Papers by Keyword: Abrasive Jet

Abstract: Based on the modeling and experiments concerning the surface roughness in abrasive jet finishing with grinding wheel as restraint, the effect of abrasive size, abrasive fluid concentration, machining cycle, wheel velocity and carrier fluid on machined surface quality was investigated. Surface grinder M7120 was employed in a jet machining experiment conducted with W18Cr4V and 40Cr materials, profilometer TALYSURF was used to measure the micro geometrical parameters after machining, and SEM was used to observe surface micro-morphology. Experimental results show that with W7 Al2O3 powder at the mass fraction of 10% and antirust lubricating liquid being adopted in jet machining for 20 to 30 cycles, not only high surface shape precision can be kept or obtained, but also defect-free machined surface with the roughness of Ra0.15～1.6µm can be obtained with high efficiency. Experimental observation and experimental results proved that the experimental results agree well with a mechanism-based machining model.

Abstract: The abrasive jet finishing process with wheel as restraint is a kind of compound precision finishing process that combined grinding with abrasive jet machining, in which inject slurry of abrasive and liquid solvent to grinding zone between grinding wheel and work surface under no radial feed condition when workpiece grinding were accomplished. The abrasive particles are driven and energized by the rotating grinding wheel and liquid hydrodynamic pressure and increased slurry speed between grinding wheel and work surface to achieve micro removal finishing.In the paper,the finished surface morphology was studied using Scanning Electron Microscope (SEM) and microscope and microcosmic geometry parameters were measured with TALYSURF5 instrument respectively. According to the metrical results, the surface topographical characteristics were evaluated with correlation function and PSD (Power Spectral Density) of random process about machined surface before and after finishing. The results show that longitudinal geometry parameter values of finishing machining surface were diminished comparing with ground surface,and the mean ripple distance was decreased and, ripple and peak density were increased. Furthermore, the finished surface has little comparability compared to grinding machining surface.The isotropy surface and uniformity veins at parallel and perpendicular machining direction were attained by abrasive jet precision finishing with grinding wheel as restraint and the surface quality is improved obviously.

Abstract: The process technique on abrasive jet finishing process with wheel as restrain was investigated by experimental. The effects of different particle size, abrasive concentration, machining cycles, the velocity of grinding wheel and medium type on surface quality were analyzed. Experiments were performed with plane grinder M7120 and workpiece material 40Cr steel. The machined surface morphology was studied using Scanning Electron Microscope (SEM) and microscope and microcosmic geometry parameters were measured with TALYSYURF5 instrument respectively. The experimental results under percentage 10 abrasive concentration, Al2O3 abrasive particle with W7 size and machining 20～30 circles showing the novelty process method, not only to attain higher surface form accuracy, to diminish grinding defects such as severely deformation, surface layer pollution and ground burnout, but also to can acquire efficiently free defects finishing surface with Ra0.15～1.6µm and finally achieve high efficiency, high precision and low roughness values. Furthermore, integrate grinding process and abrasive jet finishing process into one feature.

Abstract: The erosion process in micro-machining of brittle glasses using a low pressure slurry jet is discussed. The process capability of the technique is assessed by examining the machined surface integrity in relation to fluid flow dynamics in micro-hole generations. The holes produced are characterised by a “W” shape in the cross section, while the surface morphology is distinguished by three zones associated with the fluid flow behaviour, i.e. a direct impact zone, a wavy zone and an accumulation zone. The surfaces appear to be smooth and without cracks, indicating a predominance of the ductile mode erosion process. With the increase of pressure, the erosion rates can be enhanced as a result of the expending of the accumulation zone while the outer diameter of the holes remains unchanged. This study shows that this technique can be used for micro-machining with high surface quality, and provides an essential understanding for further research in the avenue.

Abstract: Abrasive jet finishing process is a novel process whose objective is to remove surface defect layer and to diminish roughness and ripple after grinding. Experiments were performed with plane grinderM7120 and workpiece material 45# steel which was ground with the surface roughness values of Ra =0.2-0.6 μm . The machined surface morphology was studied using SEM and the microcosmic geometry parameters were measured with MICROMESVRE2 instrument. In this paper, with the fractal dimension, Ra , Rq and the supporting rate curve, the surfaces of grinding machining and abrasive jet finishing machining were researched. The result indicated that the machined surfaces changed from continuous parallel micro-groove and plough to randomly distributed discontinuous micro-pit could be observed with the increase of machining circles and surface roughness was obviously improved. Furthermore, the isotropy surface and uniformity veins both parallel and perpendicular machining direction were attained by abrasive jet precision finishing with grinding wheel as restraint. The supporting rate curve of the surface profile can be increased. This is favorable for the wearable capability of the workpiece.

Abstract: The models for three-dimensional velocity and hydrodynamic pressure of abrasive fluid in contact zone between wheel and workpiece on abrasive jet finishing with wheel as restraint were presented based on Navier-Stokes equation and continuous formulae. The emulational results shown that the hydrodynamic pressure was proportion to grinding wheel velocity, and inverse proportion to the minimum gap between wheel and workpiece and the maximum pressure was generated just in the minimum clearance region in which higher fluid pressure gradient occur. It can also be concluded the pressure distribution was uniform in the direction of width of wheel except at the edge of wheel because of the side-leakage. The velocity in the x direction was dominant and the side-leakage in the y direction existed. The velocity in the z direction was smaller than the others because of the assumption of laminar flow. The smaller the gap distance is, the larger the velocity in the x direction. The magnitude of the velocity is also proportional to the surface velocity of the wheel.