability investigation finds crucial especially during grinding. In the present work, the machinability of gamma titanium aluminide of two different compositions was investigated by analysing the normal and tangential force, surface integrity, chip morphology and the condition of grinding wheel after the experiments. The minor variation in the composition of titanium aluminide has influence on the generated cutting forces, the knowledge of which is essential for satisfactory use of this material in various applications. The observations from the machined surface have shown the presence of various surface defects and the analysis of chip morphology revealed the occurrence of high temperature during the grinding. The topography of the grinding wheel is also investigated after the experiments.
Environmentally friendly drilling of intermetallic titanium aluminide at different aspect ratio
(Elsevier, 2017-01) Mathew, Nitin Tom
There is an increasing attempt to implement green manufacturing in almost all fields of engineering. Minimum quantity lubrication is considered as a relevant and promising candidate in promoting environmentally friendly machining since it bridges the gap between dry and wet condition. It can keep the work material temperature lower than those in a dry environment by reducing the frictional heat generated during the machining processes and deliver certain amount of cooling effect in the tool-workpiece contact region. The present work is focussed on the drilling of this intermetallic titanium aluminide alloy at low and high aspect ratio under minimum quantity lubrication environment and is compared with dry and wet environments. The feasibility of using minimum quantity lubrication is evaluated based on the thrust force and torque. Burr, being an important factor in drilling have also been studied, and the findings show the presence of uniform burr in minimum quantity lubrication condition. In a complex process like drilling, chip flow is restricted only through the flutes and hence there occurs transformation of chip shape, chip thickening and changes in force and torque as the depth of hole progresses. In order to study these changes peck drilling was adopted and the depth at which the transformation of chip shape occurs is identified.
Fabrication of microchannels for microfluidic devices using laser micromachining
(Elsevier, 2023-08) Mathew, Nitin Tom
Micro machining is widely used to create micro features for various applications. Laser micromachining is gaining importance for its flexibility, accuracy, and its ability to process a wide range of materials. The various challenges in CO2 laser micro machining include achieving high surface finish and variable cross-sectional profile of micro channels. In this work, the micro channels machined on polymethyl-methacrylate are studied. The effect of laser machining overlap and repeated machining on the profile of micro channels at constant laser power and machining speed is investigated. The influence of the parameters on the width of the channel and surface quality is studied in this work.
Fabrication of Ti-6Al-4V thin sheet using wire-EDM and its characterisation
(Inder Science, 2022-02) Mathew, Nitin Tom
An appreciable demand for thin titanium sheets is observed in recent years due to technological development in various sectors. The existing sawing methods are uneconomical to produce high aspect ratio sheets with good dimensional accuracy. The current work focuses on extracting thin sheet of 380 mm × 50 mm × 0.2 mm from Ti-6Al-4V using wire electric discharge machining and investigated the dimensional and surface variations. The preliminary study using usual wire EDM procedure resulted in poor dimensional accuracy for a thickness in the range of 500 µm due to the lateral movement of sheet free end. Hence, in this work, a support system is attached to workpiece to minimise sheet movement and to improve the flushing during extraction. This helped to reduce the thickness variation up to 6% for a 0.2 mm Ti-6Al-4V sheet. The root mean square roughness is found to be consistent up to a height of 240 mm from the top surface. Also, majority of the measured skewness are positive. Altogether, the results of the study can be applied to fabricate thin sheets for additive manufacturing process.
Grindability study of intermetallic titanium aluminide using various abrasive wheels
(Elsevier, 2023-07) Mathew, Nitin Tom
Nickel (Ni) and Titanium (Ti) based superalloys satisfy the properties of a material suitable for high-performance applications. Titanium aluminide (γTiAl) is a classic example that finds wide application in aerospace and automobile industries. Even though γTiAl is having attractive mechanical and thermal properties, a widespread use of this material is restricted due their poor machinability and high procuring and processing cost. γTiAl during machining often have adverse impact on tool life and surface quality. At room temperature the material exhibits high brittleness and hardness, which along with a low ductility, lower thermal conductivity and fracture toughness, high temperature dependent strength and chemical reactivity with many tool materials. This often makes its machining a challenging task and the material is often considered under the category of difficult to machine material. Majority of the present TiAl components used in aerospace industry undergoes grinding operation. A wider investigation is necessary to understand the grindability of this material, as the variation of composition of the grinding wheel have significant influence on the machining. A consistent and economical machining is essential for the wide recognition of this promising material for wider industrial application. The paper investigates the grindability of intermetallic γTiAl using various abrasive wheels.
High-throughput dry drilling of titanium aluminide
(Taylor & Francis, 2016-07) Mathew, Nitin Tom
There is always an increasing interest in and demand for materials with superior properties, particularly in aerospace and automobile industries. Intermetallic titanium aluminides have been recognized as the possible material that could be used in high-performance applications. The understanding of the machinability during various machining processes is very much essential in order to widen the usage of these materials over various fields of application. Drilling, particularly with high aspect ratio, is a complex machining process that has to be explored. In the present work, machinability of titanium aluminide has been evaluated during high-throughput dry drilling, based on thrust, torque, surface integrity, and chip morphology.
Low-Cost Automation Mechanism for Rotor Press Machine
(Springer, 2022-10) Mathew, Nitin Tom
Pressing rotors on a high-pressure press are an important stage in the manufacturing of rotors for ceiling fans and other appliances. This pressing is done mainly to eliminate bending or distortion defects formed on its surface due to the aluminum die casting process taken place before. Due to this distortion or bending defects, rotors get rejected during their assembly. The available facility at the organization for this purpose was not very efficient and was causing a lot of production as well as financial loss to the organization. For this purpose, it was proposed to conceptualize, design, and develop a low-cost automation mechanism, which would eliminate this problem. The main task in hand was to make sure the entire diameter of the rotors gets pressed properly in one single stroke of the press machine. For this purpose, design changes in the layout of the machine were done. By using this project, the organization was able to improve its production efficiency, and human intervention in manufacturing activities was reduced to a minimum.
Modelling of temperature distribution in the work material during drilling under sustainable environment
(Elsevier, 2018-12) Mathew, Nitin Tom
The knowledge of temperature distribution on the work material is essential to incorporate various sustainable techniques like dry and near dry machining. A new approach of the thermal model during dry drilling process has been established to predict the magnitude and distribution of machining-induced work material temperature. Here the classical heat source method was adopted. In the present work the contact point between the cutting edge of the drill tool and the work material is represented as a line heat source inclined at an angle, moving with a velocity. The temperature rise due to chip clogging, built-up edge formation and friction is neglected in the present model. The plots from the investigation revealed that the temperature increased with higher values of Peclet number which is a representation of the relative velocity of the heat source and the thermal properties of the conduction medium. Also, it is observed that the angle of inclination of heat source has little influence on the temperature rise at lower velocity. The model provides a cohesive basis to deal with the temperature rise in the workpiece during the dry drilling process. By using the model temperature distribution at any point on the work material can be obtained. To validate the analytical results experiments were carried keeping the cutting speed constant and varying the feed rate to measure the work material temperature rise using an infra red camera. The measured temperature during the experiment was found to be higher than the predicted temperature since some of the relevant factors like built-up edge formation, chip clogging and increase in friction were not considered in the model. Also further investigation is necessary to find the influence of point angle on the developed model.
Multi-objective optimisation in the microturning of cobalt chromium with coated and uncoated tools using the grey relational analysis
(Inder Science, 2015-06) Mathew, Nitin Tom
In this work, the microturning of cobalt chromium has been carried out using coated and uncoated tungsten carbide inserts. The experiments were conducted as per the design of experiments (DoEs) approach using the L9 orthogonal array by varying the spindle speed (S), feed (F) and depth of cut (Dcut) at three levels. The output parameters considered are the material removal rate (MRR), surface roughness (Ra) and tool wear (TW). The significant parameters and their levels were identified using analysis of variance (ANOVA) and response graphs. It is observed that the significant microturning process parameters are found to be different for different tool/workpiece combinations, for achieving a higher MRR, lower Ra and low TW individually. Therefore, a multi-objective optimisation using the grey relational analysis was performed considering MRR, Ra and TW together and the optimum level of input parameters were identified to achieve high MRR, low Ra and low TW together.
Multi-Objective Optimization of Microturning Process Parameters Using Particle Swarm Technique
(ASME, 2013-11) Mathew, Nitin Tom
In this work, for the first time an attempt has been made to carry out multi-objective optimization for tool based microturning process parameters using particle swarm optimization (PSO) technique. The input microturning process parameters considered are speed, feed and depth of cut. The output parameters considered are material removal rate (MRR), surface roughness (Ra) and tool wear (TW). The significant parameters are identified individually using ANOVA and main effect plots. However, it is observed that the main goal of the manufacturers is to produce high quality products in shorter interval of time. In order to meet the above objective, multi-objective optimization is carried out to achieve simultaneously higher MRR, low Ra and low TW using PSO. From the PSO analysis, it is observed that the combination of microturning parameters such as speed (18.25 m/min), feed (9.31 μm/rev) and depth of cut (14.61 μm) results in high MRR, low Ra and low tool wear. The PSO analysis indicates that it is a promising optimization algorithm due to its simplicity, low computational cost and good performance. A confirmation test was carried out to validate the predicted results.
A novel approach to measure kerf-width in wire-electric discharge machining
(Inder Science, 2022-10) Mathew, Nitin Tom
Wire-electric discharge machining is best suitable for manufacturing components from materials having poor machinability. Numerous studies have been carried out on the process optimisation of wire electric discharge machining for achieving better surface finish and higher material removal rates. These parameters depend on kerf loss, which is usually quantified in terms of the average kerf-width. However, arbitrary selection of discreet points to measure kerf loss often makes this method ineffective to reveal the details of actual kerf loss. An area-based measurement procedure, which considers all irregularities on the kerf wall, is proposed in this study as a solution to estimate the kerf loss. On analysing the possibility of reducing kerf loss during the machining of duplex stainless steel, it was observed that a pulse on time, current and voltage combination of 12 µs, 1 A and 80 V is suitable for achieving high dimensional accuracy.
The potential of microfluidic devices in dermatology
(Wiley, 2021-10) Mathew, Nitin Tom
The potential of microfluidic devices in dermatology. - Abstract - Europe PMC Sign in | Create an account https://orcid.org Europe PMC Menu About Tools Developers Help Contact us Helpdesk Feedback Twitter Blog Tech blog Developer Forum Europe PMC plus Search life-sciences literature (42,135,236 articles, preprints and more) Search Advanced search Feedback This website requires cookies, and the limited processing of your personal data in order to function. By using the site you are agreeing to this as outlined in our privacy notice and cookie policy. Abstract Full text The potential of microfluidic devices in dermatology. Mathew NT 1 , Mathachan SR 2 Author information Affiliations 1 author 1. Mechanical Engineering, Work Integrated Learning Programmes Division, BITS Pilani, Pilani, India. 1 author 2. Department of Dermatology, Venereology and Leprosy, Atal Bihari Vajpayee Institute of Medical Sciences
Sustainable milling of Ti-6Al-4 V super alloy using AlCrN and TiAlN coated tools
(Elsevier, 2022) Mathew, Nitin Tom
Majority of the heat energy generated during the metal removal processes disperses with the help of cutting fluids, which possess numerous challenges to environment and mankind. Dry machining with the help of coated tools is a sustainable alternative to eliminate the cutting fluids. The present work investigates the influence of AlCrN and TiAlN coating during the end milling of high-performance Ti-6Al-4 V super alloy. Experiments were also performed at high-speed condition where coated tools were employed in dry condition and uncoated tools in the presence of cutting fluid. For both the conditions, force, tool wear, surface roughness and surface morphology were investigated. The resultant force generated by the AlCrN and TiAlN coated tool under dry condition is comparable to that of uncoated tool under wet condition. It is observed that the chipping of cutting is the major mode of failure of cutting tool. This was evident while machining with uncoated tool under low-speed condition. AlCrN coated tool gave better surface finish when compared to TiAlN coated tool. At various operating conditions, various defects such as redeposition of material, side flow, presence of black spot were observed.
Sustainable Techniques for Machining Difficult to Cut Materials
(NOVA, 2020-09) Mathew, Nitin Tom
For many years machining is playing a vital role in the global economy. It is a proven fact that a tremendous amount of heat energy developed during machining. The majority of the heat energy generated during the machining disperses with the help of cutting fluids, which poses numerous challenges to the environment and humanity. Presently, the primary focus of the manufacturing industries is cost reduction without compromising product quality, along with the implementation of sustainability. With the advancement of new difficult to machine materials like superalloys, titanium aluminides, and other hardened ferrous metals in the manufacturing industries, there was a need to identify alternative cooling and lubrication techniques to machine them sustainably. These materials have numerous applications in industries such as aerospace, automobile, and power production due to their excellent physical properties. The heat energy developed during the machining of these materials is higher compared to other materials and requires an effective cooling system to remove the generated heat. The use of cutting fluids for machining has numerous benefits, but they often pose a hazard to man, machine, and material. To curb these issues and other critical issues such as a rise in consumption of natural resources, concerns due to increasing population, limited natural resources, globalization, etc. there is a necessity to switch on to sustainable manufacturing. In almost all the fields of engineering, the concern about the environment is gaining importance. Researchers have developed various techniques to compact the increased use of cutting fluids. The foremost sustainable methods for cleaner production can be categorized majorly into cutting tool processing and cooling and lubrication strategies. The combination of both techniques can bring more advantages to machine these materials sustainably. The chapter discusses various sustainable techniques to machine difficult to machine materials along with the combination of these techniques, which can be most efficient in machining these materials.
Temperature rise in workpiece and cutting tool during drilling of titanium aluminide under sustainable environment
(Taylor & Francis, 2018-05) Mathew, Nitin Tom
This work is focused on the rise in temperature of the workpiece and tool during the drilling of intermetallic titanium aluminide under minimum quantity lubrication (MQL) environment. While drilling under MQL condition there was a significant decrease in work surface and drill tool temperature due to the better cooling and lubrication ability of the fluid mist. From the microscopic investigation of machined surface, many surface defects like material pile up, side flow, chip adhesion, etc. were found. The intensity of damage during dry drilling was high when compared to MQL. From the analysis of drill tool, the presence of built-up edge was observed in both high and low aspect ratio drilling due to the high temperature produced during the process which makes the work material vicious. During MQL condition, the excess heat produced at the machining zone is carried away by the cutting fluid supplied as mist thereby controlling the built-up edge formation. The roughness of the flute region of drill tool during MQL was comparable with drill tool under the wet condition. Also, the temperature rise during MQL drilling was substantially low when compared to dry machining.
Tool condition monitoring in mechanical micromachining
(CRC Press, 2023) Mathew, Nitin Tom
Tool condition monitoring using sensors has become an integral part of machine tools to enhance product quality and productivity. The breakage of the tool causes poor surface quality and dimensional accuracy for machined parts, or possible damage to a workpiece or machine. Tool condition monitoring is considerably vital in the manufacturing industry. In this chapter, tool condition monitoring during mechanical micromachining is discussed. In mechanical micromachining the size of the tool significantly scales down and it becomes difficult to monitor the micro tool. During the micromachining process, there can be breakage of tool or tool wear which are challenging to detect with conventional methods due to the micro tool size. The micro tool is subjected to comparatively high cutting force and vibration during the micromachining process as the tool wear increases. To retain precision as well as quality in the components, it is necessary to monitor the condition of the micro tool. Tool condition monitoring supports this situation with the help of various sensors