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Machining of Metals
Published in Sherif D. El Wakil, Processes and Design for Manufacturing, 2019
Electrochemical machining is the process of removing metal by an electrochemical reaction. The mechanism with which electrochemical machining (ECM) takes place is reciprocal to that of the electroplating process. In fact, similar equipment is used in both cases. For this reason, ECM is referred to as “reverse electroplating,” in that it removes material instead of adding it. In electrochemical machining, a DC power supply is used. Therefore, the commonly available AC current has to be converted to DC by a rectifier. The workpiece is connected to the anode, while the cathode is connected to the machining tool that is usually made of copper, although brass, graphite, and copper–tungsten are also used. That ECM tool is guided along the desired path and advanced into the workpiece but without touching it. Low-voltage, high-amperage direct current is used, and a pressurized electrolyte (sodium chloride in water) is pumped into the gap between the workpiece and the tool. That gap is very small and varies between 0.003 and 0.03 inch (80 to 800 µm). Also, it has to be maintained at that level by keeping the feed rate of the ECM tool the same as the rate of corrosion of the workpiece material. As is always the case in a corrosion process, when the electrons cross the gap, the workpiece material dissolves and the tool gradually forms the desired shape in the workpiece. The electrolyte flushes away the products of the reaction from the gap.
Beneficial Industrial Uses of Electricity: Materials Fabrication
Published in Clark W. Gellings, 2 Emissions with Electricity, 2020
Electrolytic deposition/removal processes are used to deposit finishes on metal or remove metal from a metallic work piece. Electrogalvanization uses an electrolytic cell and a zinc salt solution to form a protective ring coating on steel. Electrofinishing uses electrolytic methods to produce finishes on manufactured products. Electrochemical machining passes current through an electrolyte to a conductive work piece, dissolving material by electrochemical reaction. This is useful for removing rust from tools or artifacts without altering the surface of the metal.
Single-Objective Optimization Using Taguchi Technique (Minimization)
Published in Kaushik Kumar, Supriyo Roy, J. Paulo Davim, Soft Computing Techniques for Engineering Optimization, 2019
Kaushik Kumar, Supriyo Roy, J. Paulo Davim
Electrochemical machining (ECM) is a non-conventional machining technique widely used in the modern manufacturing sector. For industrial and commercial reasons, ECM is required to have minimal undesirable effects such as overcut (OC) and surface roughness with the most achievable optimum parameter. OC is the main element of error in ECM, and the parameters involved need to be recognized.
Investigation of electrochemical machining on SS304 using NaCl and NaNo3 as electrolyte
Published in Materials and Manufacturing Processes, 2022
The electrolyte used needs a careful selection. Certain types of electrolytes form metallic oxides during the machining process, resulting in the germination of the metal oxide layer betwixt the workpiece and the tool. This layer acts, like a protective layer, thereby hindering the machining process with adverse effects on the accuracy of the hole produced.[15] For the transfer of metal oxides formed betwixt the tool and workpiece, the electrolyte is forced to flow between them. Acids are also used as electrolytes as they do not produce metal oxides during the machining operation, thereby improving machining accuracy.[16–18] Care is required while using acids as they tend to deposit material on the tool. The fumes produced during electrochemical machining using acids cause damage to the machine, to the lungs, and the eyes.[19,20] Moreover the disposal of the consumed electrolyte is also a big problem.[21] Currently, the use of neutral electrolytes in electrochemical machining is gaining popularity.[1,22,23] The most important reasons for using electrochemical machining are the absence of cracks, residual stress, and heat-affected zones in the workpiece.[24,25] However, it is to be noted that the machined surface would be free from residual stress, necessitating post-machining treatments.
Scale effects and a method to evaluate similarity in electrochemical micromachining of Nitinol
Published in Materials and Manufacturing Processes, 2021
Electrochemical machining (ECM) is one of the unconventional machining system used to machine electrically conductive materials.[1] The material removal likely to be happen when there is supply of voltage between the cathode and anode in an electrolytic cell.[2] The drive toward miniaturization and the demand of micro-electro-mechanical systems (MEMS), micro-parts, and micro-features for the humans is still high.[3] Electrochemical Micromachining (ECMM) is considered as the potential machine to produce all the miniaturized products due to its latent advantages over other traditional and nontraditional machining methods.[4] The ECM can be well thought to be used as a ECMM system when the machining dimensions are in the range of 1–999 µm.[5] ECM system and ECMM system are similar and it can be considered as a significant variant to the conventional ECM meanwhile it is found that there are still many complications in machining a micro hole with both ECM and ECMM system.[6–9]
Manufacturing methods for metallic bipolar plates for polymer electrolyte membrane fuel cell
Published in Materials and Manufacturing Processes, 2019
Oluwaseun Ayotunde Alo, Iyiola Olatunji Otunniyi, HCvZ Pienaar
Electrochemical machining (ECM) is a non-traditional machining process that utilizes anodic dissolution of the workpiece during electrolysis to achieve material removal.[99] Production of microchannels on metallic surfaces using various forms of ECM has been reported in the literature. Hackert-Oschatzchen et al.[100] applied jet electrochemical machining (JECM) to produce microchannels on tungsten carbide alloys and reported successful material removal using a mixture of sodium hydroxide and sodium nitrate as an electrolyte, with the surface finishes of the produced grooves in the range of values in mechanical grinding. Liu et al.[101] investigated the feasibility of machining dimples and grooves on TB6 titanium alloy using JECM. Using optimum process parameter of 24 V voltage, an inter-electrode gap (IEG) of 0.6 mm, the flow rate of 2.1 L/min, and 15% NaCl as electrolyte, surface roughness of 0.231 µm, 1.01 mm average overcut, and relatively high machining rate of 10.062 g/min were achieved. The MRR and surface quality of the produced part in ECM can be improved through a hybrid technology known as abrasive electrochemical jet machining (AECJM). In this process, fine size abrasive particles, mixed with the electrolyte, work together with anodic dissolution to bring about material removal by a combination of erosion and corrosion, leading to increased MRR.[102]