Multi-objective optimization of the internal diamond burnishing process

Abstract

ABSTRACT The paper presents a new single-operation two-transition technology for processing holes in sliding bearing bushings made of CuAl8Fe3 bronze. The technology was realized on a vertical machine center Haas MiniMill. During the first transition, the hole was formed by a new combined cutting tool and was then diamond burnished via a new device with an elastic beam providing the burning force. The deforming element was a spherical-ended polycrystalline diamond. The 2D and 3D surface texture parameters of the processed holes obtained after the first and second transitions were studied via experiments and regression analyses. Through one-objective optimization of the first transition, the optimal feed and cutting velocity values were found under a minimum roughness criterion. The optimal governing factors (diamond insert radius, burnishing force and feed rate) of the diamond burnishing process were determined through multi-objective optimization. The objective functions – micro-hardness and height and shape parameters of the surface texture – were selected in terms of processed hole requirements: improved lubrication conditions and increased micro-hardness. The formulated multi-objective optimization task was solved via non-dominated sorting genetic algorithm (NSGA-II). Experimental verifications confirmed the results. The processing series of holes showed that the new technology ensures good repeatability of the surface integrity characteristics.