Investigations Into the Removal of EDM Recast Layer With Magnetic Abrasive Machining

2015 ◽  
Author(s):  
Sehijpal Singh Khangura ◽  
Lakhvir Singh Sran ◽  
Anil K. Srivastava ◽  
Harinder Singh
Keyword(s):  
Surface Finish ◽  
Electrical Discharge Machining ◽  
High Hardness ◽  
Hardness Measurement ◽  
Recast Layer ◽  
Machining Process ◽  
Initial Surface ◽  
Average Improvement ◽  
En 31 ◽  
Magnetic Abrasives

Electrical Discharge Machining (EDM) is a non conventional machining process capable of accurately machining parts with high hardness and of complex shapes. The sparks produced during the EDM process cause localized melting on the work surface. The formation of recast layer is very common on EDMed surfaces. The recast layer reduces the service life of the die or mould surfaces, especially under fatigue loads. In the present work, Magnetic Abrasive Finishing (MAF) process has been explored as a method to remove the recast layer formed on a EN 31 steel cylindrical specimen machined by EDM. MAF process is one of promising methods capable of removing the material at micro/nano level under gentle mechanical forces. The diamond based sintered magnetic abrasives have been used to machine the EDMed surface. The experimental results indicate that the EDMed surface of EN-31 steel can be successfully finished with diamond sintered magnetic abrasives. On the finished surfaces, no evidence of micro cracks, voids and recast layer has been seen. Moreover, an average improvement in the surface finish up to 80% over the initial surface finish has been obtained. The micro hardness measurement on MAFed surface shows that brittle and hard layer has been removed. SEM photographs indicate the success of MAF for removal of EDMed surface.

scholarly journals Electrical Discharge Machining of Al2O3 and Si3N4 Ceramics; A Research

2019 ◽  
Vol 8 (2S8) ◽  
pp. 1806-1808
Keyword(s):  
Surface Finish ◽  
Electrical Discharge ◽  
Electrical Discharge Machining ◽  
Removal Rate ◽  
High Surface ◽  
High Hardness ◽  
Ceramic Materials ◽  
Machining Process ◽  
Low Efficiency ◽  
Edm Process

Ceramic materials which have high hardness and brittleness cannot be machined by traditional machining process because of their low efficiency and feasibility. But in non-traditional machining process, it overcomes these limitations proving it to be very useful in manufacturing process. In this review paper we are discussing about electrical discharge machining (EDM) process on Al2O3 and Si3N4 ceramic materials which are machine able. EDM parameters like material removal rate (MRR), tool wear rate (TWR), surface finish are discussed. EDM is very much suitable for ceramic materials because of its high surface finish, accuracy and efficiency.

Enhancing the Surface Quality by Iso Pulse Generator in EDM Process

2012 ◽  
Vol 622-623 ◽  
pp. 380-384 ◽  
Author(s):  
T. Muthuramalingam ◽  
B. Mohan
Keyword(s):  
Surface Finish ◽  
Material Removal ◽  
Pulse Generator ◽  
Electrical Discharge Machining ◽  
Removal Rate ◽  
Machining Process ◽  
Discharge Energy ◽  
Crater Volume ◽  
Machining Characteristics ◽  
Edm Process

In automobile and aeronautical industries, complex moulds and dies is produced by Electrical Discharge Machining process. The surface finish is determined by the crater volume in EDM process. The amount of crater volume is influenced by the amount and distribution of discharge energy. The discharge energy is directly proportional to the average discharge current. This amount of current is determined by the duration of discharging effect. This study deals about evaluating the performance of iso current pulse generator on machining characteristics in EDM. Due to its ability of reducing stochastic nature in EDM process, iso pulse generator could produce better surface finish than conventional transistor pulse train generator with higher material removal rate.

Crack-Less Electrical Discharge Machining of Molybdenum with Titanium Electrode

2014 ◽  
Vol 510 ◽  
pp. 101-105 ◽  
Author(s):  
Kaneko Kensei ◽  
Furutani Katsushi
Keyword(s):  
High Temperature ◽  
Electrical Discharge ◽  
Electrical Discharge Machining ◽  
Base Material ◽  
Negative Electrode ◽  
High Hardness ◽  
Recast Layer ◽  
Recrystallization Temperature ◽  
High Temperature Strength ◽  
Electrode Polarity

This paper describescrack-less electrical discharge machining (EDM) of molybdenum (Mo) with titanium (Ti) electrode. Mo is often machined by EDM because of its high hardness. However, a molybdenum carbide (MoC and Mo2C) layer with high hardness and brittleness is formed by EDM in kerosene oil. Moreover, Mo becomes recrystallizationembrittlement at high temperature. Therefore, many cracks occurred in the EDMed surface. On the other hand, the addition of Ti rises recrystallization temperature and improves high temperature strength of Mo.In order to decrease the cracks in the machined surface, Mo was machined by EDM with a Ti electrode in deionized water. In the case of the positive electrode polarity, many cracks occurred in the base material and recast layer. The cracks in the base material might generate by crystal grain boundary embrittlement. In contrast, the EDMed surface indicated crack-less on the negative electrode polarity. To clarify the causes of crack-less surface on negative electrode polarity, componential analysis of EDMed surface was carried out. The component ratio of Ti on the negative electrode polarity was higher than that on the positive. In addition, the recast layer was composed by Mo-Ti solid solution.

scholarly journals Study on the Influence of Metallic Powder in Near-Dry Electric Discharge Machining

2020 ◽  
Vol 66 (4) ◽  
pp. 243-253 ◽  
Author(s):  
Sanjay Sundriyal ◽  
Vipin ◽  
Ravinderjit Singh Walia
Keyword(s):  
Electrical Discharge ◽  
Electrical Discharge Machining ◽  
Removal Rate ◽  
Dielectric Medium ◽  
Metallic Powder ◽  
Machining Process ◽  
Electric Discharge Machining ◽  
En 31 ◽  
Edm Process ◽  
Dry Electrical Discharge Machining

Near-dry electrical discharge machining (ND-EDM) is an eco-friendly process. In this study, an approach has been made to make the machining process more efficient than ND-EDM with the addition of metallic powder with the dielectric medium to machine EN-31 die steel. Powdermixed near-dry EDM (PMND-EDM) has several advantages over the ND-EDM or conventional electrical discharge machining (EDM) process, such as a higher material removal rate (MRR), fine surface finish (Ra), sharp cutting edge, lesser recast layer, and lower deposition of debris. The output response variables are MRR, Ra, residual stress (RS) and micro-hardness (MH) of the machined surfaces. Further study of the workpiece was performed, and a comparative study was conducted between ND-EDM and PMND-EDM. In this proposed method of machining, the MRR, Ra, and MH increased by 17.85 %, 16.36 %, and 62.69 % while RS was reduced by 56.09 %.

Development of the Cylindrical Wire Electrical Discharge Machining Process

2001 ◽  
Author(s):  
Jun Qu ◽  
Albert J. Shih ◽  
Ron Scattergood
Keyword(s):  
Surface Finish ◽  
Electrical Discharge ◽  
Material Removal ◽  
Electrical Discharge Machining ◽  
Machining Process ◽  
Free Form ◽  
Wire Electrical Discharge Machining ◽  
Wire Edm ◽  
Cylindrical Workpiece ◽  
Cylindrical Wire

Abstract Results of applying the wire Electrical Discharge Machining (EDM) process to generate precise cylindrical forms on hard, difficult-to-machine materials are presented. The design of an underwater rotary spindle is first introduced. The spindle is added to a conventional two-axis wire EDM machine to enable the generation of free-form cylindrical geometry. Mathematical models for material removal rate and surface finish in cylindrical wire EDM of the free-form cylindrical workpiece are derived. Experiments are conducted for cylindrical and 2D wire EDM of brass and carbide work-materials. Comparing to the conventional 2D wire EDM of the same work-material, higher maximum material removal rates could be achieved in the cylindrical wire EDM. The surface finish and roundness of parts generated by cylindrical wire EDM at different part rotational speeds and wire traverse speeds are measured and analyzed.

Experimental investigations on surface integrity issues of Inconel-690 during wire-cut electrical discharge machining process

2016 ◽  
Vol 232 (4) ◽  
pp. 731-741 ◽  
Author(s):  
M Sreenivasa Rao ◽  
N Venkaiah
Keyword(s):  
Surface Roughness ◽  
Layer Thickness ◽  
Process Parameters ◽  
Electrical Discharge ◽  
Electrical Discharge Machining ◽  
Recast Layer ◽  
Machining Process ◽  
Micro Hardness ◽  
Recast Layer Thickness ◽  
Inconel 690

Nickel-based alloys are finding a wide range of applications due to their superior properties of maintaining hardness at elevated temperatures, low thermal conductivity and resistance to corrosion. These materials are used in aircraft, power-generation turbines, rocket engines, automobiles, nuclear power and chemical processing plants. Machining of such alloys is difficult using conventional processes. Wire-cut electrical discharge machining is one of the advanced machining processes, which can cut any electrically conductive material irrespective of its hardness. One of the major disadvantages of this process is formation of recast layer as it affects the properties of the machined surfaces. In this study, experimental investigation has been carried out to study the effect of wire-cut electrical discharge machining process parameters on micro-hardness, surface roughness and recast layer while machining Inconel-690 material. Interestingly, hardness of the machined surface was found to be lower than that of the bulk material. The micro-hardness and recast layer thickness are inversely related to the variation of process parameters. Recast layer thickness, surface roughness and hardness of the wire-cut electrical discharge machined surfaces of Inconel-690 are found to be in the range of 10–50 µm, 0.276–3.253 µm and 122–171 HV, respectively, for different conditions. The research findings and the data generated for the first time on hardness and recast layer thickness for Inconel-690 will be useful to the industry.

Pulsed Nd:YAG laser machining of nitinol: An experimental investigation

2021 ◽  
pp. 251659842110154
Author(s):  
B. Muralidharan ◽  
K. Prabu ◽  
G. Rajamurugan
Keyword(s):  
Nd:Yag Laser ◽  
Electrical Discharge Machining ◽  
Beam Quality ◽  
Cutting Speed ◽  
Recast Layer ◽  
Machining Process ◽  
Machined Surface ◽  
Pulsed Nd:Yag Laser ◽  
High Pulse Frequency ◽  
Micro Channels

Nickel–Titanium (Ni-Ti) shape memory alloy, commonly called nitinol alloys, finds its primary application in the production of biomedical implants, mainly because of itsrare properties such asshape memory, superelasticity and superior biocompatibility. Laser cutting is anon-traditional machining process for the production ofparts with close tolerances andcomplex geometry. Electrical discharge machining (EDM) of nitinol is associated with more heat-affected zone (HAZ) and recast layer thickness. This article aims to study nitinol’s machining characteristics by alaser source with good beam quality to have a less HAZ, recast layer and striations. Experiments were designed and carried out using central composite designs (CCD) by a pulsed Nd:YAG laser. Analysis based on the different parameters chosen was conducted to determine the parameters; effects, including laser power, frequency and cutting speed concerning the surface roughness. From the results, it is observed that the presence of HAZ is measured up to1. 48 mm from the machined surface. The topography analysis reveals that the striation is identified at high speeds, with less pulse overlapping by columnar micro channels, which can be reduced at high pulse frequency.

scholarly journals The Methodologies Adopted To Improve the Machinability in Die-Sinking EDM

2019 ◽  
Vol 9 (1S4) ◽  
pp. 645-647
Keyword(s):  
Tool Wear ◽  
Material Removal Rate ◽  
Material Removal ◽  
Electrical Discharge Machining ◽  
Removal Rate ◽  
High Surface ◽  
High Hardness ◽  
Machining Process ◽  
Work Piece ◽  
Machining Processes

Electrical discharge machining (EDM) is one of the oldest nontraditional machining processes, commonly used in automotive, aerospace and ship building industries for machining metals that have high hardness, strength and to make complicated shapes that cannot be produced by traditional machining techniques. The process is based on the thermoelectric energy between the work piece and an electrode. EDM is slow compared to conventional machining, low material removal rate, high surface roughness, high tool wear and formation of recast layer are the main disadvantages of the process. Tool wear rate, material removal rate and surface quality are important performance measures in electric discharge machining process. Numbers of ways are explored by researchers for improving and optimizing the output responses of EDM process. The paper summarizes the research on die-sinking EDM relating to the improvements in the output response.

Machining of High Aspect Ratio Micro-Holes on Titanium Alloy Using Silver Nano Powder Mixed Micro EDM Drilling

2019 ◽  
Author(s):  
Chong Liu ◽  
Asif Rashid ◽  
Muhammad P. Jahan ◽  
Jianfeng Ma
Keyword(s):  
Titanium Alloy ◽  
Aspect Ratio ◽  
Surface Finish ◽  
High Aspect Ratio ◽  
Electrical Discharge Machining ◽  
Turbine Blades ◽  
Weight Ratio ◽  
Recast Layer ◽  
Micro Edm ◽  
Micro Holes

Abstract Titanium alloy Ti-6Al-4V is used extensively in aerospace engines because of its high strength-to-weight ratio and corrosion resistance. Machining of cooling holes in turbine blades for aerospace engines is one of the major challenges faced in aerospace industries. Ti-6Al-4V is known as a difficult to be machined material by conventional machining processes, and machining of micro-through-holes with diameter less than 100 microns is even more challenging. Therefore, the objective of this study is to investigate the feasibility of machining high aspect ratio micro-through holes in Ti-6Al-4V using micro electrical discharge machining (micro-EDM) with the silver (Ag) nanopowder mixed dielectric. The machining time, overcut, recast layer, crater size, aspect ratio and surface finish of the micro-holes were evaluated. In order to minimize the positional inaccuracy and spindle runout, the microelectrodes were fabricated in-situ using block micro-EDM process. In this study, as received electrode of 300 microns diameter tungsten wire was reduced to about 50 microns diameter rod by micro block EDM using a tungsten carbide block. The effect of powder concentration, gap voltage, capacitance and electrode rotational speed was studied. It is found that high quality micro-holes of about 50 microns diameter can be achieved successfully and repeatedly using powder mixed micro-EDM (PM-μEDM). The micro-holes generated by PM-μEDM provides comparatively smoother surface finish and minimal recast layer around the rim of the micro-holes. In addition, PM-μEDM process improves machining stability, thus allowing to minimize the hole size and quality, thus enhancing the aspect ratio of micro-holes.

scholarly journals Recent Progress in Precision Machining and Surface Finishing of Tungsten Carbide Hard Composite Coatings

Coatings ◽  
2020 ◽  
Vol 10 (8) ◽  
pp. 731
Author(s):  
Christian Micallef ◽  
Yuri Zhuk ◽  
Adrianus Indrat Aria
Keyword(s):  
Tungsten Carbide ◽  
Surface Finish ◽  
Electrical Discharge Machining ◽  
Composite Coatings ◽  
Chemical Vapour ◽  
High Hardness ◽  
Diamond Turning ◽  
Surface Finishing ◽  
Mechanical And Tribological Properties ◽  
Carbide Coatings

Owing to their high hardness, fracture toughness and oxidation resistance, tungsten carbide (WC) coatings are extensively deposited on parts that operate in demanding applications, necessitating wear, erosion, and corrosion resistance. The application of thick and hard WC coatings has an inevitable effect on the original dimensions of the parts, affecting the geometrical tolerances and surface roughness. The capability of achieving a sub-micron surface finish and adhere to tight geometrical tolerances accurately and repeatably is an important requirement, particularly with components that operate in high-precision sliding motion. Meeting such requirements through conventional surface finishing methods, however, can be challenging due to the superior mechanical and tribological properties of WC coatings. A brief review into the synthesis techniques of cemented and binderless WC coatings is presented together with a comprehensive review into the available techniques which are used to surface finish WC-based coatings with reference to their fundamental mechanisms and capabilities to process parts with intricate and internal features. The binderless WC/W coating considered in this work is deposited through chemical vapour deposition (CVD) and unlike traditional cemented carbide coatings, it has a homogenous coating structure. This distinctive characteristic has the potential of eliminating key issues commonly encountered with machining and finishing of WC-based coatings. Here, six contact and non-contact surface finishing techniques, include diamond turning, precision grinding, superfinishing, vibratory polishing, electrical discharge machining, and electropolishing are discussed along with their current use in industry and limitations. Key challenges in the field are highlighted and potential directions for future investigation, particularly on binderless WC coatings, are proposed herein.

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