Using a DoE for a comprehensive analysis of the surface quality and cutting speed in WED-machined hadfield steel.

Wire electrical discharge machining (WEDM) is an unconventional machining method for manufacturing complex-shaped, precise components. Considering the high-energy intensity of the wire erosion process, its effective implementation requires a maximum cutting speed while still ensuring the best possible quality of the machined surface. For this latter purpose, we conducted a design of experiment (DoE) comprising 33 cycles and five input factors, or machine setting parameters: Gap voltage, pulse on time, pulse off time, discharge current, and wire feed. In this context, we statistically evaluated the cutting speed in Hadfield steel, as related to machine setting parameters, and also analyzed the machined surfaces of the applied samples. The actual experiment involved examining in detail the topography of the surfaces, using one contact and three non-contact profilers. The surface morphologies were observed via electron microscopy, and a lamella was prepared to facilitate the chemical composition analysis (EDX) with a transmission electron microscope (TEM). To study the subsurface layer and its defects, we produced metallographic specimens of all the samples; the items were observed by means of light and electron microscopes. With a maximum cutting speed the highest quality of the machined surface was achieved; however, the burned cavities can affect the life expectancy of the machined parts. The TEM lamella revealed that the individual alloying elements had segregated into regions, exhibiting high volumes of both manganese and the recast layer and, due to the use of WEDM, a manganese separation layer had formed at the boundary of the recast layer and the base material. [ABSTRACT FROM AUTHOR]