Fabrication of MicroNano Structures via Precision Machining by Unknown

Author:Unknown
Language: eng
Format: epub
ISBN: 9789819913381
Publisher: Springer Nature Singapore

A small Toff means a too short time was applied for transferring the corrosion products that produced in the EDM process, which caused a trouble to renew the dielectric fluid in the limited time. The corrosion products that were unable to be transferred in a timely manner that were easily non-uniformly deposited on the electrode working surface, which induced some troubles include short circuits and arc discharge. Correspondingly, micro-crater was formed on the microstructure bottom surface. With the increase of Toff, the difficulty of the corrosion products transferring was gradually declined, and the quality of the bottom surface of the microstructure gradually improved. When the Toff reached to 30 μs, defects such as discharge ridges and micro-crater were effectively disappeared. For the further increase of Toff, a too low pulse duty cycle decreased the processing energy. The phenomena of short circuits and arc discharge caused an unstable machining process, reducing the removal efficiency of discharge ridge, which led to the regeneration of micro-craters especially with a Toff of 60 μs.

Figure 5b displays the effects of Ton on the elimination of discharge ridges when the Toff was 30 μs. When the Ton was 10 μs, the result surface generated clear micro-crater and discharge ridges. With the increase of Ton, the micro-crater and discharge ridges were gradually weakened. When it increased to 30 μs, the smooth machined surface had no obvious defect. However, with the further increase of Ton, the micro-craters became increasingly visible. The crater was the most obvious when the Ton was 60 μs.

The results showed that with a small Ton of 10 μs, a low pulse duty cycle caused an unstable machining process and surface defects such as micro-crater and discharge ridges. With the increase of Ton, the duty cycle became reasonable and the quality of the bottom surface gradually improved. When the Ton increased up to 30 μs, the microstructure with a smooth surface and without clear defect. With the further increase of Ton, the MRR also improved. Within a limited time, the redundant processing products were unable to be effectively transferred, leading to short circuits and arc discharge during the process. In summary, when the Ton is out of range, defects can be easily formed on the bottom surface.

Thus, with Ton and Toff both at 30 μs, discharge ridges on the bottom surface of the machining result were effectively removed, and there were no micro-crater.

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