Surface Topography: Metrology and Properties

Vibratory finishing belongs to the wider group of near ubiquitous mass finishing processes. Components are typically bulk finished in a fluidised media bed and applications vary from performance critical polishing, to cosmetic surface preparation. The established model of surface topography development has been one of initial rapid change during a ‘transient’ process phase, with subsequent slowing and a final ‘steady state’ phase in which surface character is uniform with no dependence on process duration or initial surface finish. Recent reassessment of the steady state phase has suggested that its surface roughness oscillates with process duration about a mean value and redefines it as the ‘equilibrium’ phase. Though this new model is considered to incorporate the existing model as a special case, it is argued that it represents a fundamental shift in the process mechanics. In addition, it is argued that the new findings have potential relevance to a much wider group of stochastic processes. Thus, the current paper seeks to clarify the underlying development process by investigating the nature of the end phase surface and testing these models by examining new and existing data. Results show no statistical evidence to support any periodic oscillations in the end phase surface and a number of issues with the oscillating model are noted. In addition, it is suggested that there is no clear physical mechanism to underpin the oscillating model and that the saturating model is sufficient to describe all the presented data. In conclusion a qualitative description of the end phase topography and its dynamic but temporally uniform character is given. The idea of ‘process bandwidth’ relating to the range of surface-media interactions is introduced to help describe some of the behavioural and control aspects of this stochastic process and the surface topography it produces. PAPER 2018 Original content from this work may be used under the terms of the Creative Commons Attribution 3.0 licence. Any further distribution of this work must maintain attribution to the author(s) and the title of the work, journal citation and DOI. RECEIVED 14 May 2018 REVISED 7 September 2018 ACCEPTED FOR PUBLICATION 18 September 2018 PUBLISHED 12 October 2018 OPEN ACCESS https://doi.org/10.1088/2051-672X/aae218 Surf. Topogr.: Metrol. Prop. 6 (2018) 045002