Effect of the Cryogenically Treated Copper Nozzle Used in Plasma Arc Machining of S235 Steel

Figure 6

The 3D response surface plot for surface roughness (a, c, e) cryogenically treated nozzle and (b, d, f) nontreated nozzle: (a, b) SR vs. arc current and cutting speed under 4 bar pressure; (c and d) SR vs. arc current and cutting speed under 5 bar pressure: (e, f) SR vs. arc current and cutting speed under 6 bar pressure; figures were obtained from design expert, where red color represents maximum value, green color represents intermediate values, and blue color represents minimum values.

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(b)

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