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In this research the abrasive flow finishing process (AFF) of AISI H13 hot work steel was studied and the effects of various process parameters such as flow pressure (extrusion pressure), abrasive particles densities, abrasive particles sizes and the first quality of surfaces on variations of surface roughness and material removal have been investigated. The results showed that increasing the density of abrasive particles leads to increase in variations of surface roughness and material removal. Increase of extrusion pressure from 4 to 6 MPa causes the increase in variations of surface roughness and material removal and from 6 to 8 Mpa leads to decrease in the two latter. Electron microscopic results showed that increase of finishing process time over 4 hours causes a detrimental effect on the surface of the specimens, as a result of penetration and stabilization of abrasive particles in the form of broken particles. Also according the results of this paper, increasing the size of abrasive particles leads to higher variations of surface roughness and material removal, and this process is more effective in finishing of rougher surfaces.

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Abrasive flow machining (AFM) is a relatively new process with low material removal ratio for deburring, removing recast layers and finishing industrial components with complex shapes among non-conventional machining processes. In this process, the finishing is handled by flowing of the composition of viscoelastic and abrasive particles on workpiece surface, under the pressure of piston. In this research, the abrasive flow machining process of H13 tool steel with applied an external magnetic field around the workpiece for improve the material removal ratio and surface roughness has been investigated and the effect of magnetic field intensity, abrasive particles mesh and the hardness of workpiece as the input parameters on the process outputs including surface roughness and material removal ratio was studied. Also the regression model of MRR and surface roughness was developed and variance analysis was performed. Results of experiments indicated that increase in abrasive-particles mesh leads to decrease surface roughness and material remove ratio and increase in magnetic field intensity causes to increase material removal ratio and decrease surface roughness. Also the material removal ratio is decreased with increasing of workpiece hardness and on the same condition; better surface finish was achieved in the case of harder workpiece.

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Rotational abrasive flow machining process (RAFM) is one of the modern surface polishing processes where in the material removal in micro and nano sizes is performed by tiny abrasive particles. Rotational abrasive flow machining is very effective in finishing of complex internal and external surfaces.in comparison with other finishing methods. In this study, the rotational abrasive flow machining process has been investigated in polishing of AISI H 13 hot work steel. The main objectives of workpiece rotation was increasing the material removal rate and decreasing the surface roughness of workpiece. So the effects of rotational speed and hardness of workpiece and the mesh size of abrasive particles as input variables on the output parameters including surface roughness and material removal rate have been studied. The results showed that applying of rotational speed of workpiece leads to higher material removal rate and lower surface roughness. Furthermore, the material removal rate is decreased and surface roughness is improved by increasing the mesh size of abrasive particles. Also, increasing the hardness of workpiece leads to decreasing the material removal rate, and in similar cutting conditions, the surface of workpiece with more hardness is better polished in comparison with the surface of workpiece with lower hardness.