INTERNAL FINISHING OF THICK CYLINDER SUS 304 STEEL TUBES USING MAGNETIC ABRASIVE FINISHING SETUP
Magnetic Abrasive Finishing (MAF) is an advanced finishing method, which improves the quality of surfaces and performance of the products. Surface is finished by removing the material in the form of microchips by abrasive particles in the presence of magnetic field. The material is removed in such a way that surface finishing and deburring are performed simultaneously with the applied magnetic field in the finishing zone. The mechanism of super finishing in any finishing process is widely focused by the knowledge of forces involved in the process. This paper deals with the detailed parametric study in super finishing of stainless steel SUS 304 thick steel tube. Statistically designed experiments based on Taguchi methods show that weight of abrasive, Revolutions per minute (rpm), magnetic abrasive diameter (Mesh No.) and finishing time have significant effect on the surface roughness obtained. Analysis of experimental data showed that change in surface roughness (ΔRa) was highly influenced by mesh number followed by percentage weight of abrasives, rpm of permanent magnet, and finishing time.
Key Words: Magnetic abrasive finishing (MAF), Design of experiments, Surface roughness.
Fine surface finish is in high demand in a wide spectrum of industrial applications. An internal magnetic abrasive finishing process was proposed for producing highly finished inner surfaces of work pieces. It is difficult to finish advanced engineering materials with high accuracy, and minimal surface defects such as micro cracks, by conventional grinding and polishing techniques. To minimize the surface damage, gentle/flexible finishing conditions are required, namely, a low level of controlled force. Magnetic field assisted manufacturing processes are becoming effective in finishing, cleaning, deburring and burnishing of metal and advanced engineering material parts. Magnetic abrasive finishing (MAF) is one of the non conventional machining processes which came to the surface in 1938 in a patent by Harry P. Coats.
The countries which are involved in the study and development of this process are USA, France, England, Bulgaria, Japan and Germany. In modern time, fine surface finish is in high demand with the development of industry manufacturing technology, in a wide range of industrial applications. A relatively new finishing advanced machining process in which cutting force is primarily controlled by the magnetic field and it can achieve highly finished surfaces that conventional techniques never achieve. MAF is a fine finishing technique which can be employed to produce optical, mechanical, and electronic components with micrometer or sub micrometer form accuracy and surface roughness within nanometer range with hardly any surface defects. Finishing of bearings, precision automotive components, shafts, and artificial hip joints made of oxide ceramic and cobalt alloy are some of the products for which this process can be applied. This process can be used to produce efficiently good surface quality on at surfaces as well as internal and external surfaces of tube type work pieces. The method can, not only machine ferromagnetic materials such as steel, but can also machine non ferromagnetic materials such as stainless steel, aluminium and brass. The Abrasives generally rely upon a difference in hardness between the abrasive and the material being worked upon, the abrasive being the harder of the two substances. Shinmura et al. prepared two types of magnetic abrasives by sintering. In first sample, diameter of iron particle was varied and in second, diameter of abrasive particle varied. They reported that diameter of iron particle effects both stock removal and surface finish. Influence of the diameter of abrasive particle on stock removal was comparatively small while surface roughness was...
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