As an effective and affordable technique, deep ball-burnishing has been applied to induce the plastic deformation of material, thus resulting in an increased surface hardness, compressive residual stress, and finish quality. Recent research shows that the fast degradation of an Mg alloy implant is a prime limiting factor for its success in in vivo human trials. This paper presents a comprehensive investigation into deep ball-burnishing of a biodegradable AZ31B Mg alloy, in order to improve the alloy’s surface integrity. A series of experiments using an in-house built burnishing tool with a 10-mm steel ball have been conducted, with a key focus of exploring the influence of the major process parameters—e.g., burnishing force (750–2650 N), feed rate (150–500 mm/min), and step-over (0.05–0.15 mm)—on hardness and finish quality. With the aim of performing a parametric sensitivity study, a three-dimensional (3D) finite element (FE) model is developed to predict the deformation mechanics, plastic flow, hardness, and residual stress. The FE model agrees with the experiment, hence validating the reliability of the model. Results show that while burnishing significantly improves surface integrity compared to the untreated surface, burnishing force and step-over are shown to be dominant. The net material movement dictates generated residual stress (tensile or compressive), often negatively affecting the surface integrity (e.g., surface cracks), which may be responsible for the onset of corrosion. An appropriate burnishing strategy must therefore be planned, in order to achieve the intended process outcome. The resulting surface properties, enhanced by the deep ball-burnishing, are expected to potentially increase the corrosion resistance of AZ31B Mg alloy implants.

This paper investigates the underlying interplay between the key process parameters of magnetic abrasive finishing (MAF) in improving surface quality. The five process parameters considered were the working gap, rotational speed, feed rate, abrasive amount, and abrasive mesh when MAFed independently with two abrasive particles—SiC and Al₂O₃. A series of experiments were conducted with an in-house built MAF tool. Based on the main effect results, a model predicting roughness reduction was developed. Results show that surface quality improvement and the underlying dominant process parameters seem unique to the abrasive type used. When MAFed with SiC, the abrasive quantity and rotational speed influence the most. On the other hand, when MAFed with Al₂O₃, the trend is different to SiC, i.e., the abrasive mesh size and the working gap are dominant. The prediction model was well validated by independent experiments, indicating its accuracy in estimating and optimizing the process outcome. MAF is a simple process with a complex interplay between parameters. This is very crucial when abrasive type, size, and amount to be used are concerned, which warrants a deeper investigation in terms of underlying dynamics, interactions, and the deformation of abrasive, magnetic, and workpiece materials.