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A Study of Abrasive Jet Machining

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Abrasive jet machining falls under a category of mechanical process or it is an unconventional and nontraditional manufacturing process. In this machining fine abrasive grades or particles in a jet of inert gas hit the work piece at very high velocity (usually in the order of 200-400 m/sec). This high velocity of jet of abrasives causing the material removals from the workpiece in the form of chips. This are very effectively removes hard or brittle materials. This is use for cutting, cleaning, polishing, au etching. This effectively work on glass, silicon, tungsten and ceramic because these all under categories of hard and brittle material. This machining is not suitable for soft materials like aluminum, rubber etc. Because abrasive particles get plunged into the material, which provide additional operation like cleaning. In abrasive jet machining varies process parameter such as abrasive, gas, nozzle and velocity of fluid are usual. This paper give u perfect knowledge about the abrasive jet machining. In this machining varies abrasive are aluminium oxides and silicon carbide. This is under a category of conventional abrasive. In some new machine cubic boron and diamonds used
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  © ADR Journals 2017. All Rights Reserved. Research Artcle A Study of Abrasive Jet Machining Gulshan Kumar 1 , Monu Kumar 2 , Kulwinder Singh 3 , Ravi pal Rana 4 , Suraj Tiwari 5 Abstract Abrasive jet machining falls under a category of mechanical process or it is an unconvenonal and non-tradional manufacturing process. In this machining ne abrasive grades or parcles in a jet of inert gas hit the work piece at very high velocity (usually in the order of 200-400 m/sec). This high velocity of jet of abrasives causing the material removals from the workpiece in the form of chips. This are very eecvely removes hard or brile materials. This is use for cung, cleaning, polishing, au etching. This eecvely work on glass, silicon, tungsten and ceramic because these all under categories of hard and brile material. This machining is not suitable for so materials like aluminum, rubber etc. Because abrasive parcles get plunged into the material, which provide addional operaon like cleaning. In abrasive jet machining varies process parameter such as abrasive, gas, nozzle and velocity of uid are usual. This paper give u perfect knowledge about the abrasive jet machining. In this machining varies abrasive are aluminium oxides and silicon carbide. This is under a category of convenonal abrasive. In some new machine cubic boron and diamonds used Keywords: Abrasive jet machining, friability, material removal rate, abrasive stando distance Introducon In abrasive jet machining, nal shape of the product or workpiece is for make into desired shape by high velocity denion are suggested by various author about the abrasive jet machining. The abrasive parcles coming from the nozzle strike the surface of the workpiece with vary high velocity usually 200-400m/sec. The distance of abrasive parcles is 0.025mm and air is discharges at several atmospheres pressure [1]. The abrasives are of shape sharp edges. When the sharp shape of abrasive strikes the workpiece, it removes the material in the form of small chip or disconnuous chip. Because hard material always produces a disconnuous chip when it is under cung operaon. The sharp edge of the abrasive aer cung operaon converts in spherical shape and do not use again because its cung capacity reduces. The various process parameter that are used in abrasive jet machining which are discussed in this paper. The various denion of abrasive jet machining given by various author. Abrasive are widely used on various machine process, and it eecvely produce holes of intricate shape and provide close tolerances that are regularly for producing the engineering components [2]. Abrasives jet machining is a non-tradional manufacturing process that is include the cleaning of surface, sand blasng and cung etc. [3]. AJM also known as pencil blasng, abrasive micro blasng [4]. Abrasive jet machining is an ecient non-tradional process for machining brile and hard material and heat sensive materials, in which material is removal from the work surfaces by mechanical erosion. Mechanical erosion caused by imparng of high velocity abrasive parcles mixed with compressed air [5]. Mechanism various author suggest mechanisms used in abrasive machining. Finnie [6] suggest that mechanism of material removal for ducle material is by plasc deformaon and fracture. Mechanism of MRR is mainly depend upon the ow rate and size of abrasive parcles [7]. Stando distance eect the MRR and penetraon rates. 1, 2, 3, 4, 5  Students, Mechanical Engineering, GNA University, Phagwara, Punjab, India. Correspondence:   Gulshan Kumar, Mechanical Engineering, GNA University, Phagwara, Punjab, India. E-mail Id:   gulshankumar2695@gmail.com Orcid Id:   hp://orcid.org/0000-0003-3040-237X How to cite this arcle:   Kumar G, Kumar M, Singh K et al. A Study of Abrasive Jet Machining.  J Adv Res Appl Mech Compu Fluid Dyna. 2017; 4(3): 9-14. E ISSN:  2349-7661  l   P ISSN:  2394-7055   J. Adv. Res. Appl. Mech. Compu. Fluid Dyna. 2017; 4(3) E ISSN: 2349-7661 l  P ISSN: 2394-7055 Kumar G et al. C. N. Insulli [8] material is removed from the surface of workpiece by the impingement of the abrasive parcles of very ne in shape. These abrasive parcles move with a very high velocity through the nozzle along with the high stream of gas. When the abrasive parcles having sharp edges strike the brile and hard material with a high velocity, it makes dents into the material and again strike the workpiece it the material from the workpiece. The wear out parcles is carried away from the workpiece by the air or gas. The MRR of abrasive jet machining [9] Rahul Jain.MRR = K N δ^3K = constantN = no. of abrasive parcles imparng per unit med = diameter of abrasive parclesv = velocity of abrasiveH = hardness of work material.In AJM, gas (nitrogen or carbon di oxide or air) is supplied under a very high pressure. Aer it passed through the lter and regulator, it passed to a mixing chamber. Mixing chamber containing the abrasive parcles which are vibrang at a very high frequency by the vibraon source.Aer moving through the mixing chamber, the gas along with the abrasive parcles passes on to a nozzle. Nozzle is made of tungsten carbide and diameter of about 0.45mm. The nozzle p distance is used in abrasive jet machining is 0.81mm. the various further which inuence the material rate, geometry of cut, surface roughness and nozzle wear rate are stando distance, composion, strength, size and shape of the abrasive ow rate and pressure and velocity of carrier gas. The abrasive parcles are irregular in shape and consist of short edges which perform the cung operaon. Eect of various parameter on material removal rate Before discussing the process parameter rst we understand what are process parameter. Process parameter are that parameter which are control by manually during the machining operaon. Such as the abrasive ow rate, velocity of uid, gas, geometry of nozzle. ã Abrasives- commonly used abrasives in manufacturing are as follows. ã Convenonal abrasive- in convenonal abrasives aluminium oxide and silicon carbide is used. ã Super abrasives- In which cubic baron carbide and diamond is used. In convenonal machining process cung tool material is harder than the workpiece. Aer a number of use it is re shape on grinding wheel in case of lathe machine. But in non-convenonal machining abrasive are used which is harder than cung tool material used in convenonal manufacturing process. Super abrasives are harder than the convenonal abrasives, but its cost is high. In spite of hardness of abrasive, another important property of abrasives is its friability. Friability is the ability of abrasive growing to fracture (breakdown) into smaller pieces. This property gives the abrasive self-sharping fractures [9]. Figure 1.Abrasive Jet Machining Figure 2.Mixing rao and Abrasive mass ow rate dependence of mrr 10   J. Adv. Res. Appl. Mech. Compu. Fluid Dyna. 2017; 4(3) E ISSN: 2349-7661 l  P ISSN: 2394-7055 Kumar G et al. Abrasive are found in nature are made by synthecally now a day. Abrasive found in nature are as follow.EnergyCorundum (alumina)Quartz Diamond Sand stone. Diamond is common abrasives that produced by the industry as well as obtained from the nature. Corundum which is obtained from the nature, but now a day this are manufactured from bauxite arcial abrasives.ã Silicon carbide (sic)ã Aluminium oxideã Arcial diamond. These are the abrasives also use in grinding wheel. No mind diameter of abrasive is normally used is 10-15 µm in abrasive jet machining. Abrasives parcles are not used again and again because of the following reasons.ã Cung capacity decreases aer the one applicaon. Sharp edges of the abrasive are eliminated. ã Surface roughness is poor when we use abrasives again and again. Abrasives ow rate inuences by the pressure and ow rate of the gas, when the fracon of mass of abrasives in the owing gas increases, the material removal rate of rstly increases, but further mass of abrasives in the jet increases, it reaches a maximum and then falls. Mixing rao = volume of ow rate abrasives / volume ow rate of gas When we increase mass ow rate of abrasives parcles beyond a parcles limit. It will result in a decreases the available energy for cung acon and automacally the material removal rate [10] Gas MRR directly inuences by the air or gas pressure. Material removal rate is directly proporonal to the air or gas pressure. [11] composion of gas also eects the MRR. High pressure of gas or high velocity of gas obviously causes a low material removal rate. Nozzle The nozzle is the most important element in the AJM. Abrasives grains strikes the workpiece aer it is passed through nozzle. Nozzle is always in contact with the abrasives grains. Nozzle increases the velocity of abrasives parcles. Figure 3.Model depicng AJM Normally wc or sapphire is used. At the end of the nozzle, small hole called orice is kept cross seconal area of the orice is either rectangular or circular. The life of the nozzle is not very long, aer a number of uses it is replaced with a new one. Life of the nozzle in abrasive jet machining is dicult to achieve, but various invesgator suggest the nozzle life. A wc nozzle lasts between 12 hour to 13 hour, whereas a sapphire nozzle lasts for 300 hour approximately. Stando & Nozzle p distance These are distance between the nozzle tip and the workpiece. Both are the something. It largely eect on the material removal rate in AJM. MRR increases up to certain limit with increases of nozzle p distance. Aer that limit, constant MRR is obtained, but further decreases. 11   J. Adv. Res. Appl. Mech. Compu. Fluid Dyna. 2017; 4(3) E ISSN: 2349-7661 l  P ISSN: 2394-7055 Kumar G et al. Nozzle p distance not only eect the material removal rate, it also eect the shape and size (diameter) of cut. For opmum performance NTD of 0.25 to 0.75 is provided [11]. Figure 4.Eect of Nozel Tip distance Velocity of uid (carrier gas) The velocity of the carrier gas also eects on the MRR. With the abrasive parcles density, velocity of carrier gas changes. When the abrasive parcles density is gradually increased, the exit velocity will go on decreasing. It is due to the fact that uid kinec energy is used or ulized for conveying the abrasive parcles. Advantages of AJM ã AJM can cut holes of intricate shapes in hard material ã There is no contact between the tool and the workpiece ã Surface nish obtained by AJM is very high than convenonal machining operaonã Power consumpon is lowã Capital cost is low Limitaons of AJM ã MRR is lowã It cannot be best suited for machining so materialã Wear rate of nozzle is highã Process cause the pollute environment, so that dust collecng system is required Applicaon ã Electronic devices [12] bulter,1980 Wikipediaã Deburring of plascsã Making on electronic productsã Making of nylon and Teon partsã Cung of thin and fragile component Background This machining technology was rst started by Franz to cut laminated paper tubes in 1968 and as a commercial system was rst introduced I 1983. Abrasive jet was born in 1980 by the garnet abrasive was abbey to the water stream. In the easily 1990, Dr. Johan Olsen began to explore and explain the concept of abrasive jet cung as a praccal alternave for tradional machine shapes [13]. End seal of Dr Johan to develop a system which eliminate the noise, dust and experse demanded by abrasive jet at that me. In the last two decades, heavily deal of research and development in AJM is contributed or provides. Literature Review In this secon, various author gives the result of abrasive jet machining. Experiment related to MRR by various research has been conducts. Various author gives the inuencing factor that eects the MRR. R. Bal Subramanian at [14] said that increases the size of parcles, the material removal rate in near to the centre line of jet drascally increases, but near the periphery material removal rate very less. As the nozzle p distance increases, material removal rate also increases when we increase jet velocity near the centre line, MRR near to the centre line of jet increases. But the MRR nearer to the periphery of the jet decreases. When we increase jet velocity, the radius of edge and entry side diameter increase. It is also increase the MRR.Juk Prasad panday [15] taken the experiment (praccal) on glass work piece using aluminium oxide as an abrasive powder. To study MRR and over cut, experiment was done by considering nozzle p distance and procedure as machining or process parameter. From the experiment, i.e. gives that both pressure and nozzle p distance are important for MRR and only pressure as a signicant role in over cut. He said that individual opmal seng of parameters is taken out to decreases the over cut and increases the MRR. Mr. Barker Chandra [16] studied the material removal rate varied according to the variaon in has pressure and hole diameter accordingly to change in stando distance. He gives the various praccal on wok piece material glass alumina as a abrasive powder. 12

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