Generic three-dimensional model of freeform surface polishing with non-Newtonian fluids

• Published in: International journal of machine tools & manufacture 2022-01, Vol.172, p.103837, Article 103837
• Main Authors: Zhu, Wu-Le, Beaucamp, Anthony
• Format: Article
• Language: English
• Subjects: Abrasives; Compliant finishing; Dynamic models; Fluid dynamics; Material removal rate (machining); Newtonian fluids; Non Newtonian fluids; Non-Newtonian fluid; Polishing; Polymers; Removal mechanism; Rheological properties; Rheology; Stress distribution; Surface finish; Three dimensional flow; Three dimensional models; Workpieces
• ISSN: 0890-6955; 1879-2170
• DOI: 10.1016/j.ijmachtools.2021.103837

Non-Newtonian fluids are being increasingly considered for application in manufacturing. Their combination with compliant polishing techniques offers a promising approach for ultraprecision finishing of freeform surfaces. However, in-depth understanding of the underlying material removal mechanism and its link with slurry rheology has not been disclosed yet. In this study, a comprehensive three-dimensional dynamic modeling framework is presented, which enables accurate prediction of stress distribution, rheological flow, compliant deformation in 3D, as well as material removal behavior on curved workpieces. Supported by experimental tests and theoretical analysis, it is demonstrated that the viscosity peak gets shifted to a higher frequency by mixing starch and polymer, which makes high speed polishing with improved material removal rate possible. Meanwhile, it is found that the polymer additive prevents large size starch agglomeration and has high affinity with fine abrasives, both of which greatly contribute to the obtained scratch-free and nanoscale surface finish. Finally, the controllability and predictability of the process are demonstrated by polishing a bi-sinusoidal freeform surface onto a planar workpiece coated with nickel. [Display omitted] •A 3D dynamic model for contactless finishing enhanced by non-Newtonian fluid shearing behavior is proposed.•The model reveals the macroscopic multi-coupling and microscopic material removal behaviors associated with fluid rheology.•Simulations are carried out to derive process parameters including stress tensor, varying viscosity, flow contour, etc.•Experiments and analysis explain the essential role of polymer additives in greatly enhancing the finishing performances.•The prediction consistency validates the model accuracy, and deterministic polishing of a freeform surface is demonstrated.