M.S. Shunmugam | IIT Madras (original) (raw)

Papers by M.S. Shunmugam

Research paper thumbnail of Study of Profile Changes in Magneto-Rheological Abrasive Honing by an Ingenious Relocation Technique

Magneto-rheological abrasive finishing is a non-traditional method of improving the surface finis... more Magneto-rheological abrasive finishing is a non-traditional method of improving the surface finish of manufactured components. Performance of different variants of this finishing process in terms of surface roughness parameters and material removal with process variables have been reported in the literature. In this paper, an ingenious relocation profilometry is employed to study the changes in the surface during the process by tracing the same profile again and again. Analysis of the relocated profiles brings out the gradual changes in the profile and also the metal removal during the process unambiguously. The results of analysis are reported and discussed.

Research paper thumbnail of Finishing performance of die-sinking EDM with ultrasonic vibration and powder addition through pulse train studies

Machining Science and Technology, 2019

Die-sinking electrical discharge machining (EDM) is widely used in die and mold-making industry. ... more Die-sinking electrical discharge machining (EDM) is widely used in die and mold-making industry. Finish EDM conditions are often selected to produce good quality surfaces. Attempts to enhance the finishing capabilities using ultrasonic vibration and powder-added dielectric medium have been reported in the literature. However, the changes in the gap phenomena with ultrasonic assistance and powder addition have not been analyzed. In this article, finish EDM of hardened D3 steel has been carried out based on full factorial design of experiment with three levels of setting voltage, setting current and pulse on time. The performance of ultrasonic assisted and graphite powder-added EDM are evaluated by analyzing the voltage and current pulse trains in finishing operation for the first time. Based on two new parameters, namely energy expended over a second (E) and ratio of energy due to sparks in relation to total discharge energy (PF), the results are discussed and also compared with those obtained with conventional EDM for selected conditions. Even though E of 102.9 J (PF ¼ 0.862) with ultrasonic vibration is higher than E of 43.0 J (PF ¼ 1.0) with powder mix, the molten metal is removed effectively from the gap by ultrasonic vibration which results in a relatively better surface. The micrographs of cross-section and surface of the workpieces obtained using optical and scanning electron microscopes, respectively, also reveal their relative performance.

Research paper thumbnail of Achieving excellent microformability in aluminum by engineering a unique ultrafine-grained microstructure

Scientific Reports, 2019

During microforming of conventional materials, specimen and microstructural length-scales are clo... more During microforming of conventional materials, specimen and microstructural length-scales are close to each other. This leads to an abnormal deformation behavior of the material and reduces microformability. Engineering ultrafine-grained (UFG) microstructure in the material is a possible solution. However, micro-scale deformation behavior of UFG material is not fully understood. Present work attempts to comprehensively investigate the micro-scale deformation of four distinctly engineered microstructures: UFG with residual dislocations and elongated grains, UFG free of residual dislocation with equiaxed grains, bimodal-grained and coarse-grained. The deformation behavior is captured via micro-scale uniaxial tensile test and micro-deep drawing operation. Micro-cups generated from UFG material with equiaxed grains show excellent surface quality, form-accuracy and minimal process scatter. Postmortem microscopy of the formed micro-cups attributes this improved microformability to the act...

Research paper thumbnail of Investigations into process mechanics of rough and finish die sinking EDM using pulse train analysis

The International Journal of Advanced Manufacturing Technology, 2018

Electrical discharge machining (EDM) is extensively used for machining difficult-to-machine mater... more Electrical discharge machining (EDM) is extensively used for machining difficult-to-machine materials and complicated shapes. Its performance in terms of material removal rate and surface roughness is usually analyzed using the process parameters such as setting voltage, setting current, pulse on time, and duty factor. It is well known that interelectrode gap condition controls the EDM performance, and it is difficult to observe the gap phenomena directly. Literature reveals that the combined influence of pulse types and their individual contributions on material removal rate and surface roughness has been ignored. In the present work, rough and finish EDM conditions are identified from a large set of 125 experiments carried out on hardened D3 die steel. From the voltage and current pulse trains in each regime, pulse characteristics and five different pulse types are assessed by a unique thresholding approach. Based on the pulse details, two new parameters such as energy expended (E) at the electrode gap over a second and a performance factor (PF) giving ratio of energy associated with the sparks to total energy expended have been proposed. It is found that a higher PF of 0.757 at a relatively lower expended energy of 113.7 J leads to a favorable condition in rough machining. A relatively lower E of 29.7 J and a higher PF of 1.00 are favorable for finish machining. Cross-sectional images of the ED machined workpieces are also included as evidences. The proposed thresholding methodology has a potential for online monitoring, analysis, and control of EDM process.

Research paper thumbnail of Three-Dimensional Geometric Analysis of the Plunge Centreless Grinding Process

Proceedings of the Institution of Mechanical Engineers, Part C: Journal of Mechanical Engineering Science, 1987

The grinding action and the rounding mechanism are highly complex in centreless grinding. The axi... more The grinding action and the rounding mechanism are highly complex in centreless grinding. The axis of the workpiece not only moves laterally but also tilts during the grinding process. Rowe and Barash have developed a two-dimensional model for an infeed centreless grinding neglecting the tilt of the workpiece. In this paper, an attempt has been made to develop a simulation model which incorporates the tilt of the workpiece. The theoretical and experimental investigations have been carried out with workpieces having specific geometries and the results are discussed.

Research paper thumbnail of CAD based simulation of ball end mill manufacturing

Computer-Aided Design and Applications, 2016

The photogrammetry procedure is introduced as a cheap and-effective alternative to 3D scanning fo... more The photogrammetry procedure is introduced as a cheap and-effective alternative to 3D scanning for constructing 3D point cloud data for reverse engineering applications. The data is then manipulated to generate CAD-ready models for FEA simulations or 3D printing purposes. A practical demonstration using model cars is conducted to show the effectiveness of the procedure in generating point cloud data, and various improvements are introduced. In particular, and innovative to this research work, a feature segmentation algorithm based on color information captured from photographs is implemented. This program, embedded within the photogrammetry process, allows for automatic selection of parts and features from an assembly model, providing a leading advantage over current 3D scanners, which capture spatial data only. Moreover, an intuitive method of enhancing the selection of required features of a triangular mesh during the segmentation process is introduced. This is achieved by manually marking the boundaries on the part of the object to be selected prior to taking photos. This has been proved to be more effective where areas of the object parts have similar colors.

Research paper thumbnail of Analytical Modeling of Micro End-Milling Forces with Edge Radius and Material Strengthening Effects

Machining Science and Technology, 2012

The study aims at developing a predictive analytical force model for the micro end-milling operat... more The study aims at developing a predictive analytical force model for the micro end-milling operation taking into account the material strengthening as well as the edge radius effects that come into play at the micro level. The mechanistic models for macro end-milling process have been extensively reported in literature and such models predominantly use milling force coefficients which are empirically

Research paper thumbnail of Mechanistic approach for prediction of forces in micro-drilling of plain and glass-reinforced epoxy sheets

The International Journal of Advanced Manufacturing Technology, 2014

Aerospace and automobile industries extensively use components made of plastics and fiber-reinfor... more Aerospace and automobile industries extensively use components made of plastics and fiber-reinforced plastics which require micro-machining operations including microdrilling to be carried out. Various attempts are reported in the literature to study different strategies and model the forces in micro-drilling with a view to produce micro-holes having large aspect ratio and to reduce drill breakage. The force models are more statistical than mechanistic in approach. In the present work, an attempt is made to develop mechanistic models of thrust and torque in micro-drilling of plain epoxy sheets. Material model capturing strain rate and temperaturedependent yield strength of epoxy material and basic principles of machining are employed for this purpose. The mechanistic model for prediction of thrust and torque is validated using well-planned full factorial design of experiments. Experiments are carried out using a carbide drill of 0.5-mm diameter with three levels for speed and feed on a highspeed miniature machine tool specially developed at the laboratory. The material model is extended to glass-reinforced plastics (GRP), and drilling forces are predicted using the proposed mechanistic model. In both cases of plain and GRP sheets, the model predictions are close to the experimentally measured drilling forces.

Research paper thumbnail of Feature Recognition and Datum Extraction for Setup Planning and Operation Sequencing for Prismatic Parts

International Journal of Manufacturing, Materials, and Mechanical Engineering, 2011

An automated planning system extracts data from design models and processes it efficiently for tr... more An automated planning system extracts data from design models and processes it efficiently for transfer to manufacturing activity. Researchers have used face adjacency graphs and volume decomposition approaches which make the feature recognition complex and give rise to multiple interpretations. The present work recognizes the features in prismatic parts considering Attributed Adjacency Matrix (AAM) for the faces of delta volume that lie on rawstock faces. Conceptually, intermediate shape of the workpiece is treated as rawstock for the next stage and tool approach direction is used to recognize minimum, yet practically feasible, set of feature interpretations. Edge-features like fillets/undercuts and rounded/chamfer edges are also recognized using a new concept of Attributed Connectivity Matrix (ACM). In the first module, STEP AP-203 format of a model is taken as the geometric data input. Datum information is extracted from Geometric Dimension and Tolerance (GD&T) data. The second m...

Research paper thumbnail of Improvement of wear resistance by EDM with tungsten carbide P/M electrode

Wear, 1994

Electrodischarge machining with pulsing relaxation generator using a powder compact electrode and... more Electrodischarge machining with pulsing relaxation generator using a powder compact electrode and reverse polarity setting modifies the surface properties of a machined surface greatly. Using a hard and wear-resistant material in the compact, the wear resistance of the resultant surface can be improved. In the present investigation, tungsten carbide powder is used in the compact. The wear resistance is evaluated by cutting tests and the results show considerable improvement over the uncoated surfaces.

Research paper thumbnail of Comparison of motif combination with mean line and envelope systems used for surface profile analysis

Wear, 1987

Abstract The height and spacing characteristics of the surface profile influence the functional b... more Abstract The height and spacing characteristics of the surface profile influence the functional behaviour of the manufactured part. A new method known as motif combination has been recommended in French standards to obtain the height and spacing characteristics of the surface profiles. An attempt has been made in this paper to compare motif combination techniques with the mean line and envelope systems, taking practical profiles.

Research paper thumbnail of Wear studies in Boring Trepanning Association drilling

Wear, 1988

Abstract Boring Trepanning Association (BTA) drills are capable of machining holes having a large... more Abstract Boring Trepanning Association (BTA) drills are capable of machining holes having a large length-to-diameter ratio in a single pass. This is a unique self-piloted operation in which cutting and burnishing are both carried out at the same time. Wear studies on BTA drills reveal quite useful information regarding their life and performance. This paper deals with wear studies on 20 mm diameter BTA drills (solid boring) of the Heller design using En9 steel work samples. The studies include examination of the flank and crater wear on the cutting edge, circular land wear and the supporting pad wear. The variation in wear with respect to cutting time for different speeds and feeds is reported.

Research paper thumbnail of Tribological behaviour of an electrodischarge machined surface with a powder metallurgy bronze electrode

Tribology International, 1993

Metal transfer from the tool electrode to the machined surface is appreciable in electrodischarge... more Metal transfer from the tool electrode to the machined surface is appreciable in electrodischarge machining when a powder compact tool electrode is used under reverse polarity conditions. A powder metallurgy bronze electrode was employed in the present work and investigation of the frictional behaviour of the resultant surface showed considerable reduction in the friction coefficient. Reduction in wear was also confirmed by a new method using cutting tests, establishing that the surfaces can be used in applications involving extreme pressure and velocity.

Research paper thumbnail of Optimal sub-division of the depth of cut to achieve minimum production cost in multi-pass turning using a genetic algorithm

Journal of Materials Processing Technology, 1998

The selection of the depth of cut during optimisation in multi-pass turning is an important activ... more The selection of the depth of cut during optimisation in multi-pass turning is an important activity, along with the selection of the speed and feed. A new approach for the optimal sub-division of the depth of cut is presented using a genetic algorithm. The total production-cost minimisation is achieved by adding the minimum costs of the individual rough passes and

Research paper thumbnail of Optimal selection of parameters in multi-tool drilling

Journal of Materials Processing Technology, 2000

In hole-making operation, the final size may be obtained by drilling with a single drill or pilot... more In hole-making operation, the final size may be obtained by drilling with a single drill or pilot-drilling of one or more holes followed by enlargement to the final size. In this paper, a model based on production cost is presented and the optimal conditions are obtained considering technological and machine tool constraints. This approach is quite useful in arriving at the cutting parameters automatically in a computer-assisted process planning system.

Research paper thumbnail of Evaluation of circularity and sphericity from coordinate measurement data

Journal of Materials Processing Technology, 2003

The coordinate measuring machines (CMMs) have proven to be reliable, flexible and very much suita... more The coordinate measuring machines (CMMs) have proven to be reliable, flexible and very much suitable for determining the acceptability of manufactured parts. In this paper, techniques for evaluating circularity and sphericity error from CMM data are presented. The form error can be evaluated directly from CMM data by employing circle/sphere as assessment features and using normal deviations. The CMM data can also be transformed by applying appropriate methods that not only suppress the size but also introduce distortion. The form error is evaluated from the transformed data by employing limacon/limacoid as assessment features and using linear deviations. The methods for handling CMM and transformed data are given in this paper. The proposed methods are validated using the data available in literature.

Research paper thumbnail of Data mining applied to wire-EDM process

Journal of Materials Processing Technology, 2003

Wire-EDM is a highly complex process, which is characterized by non-linear behavior. Due to a lar... more Wire-EDM is a highly complex process, which is characterized by non-linear behavior. Due to a large number of input parameters, a data mining approach based on machine learning is followed in this paper to model this process. The model was trained on experimental data collected from carefully conducted experiments. The model was also tested on additional data. It is found that the model built using data mining provides results with desired accuracy. The important parameters have been identified and reported.

Research paper thumbnail of Simulation of whirling process and tool profiling for machining of worms

Journal of Materials Processing Technology, 2007

In comparison with machining of worm on a lathe or on a milling machine, whirling process uses a ... more In comparison with machining of worm on a lathe or on a milling machine, whirling process uses a rotating tool ring carrying tools and encompassing the work blank. Due to nature of contact between tool and work blank, simulation of whirling process is necessary to understand the geometry of worm surface generated. In this paper, an attempt is made to simulate the whirling process and analyze the effect of tilting of tool head. In some applications worm geometry is specified and tool geometry has to be arrived at. An approach for profiling of tool is explained in this paper and validation of tool profile is carried out by simulation. Two worms, namely straight-sided in axial section and involute helicoid are taken as case studies and results are discussed.

Research paper thumbnail of Multi-objective optimization of wire-electro discharge machining process by Non-Dominated Sorting Genetic Algorithm

Journal of Materials Processing Technology, 2005

Wire electro discharge machining (WEDM) is a versatile non-traditional machining process that is ... more Wire electro discharge machining (WEDM) is a versatile non-traditional machining process that is extensively in use to machine the components having intricate profiles and shapes. In WEDM, it is very important to select the optimal process parameters so as to enhance the machine performance. This paper emphasizes the selection of optimal parametric combination of WEDM process while machining on EN31 steel, using grey-fuzzy logic technique. Process parameters such as servo voltage, wire tension, pulse-on-time and pulse-off-time were considered while taking into account several multi-responses such as material removal rate (MRR) and surface roughness (SR). It was found that pulse-on-time of 115 µs, pulse-off-time of 35 µs, servo voltage of 40 V and wire tension of 5 kgf results in a larger value of grey fuzzy reasoning grade (GFRG) which tends to maximize MRR and improve SR. Finally, analysis of variance (ANOVA) is applied to check the influence of each process parameters in the estimation of GFRG.

Research paper thumbnail of Signature of Machine Tool Errors on Surface Texture by DDS

Journal of Engineering for Industry, 1992

The dynamic effect of machine tool errors leaves its signature on machined surfaces. This paper p... more The dynamic effect of machine tool errors leaves its signature on machined surfaces. This paper proposes an application of data dependent systems (DDS) methodology to recover this signature from the surfaces in a comprehensive manner and provides a realistic basis for machine-tool acceptance. The approach is illustrated by experimental results from three different lathes. It is shown that relative contributions due to the feed wavelength reveal the dynamic performance of the machine tools. The deviation from the nominal and the spread of the estimated feed wavelength quantify the accuracy and rigidity, the feed wavelength being precisely maintained with minimal spread in a machine tool with high accuracy and high rigidity. Presence of other wavelengths and their relative contribution to the RMS surface roughness serve as quantitative indicators of other machine tool errors.

Research paper thumbnail of Study of Profile Changes in Magneto-Rheological Abrasive Honing by an Ingenious Relocation Technique

Magneto-rheological abrasive finishing is a non-traditional method of improving the surface finis... more Magneto-rheological abrasive finishing is a non-traditional method of improving the surface finish of manufactured components. Performance of different variants of this finishing process in terms of surface roughness parameters and material removal with process variables have been reported in the literature. In this paper, an ingenious relocation profilometry is employed to study the changes in the surface during the process by tracing the same profile again and again. Analysis of the relocated profiles brings out the gradual changes in the profile and also the metal removal during the process unambiguously. The results of analysis are reported and discussed.

Research paper thumbnail of Finishing performance of die-sinking EDM with ultrasonic vibration and powder addition through pulse train studies

Machining Science and Technology, 2019

Die-sinking electrical discharge machining (EDM) is widely used in die and mold-making industry. ... more Die-sinking electrical discharge machining (EDM) is widely used in die and mold-making industry. Finish EDM conditions are often selected to produce good quality surfaces. Attempts to enhance the finishing capabilities using ultrasonic vibration and powder-added dielectric medium have been reported in the literature. However, the changes in the gap phenomena with ultrasonic assistance and powder addition have not been analyzed. In this article, finish EDM of hardened D3 steel has been carried out based on full factorial design of experiment with three levels of setting voltage, setting current and pulse on time. The performance of ultrasonic assisted and graphite powder-added EDM are evaluated by analyzing the voltage and current pulse trains in finishing operation for the first time. Based on two new parameters, namely energy expended over a second (E) and ratio of energy due to sparks in relation to total discharge energy (PF), the results are discussed and also compared with those obtained with conventional EDM for selected conditions. Even though E of 102.9 J (PF ¼ 0.862) with ultrasonic vibration is higher than E of 43.0 J (PF ¼ 1.0) with powder mix, the molten metal is removed effectively from the gap by ultrasonic vibration which results in a relatively better surface. The micrographs of cross-section and surface of the workpieces obtained using optical and scanning electron microscopes, respectively, also reveal their relative performance.

Research paper thumbnail of Achieving excellent microformability in aluminum by engineering a unique ultrafine-grained microstructure

Scientific Reports, 2019

During microforming of conventional materials, specimen and microstructural length-scales are clo... more During microforming of conventional materials, specimen and microstructural length-scales are close to each other. This leads to an abnormal deformation behavior of the material and reduces microformability. Engineering ultrafine-grained (UFG) microstructure in the material is a possible solution. However, micro-scale deformation behavior of UFG material is not fully understood. Present work attempts to comprehensively investigate the micro-scale deformation of four distinctly engineered microstructures: UFG with residual dislocations and elongated grains, UFG free of residual dislocation with equiaxed grains, bimodal-grained and coarse-grained. The deformation behavior is captured via micro-scale uniaxial tensile test and micro-deep drawing operation. Micro-cups generated from UFG material with equiaxed grains show excellent surface quality, form-accuracy and minimal process scatter. Postmortem microscopy of the formed micro-cups attributes this improved microformability to the act...

Research paper thumbnail of Investigations into process mechanics of rough and finish die sinking EDM using pulse train analysis

The International Journal of Advanced Manufacturing Technology, 2018

Electrical discharge machining (EDM) is extensively used for machining difficult-to-machine mater... more Electrical discharge machining (EDM) is extensively used for machining difficult-to-machine materials and complicated shapes. Its performance in terms of material removal rate and surface roughness is usually analyzed using the process parameters such as setting voltage, setting current, pulse on time, and duty factor. It is well known that interelectrode gap condition controls the EDM performance, and it is difficult to observe the gap phenomena directly. Literature reveals that the combined influence of pulse types and their individual contributions on material removal rate and surface roughness has been ignored. In the present work, rough and finish EDM conditions are identified from a large set of 125 experiments carried out on hardened D3 die steel. From the voltage and current pulse trains in each regime, pulse characteristics and five different pulse types are assessed by a unique thresholding approach. Based on the pulse details, two new parameters such as energy expended (E) at the electrode gap over a second and a performance factor (PF) giving ratio of energy associated with the sparks to total energy expended have been proposed. It is found that a higher PF of 0.757 at a relatively lower expended energy of 113.7 J leads to a favorable condition in rough machining. A relatively lower E of 29.7 J and a higher PF of 1.00 are favorable for finish machining. Cross-sectional images of the ED machined workpieces are also included as evidences. The proposed thresholding methodology has a potential for online monitoring, analysis, and control of EDM process.

Research paper thumbnail of Three-Dimensional Geometric Analysis of the Plunge Centreless Grinding Process

Proceedings of the Institution of Mechanical Engineers, Part C: Journal of Mechanical Engineering Science, 1987

The grinding action and the rounding mechanism are highly complex in centreless grinding. The axi... more The grinding action and the rounding mechanism are highly complex in centreless grinding. The axis of the workpiece not only moves laterally but also tilts during the grinding process. Rowe and Barash have developed a two-dimensional model for an infeed centreless grinding neglecting the tilt of the workpiece. In this paper, an attempt has been made to develop a simulation model which incorporates the tilt of the workpiece. The theoretical and experimental investigations have been carried out with workpieces having specific geometries and the results are discussed.

Research paper thumbnail of CAD based simulation of ball end mill manufacturing

Computer-Aided Design and Applications, 2016

The photogrammetry procedure is introduced as a cheap and-effective alternative to 3D scanning fo... more The photogrammetry procedure is introduced as a cheap and-effective alternative to 3D scanning for constructing 3D point cloud data for reverse engineering applications. The data is then manipulated to generate CAD-ready models for FEA simulations or 3D printing purposes. A practical demonstration using model cars is conducted to show the effectiveness of the procedure in generating point cloud data, and various improvements are introduced. In particular, and innovative to this research work, a feature segmentation algorithm based on color information captured from photographs is implemented. This program, embedded within the photogrammetry process, allows for automatic selection of parts and features from an assembly model, providing a leading advantage over current 3D scanners, which capture spatial data only. Moreover, an intuitive method of enhancing the selection of required features of a triangular mesh during the segmentation process is introduced. This is achieved by manually marking the boundaries on the part of the object to be selected prior to taking photos. This has been proved to be more effective where areas of the object parts have similar colors.

Research paper thumbnail of Analytical Modeling of Micro End-Milling Forces with Edge Radius and Material Strengthening Effects

Machining Science and Technology, 2012

The study aims at developing a predictive analytical force model for the micro end-milling operat... more The study aims at developing a predictive analytical force model for the micro end-milling operation taking into account the material strengthening as well as the edge radius effects that come into play at the micro level. The mechanistic models for macro end-milling process have been extensively reported in literature and such models predominantly use milling force coefficients which are empirically

Research paper thumbnail of Mechanistic approach for prediction of forces in micro-drilling of plain and glass-reinforced epoxy sheets

The International Journal of Advanced Manufacturing Technology, 2014

Aerospace and automobile industries extensively use components made of plastics and fiber-reinfor... more Aerospace and automobile industries extensively use components made of plastics and fiber-reinforced plastics which require micro-machining operations including microdrilling to be carried out. Various attempts are reported in the literature to study different strategies and model the forces in micro-drilling with a view to produce micro-holes having large aspect ratio and to reduce drill breakage. The force models are more statistical than mechanistic in approach. In the present work, an attempt is made to develop mechanistic models of thrust and torque in micro-drilling of plain epoxy sheets. Material model capturing strain rate and temperaturedependent yield strength of epoxy material and basic principles of machining are employed for this purpose. The mechanistic model for prediction of thrust and torque is validated using well-planned full factorial design of experiments. Experiments are carried out using a carbide drill of 0.5-mm diameter with three levels for speed and feed on a highspeed miniature machine tool specially developed at the laboratory. The material model is extended to glass-reinforced plastics (GRP), and drilling forces are predicted using the proposed mechanistic model. In both cases of plain and GRP sheets, the model predictions are close to the experimentally measured drilling forces.

Research paper thumbnail of Feature Recognition and Datum Extraction for Setup Planning and Operation Sequencing for Prismatic Parts

International Journal of Manufacturing, Materials, and Mechanical Engineering, 2011

An automated planning system extracts data from design models and processes it efficiently for tr... more An automated planning system extracts data from design models and processes it efficiently for transfer to manufacturing activity. Researchers have used face adjacency graphs and volume decomposition approaches which make the feature recognition complex and give rise to multiple interpretations. The present work recognizes the features in prismatic parts considering Attributed Adjacency Matrix (AAM) for the faces of delta volume that lie on rawstock faces. Conceptually, intermediate shape of the workpiece is treated as rawstock for the next stage and tool approach direction is used to recognize minimum, yet practically feasible, set of feature interpretations. Edge-features like fillets/undercuts and rounded/chamfer edges are also recognized using a new concept of Attributed Connectivity Matrix (ACM). In the first module, STEP AP-203 format of a model is taken as the geometric data input. Datum information is extracted from Geometric Dimension and Tolerance (GD&T) data. The second m...

Research paper thumbnail of Improvement of wear resistance by EDM with tungsten carbide P/M electrode

Wear, 1994

Electrodischarge machining with pulsing relaxation generator using a powder compact electrode and... more Electrodischarge machining with pulsing relaxation generator using a powder compact electrode and reverse polarity setting modifies the surface properties of a machined surface greatly. Using a hard and wear-resistant material in the compact, the wear resistance of the resultant surface can be improved. In the present investigation, tungsten carbide powder is used in the compact. The wear resistance is evaluated by cutting tests and the results show considerable improvement over the uncoated surfaces.

Research paper thumbnail of Comparison of motif combination with mean line and envelope systems used for surface profile analysis

Wear, 1987

Abstract The height and spacing characteristics of the surface profile influence the functional b... more Abstract The height and spacing characteristics of the surface profile influence the functional behaviour of the manufactured part. A new method known as motif combination has been recommended in French standards to obtain the height and spacing characteristics of the surface profiles. An attempt has been made in this paper to compare motif combination techniques with the mean line and envelope systems, taking practical profiles.

Research paper thumbnail of Wear studies in Boring Trepanning Association drilling

Wear, 1988

Abstract Boring Trepanning Association (BTA) drills are capable of machining holes having a large... more Abstract Boring Trepanning Association (BTA) drills are capable of machining holes having a large length-to-diameter ratio in a single pass. This is a unique self-piloted operation in which cutting and burnishing are both carried out at the same time. Wear studies on BTA drills reveal quite useful information regarding their life and performance. This paper deals with wear studies on 20 mm diameter BTA drills (solid boring) of the Heller design using En9 steel work samples. The studies include examination of the flank and crater wear on the cutting edge, circular land wear and the supporting pad wear. The variation in wear with respect to cutting time for different speeds and feeds is reported.

Research paper thumbnail of Tribological behaviour of an electrodischarge machined surface with a powder metallurgy bronze electrode

Tribology International, 1993

Metal transfer from the tool electrode to the machined surface is appreciable in electrodischarge... more Metal transfer from the tool electrode to the machined surface is appreciable in electrodischarge machining when a powder compact tool electrode is used under reverse polarity conditions. A powder metallurgy bronze electrode was employed in the present work and investigation of the frictional behaviour of the resultant surface showed considerable reduction in the friction coefficient. Reduction in wear was also confirmed by a new method using cutting tests, establishing that the surfaces can be used in applications involving extreme pressure and velocity.

Research paper thumbnail of Optimal sub-division of the depth of cut to achieve minimum production cost in multi-pass turning using a genetic algorithm

Journal of Materials Processing Technology, 1998

The selection of the depth of cut during optimisation in multi-pass turning is an important activ... more The selection of the depth of cut during optimisation in multi-pass turning is an important activity, along with the selection of the speed and feed. A new approach for the optimal sub-division of the depth of cut is presented using a genetic algorithm. The total production-cost minimisation is achieved by adding the minimum costs of the individual rough passes and

Research paper thumbnail of Optimal selection of parameters in multi-tool drilling

Journal of Materials Processing Technology, 2000

In hole-making operation, the final size may be obtained by drilling with a single drill or pilot... more In hole-making operation, the final size may be obtained by drilling with a single drill or pilot-drilling of one or more holes followed by enlargement to the final size. In this paper, a model based on production cost is presented and the optimal conditions are obtained considering technological and machine tool constraints. This approach is quite useful in arriving at the cutting parameters automatically in a computer-assisted process planning system.

Research paper thumbnail of Evaluation of circularity and sphericity from coordinate measurement data

Journal of Materials Processing Technology, 2003

The coordinate measuring machines (CMMs) have proven to be reliable, flexible and very much suita... more The coordinate measuring machines (CMMs) have proven to be reliable, flexible and very much suitable for determining the acceptability of manufactured parts. In this paper, techniques for evaluating circularity and sphericity error from CMM data are presented. The form error can be evaluated directly from CMM data by employing circle/sphere as assessment features and using normal deviations. The CMM data can also be transformed by applying appropriate methods that not only suppress the size but also introduce distortion. The form error is evaluated from the transformed data by employing limacon/limacoid as assessment features and using linear deviations. The methods for handling CMM and transformed data are given in this paper. The proposed methods are validated using the data available in literature.

Research paper thumbnail of Data mining applied to wire-EDM process

Journal of Materials Processing Technology, 2003

Wire-EDM is a highly complex process, which is characterized by non-linear behavior. Due to a lar... more Wire-EDM is a highly complex process, which is characterized by non-linear behavior. Due to a large number of input parameters, a data mining approach based on machine learning is followed in this paper to model this process. The model was trained on experimental data collected from carefully conducted experiments. The model was also tested on additional data. It is found that the model built using data mining provides results with desired accuracy. The important parameters have been identified and reported.

Research paper thumbnail of Simulation of whirling process and tool profiling for machining of worms

Journal of Materials Processing Technology, 2007

In comparison with machining of worm on a lathe or on a milling machine, whirling process uses a ... more In comparison with machining of worm on a lathe or on a milling machine, whirling process uses a rotating tool ring carrying tools and encompassing the work blank. Due to nature of contact between tool and work blank, simulation of whirling process is necessary to understand the geometry of worm surface generated. In this paper, an attempt is made to simulate the whirling process and analyze the effect of tilting of tool head. In some applications worm geometry is specified and tool geometry has to be arrived at. An approach for profiling of tool is explained in this paper and validation of tool profile is carried out by simulation. Two worms, namely straight-sided in axial section and involute helicoid are taken as case studies and results are discussed.

Research paper thumbnail of Multi-objective optimization of wire-electro discharge machining process by Non-Dominated Sorting Genetic Algorithm

Journal of Materials Processing Technology, 2005

Wire electro discharge machining (WEDM) is a versatile non-traditional machining process that is ... more Wire electro discharge machining (WEDM) is a versatile non-traditional machining process that is extensively in use to machine the components having intricate profiles and shapes. In WEDM, it is very important to select the optimal process parameters so as to enhance the machine performance. This paper emphasizes the selection of optimal parametric combination of WEDM process while machining on EN31 steel, using grey-fuzzy logic technique. Process parameters such as servo voltage, wire tension, pulse-on-time and pulse-off-time were considered while taking into account several multi-responses such as material removal rate (MRR) and surface roughness (SR). It was found that pulse-on-time of 115 µs, pulse-off-time of 35 µs, servo voltage of 40 V and wire tension of 5 kgf results in a larger value of grey fuzzy reasoning grade (GFRG) which tends to maximize MRR and improve SR. Finally, analysis of variance (ANOVA) is applied to check the influence of each process parameters in the estimation of GFRG.

Research paper thumbnail of Signature of Machine Tool Errors on Surface Texture by DDS

Journal of Engineering for Industry, 1992

The dynamic effect of machine tool errors leaves its signature on machined surfaces. This paper p... more The dynamic effect of machine tool errors leaves its signature on machined surfaces. This paper proposes an application of data dependent systems (DDS) methodology to recover this signature from the surfaces in a comprehensive manner and provides a realistic basis for machine-tool acceptance. The approach is illustrated by experimental results from three different lathes. It is shown that relative contributions due to the feed wavelength reveal the dynamic performance of the machine tools. The deviation from the nominal and the spread of the estimated feed wavelength quantify the accuracy and rigidity, the feed wavelength being precisely maintained with minimal spread in a machine tool with high accuracy and high rigidity. Presence of other wavelengths and their relative contribution to the RMS surface roughness serve as quantitative indicators of other machine tool errors.