Optimization of process parameter for surface finishing in abrasive flow finishing process
274 Optimization of process parameter for surface finishing in abrasive flow finishing process Ravi Gupta (M.E) Asst. Prof.(Lovely Professional University) raviarya43@gmail.com , Abstract-Abrasive flow finishing is a non-conventional finishing process that is used for finishing of work piece which are difficult to finish by conventional method i.e. by honing, lapping and other machining operations. It is used for polishing, deburring, removing recast layer of component and for cleaning of surfaces having complex shape and size of geometrical components. Abrasive flow finishing process polishes the surface by forcing the abrasive medium inside the work piece through the restricted area. One of the limitations of this process is that it is time consuming process and low material removal rate. To overcome these limitations, a structure has been developed. In this setup, centrifugal force has been generated by using a tool rod inside the hollow work piece to which rpm was provided. The abrasive mesh size, abrasive concentration, number of cycle, extrusion pressure, rotational speed of CFG rod, diameter of tool rod and shape of tool rod are the some important process parameter which affects the surface quality. In this research paper, the role of abrasive mesh size, extrusion pressure, abrasive concentration and rotational speed has been discussed on Gun metal as material of work piece. For experimentation design, taguchi approach L9 orthogonal array has been used and for analysis of result, ANOVA has been performed. KeywordsAFF, Surface roughness, rotational speed Taguchi method, ANOVA
Enhancing AFM process productivity through improved fixturing
Abrasive flow machining (AFM) is a non-conventional finishing process that deburrs and polishes by forcing an abrasive laden media across the workpiece surface. The process embraces a wide range of applications from critical aerospace and medical components to high-production volumes of parts. One serious limitation of this process is its low productivity in terms of rate of improvement in surface roughness. Limited efforts have hitherto been directed towards enhancing the productivity of this process with regard to better quality of workpiece surface. This paper discusses improved fixturing as a technique for productivity enhancement in terms of surface roughness (Ra). A rotating centrifugal-force-generating (CFG) rod is used inside the cylindrical workpiece which provides the centrifugal force to the abrasive particles normal to the axis of workpiece. The effect of the key parameters on the performance of process has been studied. The results shows that for a given improvement in Ra value, the processing time can be reduced by as much as 70–80%. It is seen that the significant process parameters are revolutions per minute of CFG rod, extrusion pressure and abrasive mesh size.
Study the Effects of Centrifugal Force on Abrasive Flow Machining Process
Abrasive flow machining is a non-conventional machining process and was developed in late 1960's as a method to deburr, polish and radius difficult to reach surfaces such as intricate geometries by flowing a semi-liquid paste over them. Abrasion occurs wherever the medium passes through the highly restrictive passage. The key components of AFM process are the machine, tooling and abrasive medium. The AFM is capable of economically producing high surface finish. One serious limitation of this process is its low productivity in terms of rate of improvement in surface roughness. Till now limited efforts have been done towards enhancing the productivity of this process with regard to better quality of work piece surface. In recent years, hybrid-machining processes have been developed to improve the efficiency of such processes. This paper discusses centrifugal force as a technique for productivity enhancement in terms of surface roughness (Ra). A rotating Centrifugal Force Generating (CFG) rod was used inside the cylindrical work piece, which provides the centrifugal force to the abrasive particles normal to the axis of work piece. The effect of the key parameters on the performance of process has been studied. Abrasive Flow Machining (AFM) is one of the latest non- conventional finishing processes, which possesses excellent capabilities for finish-machining of inaccessible regions of a component. It has been successfully employed for deburring, radiusing, and removing recast layers of precision components by extruding an abrasive laden polymer medium with very special rheological properties. High levels of surface finish and sufficiently close tolerances have been achieved for a wide range of components (7). The polymer abrasive medium which is used in this process possesses easy flowability, better self deformability and fine abrading capability. A special fixture is generally required to create restrictive passage or to direct the medium to the desired locations in the workpiece. The basic principle behind AFM process is to use a large number of random cutting edges with indefinite orientation and geometry for effective removal of material. The extremely thin chips produced in abrasive flow machining allow better surface finish upto 50nm, close tolerances in the range ± 0.5µm, and generation of more intricate surface (2). In this process tooling plays very important role in finishing of material. In order to cater to the requirement of high-accuracy and high- efficiency finishing of materials, AFM is gaining importance day by day. The AFM process has a limitation too, with regard to achieving required surface finish. With the aim to overcome the difficulty of longer cycle time, the present paper reports the findings of a hybrid process, which permits AFM to be carried out with additional centrifugal force applied onto the cutting media. The Abrasive Flow Machining process is a process that involves extruding an abrasive-filled semisolid media through a workpiece passage. The elements required for AFM process are the machine, workpiece fixture (tooling) and media. The machine used in AFM process hydraulically clamps the work-holding fixtures between two vertically opposed media cylinder. These cylinders extrude the media back and forth through the workpiece(s).Two cylinder strokes, one from the lower cylinder and one from the upper cylinder, make up one process cycle. Both semiautomatic machines and high-production fully automated system are widely used. The extrusion pressure is controlled between 7-200bars, as well as the displacement per stroke and the number of reciprocating cycles are controlled. AFM process is an efficient method of the inner surface finishing process. In practical application, it has an obvious effect on surface finishing of the industrial valves, and the parts/components of die, etc.