Study on analysis of plasma resistance variation in WEDM of insulating zirconia

ABSTRACT

Wire electrical discharge machining (WEDM) is a specialized electrothermal machining process capable of producing complex shapes with close tolerances irrespective of material hardness. Zirconia (ZrO₂) ceramic has higher fracture toughness and flexural strength which can be useful in a variety of applications, but the principle limiting factor is its electrical conductivity. Assisting electrode (AE) method is one of the methods to overcome the above limitation that serves the purpose without altering the basic properties of ceramic material. In the present research, the Zirconia (ZrO₂) is coated with a copper layer. The kerosene dielectric suggested in past literature for machining of insulating ceramics is replaced by the graphite additive mixed distilled water to provide an environment-friendly approach. The electrical resistivity of ZrO₂ imposing some restrictions for a normal machining operation, so the discharge voltage variations are analyzed at three different machining stages, namely, Assisting electrode (AE), AE-ceramic interface and insulating base ceramic. Also, the nature of the spark and its variation concerning the discharge voltage is studied with the help of images captured by a high-speed camera. The combined study of the discharge voltage pulse and the spark image helps to understand the machining phenomena.

KEYWORDS:

• Zirconia ceramic
• assisting electrode
• wire electric discharge machining (WEDM)
• insulating ceramic
• distilled water

Acknowledgements

This work has been financially supported by TEQIP-II project scheme run by the Govt. of India. Also, we would like to acknowledge the help received from Simantak Wankhede in carrying out the experimental work.

Additional information

Funding

This work has been financially supported by TEQIP-II project scheme run by the Govt. of India.