Experimental investigation on surface finish during intermittent turning of UNS M11917 magnesium alloy under dry and near dry machining conditions

• Intermittent turning of magnesium alloy is analysed.
• Finish operations are evaluated.
• A clear influence of feed rate on surface roughness is identified.
• No effect of the interruption is found on surface quality.
• A detrimental effect of the MQL system is found at the conditions tested.

In the last decades, light materials, such as magnesium, are increasing their use in a wide range of industrial applications. The growing use of magnesium encourages the study of its use under different production processes. In this sense, the present study shows an experimental investigation in intermittent turning of UNS M11917 magnesium alloy, analysing different machining conditions: cutting speed, depth of cut and feed rate, along with the use of dry machining and minimum quantity lubrication (MQL) system. To evaluate intermittent turning process, continuous bars and slotted bars were used. The process is evaluated taking as response variable the surface roughness. Full factorial experimental designs are used and their results are analysed using the Analysis of Variance (ANOVA). Main results of the statistical analysis include the identification of feed rate as the main significant factor for all the tests, explaining the most part of the variability analysed. By contrast, cutting speed and type of interruption were not found to be significant sources of variability when analysed in isolation. Moreover, more dispersion of surface roughness values, in terms of Ra, was identified when machining at low feed rates which can difficult its prediction. In addition, when analysing depth of cut, this factor and its interaction with feed rate are also found to be significant sources of variability for Ra. Finally, the influence of the environment used in the machining process is also studied, finding that the use of the MQL system can lead to slightly worse surface roughness (Ra) results at the higher feed rates tested.