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Powder mixed near dry electric discharge machining is an advanced hybrid form of electric discharge machining method which makes minimum use of dielectric oil and is quite sustainable in machining terms. In this article an approach has been made to optimize the variable parameters such as tool type, metallic powder concentration, dielectric mist pressure, and mist flow rate in order to study their effect along with their range in order to enhancing the machining performance in terms of increased material removal rate (MRR), improved surface finish, improved micro-hardness, reduction of residual stress and tool wear rate. Analysis of variance along with Taguchi L9 methodology was utilized for conducting experiments and it was revealed by the confirmation experiments that by this technique, the optimized results for improved material removal rate, improvement of surface finish, enhanced micro-hardness, reduced residual stress and tool wear rate were 0.63 (mg/s), 0.79 (pm), 249 (HV), 286 (MPa) and 1.07 (mg/min) respectively. The optimized values were obtained at Tool diameter (3mm), flow rate of mist (15 ml/min), concentration of metallic powder (8 gm/l) and mist pressure (0.5 MPa) of dielectric medium. [ABSTRACT FROM AUTHOR]

Abrasive Flow Machining (AFM) process has been a useful technique for deburring and polishing of the surface and edges through the abrasive laden media. The surface material has been removed in form of micro chips due to abrasion action of sharp cutting edges abrasive particles. A large amount of force and energy has been lost due to frictional forces between the surface and abrasive particles in AFM process. A new hybrid form of AFM process named as thermal additive centrifugal abrasive flow machining (TACAFM) has been discussed in the present investigation, which utilized the spark energy to melt the surface material. A lesser amount of force has been required by the abrasive particles to remove the molten material from the surface and also minimized the energy loss. In the present investigation central composite design response surface methodology has been used to plan and conduct the experiments using Design Expert® 11 software. Experiments have been performed to analyze the effect of input process variables such as current intensity, duty cycle, abrasive concentration, rotational speed of the electrode and extrusion pressure on scatter of surface roughness, micro hardness and % improvement in Ra of the workpiece. Also the finished surface of the brass work piece has been characterized for the microstructure study using SEM and XRD analysis. From the experimental results it has been found that duty cycle has the most significant effect towards Scatter of surface roughness with a contribution of 17.5 % while current has been contributed largest as 85.17 % towards micro hardness. Also it has been observed that current has contributed largest as 21.88% against the % improvement in Ra. The optimum scatter of surface roughness, micro hardness and % improvement in Ra has been observed as 0.15 pm, 345.95 HV and 39.52 % respectively. [ABSTRACT FROM AUTHOR]

Powder-mixed near-dry electric discharge machining (PMND-EDM) process have been attracting attention in the manufacturing community because of its capability to produce the end products with better surface quality characteristics and improved machining rate. Present work is an effort to understand the influence of process variables like tool diameter, flow rate of dielectric mist, concentration of metallic powder and mist pressure of dielectric medium. Taguchi method orthogonal array L9 was used for the conduction of experiments. Analysis of variance (ANOVA) was employed to find out the significance of process parameters. The results reveal that the optimum process parameters for the experimental condition for maximum MRR (0.11 mg s-1)was at tool diameter at A1 (2mm), flow rate of mist at B3 (15 ml min-1), concentration of metallic powder at C3 (25 gm l-1) and mist pressure of dielectric at D3 (0.6 MPa). It has been also concluded that metallic powder was responsible for surface modification to achieve higher micro-hardness value up to 530.10 Vickers hardness number along with refined surface characteristics. [ABSTRACT FROM AUTHOR]

Electrical discharge machining (EDM) is a non-conventional method of machining hard materials with intricate shapes. Near-dry electric discharge machining (ND-EDM) is an advanced method of EDM which is eco-friendly and is more efficient in terms of material removal rate (MRR) than traditional EDM. In this research, an approach has been made to perform a new electrical discharge machining operation on EN-31 steel which utilizes metallic powder as an additive along with a gaseous dielectric (for example air) in ND-EDM. This advanced method of machining is known as powder mixed near-dry EDM. This study involves modeling for output process parameter—Material Removal Rate. The mathematical model was developed using the approach of Gaussian heat distribution. FEM modeling was done on ANSYS WORKBENCH 16.0 module. The experiments were performed and comparative study was done between the results obtained by modeling and experiments. The maximum experimental MRR was 7.68 mm3/min, and the error percentage between experimental, mathematical and FEM was under 30%. It was concluded that the modeling was done successfully and results obtained do comply with the methodology of the research. [ABSTRACT FROM AUTHOR]

Centrifugal-force-assisted abrasive flow machining (CFAAFM) process has recently been tried as a hybrid machining process with the aim towards performance improvement of the abrasive flow machining process by applying centrifugal force on the abrasive-laden media with a rotating centrifugal-force-generating rod introduced in the workpiece passage. In the CFAAFM process, the surfaces are generated by erosion from random attack of abrasive particles. This article deals with the theoretical investigations into the mechanism of material removal in the CFAAFM process. Analytical model is developed to estimate the material removal during the process. A good correlation is found to exist between the theoretical results and the experimental data. [ABSTRACT FROM AUTHOR]

Centrifugal force assisted abrasive flow machining (CFAAFM) process has recently been tried as a hybrid machining process with the aim towards performance improvement of assisted abrasive flow machining (AFM) process by applying centrifugal force on the abrasive-laden media with a rotating centrifugal force generating (CFG) rod introduced in the workpiece passage. In the CFAAFM process, the surfaces are generated by erosion from random attack of abrasive grains. CFAAFMed surfaces are unidirectional but random in nature due to transient media flow conditions. In the present paper, surface morphology, surface micro-hardness, X-ray analysis, and surface compressive residual stress produced in the finished surface layer by CFAAFM process is described. The CFAAFM process was performed under different rotational speeds of CFG rod while keeping other input parameters constant during the experiments. The increase in surface microhardness and compressive residual stress of the workpiece with an increase in the rotational speed of CFG rod is attributed to the work-hardening surface that possibly occurs due to ‘throw’ of abrasive particles upon specimen surface. [ABSTRACT FROM AUTHOR]

Abrasive flow machining (AFM) is one of the important non-traditional metal finishing technologies which was introduced during the late 1960s. The process has found applications in a wide range of fields such as aerospace, defence, surgical and tool manufacturing industries. Recently, an effort has been made towards the performance improvement of this process by applying centrifugal force on the abrasive media with the use of a rotating centrifugal force generating (CFG) rod introduced in the workpiece passage. The results have been encouraging. The present paper discusses the results of changing the parameters like shape and rotational speed of CFG rod, extrusion pressure, number of process cycles and abrasive grit size. The results indicate that all the input variables have significant effect on the response parameters, which for the present study were taken as material removal and surface roughness. An analytical model is proposed for the velocity and the angle at which abrasive particles attack the workpiece surface in the process. [ABSTRACT FROM AUTHOR]

Extrusion honing, known as abrasive flow machining (AFM), deburrs, polishes, and radiuses surfaces and edges by flowing an abrasive-laden media over these areas. The process is particularly used on internal shapes that are difficult to process by other nonconventional machining processes. Because abrasive action occurs only in areas where the flow is restricted, tooling is used to direct the media to the appropriate areas. Like other nonconventional machining processes, AFM has the limitation of lower material removal rates. The application of centrifugal force (by using rotating rectangular rod inside the hollow workpiece) has been explored for the productivity enhancement of the process. This article reports that centrifugal force enhances the material removal rate (MRR) and improves the scatter of surface roughness (SSR) value in AFM. It outlines the development of a system that determines sets of viable process parameters for a new process called centrifugal force-assisted abrasive flow machining (CFAAFM). Cylindrical workpieces of brass are used for the experiment. During the experiments, parameters, such as rotational speed of rectangular rod, extrusion pressure, and grit size, were varied to explore their effect on material removal and scatter of surface roughness. Taguchi's parameter design strategy has been applied to investigate the effect of process parameters on the MRR and SSR values. [ABSTRACT FROM AUTHOR]