Chitra Sharma

Research Developments in Additives Mixed Electrical Discharge Machining (AEDM): A State of Art Review

Electrical discharge machining (EDM) is a well-established modern machining process used to manufacture geometrically complex shapes, process hard materials that are extremely difficult to machine by conventional machining processes. This noncontact machining technique is continuously emerging from a mere tool and dies making process to a microscale machining applications. In recent years, researches have emphasized on increasing machining performance coupled with deliberate surface treatments. Additive mixed electrical discharge machining (AEDM) is a novel innovation for enhancing the capabilities of electrical discharge machining process in this direction. This article presents comprehensive history, mechanism of AEDM process, and reviews research literature in this area. The last part of this article outlines trends for future AEDM research directions.

A Study of Multiobjective Parametric Optimization of Silicon Abrasive Mixed Electrical Discharge Machining of Tool Steel

In this article, a technique for optimization of abrasive mixed electrical discharge machining (AEDM) process with multiple performance characteristics based on the orthogonal array with grey relational analysis has been studied. The process input parameters, i.e., concentration of silicon abrasive powder in dielectric fluid, peak current, pulse-on time, and duty factor, were chosen to study process performance in the form of MRR and surface roughness. The research outcome identifies significant parameters and their effect on process performance on EN-24 tool steel using copper electrode with silicon powder (2 g/l) suspended in kerosene dielectric. The optimum process conditions have been verified by conducting the confirmation experiments.

Technological Advancement in Electrical Discharge Machining with Powder Metallurgy Processed Electrodes: A Review

Electrical discharge machining (EDM) is a well-established machining option for processing hard materials with complex geometrical shapes which are extremely difficult-to-machine by conventional machining processes. These hard materials find applications where lower surface cracks, wear resistance, corrosion resistance, etc. are desirable surface properties. In recent years, research has been carried out to determine the possibility of employing electrode as feed stock material in an effort to produce significant surface alloying. These electrodes are generally produced through powder metallurgy (PM) technique in order to achieve necessary combination of operating characteristics. This paper reports state of art related to the usefulness of PM-processed electrodes in imparting desirable surface properties and modification of the machined surface. The final part of the paper outlines the trends for future EDM research using PM-processed electrodes.

Analysis of Machining Characteristics in Additive Mixed Electric Discharge Machining of Nickel-Based Super Alloy Inconel 718

Additive mixed electric discharge machining (AEDM) is a recent innovation for enhancing the capabilities of electrical discharge machining process. The objective of present research work is to study the influence of operating process input parameters on machining characteristics of nickel-based super alloy (Inconel 718) in aluminium AEDM with copper electrode. The effectiveness of AEDM process on Inconel is evaluated in terms of material removal rate (MRR), surface roughness (SR), and wear ratio (WR) using one variable at a time (OVAT) approach. It is found experimentally that particle concentration and size significantly affect machining efficiency. Aluminium powder (325 mesh size) particles of concentration 6 g/l in AEDM produce maximum machining rate, minimum SR, and 4 g/l produces minimum WR within experimental conditions.

Machining Efficiency Evaluation of Cryogenically Treated Copper Electrode in Additive Mixed EDM

The present experimental investigations have been carried to evaluate machining efficiency with additive powder mixed in dielectric fluid of electrical discharge machining on Inconel 718 with copper and cryogenically treated copper electrodes. Experiments have been conducted to study the effect of input parameters viz. polarity, type of electrode, peak current, pulse on time, duty cycle, gap voltage, retract distance, and concentration of fine graphite powder on machining efficiency. Machining efficiency is evaluated in terms of tool wear rate (TWR) and wear ratio (WR). The optimum factor/level combination of process parameters has been determined by Taguchis approach treating performance measure as single objective response. Analysis of variance (ANOVA) is employed to indicate the level of significance of machining parameters for TWR and WR. The recommended optimal process input conditions have been verified by conducting confirmation experiments and significant improvement in TWR and WR is observed.

Optimisation of electrical discharge machining process with CuW powder metallurgy electrode using grey relation theory

In this paper, an attempt has been made to correlate the usefulness of powder metallurgy (PM) electrodes in electrical discharge machining (EDM). This paper explains the same with the help of experimentation on AISID2 steel in kerosene with CuW (25% Cu and 75% W) PM electrode. An L18 orthogonal array was used to identify the effect of process parameters (viz. electrode material, duty cycle, flushing pressure and current) on the performance characteristics i.e., material removal rate surface roughness and surface hardness. A grey relation grade obtained from the grey relation analysis is used to solve the EDM process with multiple performance characteristics. Experimental results have shown that electric discharge machining process performance can be improved efficiently through this approach. It is found that copper tungsten PM electrode gives better multi-objective performance than conventional copper electrode.

The development and characterization of a square ring shaped force transducer

Though various types of force transducers have been developed over many years, research is continuing through the globe regarding the development of different types of force transducers. The present paper discusses the development of square ring shaped force transducers and their metrological characterization based on the calibration procedures according to standards ISO 376:2004 and IS: 4169-1988 (reaffirmed 2003). The force transducers have been developed as a modification of ring shaped force transducers and strain gauges have been mounted on suitable locations. The force transducers have been studied analytically and computationally. The force transducers are found to have good metrological characteristics and further efforts are being focused on improving the metrological characteristics of force transducers.

Strategic planning of service supply chain using dynamic SAP-LAP model: a case study of a leading gas organisation in India

A supply chain management (SCM) practice in services is an ongoing process and needs continuous efforts on total quality management (TQM) practices and flexible systems (FSs) practices fronts. Implementation of new practices and proper strategic planning in accordance with the vision and mission of the business will enhance SCM programme, as these are directly responsible for the customers relationship and strategic relationship of final products. As per our study, information sharing is playing significant role. A detailed case study of Indias leading gas utility company has been undertaken. The case study of GAIL (India) Ltd. formerly called as Gas Authority India Limited (GAIL) has been taken into account using dynamic SAP-LAP model. As a conclusion, SCM practice in services is a part of strategic relationship and customers relationship of the organisation as a final product. SAP-LAP framework helps us to understand the SCM practices in the case study taken here.

Role of finite element analysis in improving hysteresis error of force transducers

Finite element analysis has been proved a vital factor for design studies of mechanical elements. The present paper discusses the role of finite element analysis in finding the locations of strain gauges so that the performance of the force transducers may be improved. Two ring-shaped force transducers of capacities 20 and 50 kN have been developed and the strain gauges have been placed suitably at the different locations according to the stress–strain distributions. Both force transducers have been metrologically characterized according to the calibration procedure based on standard ISO 376-2004 and IS 4169-1988 (re-affirmed 2003). The metrological results have ruled that both the force transducers have significant variations in the relative hysteresis deviations, while the differences between other factors like relative deviations because of repeatability error, reproducibility error, resolution error and zero error are not significant and thereby improve metrological properties. The results have been discussed and presented here.

Multi-objective parametric optimisation during electrical discharge machining of Inconel 718 with different electrodes

This paper presents multi-objective parametric optimisation of electrical discharge machining (EDM) process by the Taguchi method with grey relation analysis. Experimental investigations are performed on Inconel 718 with three different electrodes. Orthogonal array (L36) is used to identify the effect of process parameters (viz. polarity, electrode type, peak current, pulse on time, duty cycle, gap voltage, retract distance and flushing pressure) on the performance characteristics in terms of material removal rate surface roughness and tool wear rate. Using grey relational analysis, grey relational grade has been determined, which effectively represents the aggregate of different process attributes. As a result, a multi-objective parametric optimisation is converted into optimisation of a single grey relational grade. Experimental results have shown that utilisation of optimal machining parameter combination enhances a significant improvement of the grey relation grade and the grey relation grade is improved by 8.72%.