Applied Mechanics and Materials Vols. 813-814

Abstract: Electric Discharge Machining (EDM) is one of the most commonly used non-traditional machining processes. Complex geometries can be easily manufactured using EDM. Material removal is achieved by producing continuous spark occurring between well shaped tool electrode and work piece. EDM does not involve direct contact of tool and work piece. Machining process involves a number of input variables like, current, voltage, pulse on/off which in turn affect the machining efficiency of EDM. These process parameters must be optimized to attain high material removal rate and low tool wear rate. The present paper presents theoptimization of tool wear rate of copper and brass electrode on machining of EN-47 using Response Surface Methodology (RSM).

Abstract: This paper provides an inclusive review of literature, mostly from the past decade, on optimization techniques of composite materials machining, both conventional and non-conventional process. Composite materials are continually replacing conventional materials due to their excellent corrosion resistance, higher strength to weight ratio, but the machining of composites is a challenging process. Experimental trials notwithstanding, researchers have also used various optimization techniques such as Taguchi method, Genetic Algorithm, Simulated Algorithm, Response Surface Method, and Fuzzy Logic with ANOVA etc., to identify the optimal parameters for the machining processes. Also predictive modeling techniques such as Artificial Neural Networks and Finite Element Methods have also been employed as an optimization tools for studying the composite machining process. It was found that Taguchi method is the most preferred technique in the optimization studies.

Abstract: In metal cutting, increasing cutting spped and feed achieve higher productivity, but it will affect dimensional accuracy and surface integrity of the work surface, wear resistance and life of tool. Cutting fluids when appropriately chosen and applied will minimize these problems. This work deals with the optimization of process parameters in turning of EN24 and SS316L Steels with different cutting fluids with different cutting inserts under different machining conditions using Taguchi’s Robust Design Methodology. The control factors selected are machining environment, cutting speed, feed, depth of cut, work piece material and type of tool. Investigations are carried out on conventional lathe using the prefixed cutting conditions. Tool Wear and Surface Roughness are measured and anlysed using ANOVA and appropriate conclusions are derived.

Abstract: This work focuses on the analysis of the compositional variation made during stir casting of Al-B₄C metal matrix composite (MMC) and the properties of GTA weldments. Pulsed current gas tungsten arc (GTA) welding, a novel variant of traditional GTA weld process, was tried on two different composites, viz. 2 % and 4 % B₄C particulates in aluminium matrix. For a chosen current and voltage, two different pulsing frequencies (2Hz & 5Hz) were combined with three different pulse on time periods (40%, 50 % & 60%) and the weldments were compared with that of constant current weldments. An attempt has been made to study the time-temperature effect of pulsed GTA welding process parameters on microhardness in as-welded condition. Pulsed current resulted in better grain refinement and the same is reflected in the microhardness values. The increase in the reinforcing composition showed increased effect on the fusion zone weld hardness levels. Increase in Pulse on time and pulse frequency of PC weldments resulted in increased hardness of both the compositions.

Abstract: Joining of dissimilar aluminum alloys are widely used in automobile, aerospace and shipbuilding industries. Friction Stir Welding (FSW) has been established as one of the most promising processes to defects free joining of aluminum alloys. The aim of present work is to compare the predicted results of FS welded joint through Artificial Neural Network (ANN) modeling and regression modeling. Three responses tensile strength, average microhardness at weld nugget zone (WNZ) and average grain size at WNZ have been selected. The predicted values by ANN modeling and regression modeling of TS, MH and GS values have been found close to the experimental values. The overall average percentage prediction error of ANN model is small as compared to regression model.

Abstract: The dissimilar material welding at lower expensive is one of the popular techniques which are used in power generation services such as mining, petro chemical refineries and mineral processing plant as well as recuperator in furnace system. For these applications, the insulation plays an important role for effective result. Fluid flow from one medium to another medium is carried out through insulation materials to prevent the transmission of excessive heat. If it gets wet, it loses all its insulation properties. It is easily crushed if the pipe gets stepped on. The materials serves important role to save the heat energy in operating and constructing the power plant. In this research work, mild steel and stainless steel SS 409 are welded together by ER 309 L electrode by TIG welding process to achieve these applications. Service temperature is sensible; inside temperature is maintained low because of rapid cooling. This research concludes that, insulation material is not necessary for dealing out the material (below 700°C). Stainless steel SS 409 tends to contract and expand more and serves as good corrosion resistant material at the service temperature. Mild steel is a good heat conductor; it cools quickly and contract earlier as the joint cools and the heat is removed from the metal surface.

Abstract: The aim of this research is to study the effect of Friction Stir Welding (FSW) process parameters such as tool rotational speed and welding speed on temperature distribution and tensile strength of dissimilar AA5083-O and AA6063-T6 joint welded by FSW. Peak temperature at retreating side was observed lower as compared to advancing side for each experiment. Peak temperature decreases with decreasing the tool rotational speed but vice versa with welding speed. ANOVA indicated that the temperature profile was strongly dependent on the tool rotation speed than the welding speed and it also showed that welding speed is the main process parameter that has highest effect on tensile strength of welded joint.

Abstract: In this investigation, the effect of friction stir welding (FSW) parameters such as D/d ratio, tool tilt angle and welding speed on the mechanical properties of tensile strength, and impact energy of AA 6061 alloy was studied. The experiments were carried out as per Taguchi parametric design concepts and an L9 orthogonal array was used to study the influence of various combinations of process parameters. Statistical optimization technique, ANOVA was used to determine the optimum levels and to find the significance of each process parameter. The results indicate that D/d ratio, welding speed are the most significant factors, followed by tool tilt angle in deciding the mechanical properties of friction stir welding aluminum alloy.

Abstract: A key factor in the performance of Gas Metal Arc welding (GMAW) is the feedability of the filler wire. Variations in the wire feed speed (WFS) are caused by adverse conditions during welding. These include damaging effects such as “stick-slip” motion of the welding wire, premature wear of the contact tube and, in general, the conduit cable usage during welding. Experiments were conducted to study these issues. The welding parameters such as arc current and voltage were captured by using data logger and the stick-slip effect was analyzed. It was observed that arc waveforms were found to have significant influence because of the stick-slip effect. The corresponding fusion characteristics of the weldments were studied. The voltage change was suggested to specific conduit cable configuration.

Abstract: The friction stir welding process is the newly developed material joining process used to join the different materials which are very difficult to join in the conventional fusion welding process. In this investigation using the specially designed straight cam profiled tool, the multiple responses of Ultimate tensile strength, Ultimate yield strength and Percentage of elongation with the process parameters of rotational speed, tool tilt angle and feed rate are optimized. The five level, three factor rotatable central composite design is selected to optimize the responses of friction stir welded AA 8011 aluminium alloys. The highest gray relational grade with the highest relative efficiency is found using the gray relational analysis coupled with the data envelopment analysis to predict the optimum parameters. It exposes that at the rotational speed of 680 rpm, the tool tilt angle of 98 degrees and the feed rate of 24 mm/min the good weld quality can be attained.