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.
Declaration of conflicting interests
The authors declared no potential conflicts of interest with respect to the research, authorship, and/or publication of this article.
Acknowledgments
This work was supported by the European Regional Development Fund within the OP „Science and Education for Smart Growth 2014-2020”, Project CoC “Smart Mechatronics, Eco- and Energy Saving Systems and Technologies”, №BG05М2ОР001-1.002-0023.
Disclosure statement
No potential conflict of interest was reported by the author(s).