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Moran Xu,Rong Wei,Changping Li,Rendi Kurniawan,Jielin Chen,Tae Jo Ko 한국정밀공학회 2023 International Journal of Precision Engineering and Vol.10 No.2
Previous research had validated the machinability of the new machining method of electrical discharge assisted milling (EDAM). However, the EDAM tool has shortcomings, such as its inability to compensate for the electrodes and small discharge area, which restricted further popularization and applications of the method. So, this research introduced a high frequency EDAM (HF-EDAM), based on a novel tool with flexible electrodes. Notably, the material removal mechanism of HF-EDAM under different machining parameters was deeply explored in this study. In particular, the discharge signal, electrode and workpiece surface topographies, cutting force, tool wear, and machined-surface integrity of HF-EDAM were analyzed to find the machining mechanism of HF-EDAM under different machining parameters. At the same time, a two-dimensional cutting force model of HF-EDAM was also established, and a series of experiments showed that the model had good prediction accuracy for cutting forces. Furthermore, the experiments also showed that the HF-EDAM greatly reduced the cutting force and tool wear, and improved the machined-surface integrity as compared to those under CM, respectively. In essence, the excellent machinability of HF-EDAM was verified by experiments and modeling. Hence, HF-EDAM is an effective method for high-quality and efficient machining of titanium alloys, which are difficult to machine.
Moran Xu,Changping Li,Rendi Kurniawan,Jielin Chen,Tae Jo Ko 한국정밀공학회 2022 International Journal of Precision Engineering and Vol.23 No.10
The machinability of the hybrid machining method for electrical discharge assisted milling (EDAM) has been validated in previous research. The influence of three different dielectrics (kerosene, EDM oil, and deionized water) on the performance of the EDAM was investigated in this study. An analysis of the discharged signal, surface morphology, and elemental composition of the electrode under different machining parameters reveals the influence of different dielectrics. The results show that compared with deionized water, kerosene and EDM oil have a higher discharge frequency. After long-term discharge, debris and carbides will be generated during processing, which will affect the microhardness and discharge stability of the processed material. Among the result of EDAM, EDM oil produced the best surface integrity, with surface roughness values 34.93%, 87.92%, and 121.68% lower than those of kerosene, deionized water, and conventional milling (CM), respectively. The results show that EDAM reduces the microhardness after machining by reducing the plastic deformation of the surface.
Formation Mechanism and Adhesion Evaluation of Debris in Ti–6Al–4V Alloy Turning
Changping Li,Xiangyu Liu,Moran Xu,Jielin Chen,Shujian Li,Pengnan Li,Tae Jo Ko 한국정밀공학회 2023 International Journal of Precision Engineering and Vol.10 No.5
In this paper, the formation mechanism of adhered debris on the surface of turned titanium alloy was studied. The adhesion rate of debris was calculated and evaluated using image extraction technology. The effects of cutting parameters and cooling conditions on the debris adhesion rate were also studied. Moreover, the chip temperature and trajectory in the turning process are analyzed using a finite element simulation and a thermal camera. The results show that there are three primary sources of adhered debris: the adhesion of the built-up edge, the micro-chips formed during the cutting process, and the micro-chips generated by the friction between the chip and the machined surface. In addition, the cutting speed is also one of the most significant factors affecting the adhesion of debris. The debris adhesion rate drops significantly as the cutting speed decreases. It was also found that the coolant can effectively reduce the debris adhesion rate, and this effect is more evident at low feed rates.
Yini Chen,Changping Li,Shuang Li,Moran Xu,Lei Huang,Shujian Li,Pengnan Li,Xinyi Qiu,Tae Jo Ko 한국정밀공학회 2023 International Journal of Precision Engineering and Vol.24 No.3
Electric discharge machining (EDM) is used widely in machining titanium alloys, but the modified layer formed can weaken the mechanical properties of the parts. The present study examined the formation of craters and the evolution of the modified layer (melting layer + heat-affected layer) in RC-type EDM using a fluid–solid coupled temperature field model. This model adopts the level set method to track the liquid–solid two-phase and the driving force equation to control the recoil pressure. The results showed that the discharge energy has a significant effect on the formation of the modified layer. The formation of the modified layer showed phased characteristics with time. The variation law and formation mechanism of the modified layer are described in detail. A verification experiment showed that the diameter and depth of the crater were in good agreement with the simulation results. These results can provide an important reference for EDM to formulate the machining parameters.