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Wire electrochemical discharge machining (WECDM) results in irregular processing markings on the machining surface; this increases surface roughness and thus lowers product performance and quality. In this work, the WECDM-machined side walls of a slot in a quartz wafer were polished by using an ultrasonic-assisted wire electrophoretic deposition method. Through an innovative electrophoretic deposition device, silicon carbide particles were deposited on the surface of the wire electrode to form a polishing wire for polishing the side wall of the quartz wafer slot. Introducing ultrasonic vibration during polishing after WECDM further decreased the surface roughness. In experiments, the polishing effect improved when appropriate processing parameters were adopted. From an initial surface roughness of 0.876 μm Ra, a surface roughness as low as 0.112 μm Ra was achieved (an improvement of 87.2%) under a working voltage of 12 V, a SiC particle concentration of 13 wt.%, feed rate of 10 μm/s, four polishing repetitions, and an ultrasonic power level of 2.

This study presents a novel structure for electrochemical discharge machining (WECDM) of nonconductive quartz wafers with continuous electrolyte flow. A small and stable insulating gas film was formed in the gap between the wire electrode and workpiece to achieve improved WECDM in a small area. A pulsed power supply and ultrasonic-assisted processing were combined to machine the quartz workpiece. This approach can considerably reduce unstable discharge phenomena and discharge heat generation. Furthermore, it can avoid easy breakage and subsequent loss of the wire electrode. The machining accuracy and the machining speed can be improved using appropriate WECDM parameters. Experimental results revealed that a minimum slot width of 0.208 mm was obtained at a voltage of 44 V, duration time of 100 μs, duty factor of 40%, feed rate of 20 μm/s, and ultrasonic power level of 2. Accordingly, the proposed design can obtain a smaller slot width, which improves processing accuracy.

The machining of quartz due to hard, non-conducting and brittle behavior with desired accuracy and precision is always a challenge. Quartz is widely used in MEMS/MOEMS applications. However, wire electrochemical discharge machining (WECDM) has great potential to machine hard and brittle materials like quartz, glass FRP, etc. The WECDM process is a hybrid non-conventional manufacturing process which combines characteristics of electrochemical machining (ECM) and wire-electrical discharge machining (W-EDM). The present study discusses the investigation of the effect of the governing process parameters such as voltage, electrolyte concentration, and wire speed (feed) on material removal rate (MRR) and surface roughness (Ra) during the micro-machining of quartz using self-developed tabletop desktop WECDM setup. The hybrid methodology of Taguchi orthogonal arrays and Analysis of variance (ANOVA) is used to find the optimum parameters and their significant contribution to response parameters respectively. Experimental results reveal that a better surface finish and high material removal rate was obtained by zinc layered brass wire (150 μm diameter). The machining of quartz under the zinc layered brass wire can indeed enhance the surface quality characteristics and material removal rate. Also, the mathematical models were established in order to derive the relationship between input and response parameters which was successfully validated by the confirmation experiment. Furthermore, the machining quality observed by a Scanning electron microscope (SEM), reveals the presence shallow cracks at higher-end input parameters.

With the rapid development of micro-electro-mechanical systems (MEMSs), the demand for glass microstructure is increasing. For the purpose of achieving high quality and stable machining of glass microstructures with a high aspect ratio, ultrasonic vibration is applied into the micro-wire electrochemical discharge machining (WECDM), which is proposed as ultrasonic vibration-assisted WECDM with a micro helical electrode. Firstly, the formation of a gas film on the surface of the helical electrode in WECDM machining is simulated, meaning the thickness of the gas film can be reduced by adding suitable ultrasonic amplitude, thus reducing the critical voltage, then the machining localization and stability were enhanced. Then, the micro helical electrode with a diameter of 100 μm is used to carry out sets of experiments that study the influence of ultrasonic amplitude, machining voltage, duty factor, pulse frequency, and feed rate on the slit width. The experimental results show that the machining stability and quality are significantly improved by adding suitable ultrasonic amplitude. When the amplitude was 5.25 μm, the average slit width was reduced to 128.63 μm with a decrease of 20.78%. Finally, with the optimized machining parameters, micro planar coil structure and microcantilever structure with a high aspect ratio were fabricated successfully on the glass plate. It is proved that ultrasonic vibration-assisted WECDM with the micro helical electrode method can meet the requirements of high aspect ratio microstructure machining for hard and brittle materials.

Quartz, being hard and brittle, is difficult to machine. Although good machining effects of quartz have been achieved by wire electrochemical discharge machining (WECDM), the surface quality of microslits obtained needs to be enhanced and higher machining precision is desired. To attain improvement in quartz machining, this study performs WECDM under titrated electrolyte flow with the addition of silicon carbide (SiC) powder. On the one hand, titrated electrolyte can facilitate rapid replenishment of the electrolyte, which contributes to maintain the stability of the insulating gas film, thus ensuring frequent and steady electrical discharge for better machining precision. On the other hand, the SiC powder added can help polish the finished workpiece for surface quality enhancement. Experiments are conducted to determine the appropriate machining parameters and to explore the processing mechanisms involved. Comparison in terms of machining precision and surface quality is made for WECDM conducted with and without additives. Experimental results show that better surface roughness and precision of microslits can be obtained with brass wire electrodes of 150 μm diameter and SiC powder of 11 μm at 5 wt%. The addition of abrasive SiC powder helped decrease surface roughness from 1.13 to 0.22 μm, an improvement in surface quality by 80 %. Moreover, the mean slit width was also reduced from 200 to 185 μm. Hence, WECDM of quartz glass under titrated electrolyte with SiC powder added to the electrolyte can indeed enhance surface quality and precision of the microslit. Moreover, not only does such approach use less electrolyte, but also it incurs lower cost and less pollution, making it cost effective and environmental friendly.

The SiC reinforced z-pinned composites are becoming advantageous in the field of aerospace and defense sector due to their superior mechanical properties. The reinforcement of SiC particles makes them difficult to machine with conventional machining processes. In the present research investigation, the micro-slicing of SiC reinforced z-pinned composites has been attempted using wire electrochemical discharge machining (WECDM). WECDM is newly emerging technique which combines the process features of electrochemical machining (ECM) and wire electrical discharge machining (WEDM) processes. The experiments were planned using Taguchi’s methodology using L 9 Orthogonal array to study the effect of various process parameters i.e. applied voltage, wire feed rate (WFR) and duty cycle on the output quality characteristics such as diametric overcut (DOC) and material removal rate (MRR). The grey relational analysis (GRA) methodology was implemented for multi-response optimization. The diametric overcut and material removal rate of machined samples at optimum parametric conditions of GRA method improves from 71.87 μm to 60.20 μm and 34.20 mg/min to 32.30 mg/min respectively. The morphology of micro-sliced sample using GRA method signifies better quality machined surface with minimization of micro-cracks and uniform cutting.

Wire electrochemical discharge machining (WECDM) has the potential for cutting insulating materials. In order to achieve electrochemical discharges, WECDM is usually conducted on horizontal wire setup. It makes the design of machine tool difficult, especially in machining parts which require multi-axis control. The control of electrolyte level that has a significant influence on machining stability is also a complicated problem. In addition, the electrolyte cannot be sprayed to the machining zone with a relative high velocity to ensure a good electrolyte circulation, else the vulnerable hydrogen gas film that is used to electrically insulate the tool wire from the electrolyte can be destroyed. This paper proposes an oil film-assisted WECDM method. The oil film is online covered on the tool wire, and so the electrolysis only occurs at the positions where the oil film is absent. As a result, a stable insulating film, which consists of oil and hydrogen gas, is formed on the tool wire. Experimental results showed that electrochemical discharges were obtained during machining a 10.0-mm thick quartz glass on a vertical wire setup with spraying electrolyte condition. Finally, the effects of process parameters (applied voltage, electrolyte spraying velocity, wire speed, and workpiece feed rate) on machining performance were analyzed based on cutting experiments.