Browsing by Author "Bera, T.C."

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Comparative Study of Estimated Surface Roughness Using GA and PSO Techniques for Milling of Thin-Walled Structures
(Springer, 2022-04) Bera, T.C.
Thin-walled structures, due to their lightweight, have found significant applications in the aerospace industry. For the manufacturing of any component, its surface quality index is of prime importance. A very well-known measure of this surface quality is surface roughness. For a product of high quality, the surface roughness value is often desired to be minimum. However, the machining parameters for the production of such surfaces often rely on the engineer's experience and expertise, which always do not lead to the best possible results. In this study, a neural network was first created for surface roughness estimation, then evolutionary algorithms such as Genetic Algorithm and Particle Swarm Optimization were used to minimize the surface roughness value. During this process, the impact of milling parameters such as rake angle, nose radius, and approach angle on the surface roughness value was also studied with the aid of surface plots of surface roughness developed by taking two parameters at a time and holding the third parameter constant.
Developing Energy Efficient Milling Strategy for Variable Curved Geometry Using Constant Engagement Method
(Elsevier, 2023) Sangwan, Kuldip Singh; Bera, T.C.
The continuous fluctuation in force profile in milling of variable curved geometry creates a barrier in stable machining and in cutting power consumption. The fluctuation in force profile happens due to alteration in chip load in the presence of workpiece curvature. The present study aims to develop an energy efficient machining strategy for milling of variable curved geometries where more uniform cutting force and cutting power consumption profiles are accomplished due to constant chip load along the peripheral length of curved geometry. The proposed strategy involves mechanics of milling, instantaneous cutting force and cutting power consumption. It is formulated based on constant chip load by regulating entry angle of milling cutter according to workpiece curvature along the peripheral length. Thus, the cutting power fluctuation that is occurred due to variation of workpiece curvature is reduced by regulating tool-workpiece engagement. The energy consumption is reduced almost 18 % using the proposed approach. It results into developing an energy efficient machining strategy for milling of variable curved geometry. It also provides stable machining process and increased tool life by reducing tool wear due to reduction of force fluctuation during metal removal process.
The effect of ultrasonic vibrations on residual stresses and material properties of steel tubes during the cold tube drawing process
(Taylor & Francis, 2022-09) Bera, T.C.
In this study, the ultrasonically assisted plug vibrating tube drawing system was developed for an industrial draw bench and investigated using experimental and finite element (FE) modelling. The effect of ultrasonic vibrations on the induced residual stresses on the drawn steel tubes is evaluated using the mechanical and X-ray diffraction (×RD) method. The results indicate that the distribution of induced residual stresses mostly shows compressive stresses under ultrasonic vibrations. In contrast, the residual stresses are tensile in nature for conventionally drawn tubes, which are not very desirable. The experimental results show 11% reduction in draw load, while the FE analysis shows a 13% reduction in draw load, which indicates that the experimental and FE results are in good agreement. In addition, the effect of ultrasonic vibrations on the tensile strength, yield strength and percentage elongation is investigated and compared with samples from conventionally drawn tubes. The ultrasonic-assisted tube drawing has resulted in favourable tensile properties, which helps in improving the formability limit of the tubes. The Von Miss stress distribution obtained indicates that the ultrasonically assisted drawing results in a more uniform and lower Von Mises stress when compared to conventionally drawn tubes.
Energy consumption modelling in milling of variable curved geometry
(Springer, 2022-02) Sangwan, Kuldip Singh; Bera, T.C.
The accurate estimation of energy consumption is beneficial to manufacturing enterprises economically as well as to overcome global energy crisis. The present work concentrates on developing an energy consumption model in milling of variable curved geometries where magnitudes and directions of workpiece curvature vary along tool contact path of a component. The current work deals with estimation and analysis of energy consumption in peripheral milling of variable curved surfaces where cutting forces differ along tool contact path in the presence of workpiece curvature. The proposed hybrid model developed in MATLAB involves process mechanics, cutting forces and energy consumption and has modules for idle, auxiliary and cutting power. The proposed model is validated by the experimental work. The model is generic and versatile in nature and is useful for milling of straight, circular and curved surfaces. In addition to it, the influence of workpiece curvature on power consumption has been investigated to realize the variation of power consumption along the tool contact path. The developed model offers a basic platform to understand and characterize the energy consumption for general peripheral milling considering workpiece geometry. The comparison of predicted and measured results indicates that the model is capable to estimate the power consumption accurately. The proposed model will be used by the practitioners to find the optimum cutting conditions to reduce power consumption during the machining of curved geometries – a pragmatic condition but not much researched condition in machining.
Error compensation in flexible end milling of tubular geometries
(Elsevier, 2011-01) Bera, T.C.
There are many machining situations where slender tools are used to machine thin walled tubular workpieces. Such instances are more common in machining of aircraft structural parts. In these cases, cutting force induced tool as well as workpiece deflections are quite common which result into surface error on machined components. This paper presents a methodology to compensate such tool and workpiece induced surface errors in machining of thin walled geometries by modifying tool paths. The accuracy with which deflections can be predicted strongly depends on correctness of the cutting force model used. Traditionally employed mechanistic cutting force models overestimate tool and workpiece deflections in this case as the change of process geometry due to deflections is not accounted in modeling. Therefore, a cutting force model accounting for change in process geometry due to static deflections of tool and workpiece is adopted in this work. Such a force model is used in predicting tool and workpiece deflection induced surface errors on machined components and then compensating the same by modifying tool path. The paper also studies effectiveness of error compensation scheme for both synclastic and anti-clastic configurations of tubular geometries
An Investigation Of Surface Errors In Thin-Walled Machining
(i-Manager, 2012) Bera, T.C.
Prediction of surface errors in milling of thin-walled structures is not trivial due to cutting force induced deflections of workpiece. The situation becomes more complicated when the end mill adds cutter deflection errors to workpiece deflection. It is important to predict and analyze such variation of surface error from process planning and process control point of view. The study of surface error is also essential while overcoming the same by applying various compensation methods. This paper investigates cutter and workpiece deflection induced surface errors in peripheral milling of thin-walled straight and curved geometries. A flexible tool-workpiece system has been developed to estimate surface error in the presence of both tool and workpiece deflections. The effects of chip load and workpiece curvature on surface errors have also been investigated by using experimental and computational methodology. Based on the outcomes of the present study, it is concluded that the complex nature of tool and workpiece deflection induced surface error can be predicted both qualitatively and quantitatively in thin-walled machining. The results presented here provide useful insights into qualitative and quantitative nature of surface errors which will be helpful for product designers as well as process planners in improving machining productivity without sacrificing quality.
An Investigation on Reduction of Cutting Energy Consumption Using High Efficiency Machining Strategy
(Elsevier, 2022) Bera, T.C.; Sangwan, Kuldip Singh
A large number of machine tools are used on regular basis consuming a large amount of energy. Moreover, the machine tools have poor energy efficiencies and thus, they are ideal candidates for energy saving strategies. Improvement in energy efficiency of machining system will not only benefit the industries economically but also help the world in taking care of energy crisis and air pollution. Therefore, an attempt has been made in the present work to reduce the cutting power consumption using a high efficiency machining (HEM) strategy. The HEM strategy has been used primarily for roughing operation utilizing a lower radial depth of cut (RDOC) and a higher axial depth of cut (ADOC) for milling. During machining, the radial chip thinning occurs with varying RDOC that results into variation in uncut chip thickness and respective chip load. Based on process geometry of milling, a specific energy consumption (SEC) model has been analyzed for the milling. Next, the cutting power has been reduced using high efficiency milling approach. The proposed HEM strategy can reduce cutting time that results into less power consumption and increased productivity of milling by removing more material in unit time. Therefore, the present study is able to contribute significantly towards energy-efficient manufacturing and cleaner production.
A Method to Determine Cutting Force Coefficients in Turing Using Mechanistic Approach
(IJMMM, 2018) Bera, T.C.
During performing turning operation, cutting force plays a significant role in metal cutting process affecting tool-workpiece deflection, machine tool vibration and eventually part quality. The present research work aims to develop a mechanistic cutting force model that will be used in development of tool-workpiece flexible system of thin-wall machining. It also concentrates to study the mechanistic constants used in the force model in case of turning operation. The proposed model can be used for the reliable and accurate estimation of the cutting forces establishing relationship of various force components (cutting force and feed force) with uncut chip thickness. The accurate estimation of cutting force is required to improve thin-walled part accuracy by controlling the tool-workpiece deflection induced surface errors and tool-workpiece vibration.
Modelling of dimensional and geometric error prediction in turning of thin-walled components
(Elsevier, 2021-11) Bera, T.C.
In die-mold manufacturing and aircraft industry, many components that have thin-walled features are produced by turning operation. The major problem encountered during internal or external turning is cutting force induced deflection of workpiece along the periphery as well as axial length of a component. The present research work aims to develop a mathematical model for estimating dimensional and geometric errors during turning of thin-walled hollow cylinder qualitatively and quantitatively. In the proposed model, a mechanistic approach which is semi-analytical in nature is followed to achieve accuracy of the predicting results. First of all, process geometry model for thin-wall turning is developed based on process geometry variables such as uncut chip thickness, actual feed per revolution, actual depth of cut, peripheral cutting speed, effective cutting area etc. Using these process geometry variables and mechanistic cutting constants, a force model of turning is developed to estimate the tangential and radial force components. Later on, based on the predicted forces, tool-workpiece combined deflection model is developed to estimate radial, diametric and various geometric errors of the turned surface. The developed models are able to predict radial, diametric and various geometric errors such as straightness, circularly and cylindricity errors without conducting expensive actual machining operation. Hence, the present study will be helpful to take care of precautionary measures for controlling of dimensional and geometric errors more efficiently and reliably. Therefore, an attempt has been made to provide a basic platform to machining practitioners and process planners for in-depth comprehension and characterization of dimensional and geometric errors of the entire turned surface for varying machining conditions.
Modelling of Energy Consumption for Milling of Circular Geometry
(Elsevier, 2021) Sangwan, Kuldip Singh; Bera, T.C.
Machine tools are dominant end users of electrical energy in manufacturing, and responsible for high carbon emissions. There is hardly any research work on the energy modelling for curved surface milling. The present study aims to develop energy consumption model for milling of circular geometries as a part of process planning for machining operations to reduce cost, improve energy efficiency and general productivity. The circular geometry may have concave or convex shape which leads to change in magnitude of curvature. Therefore, the magnitude and distribution of cutting forces and concerned cutting powers are quite different in both these machining situations. This necessitates the need to investigate this aspect comprehensively. A process geometry model is developed based on process geometry variables of feed per tooth along cutter contact path, entry and exit angles of tooth, engagement angle, undeformed chip thickness, etc. Next, the process geometry variables in conjunction with mechanistic cutting constants are used to develop a force model for estimating the feed force and normal force components. Lastly, a power consumption model is developed based on the instantaneous force component and velocity of milling cutter to estimate both the instantaneous and average power consumed during the milling process. Machining experiments are performed to conform the validity of the proposed model by comparing the measured power to their predicted counterpart. The developed model can be used for estimating the power consumption for milling of circular geometries reliably and efficiently without conducting the costly experiments. In addition to this, the proposed model extends the existing model by considering the effect of workpiece curvature and aims at providing a useful aid for prediction of power consumption in peripheral milling of circular surfaces. Therefore, an attempt has been made to provide a basic platform for in-depth comprehension and characterization of energy consumption. The proposed model has many applications particularly in die-mold manufacturing and aircraft industry and it can be extended to curved geometries having variable curvatures
Modelling of spindle energy consumption in CNC milling
(Elsevier, 2022) Sangwan, Kuldip Singh; Bera, T.C.
In manufacturing industries, machine tools are frequently used and required a lot of energy to work. Spindle acceleration is a common process when machine tools are in use. It generates a high-energy intensive power peak. The total energy consumption of machine tools in the machining process is strongly affected by these high-power peaks of short duration. Many researchers have overlooked the energy consumption of spindle acceleration resulting into inaccuracies in the prediction of overall energy consumption of machine tools. Therefore, the present study aims to develop a model to predict the spindle acceleration energy consumption of computer numerical control (CNC) milling machines. The proposed model is based on the principle of spindle motor control and includes the computation of moment of inertia of the spindle drive system. To validate the effectiveness of the proposed model, machining experiments are carried out on a CNC milling machine. Without performing time-consuming experiments, the proposed models can be utilized to estimate the power, time, and energy consumption of spindle acceleration. The proposed model helps to determine total energy consumption during machining process correctly.
On milling of thin-walled tubular geometries
(Sage, 2010-05) Bera, T.C.
Machining of thin-walled tubular geometries poses interesting problems from a process planning perspective. In machining of such geometries by milling, cutting force-induced tool and workpiece deflections have to be overcome in order to realize part accuracies without compromising productivity. This calls for a systematic study of surface errors on machined parts due to both tool and workpiece deflections. The present paper investigates the effect of cutter and workpiece flexibilities on surface error during peripheral milling of thin-walled tubular geometries. Unlike previous attempts to study milling of thin-walled straight geometries, the present work focuses mainly on machining of tubular geometries. Tubular geometries need to be treated differently from a process planning perspective by exploiting the workpiece rigidity they offer. The process planner has an option of synclastic and anticlastic machining possibilities during machining of tubular geometries which needs to be explored and understood. More importantly, the complex and varying profile of surface error with cutting conditions has to be accounted for. From the outcomes of the present work it can be summarized that surface errors in machining of closed tubular geometries are due to multiple factors which include workpiece rigidity, tool overhang, curvature effects, thinning effects, and nature of tool and workpiece engagements. All of these parameters are affected by process parameters chosen during machining. The present study also demonstrates that the understanding of surface error profiles due to cutter and workpiece deflections not only helps in realizing dimensional accuracy, but geometric tolerances as well.
Parametric optimization of the generation of the porous layer for lubrication in tube drawing process
(Elsevier, 2020) Bera, T.C.
For severe metal deformation processes such as metal drawing operations, the use of porous lubricant carrier layer on metal surfaces has been proposed in recent literature for better lubricant retention and effectiveness under extreme conditions. The porous layer may be generated by different methods and the method chosen in this study involves electroplating a thin layer of an alloy of tin and zinc on the parent metal and subsequent selective etching of zinc. The aim of this study is to optimize parameters for specific application of the new technique in steel tube drawing operation using Taguchi's experimental design procedures. Experiments are designed based on three controllable factors namely electric current density, process time and Sn-Zn composition by weight in electrolyte at three levels. L9 orthogonal array is used for this study. The regression models have been constructed for drawing force and surface roughness along with verification of the model fit using (R2) values and analysis of variance (ANOVA). The optimal values for parameters have been identified using signal to noise (S/N) ratio. All the calculations are obtained by using Minitab software. The optimal levels for: current density (I) is 1 A/cm2; for plating time (T) is 12 min and; Sn:Zn composition is 1:6. This study may pave the way for industrial adoption of the new technique of using porous layer in tube drawing operations to bring out the associated benefits of doing away with the conventional lubrication systems that have proven environmental hazards.
Producing high quality cold-drawn steel tubes using an optimal thickness of tin as a tribo-layer
(Springer, 2022-07) Bera, T.C.
In this paper, the tin coating layer is utilized as a solid lubricant for the cold steel tube drawing process. The effect of different thicknesses of tin coatings as a tribo-layer has been investigated. The electroplating process has been used for depositing a tin coating layer by deploying an environmentally benign citric acid–based electrolyte bath and the layer thickness is controlled by varying the time of the electroplating process. Characterization of the coating layer is carried out using SEM, EDS, and 3D digital microscopy techniques. Experimental trials of the tube drawing process have been conducted for tin-coated tubes and the effects on drawing force and surface roughness have been analyzed. The draw force gradually decreases and reaches a minimum value as the tin layer thickness increases from 4.5 to 16.5 μm, while for further increase in layer thickness, the draw force increases again, yielding an optimal tin layer thickness of around 16.5 μm. The drawn tube samples are found to have a superior surface finish with roughness (Ra) as low as 0.165 μm even for the smallest tin coating thickness of around 5 μm while it improves marginally up to 0.134 μm when the tin layer thickness is increased gradually to around 25.7 μm. A sizeable thickness of tin coating is retained on the drawn tube, which enhances the surface appearance as well as corrosion resistance. The tape adhesion test was carried out as per the ASTM D3359 standard and it confirmed the adequacy of adhesion of the coating on the drawn tubes. Also, comparison of draw force variation with the well-known Stribeck curve and the insights into the working mechanism of soft metal as a lubricant are presented.
A Statistical study on effects of fundamental machining parameters on surface topography
(DP Publications, 2017-03) Bera, T.C.
Tin Layer as a Solid Lubricant for Cold Tube Drawing Processes
(Springer, 2021-02) Bera, T.C.
This paper reports an investigation into the deployment of a thin layer of tin as a lubricant on low carbon steel tube for tube drawing process. The layer was deposited using electro-deposition technique using a green technology of citric acid based electrolyte bath. Coating layer is characterized using SEM, EDS and 3D digital microscopy technique before and after drawing processes. Experimental trials of drawing operation were conducted and promising results were observed with respect to drawing load and surface quality. The observed drawing load is comparable to that with the conventional lubrication system thereby proving the effectiveness of the new proposed lubrication system. The use of proposed lubrication resulted in greatly improved finish as well as better corrosion resistance yielding an additional promise for better value in service life, better market potential as well as a gain on environment front as the proposed method has the potential to eliminate some after operations after drawing as the drawn tube is ready to use after drawing operation.
A turning simulation environment for geometric error estimation of thin-walled parts
(Springer, 2021-11) Bera, T.C.
Machining of thin-walled parts is a key process in many industries such as aviation and marine and power engineering. During such machining operation, very aggressive cutting conditions such as large feed rate, higher cutting speed, and large depth of cut are used to achieve higher material removal rate. During machining, thin-walled workpiece faces significant elastic deformation due to higher cutting forces leading to dimensional and geometric inaccuracy to the component. The present research work aims to develop a multi-step and multi-level turning simulation environment for estimation of various geometric errors such as straightness, circularity, and cylindricity of thin-walled part. In the proposed simulation environment, various modules such as process geometry, cutting force, tool deflection, and surface error generation have been developed in MATLAB©. On the other end, the modules such as part geometry, workpiece deflection, and material removal are made using finite element analysis technique in APDL environment of the ANSYS© commercial software. The estimated 3D turned surface and concerned geometric errors can be obtained as outcomes of the simulation environment without conducting expensive actual machining operation for varying cutting conditions. In order to estimate geometric errors accurately, the combined effect of tangential and radial force components are equally important to take care of geometrical shape change and peripheral thinning of thin-wall parts. The proposed simulation environment can be used as a convenient and cost-effective tool for process planners and machining practitioners for adopting a suitable error compensation strategy. Machining experiments are performed further to conform the validity of simulation environment by comparing the predicted results to their measured counterparts.