Process Characteristics Of Abrasive Jet Machining

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Published by :http://www.ijert.orgInternational Journal of Engineering Research & Technology (IJERT)ISSN: 2278-0181Vol. 8 Issue 11, November-2019Process Characteristics of Abrasive JetMachiningSyed Aiman*, R. S Bhargav*, Vikhyath. V*, Darshan K. A*, Ashitraj. V*, Dr. T. S. Nanjundeswaraswamy***Students, **Associate ProfessorDepartment of Mechanical EngineeringJSS Academy of Technical Education, Bangalore- 560060, IndiaAbstract:- Abrasive Jet Machine is the device used to removematerial by means of high velocity carrier gas and Abrasivemixture. It is a non-traditional machining process where thereis no physical contact between tool and work-piece. TheAbrasive Jet machining can be employed for machining superalloys and refractory from materials. This process is based onsurface erosion process. The process parameters that controlmetal removal rate are air quality and pressure, Abrasivegrain size, nozzle material, nozzle diameter, stand of distancebetween nozzle tip and work surface.INTRODUCTION:Abrasives are costly but the abrasive jet machining requiresvery less investment and less maintenance cost.Thecarrier gas is used as coolant, the cutting action is accurateand therefore better surface finish is obtained. In thecurrent day situation it is widely used in manufacturing ofelectronic devices such as LCD's, PCB, MEMS, andsemiconductors. There is increase in demand fordevelopment of micromachining technologies for materialswhich are difficult-to-machine because of their propertiessuch as extreme hardness, brittleness, corrosion resistanceand low melting temperatures.AJM is used to carry out operations like cutting,cleaning, polishing, de burring, etching, drilling andfinishing the operation. The nozzle is the most importantpart in the abrasive jet apparatus/setup. The process ismainly used to cut difficult and deep shapes in hard andbrittle materials which are sensitive to heat. The processcan be easily controlled by varying the parameters such asVelocity, Flow rate, Pressure, Standoff distance, Grit size,and nozzle angle. Abrasive jet machining (AJM) is anontraditional machining process which operates workpiece without producing heat and shock.PRINCIPLE OF AJM:Fine micro abrasive particles are accelerated in a gasstream. The particles are directed towards the focus ofmachining approximately less than 3 mm from the tip. Asthe particles impact the work-piece surface, they fracturethe surface and create holes/cavities. Once the particle hitsthe surface, it causes a small damage, and the gas streamcarries both the abrasive particles and the fractured (wear)particles with it.Abrasive particles used in abrasive jet machining:In AJM, it is considered that hard abrasive particles takepart in material removal process, whereas carrier gas helpsto blow away removed particles from machining zone.Such abrasives must have few basic properties for efficientremoval of material and also to get desired quality offinish. Amongst the desired characteristics proper hardness,irregular shape, presence of sharp edges and proper flowfeatures are must. Different types of abrasives having arange of grit size can be used depending on work piecematerial and the operation which needs to be performed.Aluminum oxide (alumina) of average grit size 10 – 50µmis commonly used for grooving and drilling operations,moreover when work-piece is hard. Whereas for very hardwork-piece silicon carbide (SiC) is preferred because it isharder than alumina. For other processes like polishing andcoating removal, glass beads and crashed glass are mostlyused. Size of abrasives have a great impact on quality offinish as well as material removal rate. Larger grit sizeproduces larger cavity and thus MRR improves with thekind of surface finish. Whereas, fine abrasives reduceMRR but improve surface finish and accuracy.FIGURE 1: SCHEMATIC DIAGRAM OF work is licensed under a Creative Commons Attribution 4.0 International License.)593

Published by :http://www.ijert.orgInternational Journal of Engineering Research & Technology (IJERT)ISSN: 2278-0181Vol. 8 Issue 11, November-2019LITERATURE REVIEW:The experiment and research is done by the variousresearchers with respect to abrasive jet machining.Parameters like velocity of gas, pressure, nozzle tipdistance (NTD) , material removal rate (MRR), substanceintegrity are studied and explained along with operationssuch as cutting, drilling.Jiuan-Hung Ke (2012) examined on qualities ofadaptable attractive rough in abrasive jet machining whichrecommends that independent attractive grating withversatility are used to get machining attributes in Abrasivejet machining . Abrasive jet machine has many differentpoints of interest as high etch rate, great machiningadaptability low capital and activity cost. These days thenature of abrasive jet machined surface could be improvedby parameter streamlining on the grounds that flewparticles was influenced via air opposition in the wake ofplaying out the examination they made an outcome,Taguchi trial . According to Jiuan-Hung Kea,attractive field is a primary factor for surface roughnesscontrast and material evacuation. In abrasive jet machining,they utilize the adaptable attractive rough not exclusivelyto limit the abrasive jet bearing and upgrade increasinglyuniform genuine operational region and material removalrate yet in addition have a changeless impact to acquiregreat surface harshness than typical machining process.Kumar Abhishek, (2016) considered wide uses ofthe micro abrasive jet machining. For example machiningof Micro-gaps on Soda lime Glass utilizing micro abrasivejet machine to deliver smaller scale features, for example,micro holes on brittle materials. This procedure is likewisegreat to machine heat sensitive materials. It has widemodern applications and in building fields too. This paperinvestigation gives ideal machining parameter tomachining hole on soda lime glass thickness.FIGURE (2): FABRICATED PORTABLE ABRASSIVE JET work is licensed under a Creative Commons Attribution 4.0 International License.)594

Published by :http://www.ijert.orgInternational Journal of Engineering Research & Technology (IJERT)ISSN: 2278-0181Vol. 8 Issue 11, November-2019P.M.Khodke, (2013) analysed on Opticalmicroscopy has indicated that abrasive particles utilized inabrasive jet machining have sharp edges with shapes likecone or pyramid. Also, microscopic assessment of crosssection of work samples dissolved by AJM shows that, forbrittle materials, material removal is because ofconvergence and propagation of cracks created by adjacentparticles on target surface. An analytical model has beenS. Madhu, (2018) Researched that Abrasive jetmachining is applied to rough finishing, for example, deburring and machining of earthenware production andelectronic gadgets. AJM has become a important methodfor small scale machining. It has different kinds ofadvantages over the other non-traditional cutting methods,which are high machining flexibility, least weights on thesubstrate. This paper manages a few trials that have beendirected by many scientists to survey the impact of abrasivejet machining process parameters, for example, abrasiveparticle, Abrasive Particle size, Jet weight Nozzle tipseparation. Different tests were conducted to survey theimpact of abrasive jet machine. Abrasive jet machiningotherwise called abrasive micro blasting or Pencil blastingis an abrasive blasting machining process that utilizesabrasives moved by high speed gas to erode material fromthe work piece.Venkatesh, (2009) Their paper gives the resultsof machining under different conditions. A commercialAJM machine was utilized, with nozzles of diameterextending from 0.45 - 0.65 mm, the nozzle materialsutilized is either tungsten carbide or sapphire, which havehigh tool lives. Silicon carbide and aluminum oxide werethe two abrasives utilized. Other parameters consideredwere nozzle tip separations (5–10 mm), spray angle (60 and 90 ) and pressures (5& 7 bars). The materialsmachined were glass, pottery, and electro-release machined(EDM) die steel. Material removal rate (MRR) and themachined cavity measurements were estimated. The blindholes that were penetrated were seen as non circular andtube shaped but rather practically circular and chimemouthed. High material removal rate conditions didn'treally yield little tight clean-cut machined regions, analluring component for AJM applications. Exactassessment was done to portray quantitatively the impactsof different machining conditions. Throughout theseIJERTV8IS110135created dependent on the above perceptions for foreseeingthe material removal in abrasive jet machining process. Themodel additionally proposes the basic estimation of massflow rate which has been substantiated tentatively.Furthermore, the impact of speed and mass flow rate ofabrasive particles on material removal rate is examined andstudied.examinations a super hot area was found to frame underspecific conditions and joined by high material removal; ametallurgical investigation of this intensely hot zone and itsconnection to ideal AJM machining conditions arepresented. Abrasive jet machining (AJM) is a process thatremoves material by directing a high speed stream ofabrasive particles onto a work piece.R. Balasubramaniam, J. Krishnan, (1998) Examined theabrasive jet de-burring process parameters and the edgenature of abrasive jet de-burred parts. Experimentalconfiguration dependent on Taguchi Orthogonal exhibitwas utilized to methodically measure the impact of thesignificant cutting parameters on abrasive jet de-burredexamples. The experimental examples utilized were 1.5mmthick, 25mm square evaluation AISI304 tempered steelsheets. Burrs were created by the face processing tasks.ANOVA technique was utilized for the visual review ofedge quality. It was discovered that the de-burringprocedure is altogether influenced by 'tallness of thestream' and 'impingement angle'. It was reasoned thatAbrasive Jet de-burring process beneficial than manual deburring process. The nature of de-burred segmentprincipally increments by the age of edge radius.S. Kanzaki, Y. Yamauchi, (2003) considered the impactsof work piece properties on machinability in abrasive jetmachining of clay materials. The three kind of basicabrasives which are, Aluminum Oxide, Silicon Carbide,and manufactured precious stone were utilized forconducting the experiment. The objective materials utilizedwere four kinds of ceramic which are, ZrO2, Si3N4,Al2O3, SiC. A laser scanning magnifying lens was utilizedto measure the volume that was removed by abrasive jetmachining. The machinability of the AJM process wascontrasted and the established models of solid particledisintegration, wherein the material expulsion is expectedto begin in the perfect crack formation system. Further, work is licensed under a Creative Commons Attribution 4.0 International License.)595

Published by :http://www.ijert.orgInternational Journal of Engineering Research & Technology (IJERT)ISSN: 2278-0181Vol. 8 Issue 11, November-2019was discovered that the AJM test results didn't rely uponthe erosion models, on the grounds that the overallhardness of the abrasive against the target material, whichhas not considered in the models, is basic in the machiningprocedure. It was additionally presumed that AJMprocedure had high potential micromachining strategy asharm free for some materials in light of the fact that thecracks didn't broaden downwards by the effect of themolecule during the machining process.S. Ally,, (2012) Utilized surface developed models toforesee Abrasive jet machining of metallic substrates. Theabrasive jet angle of erosion rate was estimated. Thematerial is Aluminum 6061-T6, Ti-6Al-4V Titaniumcombination and 316L stainless steel. The jet inclinationangle was estimated utilizing 50 micrometers Al2O3abrasive powder propelled at a normal speed of 110m/s.The peak erosion rate was found to occur 200 to 350comparative with the surface for every one of the threeframeworks. It was discovered that Aluminum has a highvolumetric disintegration rate than Titanium amalgamwhich is higher than the hardened steel erosion rate on avolumetric basis, which inturn is essentially lower than abrittle material, for example, glass and polymers. It waslikewise discovered that where a high level of controlcarves is wanted; AJM of metals is most appropriate forscratching of moderately shallow highlights. It was inferredthat scanning electron micrograph and EDX examination ofthe eroded surface of 316L pure give a lot of moleculefollowing with a less sum in the Titanium composite.N. S. Pawar,, (2013) Investigated abrasive materialsea sand in vibrating chamber. The tungsten carbide nozzlewas used in the abrasive jet micro machining process. Thesand of 100-150 micron was used for the experiment. Thework piece used was a glass of thickness 4 mm. Theevaluated performances were material removal rate andflow rate. It was found that the impact through nozzlecaused severe erosion on the material work piece. It wasdemonstrated that the erosion of material surface dependedon velocity, direction and brittleness of the material. Theexperiment was performed by using the combination oftwo different parameters viz. Standoff distance andpressure. From the result, it was concluded that materialremoval rate and flow rate were similar to actually abrasiveused like aluminum oxide, silicon carbide, etc. It wasnoticed that by increasing feed rate width of the cut wasalso increased. It was also found that at greater stand–offdistance and feed rate, taper cut was found to be a higherslot.Rajkamal Shukla, Dinesh Singh. (2017) Used Taguchimethod for experimental investigation of abrasive water jetmachining parameters. The material used is AA6351aluminum alloy. Parameters such as transverse speed,standoff distance and mass flow rate are considered toobtain the influence of these parameters on kerf top widthand taper angle. Regression models have been developed tocorrelate the data generated using experimental results. Thepercentage contribution of standoff distance in kerf topIJERTV8IS110135width and taper angle is found to be 77.642% and 81.774%respectively.A. Ghobeity, T. Krajac. (2008) Predicted models ofabrasive jet micro machining for masked and unmaskedborosilicate glass channels by using 25 micro meteraluminum oxide. A novel technique is used for the velocitydistribution of the particles in the jet of an abrasive jetmicro machining. It was found that the velocity decreasedlinearly from the center line of the jet to the periphery,Weibull distribution followed by the probability of aparticle arriving at the surface a given radial distance fromthe center of the impacting jet. To predict the crosssectional profile of unmasked channels this Weibulldistribution was used with an extension of the alreadyexisting model. Time-dependent particle mass flux andvelocity distribution were used for modeling of the effectof the nozzle.Process Parameters of Abrasive Jet machining (AJM) arefactors that influence its Metal Removal Rate (MRR).In amachining process, Metal Removal Rate (MRR) is thevolume of metal removed from a given work piece in unittime.The following are some of the important processparameters of abrasive jet machining:1. Abrasive mass flow rate2. Nozzle tip distance3. Gas Pressure4. Velocity of abrasive particles5. Mixing ratio6. Abrasive grain sizeABRASIVE MASS FLOW RATE:Mass flow rate of the abrasive particles is a significantprocedure parameter that impacts the metal removal rate inabrasive jet machining. In AJM, mass flow rate of the gas(or air) in abrasive jet is contrarily corresponding to themass flow rate of the abrasive particles. Because of thisreality, when persistently expanding the abrasive mass flowrate, Metal Removal Rate (MRR) first increments to anideal worth (as a result of increment in number of roughparticles hitting the work piece) and afterward diminishes.However, if the blending ratio is kept steady, MetalRemoval Rate (MRR) consistently increments withincrement in rough mass flow rate.NOZZLE TIP DISTANCE:Nozzle Tip Distance (NTD) is the gap provided betweenthe nozzle tip and the work piece.Up to a certain limit, Metal Removal Rate (MRR) increaseswith increase in nozzle tip distance. After that limit, MRRremains constant to some extent and then decreases. Inaddition to metal removal rate, nozzle tip distanceinfluences the shape and diameter of cut. For optimalperformance, a nozzle tip distance of 0.25 to 0.75 mm isprovided.Gas work is licensed under a Creative Commons Attribution 4.0 International License.)596

Published by :http://www.ijert.orgInternational Journal of Engineering Research & Technology (IJERT)ISSN: 2278-0181Vol. 8 Issue 11, November-2019Air or gas pressure has a direct impact on metal removalrate. In abrasive jet machining, metal removal rate isdirectly proportional to air or gas pressure.Velocity of abrasive particles:Whenever the velocity of abrasive particles is increased,the speed at which the abrasive particles hit the work pieceis increased. Because of this reason, in abrasive jetmachining, metal removal rate increases with increase invelocity o abrasive particles.Mixing ratio:Mixing ratio is a ratio that determines the quality of the airabrasive mixture in Abrasive Jet Machining (AJM).It is theratio between the mass flow rate of abrasive particles andthe mass flow rate of air (or gas).When mixing ratio isincreased continuously, metal removal rate first increasesto some extent and then decreases.Abrasive grain size:Size of the abrasive particle determines the speed at whichmetal is removed. If smooth and fine surface finish is to beobtained, abrasive particle with small grain size is used. Ifmetal has to be removed rapidly, abrasive particle withlarge grain size is.ABRASIVE PARTICLES USED IN ABRASIVE JETMACHINING:In AJM, it is expected that hard abrasive particles take aninterest in material removal activity, while transporter gashelps to overwhelm disintegrated particles from machiningzone. Such abrasives must have barely any essentialproperties for productive expulsion of material just as toget wanted nature of cut. Among the ideal propertiesadequate hardness, unpredictable shape, presence of sharpedges and great stream attributes are fundamental. Variousabrasives having a range of grit size can be used dependenton work piece material and the activity it is expected toperform. Aluminum oxide (alumina) of normal grit size 10– 50µm is regularly utilized for cutting and penetratingactivity, particularly when work material is hard. However,for difficult work material, silicon carbide (SiC) is favoredas it is more harder than alumina. For cleaning andcovering evacuation purposes, glass beads and crashedglass are routinely utilized. Size of abrasives impactsnature of cut just as material evacuation rate. Bigger gritsize will in generally produce bigger cavity and in this wayMRR improves with the sacrifice of surface finish. Thenagain, fine abrasives lessen MRR however improve surfacequality and exactness.CARRIER GAS FOR ABRASIVE JET MACHINING:Basic purpose of carrier gas in abrasive jet machining is toaccelerate fine abrasive particles (by momentum transfer).A compressor is used to elevate pressure of the carrier gas(as high as 20bar); abrasive grits are mixed with it in amixing chamber (as per mixing ratio), and a nozzle is usedto convert pressure energy into kinetic energy (in the formof high velocity jet). Carrier gas pressure along with nozzleIJERTV8IS110135diameter determines final jet velocity and thus machiningperformance.Among various gases, air is commonly used in AJM as it isabundantly available at free of cost. Sometimecommercially pure carbon di-oxide and nitrogen are alsoused to harness better

Abrasive Jet machining can be employed for machining super alloys and refractory from materials. This process is based on surface erosion process. The process parameters that control metal removal rate are air quality and pressure, Abrasive grain size, nozzle material, nozzle diameter, stand of distance between nozzle tip and work surface. INTRODUCTION: Abrasives are costly but the abrasive .

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