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Subrata Mondal ¹, Asish Bandyopadhyay ², Pradip Kumar Pal ²

Affiliations
1 Mechanical Engineering Department, Techno India- Salt Lake, Sector-V, Kolkata-700 091, IN
2 Mechanical Engineering Department, Jadavpur University, IN

Abstract

The drill-bit assisted abrasive flow machining (AFM) process is usually chosen for finishing operation in manufacturing industries where the fine surface finish of the component is an important criterion and considered as primary response in the present work. A number of experiments have been conducted according to Box-behnken design considering EN 24 as work piece material. Experiments were performed under different machining conditions by varying the parameters such as abrasive particle size, media viscosity, drill bit diameter and number of process cycle. The material removal rate (MRR) has been considered as secondary response of this process. In the present paper, a multi-objective optimization technique using Taguchi based Grey relational analysis has been applied to optimize the process performance of the drill-bit assisted AFM. How could a complicated multiple performance characteristics simplified to a single objective optimization problem has been presented here by this approach. The specific targets are minimum surface roughness and maximum material removal rate. According to importance of quality characteristics there are three criteria for optimization in grey relational analysis, which are „Larger-the-Better‟, „Smaller-the-Better‟ and „Nominal-the-Best‟. In the present analysis the lower value of surface roughness represents smooth surface i.e. better finishing performance, therefore „Lower-the-Better‟ criteria is chosen for surface roughness. On the other hand the higher value of MRR indicates more economical as compared to other finishing processes, therefore „Higher-the-Better‟ is chosen for MRR. In the present work smaller surface roughness and larger MRR are desirable. The optimal parametric setting obtained from grey relational analysis has been validated by a confirmation test.

Keywords

Optimization, Taguchi Method, AFM, GRA, Surface Finish.

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Md. Ismail ¹, Asish Bandyopadhyay ², Santanu Das ¹

Affiliations
1 Department of Mechanical Engineering, Kalyani Government Engineering College, Kalyani, West Bengal, IN
2 Department of Mechanical Engineering, Jadavpur University, Kolkata, IN

Abstract

Submerged arc welding process is usually employed for welding of thick workpieces. Quality of submerged arc welded components depends on various factors. Selection of appropriate process parameters for joining metallic components is needed to obtain sound weldment. Many researchers carried out investigations to find out appropriate process conditions to obtain quality submerged arc welded components with typical applications. In the present work, Taguchi's L9 orthogonal array is used to find out the parameter combinations of the experiments to perform. Weld current, weld speed and type of flux are varied to three levels to find out the appropriate condition to obtain desired bead-on-plate quality within the domain of experimental conditions chosen. It is found out that at a weld current of 400 A, welding speed of 450 mm/min and with flux with basicity index of 1.2, desired weld deposition can be obtained.

Keywords

Welding, Submerged ARC Welding, Orthogonal Array, Optimization, Process Parameter Selection, Bead-On-Plate Weld Deposition, Flux.

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Saurav Dutta ¹, M. Sundar ², Asish Bandyopadhyay ³, Pradip Ku. Pal ³, Gautam Nandi ³, Subhash Ch. Ray ³

Affiliations
1 Department of Mechanical Engineering, B.P. Poddar Institute of Management and Technology, 137, V.I.P. Road, Kolkata-700052, IN
2 School of Laser Science and Engineering, Jadavpur University, IN
3 Department of Mechanical Engineering, Jadavpur University, Kolkata-700032, IN

Abstract

Submerged arc welding (SAW) is one of the chief metal fabrication processes in industry. It works with high current density and can effect high metal deposition rate. The present work emphasizes on the study of influence of process parameters on quality and performance of submerged arc weldment, by incorporating multiple linear regression method. Based on 3³ factorial design without replication, experiments were conducted with three different levels of process parameters like voltage, welding current and electrode stick out to obtain butt joints from mild steel plates. Experimental data have been utilized to develop a mathematical model which reveals the linear relationship among various process control parameters and response variables in relation to submerged arc weldment. Graphical representations of the experimental data as well as the predicted data, obtained from the developed model, are supposed to contribute valuable information for quality control of submerged are welding process. This would help to obtain superior quality weld and also to achieve higher productivity.

Keywords

Submerged Arc Welding, Regression Analysis, Factorial Design.

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Rajib Kumar Mandal ¹, Asish Bandyopadhyay ², Santanu Das ¹

Affiliations
1 Department of Mechanical Engineering, Kalyani Government Engineering College, Kalyani-741235, West Bengal, IN
2 Department of Mechanical Engineering, Jadavpur University, Kolkata-700 032, IN

Abstract

Laser beam welding (LBW) uses high energy density beam making it suitable for welding of wide category of materials. As energy density around the focal point of laser beams is quite high, this technique is being increasingly used in the fabrication industry. Since laser beams follow the principle of optics, it can be easily regulated by selecting appropriate lenses. In this paper, a report on the experimental work involving laser beam welding (LBW) is presented where lap joints of two acryalic (polycarbonate) flats-one opaque and the other transparent, are tried to make. Laser beam passes through the transparent piece of plastic flat, and is focused on to the opaque flat around the interface region. Laser beam gets absorbed in the opaque flat in the interface region and generates heat energy causing local melting, and subsequent welding of both the flats. This method is named as through transmission laser welding. The bonding between the two components is likely to occur by interpenetration of molecular chains in the area that is promoted by fluidity of acrylic during welding. Process parameters such as clamping pressure and current are varied at some selected scanning speeds to explore the appropriate condition to obtain sound, strong weld joint within the experimental domain. The laser has a repetitive operating current less than 60 A with pulse frequency of 0.25-10 kHz. The used 30 W laser system is having spectral width of 1.69 nm, beam divergence of less than 0.20 N.A. and beam diameter of 800 urn with a wavelength of 809.40 μn. Scanning speed of 240,280,320 and 360 mm/min, current flow of 25,28,31 and 34 A, and clamping pressure of 20, 30,40 and 50 Kg/cm² are chosen in this work. Sound welded joint between transparent and opaque acryalic components with high weld strength above 8 MPa is obtained under scanning speeds of 280 and 360 mm/min and 20 Kg/cm² clamping pressure with weld current setting of 28, 31 and 34 A. Suitable heat input to the weld interface may have resulted in this observation. Therefore, these conditions may be recommended to apply to obtain large weld strength.

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Rajib Kumar Mandal ¹, Asish Bandyopadhyay ², Santanu Das ¹

Affiliations
1 Department of Mechanical Engineering, Kalyani Government Engineering College, Kalyani-741235, West Bengal, IN
2 Department of Mechanical Engineering, Jadavpur University, Kolkata-700 032, IN

Abstract

Laser beam welding (LBW) is nowadays increasingly used in the fabrication industry due to some of its distinct advantages. LBW offers high energy density around its focus thereby making it well suited for welding of certain category of materials that are considered difficult-to-weld. Since the laser follows the principles of optics, it is easy to regulate the laser beam by selecting appropriate lenses. In the present work, laser beam welding (LBW) is carried out to make lap joint of two acrylic flats- one opaque and the other transparent. Laser beam passes through the transparent piece of plastic flat and is focused on to the opaque flat around the interface region. Laser beam gets absorbed in the opaque flat in the interface region and generates heat energy causing local melting, and subsequent welding of both the flats. Clamping pressure is varied four times, and two levels of current flow and scanning speeds are set to find out a condition corresponding to sound, strong weld joint within the experimental domain. Good quality joint between transparent and opaque acrylic components with high weld strength of 8.33 MPa is obtained under 280 mm/min scanning speed and 2 MPa clamping pressure with 34 A weld current set, and hence, this condition may be recommended to apply to obtain enough weld strength.

Keywords

Laser, Welding, LBW, Laser Beam Welding, Acrylic, Plastic Welding.

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Bharat Chandra Routara ¹, Saumya Darsan Mohanty ², Saurav Datta ², Asish Bandyopadhyay ³, Siba Sankar Mahapatra ²

Affiliations
1 Dept. of Mechanical Engg., KIT University, Bhubaneswar, IN
2 Dept. of Mechanical Engg., National Institute of Technology (NIT), Rourkela, IN
3 Dept. of Mechanical Engg., Jadavpur University, Raja S. C. Mallik Road, Kolkata, IN

Abstract

The present study highlights a multi-objective optimization problem by applying weighted principal component analysis (WPCA) coupled with Taguchi method through a case study in cylindrical grinding of 6061-T4 Aluminum. The study aimed at evaluating the best process environment which could simultaneously satisfy multiple requirements of surface quality. In view of the fact, that traditional Taguchi method cannot solve a multi-objective optimization problem; to overcome this limitation, WPCA has been coupled with Taguchi method. Furthermore to follow the basic assumption of Taguchi method i.e. quality attributes should be uncorrelated or independent; which is not always satisfied in practical situation. To overcome this short coming the study applied Weighted Principal Component analysis (WPCA) to eliminate response correlation and to evaluate independent or uncorrelated quality indices called Principal Components which were aggregated to compute overall quality index denoted as multi-response performance index (MPI). A combined quality loss (CQL) was then estimated which was optimized (minimized) finally. The study combined WPCA and Taguchi method for predicting optimal setting. Optimal result was verified through confirmatory test. This indicates application feasibility of the aforesaid methodology proposed for multi-response optimization and off-line control of correlated multiple surface quality characteristics in cylindrical grinding.

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Spandan Guha ¹, Tapas Banerjee ², Asish Bandyopadhyay ³, Santanu Das ³

Affiliations
1 Department of Mechanical Engineering, Sikkim Manipal Institute of Technology, Sikkim-737136, IN
2 Department of Mechanical Engineering, Jadavpur University, Kolkata- 700032, IN
3 Department of Mechanical Engineering, Kalyani Government Engineering College, Kalyani - 741235, IN

Abstract

Milling is one of the commonly used processes in machining industry. In this experimental work, slab milling operation has been performed on cast iron blocks to obtain suitable machining parameters in order to get low surface roughness, low vibration and high material removal rate. Experimental design has been considered according to the Taguchi’s L₂₅ OA series. Taguchi’s signal to noise (S/N) ratio and composite desirability of response surface methodology (RSM) have been utilized to get optimum combination of machining parameters corresponding to low surface roughness, high material removal rate (MRR) and low vibration. Feed is found to have maximum influence on surface roughness, MRR and vibration within the domain of this experimental investigation.

Keywords

Slab Milling, Cast Iron, Taguchi Method, Composite Desirability.

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Saurav Datta ¹, Asish Bandyopadhyay ²

Affiliations
1 Department of Mechanical Engineering, National Institute of Technology, Rourkela, Orissa, IN
2 Department of Mechanical Engineering, Jadavpur University, Raja S. C. Mallik Road, Kolkata, IN

Abstract

Submerged arc welding (SAW) is a useful metal joining process in fabrication industry. The process is characterized by the use of granular flux blanket that covers the molten weld pool during operation. This arrangement avoids atmospheric contamination to the weld bead, facilitates slower cooling rate and, thereby, enhancing mechanical-metallurgical characteristics of the weldment. It is well-known that several process control parameters influence (directly or indirectly i.e. factorial interaction) various quality features of the weldment. Work, to a far extent, has already been done to study the effects of the parameters (as well as their interactions) like voltage, current, electrode stick-out, wire feed rate, traverse speed etc. on bead geometry, weld quality and performance attributes in terms of mechanical-metallurgical-chemical characteristics of the weld produced by submerged arc welding on structural steel. But the search is still being continued and results thereof are being reported which indicate the necessity of acquiring in depth knowledge in this regard. Control of the above parameters, in a more precise manner, can essentially improve weld quality, enhance the possibility of increased deposition rate and economize the overall process. In consideration of the above, the present reporting outlines the trends of research on various aspects of prediction-modeling, simulation and optimization of submerged arc weld. The application feasibility including relative merits as well as demerits of various modeling-optimization methodologies proposed and adopted by previous investigators in examining the process behavior of SAW has been illustratively highlighted. It is felt that the information provided in this reporting may definitely give an insight to the young researchers especially to identify the ischolar_main locus of the past research progressed in the said field and, thereby, helping them in selection of proper direction of work towards value added outcome for the benefit of both academic fraternity as well as industry personnel.

Keywords

SAW, Modeling, Simulation, Optimization.

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Saurav Datta ¹, Asish Bandyopadhyay ², Pradip Kumar Pal ²

Affiliations
1 Department of Mechanical Engineering, B. P. Poddar Institute of Management & Technology, 137, VIP Road, Poddar Vihar, Kolkata - 700052, IN
2 Department of Mechanical Engineering, Jadavpur University, Kolkata-700032, IN

Abstract

In the present research work the reconsumption of the slag, generated during conventional submerged arc welding, has been proposed during subsequent runs by incorporating appropriate treatment and mixing it with fresh flux, with certain proportions. Experiments have been carried out by using four different levels of process parameters like welding current, flux basisity index and slag-mix percentage (percentage of slag in the mixture of fresh flux and fused slag) to obtain bead-on-plate weldment on mild steel plates. Parameters associated with bead geometry like bead height, bead width, depth of penetration have been measured for each experimental run. Heat affected zone (HAZ) geometry in terms of HAZ width has also been obtained. Assuming simple geometry of the weld bead and unit length of the job, approximate bead volume has also been calculated. All these data have been efficiently utilized to develop mathematical models for prediction of geometry and quality of weld bead as well as heat affected zone. Quadratic response surface methodology (RSM) has been applied to develop the mathematical models between predictors and responses. Based on multiple linear regressions, the coefficients of the predictors, used in the models, have been determined. Analysis of Variance Method (ANOVA), F- test and Student's t test have checked the significance of the coefficients. Reduced models with significant coefficients have also been developed. Experimental data as well as generated data have been used to represent graphically the direct and interactive effects of process parameters (slag mix% has given special emphasis in this exercise) on selected response variables associated with weld bead and HAZ. Hardness Test has also been carried out to reflect graphically, the influence of using slag-mix in SAW process on mechanical property of the weldment i.e. hardness of weld metal as well as HAZ. Finally it has been concluded that effect of using slag-mix (up to 20%) do not impose any alarming adverse effect on features of bead geometry and HAZ. Therefore, the use of slag-mix, in submerged arc welding can be recommended to apply it in practical cases, which may make the process more economical.

Keywords

SAW, Slag-Mix, HAZ, RSM, ANOVA.

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