Abstract
Electrical discharge machining (EDM) has been widely used in the machining of mechanical parts. However, the parts obtained by EDM have recast layers and micro-cracks on their surface, which seriously affect their mechanical properties. In order to remove the recast layers and micro-cracks resulted from EDM, this paper proposed to combine micro-EDM with negative polarity micro-EDM. First, the mechanical part was machined using conventional EDM, after which the surface of the part had a distinct recast layer and micro-cracks. As the conventional EDM was nearing completion, the power supply was replaced by a micro-EDM power supply and then the part was processed by micro-EDM to reduce the thickness of the recast layer. After micro-EDM, the part was processed by negative polarity micro-EDM, which can remove the recast layer and the micro-cracks on the surface of the part. Conventional EDM was performed on 304 stainless steel using a copper electrode with voltage of 250 V, pulse width of 7 ms, and pulse interval of 5 ms. The experimental results showed that the recast layer and micro-cracks on the surface of the part were obvious and the surface quality of the part was poor. After that, the same part was sequentially subjected to micro-EDM and negative polarity micro-EDM with voltage of 110 V, pulse width of 0.5 μs, and pulse interval of 15 μs. The experimental results showed that the recast layer and micro-cracks on the surface of the part were almost invisible and the surface quality of the part was greatly improved.
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Acknowledgments
The authors are grateful to their colleagues for their essential contribution to the work.
Funding
This work is supported by the National Natural Science Foundation of China (No. 51605304, No. 51805333, No. 51575360), the Natural Science Foundation of Guangdong Province (No. 2017A030313309, No. 2016A030310036), and the Science and Technology Innovation Commission Shenzhen (No. JCYJ20170817094310049, No. JSGG20170824111725200).
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Xu, B., Chen, Sg., Liang, X. et al. Recast layer removal of 304 stainless steel by combining micro-EDM with negative polarity micro-EDM. Int J Adv Manuf Technol 107, 4713–4723 (2020). https://doi.org/10.1007/s00170-020-05312-y
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DOI: https://doi.org/10.1007/s00170-020-05312-y