Fast Regime – Fluidized Bed Machining (FR-FBM) of Thermally Sprayed Coatings

Finishing of thermally sprayed metallic, ceramic and cermet coatings is required in order to meet tolerances and requirements on surface roughness in most industrial applications. Conventional machining is a costly and time-consuming process, difficult to automate. Therefore, this study investigates and develops a new technique highly amenable for automation: Fast Regime - Fluidized Bed Machining (FR-FBM). Atmospheric Plasma Sprayed (APS) TiO₂, Cr₂O₃ and HVOF-sprayed WC-17%Co and Tribaloy-800 coatings, deposited on AISI 1040 steel substrates, were subjected to FR-FBM treatment. The effects of the leading operational parameters, namely, abrasive size, jet pressure and processing time, were evaluated on all coatings by using a two/three-levels full factorial Design Of Experiments (DOE). The FR-FBM treated surfaces were observed by FE-SEM and their surface finishing was evaluated by contact profilometry. Significant improvements in surface finishing of all the machined thermally sprayed coatings can always be detected, with FR-FBM being able to guarantee the precision and the respect of the closest geometrical tolerances.