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Improving Sustainability of SE-based Processes
Published in Neelesh Kumar Jain, Kapil Gupta, Spark Erosion Machining, 2020
S. Kanmani Subbu, M.J. Davidson
Earlier, the dielectric fluid used in SE-based processes included hydrocarbon oils such as kerosene, mineral oil, transformer oil, synthetic oil or silicon oil. Despite their potential advantages in terms of higher productivity, lower tool wear and better surface integrity of the SEMed product, there were several sustainability issues such as by-product gases, vapours, hazardous smoke, decomposed heavy metals and their products, aerosols, heavy metallic sharp-edged irregular debris, fire, and exhibition electromagnetic radiation irrespective of the dielectric used (Rajurkar et al. 2017). Moreover, SEM is mostly used for different difficult-to-machine metals and alloys such as nickel, titanium carbide, chromium, tungsten carbide, producing their micron-sized particles. The size of these particles depends on the combination of workpiece, tool, and dielectric fluid. Therefore, many protective measures should be taken for the protection of the health of machine operators, and the safety of the environment in view of energy consumption.
Machining of Metals
Published in Sherif D. El Wakil, Processes and Design for Manufacturing, 2019
Electrical discharge machining or EDM was discovered by Russians and Americans, more or less at the same time, toward the middle of the past century. The concept of the process involves rapid and recurring discharge of electrical current between an electrode and a workpiece, which are separated by a dielectric liquid. The dielectric fluid acts as an electrical insulator until the applied voltage becomes high enough to bring it to its ionization point, when it becomes an electrical conductor. The resulting sparks gradually erode the workpiece to form a desired shape by removing minute chips that take the form of hollow spheres. Other names for this process include spark machining and arc machining. There are three types of EDM machines; all operate on the same principle of erosion by electrical discharge. They include die sinker (ram EDM), wire EDM (cheese cutter), and hole-drilling EDM (hole popper).
Electrical Discharge Machining (EDM)
Published in Gary F. Benedict, Nontraditional Manufacturing Processes, 2017
Electrical discharge machining is a relatively simple manufacturing process to set up and perform. The electrically conductive workpiece is positioned in the EDM machine and connected to one pole of a pulsed power supply. An electrically conductive electrode, shaped to match the dimensions of the desired cavity or hole, is connected to the remaining pole of the power supply. The electrode and workpiece are then positioned in such a way that a small gap is maintained between the two. To provide a controlled amount of electrical resistance in the gap, an insulating (dielectric) fluid is flooded between the electrode and workpiece.
Thermal Modeling and Experimental Validation of Mid-Conductor Winding Cooling
Published in Heat Transfer Engineering, 2023
Ilya T’Jollyn, Jasper Nonneman, Michel De Paepe
In conventional motors, windings are impregnated to fill the gaps in between the wires. This cannot be done for this cooling method, as the coolant needs to flow through these gaps. This poses some additional challenges, as the impregnation has multiple purposes. It improves heat conduction through the winding, serves as additional electrical insulation, provides mechanical strength, and dampens vibrations. Improvement of heat conduction is not necessary in this method, as the coolant is in direct contact with the wires. To ensure proper electrical insulation, a dielectric fluid should be used as coolant. The mechanical strength of the winding must be provided by the housing. The outer surface of the winding can be varnished to adhere to the housing for additional strength. Vibrations of the wires can be dampened by the fluid in contact with the individual wires. Although these challenges are of interest for further research, they are not further elaborated on here, as the focus of this paper is on the thermohydraulic feasibility of the cooling method.
The evaluation of machining performances and recast layer properties of AISI H13 steel processed by tungsten carbide powder mixed EDM process in the semi-finishing process
Published in Machining Science and Technology, 2022
In Figures 16 and 17, the APCS values of surfaces were processed by EDM and PMEDM processes at Ip = 3 A and 4 A. APCS of PMEDM was relevantly improved and lower than that of EDM. At the set of processing parameters {Ip=3A; Ton=32µs; Cp=40g/l}, APCS is best improved with a reduction of 41.093% versus that of the EDM process. The reason is the apparition of powder in the discharge process and can be explained in aspects: the discharge process is changed by conductive particles of powders and becomes more even. This causes the generation of residual stresses on the surface of specimens to be reductive (Rouniyar and Shandilya, 2020). The viscosity of the dielectric fluid is reduced by the suspension of powders (Sahu et al., 2018). This produces the process of pushing debris out of the discharge area better. Thus, the molten material is less deposited on the surface of samples. In addition, the dielectric fluid has a heat transfer capacity better. These decrease the residual stress of surfaces after PMEDM. Therefore, APCS is also significantly reduced and improved.
Critical review on the impact of EDM process on biomedical materials
Published in Materials and Manufacturing Processes, 2021
As discussed above that, the thermal effect is created in the EDM process due to the electric discharge series in a dielectric fluid that causes removal of material .[76–81] This removal is very small in quantity and this removal causes craters on the surface due to thermal discharge and ultimately leads to definite texture. These resulting surface properties depend on the electrical or thermal energy generated during the discharge phase. Separately from thermal and electrical energy, the surface topography is also dependent on the machined part’s cooling rate along with the dielectric fluid’s cooling rate .[82–84] This cooling rate consequently results in a change in structure, mechanical stress, and strength as well also affect the creation of surface pores and cracks .[85–87]