Investigation of Surface Quality for Minor Scale Diameter of Biodegradable Magnesium Alloys during the Turning Process Using a Different Tool Nose Radius

The main objective of the study is to analyze the various cutting parameters to investigate the surface quality of the minor scale diameter of magnesium alloy in the dry turning process using a different tool nose radius (r). The surface roughness (Ra) was gauged, and micro-images produced by scanning electron microscopy (SEM) were reviewed to evaluate the machined surface topography. The analysis of variance (ANOVA), linear regression model and signal-to-noise (S/N) ratio were applied to investigate and optimize the experimental conditions for surface roughness. The study results imply that the feed rate and tool nose radius significantly affected the surface quality, but the spindle speed did not. The linear regression model is valid to forecast the surface roughness. The cutting parameters for optimum surface quality are a combination of a spindle speed of 710 rpm, a feed rate of 0.052 mm/rev and a tool nose radius of 1.2 mm. The machined surface topography contains the feed marks, micro-voids, material side and material debris, but they become smaller and decrease at a lower feed rate, larger tool nose radius and higher spindle speed. These results show the good surface quality of magnesium alloys in a dry turning process, which could be applied in implant, orthopedic and trauma surgery.

Turning parameters effects in residual stresses of AISI 1045 steel

The main objective of this work was to evaluate the influence of turning parameters on the generation of residual stresses in AISI 1045 steel bars. Therefore, effects of four main parameters as feed rate, cutting velocity, tool nose radius, and rake angle were analyzed. Residual stresses investigation through X-ray diffraction (XRD) was carried out at different depths (surface, 5, 10, 20, 50, and 75 μm). As the samples showed distinct roughness patterns with variable amplitude and shape, and based in a previous work, samples were classified in two main groups accordingly with surface finishing (regular and irregular). The current results showed that feed rate and cutting speed played the major influence on residual stress distributions. Moreover, the tool nose radius affected surface residual stresses, whereas the rake angle did not significantly change it. Finally, samples could be divided in two residual stress groups, showing a direct relation of surface finishing quality and residual stresses.