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Module 1: Abrasive Machining Processes

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Cutting Fluids Application in Machining Region

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Video 1: Minimum Quantity Cutting FluidSo, now we are going to cutting fluid applications in machining region, how we have to applythe cutting fluids in the machining region we will see now, still now we have seen thecomparison between eco friendly cutting fluids, as well as mineral oils what is the rheologicalaspects what is the flow ability how the capillary action takes place and all those things, thermalaspects also we have seen and ah we also see the thermal aspects I mean to say that conductivityand specific heat of the cutting fluid all those things.We also see here as a integral part of a some subject, at the same time we also seen thebiodegradation, how the biodegradation will takes place between a mineral oil as wellas bio cutting fluid.If we have seen all these things from the cutting fluid composition point of view, andnow we have to see another aspect how to improve the performance for that purpose . We aremoving into how precisely we have to apply and what are the parameters that we have toconsider that particular aspects we will see in this lectureSo, minimum quantity cutting fluid it is a one of the best techniques.So, we will see about introduction to minimum quantity cutting fluids and how economicallywe can develop this system and commercially what are the available nozzles, how to decideand the MQCF parameters that what are the parameters that will decide the performanceand all those things.What are the minimum things that one should take care scientifically, so that ah he cancome up with better solution for the performance point of view as well as from the ecologicalpoint of view.So, cutting fluid composition here we will see the ah thermal conductivity experimentagain we will go through again just some glimpse at the same time we will also these standof distance, how far we have to keep it and the nozzle angle at what the nozzle anglewe have to.So, these are all about the minimum quantity cutting fluid, some of you may not have presentin the ah previous lecture.Let me brief you that minimum quantity cutting fluid is a best process of compare to theflood cooling process ok.So, if you have not seen you can just go through the videos what are the comparison betweenah minimum quantity cutting fluid as well as flood cooling, and then you can read aboutthis one or you can go about this one then, we go for the practical comparison of floodcooling process with respect to minimum quantity cutting fluid.This particular chapter mostly we deal with the those research oriented papers not withrespect to the introduction that is available in traditional books and all those thingsSo, most of the people who may be interested in taking up this job as either project work,they can ah clearly follow how the things are working how you have to choose scientificallyand all those things shape of the machining region and the chip tool interface.The first and foremost thing is what is the shape in the machining region, if you seethe tribiological aspect this is the picture is known to you since they have shown oneor twice in the previous.If you see a machining region where the chip tool interface is there this is the ah regionwhere chip tool interface is there.So, the chip is moving on the red surface, and it has a sticking region as well as slidingregion and if you see the three dimensional surface profile of the cutting tool this onethis is the 3D surface profile ok.Here normally what is the sticking region mostly we are concentrating about the stickingregion and sliding region is slightly . So, the areal is a elliptical shape normally ifyou see here it is a elliptical shape where it will have a minor axis as well as majoraxis.So, let me draw this ah in outside if you have a elliptical shape , you have a minoraxis you have a major axis ok . So, your then which is important for you whether it is aminor axis is important or major axis is important from the cutting fluid, application sinceyou are going to apply your cutting fluid in this direction, let me slightly erase thesome other previous material.So, you are going to apply the cutting fluid in this direction, so like this .In that circumstances I am mostly worried about my minor axis , how to reduce my minoraxis that is a concern for that purpose, how we have to go about and choose various parametersand all those things, that is what about the this particular class revolve around .So, various ecofriendly cutting fluids, if you have seen this is the just a glimpse comparedto mineral oil based cutting fluid, sunflower oil , coconut oil, as well as canola thenyou can also look into the liquid nitrogen and all those things, but liquid nitrogenif you are going from the point of economy it may not be economic.So, you always can go with ecofriendly cutting fluids which are vegetable based cutting fluids, any combination of this vegetable oils you can go ahead and you can form your own cuttingfluid or there are commercially available bio cutting fluids are there you can procureit ok.If you see here there are the solutions, flood cooling technique high pressure cooling techniquethis is the flood cooling technique.This is high pressure cooling and this is the cryogenic cooling this is a MQL or MQCF. So, basically we go for MQCF, because normalin flood cooling is 400 to 600; that means, average it is been be 500 ml per minute inthat circumstances lot of emissions will takes place consumption of cutting fluid also have15 to 17 percent of the product cost in that circumstances normally we have to minimizethe cutting fluid, but we have to maximize the performance for that purpose if the heattransfer performance factors we have seen heat transfer lubrication flushing actionmist generation corrosion inhibition these are the things that also we have seen, andmost importantly you have to generate this MQCF that is the minimum quantity cuttingfluid set at the economical price and all those things.So, that it will be environmentally friendly as well as it should not cause health hazards,looking at all these aspects we can design our system for economic as well as the productcost should be low and the performance should be better for that purpose we are going towardsminimum quantity cutting fluid.So, minimum quantity cutting fluid normally to make the more sustainable, sustainabilitycan be defined in three ways one is it should be economically , friendly, environment friendly, and the third one is social friendly . Economic friendly means it should be lesscost, environment friendly means it should not cause any type of ah emissions or somethingat least it should emit minimum emissions, social friendly means it should not harm theend user, basically assume that I am making a rod with sharp edges what will happen ifduring usage operator or any common man who is using it.He may hurt this hands and fingers that should not be.
Video 2: Minimum Quantity Cutting Fluid Parameters So, if you can see you need some of the components like compressor you need, and you need a nozzle.Where two nozzle you can develop and in the system, I will explain where twin hole nozzleyou require and cutting fluid tank . So, what is your going to do here is yourcutting fluid is coming from this pipe, you can see this pipe this is a pipe.Which is sending my cutting fluid horizontally at the same time compressed air is cominglike this, and both are mixing externally.Here we are using external , mixing , external mixing you might have already seen this slide. The external mixing is taking place by thevirtue of pressure difference between your cutting fluid, which is coming certain heightnormally this cutting fluid is kept at a certain height in the next slide you will see fromthe machining region, by the virtue of gravity it is falling at the same time it will alsosuck because of air pressure air you are sending at five bar pressure seven bar pressure andall those thing, because of the pressure difference that is generating here one nozzle exit islike this another nozzle exit is like this both here you are coming cutting fluid anotherone here you are getting air compressed air.So, both will mix here and divert in this direction , so machining region is here.So, in that way you will can generate the mix you can see here mix this is the mistthat is formed and from the machining the exit it will falling a diverging.So, that you can design your system, so that it will fall on my cutting tool, this is thecutting tool this is about the machining system with minimum cutting fluid how the zoomedversion look like.If at all I want to see the overview, how the overview it look like this look like thisis the cutting fluid tank, cutting fluid tank this is and you can have a graduator scalehere this is the graduator scale.Where the graduations are there , how you can measure the cutting fluid quantity howmuch is flowing and all those things this is the air pipe, this is the cutting fluidpipe , and this is the air which is compressed air air is coming from this one.So, this is the twin hole nozzle and you are generating the mist and sendingwhich you can see in the previous slide this is how the mist is generated from this particularsetup.But the problem here is your work piece is rotating at certain speed and there may bea splashing takes place, for that purpose to keep the operator safe what we have donea shutter.Where, if there is any splash also it will fall on this one at the same time one thingis not visible here that is operator is looking from this side.So, this type this particular shutter has a transparent window where which is made upof a percepts.So, that operator clearly can see what is going on in the machining region, at the sametime once the operation is completed he need not to completely dismantle from the setup.He can just this is a hinge is there you can see here it is a nut system just you can liftthat one, and you can take out your product is as simple as that one this will be movable.So, this is about how you can develop with the existing materials in a small scale laboratoryalso, this is cutting fluid tank made up of percepts you can join this percepts by chloroformand you can make your cutting fluid tank you can put a small scale where the radiationsare there and you can connect this cutting fluid tank with respect to cutting fluid andcompressed air pipe.And compressor you can put at certain part of your laboratory and you can get the compressedair, and twin hole nozzle you can develop using your stove nozzles also just you makealuminium twin hole nozzle just you fix it with your stove nozzles, that is what herethe authors have done and splashing protection you can also done by some of the aluminumbased sheets and all those things.So, this is about how you can develop economically.And you can also control the ah cutting fluid mist generation by these output pressure regulatorok, output pressure regulator knob is there just you adjust output pressure regulatornozzle and you can also check how the cutting fluid is sucking and what is the particlesize that is the droplet size and all those things also you can measure, the droplet sizemeasurement and simulation and all those things we will see in the grinding that is the partof grinding.Where we will see the some of the simulations of some of authors how the particle generationwith respect to atmospheric air pressure, what is the the droplet size that is comingin the machining region from the minimum quantity cutting fluid and all those things we willsee.These are the commercially available setups if you see till now, what you have done ishow you can develop in the laboratory how with minimum cost you can generate if at allyou have some money.So, you can go up ah you can go ahead with purchasing of the nozzles where if you cansee here, the nozzle system which is cutting fluid is there as well as ah you have theair is there both are mixing internally and sending the mist like this.So, this is ah one of the systems at the same time you can have another systems also whereyou, you can mix internally and send the spray like this everywhere it is ah spreading one.So, different, different companies will produce different, different nozzles and the mixingmechanisms.These mixing mechanisms are patented by themselves they can have the internal mixing, externalmixing in internal mixing also many varieties are there.So, different, different nozzle systems are different, different varieties are mixingis there just you have to choose a right variety of nozzle for your application.So, that your performance of the machining improves at the same time ecological aspectsalso considered during the performance testing ok .These are the nozzles how normally you can see it is 0 degree nozzle, 15 degree diverging,25 degrees and 40 degrees.How these are practically shown during the machining operation you can see here.So, these are the nozzle, nozzles will be given some of the colors how to differentiateand all those things.How this area how much area it will fall and other things you can check from this one,you can choose if you are going for a turning operation which one I want, if you are goingfor a milling operation which one I want, if you are going for a grinding operationwhich type of nozzles I want and all those things this will help you in choosing a rightnozzles for your application ok.These are the other varieties of nozzles which you have seen already I want to emphasizetwo things, one is internal mixing as well as external mixing that is if the cuttingfluid and air both are mixing outside the nozzle that is called external mixing.If both are mixing internally; that means, that within the nozzle system there is a mixingchamber will be there if there it is mixing and, and coming the mist outside that is calledinternal mixing, if it is mixing outside the nozzle it is external mixing it within orbefore the nozzle exit if it is mixing that is called internal mixing.
Video 3: Selection of Nozzle We have selected the optimum composition, that is where thermal conductivity is betterand specific heat should be better from this we have considered the cutting fluid composition,whatever the region whether you want one point 1 is to 8 or 1 is to 16 and all those things, now we are going to optimum standoff distance.How far the nozzle has to kept in the machining region.So, if you see the MQCF system distance between machining zone and nozzle position is knownas the standoff distance, this is the standoff distance how far you are keeping your nozzlefrom the machining region.This distance governed by the mist formation , how the mist formation the standoff distanceis too large what will happen jet flaring will takes place; that means, that if yourwork piece is here , you will have this much only if your work piece is here what willhappen you will have more flaring that is more diverging will takes place ok.So, for the smaller distances MQCF may not be completely cover the machining region . So,you need minimum flaring at the same time it has to cover your machining region, sinceyou have already seen the machining region that you are going to talk about is the machiningregion is approximate like elliptical surface you have a minor axis and major axis . So,in it has to cover that much particular area at the same time flaring should be minimum.So, for that purpose how we can decide that what is the standoff distance optimal standoffdistance?So, that it can cover this machining area completely in terms of minor axis, becausemajor axis how one can cover that will also we will see that ah you can take your nozzlea slit type of nozzle; that means, that you have a slit type of nozzle.If you take like this what will happen it will cover your major axis, instead of goingfor a whole type of nozzle exit.If you take a slit type of nozzle then it will cover your major axis only this willalso diverges from the slit it will comes like this; that means, that my slit is coveringmy major axis and diverging in the perpendicular diversion cover my minor axis for that purposeyou have to choose a right type of nozzle.So, the selection of optimum nozzle, standing distance how you are going to select thatis the standoff distances are varied from 10 to 100 mm with the interval of 10 mm; thatmeans, that the experimental set up if you see here this is the dynamo meter and acrylicsheet is fixed on dynamo meter then you are putting your nozzle perpendicular to it andyour spray with distance of 10 mm, 20 mm, 30 mm, so on, so on to 100 mm.So, as the distance increases what will happen same time we have to do this experiment multipletimes, because to get the good repeatability and accuracy values that is what it is recordedmultiple times and average force values are reported or recorded .If you see that one as ah nozzle standing of distance is increasing; obviously, theforce exerted by spray is going to decrease.If the distance increases the force decreases at the same time flaring that is divergingwill also get.So, this is what you can expect without doing experiment also, but you can say quantitatively;that means, it will decrease that much you can say, but you cannot say how much it willdecrease that is called quantitative value you cannot see for that purpose how much itis decreasing confirmation one has to do for that purpose the experimentation is done andthough it is falling the similar trend what we are expecting now we know what is the standoffdistance versus the force exert.Now, we go ahead with machining area to be cooled with this force in our mind , we aregoing ahead with area to be cooled for that purpose as from the part of the force exertedby spray also important for the completely covering the high temperature machining region;that means, it has to cover the temperature region, we have seen in the first slide orthe second slide where you have a elliptical region of sticking and sliding region to confirmit we also do with the infrared camera in the this particular slide.Infrared camera is used to measure the thermo gram and required area to cool if you seethe picture.So, this is the machining region I don't know how far you can see this one there is thisis the head stock , and this is the rod that is the work piece is here and your tool interfaceis in this region , let me erase this particular section , so that I will explain you in detail.So, this is what the chip is jumping from the machining region and this is the machiningregion machining region follows the elliptical, which is also we get from the first pictureof this particular class where you have seen the sticking and sliding region and we wantto cool this chip tool interface which is also proved by this particular thermo graphicalimage . Where you are going to have a elliptical shape, this is particularly the ellipticalshape this region one has to cool.How to cool for that purpose selection of optimum.Spray which type of spray you want for that purpose the first one is flat fan this isthe convex distribution this is how the distribution takes place , and the shape of the cuttingfluid how it is fall is given here.Similarly, flat fan even distribution is there.So, here the convex distribution is there here the flat distribution is there even distributionacross that one full cone normally it is also will have a convex.Where the full cone is there and again full cone even distribution, I mean to say fullcone means it is like this the density of the center is very high.And the density goes to the periphery if the density is reducing, here it is even whereveryou take it is completely even and the hollow cone if at all the some of the applicationswhere you are looking you can have the hollow cone also where here no cutting fluid andyou have on the periphery at the same time straight you will have a point coherent type,but it is cannot be coherent like lasers and all those things you will have still approximatelya point type of thing that is a circle of small diameter will have ok.From our previous literature of the thermo graphical image at the same time from theprevious experience of the sticking and sliding region, now we have to choose which type ofnozzle we want depend on their area of coverage.For that purpose for particularly for our application we want flat fan with convex distributionwe can go ahead . So, area of spraying how to check the areaspraying, if you see for this particular purpose also since already we have seen a dynamo meteris there on top of it there is a precepts plate is there, on top of it we are just puttinga chart and use just spray on it instantaneously you just spray and stop it and you immediatelyyou have to put some focusing high resolution cameras.And you have to take the images because once the spray falls on the chart it tries to spreadin all directions to get a right image the photographers should be there in all the directionsimmediately they should be wait and they should be high without any time they should be catchingthe images.So, for that we have worked a lot and ah different, different photographers are standing on thedifferent, different directions to measure properly at the same time instantaneouslythe photographer will start before the spring starts and it will continuously takes in aspectrum of images and.So, that we can take the required image as soon it fall on the machining region .If you see that one , so the nozzle standing of distance and the minor axis we if you seehere the nozzle just I am talking about the nozzle here, it has a rectangle type of slitthat is which whose the length is around 5 mm.
Video 4: Comparing Flood Cooling and MQCFSo, now we have already seen the composition as well as standoff distance and angular positionfrom that, how we can implement this in a practical situation and it is not a singleparameter that will decide.It is multiple parameter at the same time combined effect is another thing to be understand,we have to understand the how the nozzle angular position plus standoff distance plus compositionplay a role and 2 parameters effect 3 parameters effect and all those things also play majorrole for that purpose just a preliminary experimentation is carried out and we demonstrate.How the MQCF is better for that purpose work piece material we have taken the hard steel, which is around ah 56 HRC, normally the work piece is ah taken then case hardeningis done by some of the techniques.So, tool material is taken that is tungsten carbide tool material whose coating is doneon a flank surface, that is why we are concentrating on the crater surface that is nothing, butthe rake surface tool holder this is geometry and tool geometry is given here and the workpiece and tool are given here.Work piece is tungsten carbide and H 13, if you see the hardness it is 56 plus or minus2, because it is hardened work piece.We have taken from the supplier then we have done the hardening and then we have done themachining operations for here, if you see the density and modulus fluctuals and thermalcoefficient of expansion and all those things are given in the table for your kind reference.The overview if you see this is the machine , at the same time this machine into the machiningregion zoom up is done in the machining region, here then this zoom up is done here.So, that you can see the cutting fluid mist how it is falling in the machining region,in this region you can clearly see and you can also see the temperature measurement hereit is in the second picture this is t stands for temperature measurement here the dynamometer also is there this is the dynamo meter and this is the infrared camera is there herealso it is already indicated.So, you can catch up the temperature that is in the machining region at the same timeyou can also measure the forces that is what I want to show for particular machining applications.Whenever you are machining with minimum quantity cutting fluid as well as flood cooling , thisis the two things at the same time minimum quantity cutting fluid of the mineral oilas well as bio cutting fluid how we can compare this 4.Preliminary experimentations, so cutting speed feed and depth of cut are used in this rangeand the minimum quantity cutting fluid and bio cutting fluid are used .If you see here the cutting force versus cutting speed and flood cooling FCS stand for floodcooling , MQCF stands for minimum quantity cutting fluid, so .In flood cooling two types of cutting fluids are used that is mineral oil as well as BCF, in MQCF also you have used two types one is mineral oil another one is bio cuttingfluid ok, that that should be noted here ok let me erase because in ah next slide youwill get all the things that is about the all the graphs will be compared like that.If you see the comparison of the cutting force what is our requirement our requirement shouldbe minimum, force that to be generated during the machining operation for that purpose ifyou see the least curve that is called MQCF for BCF is giving less; that means, that whateverif things that I want, which I want to prove that is coming good here also you are goingto get bio cutting fluid with minimum quantity cutting fluid is giving better results because,it has a better cooling ability as well as better lubricating ability.So, that the tool can maintain its original hardness at the same time sharpness radiusalso, so that the forces can be minimum in other case minimum quantity cutting fluidwith mineral oil slightly better.But the flood cooling is lot better as you have seen in the force convection , Feed forcessimilar things are there , but only one noting point here is your minimum quantity cuttingfluid mineral oil plus minimum quantity cutting fluid ah bio cutting fluid in this range thereis a cross over at this particular point so; that means, if you want just concentrate Iam erasing this one if you see this region.If you see this region the cutting speed is low in this region, region one and regiontwo if the cutting speed is low; that means, my rubbing action is high that in that circumstancesmy minimum quantity cutting fluid with the mineral oil is giving better result; thatmeans, that forces are less; that means, that mineral oil possesses good lubricating characteristicscompared to bio cutting fluids; however, bio cutting fluid is having better lubricatingproperties because at higher speeds the temperature phenomena will be higher.So, it is having a better cooling abilities that is what I want to convey from this particularthe same thing you can also see here the crossover is there . So, same attributes here also;that means, bio cutting fluid has better cooling properties whereas; mineral oil has betterlubricating properties at different, different speeds.Coefficient of friction also calculated from the equation tan alpha equal to tan lambdaplus tan inverse frictional force by the cutting force and all those things . So, if you seein this case also normally MQCF gives better results; that means, that friction is lessat higher feed rates if the friction is less friction coefficient is less; that means,that my power which is consumed in the machining processes will be used for useful purposerather than the waste it is one of the power that I am giving input is equivalent to shearingplus friction.