Progress in fluidized bed assisted abrasive jet machining (FB-AJM): Internal polishing of aluminium tubes

Abstract

This paper deals with the internal finishing of tubular components made from a high strength aluminium alloy (AA 6082 T6) using a fluidized bed assisted abrasive jet machining (FB-AJM) system.Firstly, a Taguchi's experimental plan was used to investigate the influence of abrasive jet speed, machining cycle, and abrasive mesh size on surface roughness and material removal trends. Secondly, the leading finishing mechanisms were studied using combined 3d profilometer-SEM analysis to monitor the evolution of the surface morphology of machined workpieces. Finally, the circumferential uniformity and precision machining of the inner surface of workpieces were tested by evaluating the values of the more significant roughness parameters in different circumferential locations.Consistent trends of surface roughness vs. operational parameters were measured, and significant material removal was found to affect the workpieces during machining. As a result, FB-AJM was found to preferentially machine the asperities and irregularities of the surface, thereby altering the overall surface morphology producing more regular and smoother finishing. Moreover, the good circumferential uniformity and machining accuracy FB-AJM guarantees even on ductile aluminium alloy workpieces ensure that this technology can be applied to a diverse set of industrial components. r

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

“…This way, the measurement of the mass variation is altered by the presence of abrasive residuals into the machined surface, as the evidence of SEM image in Fig. 3 shows and in agreement with what is reported in the pertinent literature for similar process conditions (Ref [8][9][10].…”

“…The description of FR-FBM system is detailed elsewhere (Ref [8][9][10]. Figure 1 shows a sketch of the system, which consists of an air feeding system (mostly, a blower), an air plenum chamber to ensure the proper air feeding to the fluidization column and its distribution across the column, a porous plate distributor, which allows the fluidization air to pass through while it retains the powders to be fluidized, a fluidized bed column in which the fluidization takes place, a couple of cyclones, a static or rotating sample holder, and, then, controls, tubes, valves, and all the necessary fittings.…”

Progress in abrasive fluidized bed machining

“…However, in critical cases, such as for small equipment, brittle workpieces and/or faster machining operations, they can be easily removed by sedimentation (if the abrasives are lighter than the machining debris), elutriation (if the abrasives are heavier than the machining debris) or filtration (if the abrasives have an average dimension greater than that of the machining debris). Although such issues need to be considered, it is worth emphasizing that the aforementioned operations are generally performed automatically and do not involve any great effort, as reported for several studies Barletta et al, 2007aBarletta et al, ,b, 2006b.…”

“…17f and g). In this way, average roughness of 0.1 m and lower can be achieved for harder and tougher metals such as D2 steel and Inconel Barletta et al, 2007b) and in the range 0.2-0.4 m for softer metals such as aluminum and brass (Barletta et al, 2007a;Barletta, 2003). Moreover, improvements in cylindricity can be considerable (Davidson et al, 1985), sometimes up to an order of magnitude.…”

Fast Regime-Fluidized Bed Machining (FR-FBM) of Atmospheric Plasma Spraying (APS) TiO2 coatings

“…Details on the technology used are reported elsewhere [13][14][15]. The system consists primarily of a compressor, a fluidization chamber, the bottom of which is a porous plate, a couple of cyclones, a movement system, plus controls, tubes, valves and all the necessary fittings (Fig.…”