Enhancing the surface integrity of gas turbine compressor blades using alumina abrasives in magnetic finishing: an experimental approach

Magnetic Abrasive Finishing (MAF) is a highly effective technique for enhancing the surface integrity of high-value components with complex geometries, owing to its non-contact, flexible, and precisely controllable nature. This study investigates the use of Al₂O₃ (alumina) powder as an abrasive medium in the MAF process, selected for its high hardness, thermal stability, and chemical inertness. Although Al₂O₃ is only weakly paramagnetic, it was successfully incorporated into the magnetic abrasive brush through mechanical blending with ferromagnetic particles that respond to the magnetic field. This hybrid abrasive system enables effective control of finishing forces, leading to significant improvements in surface quality and the elimination of surface defects. A series of controlled experiments was conducted to evaluate the influence of key process parameters—rotational speed, working gap, abrasive mixing ratio, and processing time—on surface roughness and material removal. The results demonstrated that the inclusion of Al₂O₃ in the MAF process significantly enhanced surface finish and micro-crack removal without compromising dimensional accuracy. Optimal finishing performance was achieved at a rotational speed of 630 rpm, a gap of 1.8 mm, and a mixing ratio of 30%, resulting in a maximum surface roughness improvement of 33.7%. Furthermore, the elimination of micro-cracks contributed to a substantial increase in fatigue resistance. While most trials yielded consistent results, one test showed slightly lower performance due to an increased working gap, reduced brush flexibility, and potential contamination from dense Al₂O₃ particles. The study suggests that Al₂O₃-enhanced MAF is a promising method for extending the service life of metal components.