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Video 1: Work Piece MaterialSo, we are discussing about the tool wear and tool life and ah we are also into thevariables, that are affecting the tool life ok. Till now, we have seen these are the , variablesthat are affecting the cutting conditions, tool geometry and ah tool materials or materials, as well as the type of cutting fluid and the cutting fluid application techniqueNow, we are discussing about the variables affecting the tool life, as you can see theseare the a to f are the variables , that affects the cutting tool life , the cutting conditions, tool geometry, tool materials , work piece materials, cutting fluid type , and it isapplication techniques there are various techniques ok . So, till now we have seen 3 things thathere is ah cutting conditions, we have seen tool geometry, we have scene and the toolmaterials different materials, that are from HSS to diamond we have seen .Now, we are going to see how various work piece materials that will affect the toollife? ok . So, the m number of materials as the world progresses, we are coming acrossthe variety of materials . So, those are nothing but the work piece material as the world growsthe advancement grows , you are coming up with various work piece materials . If thework piece material is harder , you will need to take the tool materials also harder ok. So, that is ah about the work piece material. Now, we will go into the work piece materials. So, there are variety of work piece materials ranging from , soft tool hard tool brutalductile . It is a overview slide where you can find the many of the world peace materialbrass these 2 are not the brass , but ah these are the brass work piece material , copperwork piece material and the gold. Normally I cannot say that do the machining operation, but ah some of the special cases one uh do the machining operation , such as to fabricatethe car and all those things and the silver and all .These are the overview of materials and ah the world progresses we Come across with tosome of the biomaterials, ceramic materials and all those things Come across with to someof the biomaterials, ceramic materials and all those things Come across with to someof the biomaterials, ceramic materials and all those things .Anyhow this is just a overview t, we just go into the different materials that we comeacross ok . Silicon carbide is one of the ceramic material , it is very difficult tomachine the ceramics , because ah these are the brittle materials and hard materials ok. These are 2 properties . These are the brittleand another one is is a hard materials . So, because of this it is very difficult to machinethis material, another advanced material is the Titanium and bits allowsok . So, the basic problem in machining of Titanium is that, it is a poor thermal conductor, suppose if I want to machine this one what will happen? If it is a portable conductorduring the machining operation . If at all I want to cut the Titanium, the chip is movingand the it is a poor conductor. So, the temperature stays in the machiningregion , itself are at the same time the temperature stays at the bottom of the chip . So, thebottom of the chip gives the temperature to the work piece, are the same thing the temperaturethat is staying on the one piece also, will important to the tool .So, the tool thermal softening will takes place at early stages that is one of the disadvantage,but the same is take considered as the advantage in machining of aero specialized, for turbineblades and all those things . If the temperature is ah stays on the surface, whenever the flight is travelling at a higher altitude , the air comes and give the surfacetemperature is very high that cold air will takes off the heat that is generated . Thatis one of the advantage , that is why mostly Titanium and it is allies are used in 2 applications, one is ah biomedical application , another one is aerospace application the .So, these are the 2 applications normally , see in the aerospace I already said theturbine turbine components and all those things , if you come to the biomedical applicationsnormally, Titanium and the Titanium alloys are uh considered to be the bio inert materials. So, they will cause ah anything to the body that is why, some of the implants like kneeimplants hip implants , these are all developed by the Titanium .So, you know we will come across how these are machined and all those things in a bigway, I mean to say in a elaborate way in upcoming classes; however, I will show you some ofthe glimpse just to do the introducing of these materials in this class ok . So, thatis about advancement of the materials ok, I can say these are the advance materialsok . Now, coming to the ductile materials, thefirst variety of the work piece materials are ductile materials. Normally the leopardmaterial ranging from stainless steel , this is a stainless steel and this is the copperok . So, the stainless steel are uh with iron based steals ok . So, machining this normallygenerates the continuous chip, as you can see here it generates the continuous chips.Most of the ductile materials generate continuous chip, because of each tool life . Because,why we are saying because we are studying the effect of this work piece material onthe tool life . So, if a continuous chip is flowing on the red surface of the tool , therewill be a continuous heat going into the tool , at the same time the there is no vibrations, because the system is continuous and the tool life will be good and all those things. So, if the only problem with these materialsis , entanglement of these chips and on the finishing region or the machining region isanother problems ok, apart from it there is no much problem . That is why, normally wehave studied in the previous classes , the continuous chip is good from the point ofpower consumption, because low power is consumed at the same time surface means point of view. But whenever this chip, if you see the figurenumber 2 figure number 2, if you see where the chip is entangled there itself ok . Ifthe chip is entangled there , if it is slightly entangled under finish surface , if you seethis machined surface this is unmachined surface ok .So, if the chip rub circle as this one , what will happen? this will damage the surfacefinish of the work piece . So, I do not want this to be entangling , for that purpose normallysome chip breakers are used . So, this is about the tool life ok. Tool life in the improve, if we can use chip breaker from the continuous chip , whenever admission in the contiguous. So, whenever we are going to the brittle materials, ductile materials will give the continuous chip , but the brittle materials normallythe basic examples of the brittle materials is the cast iron . The first one wheneverwe think about the brittle material is a cast iron, normally in the short from we call itas a CI . So, it will generate the discontinuous chipsok . The second is brass and you can see the discontinuous chips , discontinuous chipsare lying on the lay bled ok . So, the one noting point that you can seehere is , on the tool life . The first I will speak about the tool life and I will speakabout ah some other thing about the cutting fluid also , I will come to the point cuttingfluid later whenever we are machining these materials , tool life will be good. If atall you are machining a a basic brittle materials, like cast iron and brass , because if theseare the very hard materials normally, if you go to the brittle materials like Silicon carbide,Alumina , Titanium nitride , ah boron carbide these are the very hard materials .So, if you what are you are going for there , because of the interaction between these2, the hardness ratio if you are maintaining the tool which is much much harder than thework piece that are using , then there is no problem . Whenever you are going for theharder materials , then assume that I want to be thin Al2O3 or SiC and still my cuttingtool is coated Carbide , then hardness ratio between 2 will be very less ok . The workpiece hardness to the tool hardness is very less . In that circumstances the basic problemcomes is , tool where will be high ok . So, from the chip point of view this is better. Discontinuous chips are coming so, it is; obviously, better. So, there is no formationof continuous chip and damaging of the final machine surface is not problem ok .So, now the my question to you is , regarding the machining of the cast iron . There aresome questions, whenever you go to the interviews because I face this question when I was mastersok . So, the question is that a which type of cutting fluid that you will use when youare machining the cast iron ok ? So, let me answer this question , normallycast iron will have high amount of carbon, and the carbon in the form of graphite ok. So, the answer is just it is a confusing answer, whenever somebody asked about themachining of the cast iron . So, normally nobody are minimally you do notuse the cutting fluids, the reason I mean to say cutting fluid is not used, just theymay have asked to know the technicality of this process and all those things ok.So, no cutting fluid will be used practically, but whenever the high depth of kerten highfluid, if you are going may be used , but normal conditions whenever you are going fora low depth of kertan in the low feed rate in that circumstances cast iron will have,high percentage of carbon will be there . So, carbon in the form of graphite ok . Graphiteif you see nowadays people talks about graphing and all those things. So, the graphite actas a self-lubricant basically . So, whenever you drill a hole in a cast iron , wheneveryou do machining like if you see for example, here cast iron is machined here .So, no cutting fluid is used , because the carbon content which is in the form of a graphite , in a cast iron will act as a self-lubricate.
Video 2: Machining of Bio-MaterialsNow, we are discussing about the variables affecting the tool life, as you can see theseare the a to f are the variables , that affects the cutting tool life , the cutting conditions, tool geometry, tool materials , work piece materials, cutting fluid type , and it isapplication techniques there are various techniques ok . So, till now we have seen 3 things thathere is ah cutting conditions, we have seen tool geometry, we have scene and the toolmaterials different materials, that are from HSS to diamond we have seen .Now, we are going to see how various work piece materials that will affect the toollife? ok . So, the m number of materials as the world progresses, we are coming acrossthe variety of materials . So, those are nothing but the work piece material as the world growsthe advancement grows , you are coming up with various work piece materials . If thework piece material is harder , you will need to take the tool materials also harder ok. So, that is ah about the work piece material. Now, we will go into the work piece materials. So, there are variety of work piece materials ranging from , soft tool hard tool brutalductile . It is a overview slide where you can find the many of the world peace materialbrass these 2 are not the brass , but ah these are the brass work piece material , copperwork piece material and the gold. Normally I cannot say that do the machining operation, but ah some of the special cases one uh do the machining operation , such as to fabricatethe car and all those things and the silver and all .These are the overview of materials and ah the world progresses we Come across with tosome of the biomaterials, ceramic materials and all those things Come across with to someof the biomaterials, ceramic materials and all those things Come across with to someof the biomaterials, ceramic materials and all those things .Anyhow this is just a overview t, we just go into the different materials that we comeacross ok . Silicon carbide is one of the ceramic material , it is very difficult tomachine the ceramics , because ah these are the brittle materials and hard materials ok. These are 2 properties . These are the brittleand another one is is a hard materials . So, because of this it is very difficult to machinethis material, another advanced material is the Titanium and bits allowsok . So, the basic problem in machining of Titanium is that, it is a poor thermal conductor, suppose if I want to machine this one what will happen? If it is a portable conductorduring the machining operation . If at all I want to cut the Titanium, the chip is movingand the it is a poor conductor. So, the temperature stays in the machiningregion , itself are at the same time the temperature stays at the bottom of the chip . So, thebottom of the chip gives the temperature to the work piece, are the same thing the temperaturethat is staying on the one piece also, will important to the tool .So, the tool thermal softening will takes place at early stages that is one of the disadvantage,but the same is take considered as the advantage in machining of aero specialized, for turbineblades and all those things . If the temperature is ah stays on the surface, whenever the flight is travelling at a higher altitude , the air comes and give the surfacetemperature is very high that cold air will takes off the heat that is generated . Thatis one of the advantage , that is why mostly Titanium and it is allies are used in 2 applications, one is ah biomedical application , another one is aerospace application the .So, these are the 2 applications normally , see in the aerospace I already said theturbine turbine components and all those things , if you come to the biomedical applicationsnormally, Titanium and the Titanium alloys are uh considered to be the bio inert materials. So, they will cause ah anything to the body that is why, some of the implants like kneeimplants hip implants , these are all developed by the Titanium .So, you know we will come across how these are machined and all those things in a bigway, I mean to say in a elaborate way in upcoming classes; however, I will show you some ofthe glimpse just to do the introducing of these materials in this class ok . So, thatis about advancement of the materials ok, I can say these are the advance materialsok . Now, coming to the ductile materials, thefirst variety of the work piece materials are ductile materials. Normally the leopardmaterial ranging from stainless steel , this is a stainless steel and this is the copperok . So, the stainless steel are uh with iron based steals ok . So, machining this normallygenerates the continuous chip, as you can see here it generates the continuous chips.Most of the ductile materials generate continuous chip, because of each tool life . Because,why we are saying because we are studying the effect of this work piece material onthe tool life . So, if a continuous chip is flowing on the red surface of the tool , therewill be a continuous heat going into the tool , at the same time the there is no vibrations, because the system is continuous and the tool life will be good and all those things. So, if the only problem with these materialsis , entanglement of these chips and on the finishing region or the machining region isanother problems ok, apart from it there is no much problem . That is why, normally wehave studied in the previous classes , the continuous chip is good from the point ofpower consumption, because low power is consumed at the same time surface means point of view. But whenever this chip, if you see the figurenumber 2 figure number 2, if you see where the chip is entangled there itself ok . Ifthe chip is entangled there , if it is slightly entangled under finish surface , if you seethis machined surface this is unmachined surface ok .So, if the chip rub circle as this one , what will happen? this will damage the surfacefinish of the work piece . So, I do not want this to be entangling , for that purpose normallysome chip breakers are used . So, this is about the tool life ok. Tool life in the improve, if we can use chip breaker from the continuous chip , whenever admission in the contiguous. So, whenever we are going to the brittle materials, ductile materials will give the continuous chip , but the brittle materials normallythe basic examples of the brittle materials is the cast iron . The first one wheneverwe think about the brittle material is a cast iron, normally in the short from we call itas a CI . So, it will generate the discontinuous chipsok . The second is brass and you can see the discontinuous chips , discontinuous chipsare lying on the lay bled ok . So, the one noting point that you can seehere is , on the tool life . The first I will speak about the tool life and I will speakabout ah some other thing about the cutting fluid also , I will come to the point cuttingfluid later whenever we are machining these materials , tool life will be good. If atall you are machining a a basic brittle materials, like cast iron and brass , because if theseare the very hard materials normally, if you go to the brittle materials like Silicon carbide,Alumina , Titanium nitride , ah boron carbide these are the very hard materials .So, if you what are you are going for there , because of the interaction between these2, the hardness ratio if you are maintaining the tool which is much much harder than thework piece that are using , then there is no problem . Whenever you are going for theharder materials , then assume that I want to be thin Al2O3 or SiC and still my cuttingtool is coated Carbide , then hardness ratio between 2 will be very less ok . The workpiece hardness to the tool hardness is very less . In that circumstances the basic problemcomes is , tool where will be high ok . So, from the chip point of view this is better. Discontinuous chips are coming so, it is; obviously, better. So, there is no formationof continuous chip and damaging of the final machine surface is not problem ok .So, now the my question to you is , regarding the machining of the cast iron . There aresome questions, whenever you go to the interviews because I face this question when I was mastersok . So, the question is that a which type of cutting fluid that you will use when youare machining the cast iron ok ? So, let me answer this question , normallycast iron will have high amount of carbon, and the carbon in the form of graphite ok. So, the answer is just it is a confusing answer, whenever somebody asked about themachining of the cast iron . So, normally nobody are minimally you do notuse the cutting fluids, the reason I mean to say cutting fluid is not used, just theymay have asked to know the technicality of this process and all those things ok.So, no cutting fluid will be used practically, but whenever the high depth of kerten highfluid, if you are going may be used , but normal conditions whenever you are going fora low depth of kertan in the low feed rate in that circumstances cast iron will have,high percentage of carbon will be there . So, carbon in the form of graphite ok . Graphiteif you see nowadays people talks about graphing and all those things. So, the graphite actas a self-lubricant basically . So, whenever you drill a hole in a cast iron , wheneveryou do machining like if you see for example, here cast iron is machined here .So, no cutting fluid is used , because the carbon content which is in the form of a graphite,in a cast iron will act as a self-lubricate.
Video 3: Cutting FluidsSo now, the variables we have covered is a to d we have covered, and next one is thetype of cutting fluid , as we see our process machining fluids .And we come elabaratively about the cutting fluids in upcoming classes . However justa slight glimpse I will give to you . So, the cutting fluid basic function if yousee that, it reduces the friction and wear and cools the cutting zone , that is nothingbut cooling and lubrication this is called as lubrication, and this is nothing but cooling. So, 2 primary a functions of cutting fluid is cooling and lubrication, that is what Imean to say it from the first 2 points . Last about chips, because there should notbe any entanglement are sticking to the . So, washed away the chips , normally this wallcomes in terms of dealing operation . So, prevent corrosion. So, in order to preventcorrosion it will have lot of ah corrosion inhibitors and all those things that willhelp the cutting fluids , reduces the forces and energy consumption normally lubricationwill help from the point of ah reducing the forces we have seened already power consumptionequal to your C into V . So, cutting force if ah the lubrication isthere, proper lubrication is there the cutting force will be minimized or reduced. If thecutting force religious normally the power requirement goes down that is about the cuttingfluids . So, now cooling properties normally if atall I wanted a cooling properties, in a dominating cooling properties. Waters used to be as acoolant type , basic coolant type normally the cooling variety of cutting fluids areused in high speed applications because high speed applications temperature generationwill be high. So, you have to take out the that whateverthe heat develop due to the temperature and all those things, for that purpose coolingdominating cutting fluids are used . The most effective cool material that can susceptibleis HSS , tool materials susceptible for temperature failures is HSS; that means, that the HSScannot sustain for higher temperature. Normally in the previous classes, when weare talking about the HSS the basic drawback of high speed steel is it is hot hardness, the hardness at elevated temperatures is low that is a problem ok . So, it is a toughmaterial . So, it can take the impacts, but ah hot hardness is low ok .So, the lubricants normally lubrication dominate in cutting fluids usually, are oil-based fluidsnow what I mean to say is that, coolant based are dominating cooling properties and lubricatebased are dominated by the lubricating; that means, that the friction reducing agents ok. Most effective or the lower cutting speeds , normally lower cutting speeds abrasion willbe more . So, at lower cutting feeds friction and abrasionwill be very high, for there the lubrication is required of that purpose normally lubricantbased cutting fluids are used , also reduces the temperature and operation if the frictionis reduced partially you can reduced also the temperature ok . So, this is another function. If you see already the lubricating propertiesand all those things, any how this ah graph we will see in the whenever we are talkingabout the cutting fluids and all those things still since we have seen already, the coolingproperties and the lubricating properties .So, if at all I want the better cooling property , water is the better cooling property . Atthe same time if at all I want at the better lubricating property oils mineral oils orpetroleum oils are very good . So, I want partially lubricating properties , but dominatingcooling properties then I will use some water with some of the additives.Now, I can go even for lean emulsions ok emulsions are nothing but, ah wherever we mix 2 fluidsnormally this will become the emulsions . These are the other one commonly used, if at allI want to go for the better lubrication and the low cooling properties that is what Iwas talking about, the mineral oil with additives can be used.So, the most of the time they commonly used are emulsions ok . So, that I can have optimalcooling properties and optimum ah lubricating properties, for that purpose the emulsionswill be used, if at all I want to add some other additives like ah biocides , the rustinhibitors and ah r is also called as ah corrosion inhibitors ok both are same .So, high pressure additives, many additives are there that you can add to the emulsionsok. This is about the differentiation, ah at the plot between lubricating propertiesof the cutting fluid to the pulling properties of the cutting fluid .So, there are varieties of cutting of cutting fluids . 4 basic styles are there one is straitoils and the synthetic fluids , soluble oils and semi synthetic fluids these are the 4varieties ok . The synthetic foods are not the naturallyoccurring, one mark to these are prepared in the laboratory these are called as a syntheticfluid . Soluble oil they soluble with the water and all those things. Semi syntheticis some of the things are naturally taken, some of the things are developed at the ahlaboratory and all those things . These are the basic categories which you can find voltagetext books and all those things ok . Whenever we want to go for the advanced versions, these are the advanced version of the cutting fluids . If you see the first and foremostis the cryogenic cutting fluid, normally cryogenic cutting fluid is nothing , but a liquid nitrogenbased fluid . This is basically used for ah high temperature applications, wherever ifat all the Titanium is machined are ceramic materials machined and all those things .See here the temperature goes minus 160 degrees and all those things ok. This is about thecryogenic fluids cryogenic, whenever you ah in the next slide , I will show you how thecryogenic fluid is used and all those things , that is why I am not talking about muchabout this cryogenic fluid here . So, the second verity is is solid lubricants, solid lubricants it cannot be a big solid or something . Normally, this solid lubricantare the solid nano particles or micro particles, you just mixed with the externally mixingor internally mixing the aid and you can send to the machining zone , that is nothing butyou have a normally these are, ah MoS 2 or it is CaF2 sorry it is subscript you can seehere . So, MoS 2 CaF 2 that is Calcium Fluoride andTungsten Disulphide . So, these are the common lubricating properties, even graphite also. Just you make a power of this , which are the lubricating properties and you send alongwith a highly compressed day . So, this jet of a along with solid lubricant,will go into the machining zone and it will help in the lubrication ok. The noting pointhere is, the cooling properties of this one will be very low. This will help in termsof lubrication . So, it will reduce the friction in the machining region ok, that is aboutthe solid lubricants . Nano fluids is ah taking up in a anonymousway . The nano fluids are nothing but, you have the cutting fluid you and you have theparticles , some of the people are using copper nano particles or copper micro particles someof the people are using Al 2 O 3 ceramic particles , some other people are using MoS 2 solidlubricants ok . What they are doing is? They are taking a cutting fluid they are takingthe nano particles, they are mixing it and they are sending ok .So, the beauty about it is if you take the cutting fluid , and assume that you are addinga ah ah MoS 2 to it ok . So, you have to check before that what is the chemical compatibility?and all those things, and you make a mamo fluid, assume that I have a 2 things cuttingfluid is there, Plus MoS 2 is there . So, I am mixing and I am sending with highpressure what will happen? The density of particles is very high compared to my fluid. So, there is a tendency that in the chip tool interface, the particles will go andoccupy this interior regions . So, that it may help in the lubrication also , at thesame time it may try to lift by some of the nano meters or something.