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Module 1: Abrasive Machining Processes

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Single Point Tool Operations

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Video 1: Boring and Threading ProcessNow after some machining processes as well as Machining Fluids, now we are moving tothe practical machining processes in this particular course and in particular in thisclass ok. So, what are we have done in the classificationof machining process single point we have done turning process that is a basic machiningprocess, we have done and we are moving to another practices.So, if the classification is single point cutting tool multiple point cutting tool andabrasive process all processes we will deal in this particular course, till now we haveconducted the lectures on the turning process, which is also a basic machining process, whereyou can understand the basic physics in the introduction as well as the machining fluidsin particular slightly in deep analysis. So, now we will move on to the other processesin this particular class we deal with boring, shaping, planning, threading and the tapping,broaching and sawing. These are the processes that we are going to take up and these arealso called as a some of the practically applicable processes, I mean to say that the turningis not a practical process a move ahead these are the other processes that are practicallyuseful. Now, we will move to the some of the singlepoint cutting tool process some of the multiple point cutting tool process, and which areit is named in a some of the books like a practical machining processes. That is whyI also called it as a practical machining processes and so on, we will follow in thenext class other multi point cutting tool processes and followed by the abrasive processesand all those things. Now, we will go to the boring process as afirst process, if you see the boring processes. It is normally looks like this just and Iwill explain you that boring process is producing the circular internal profiles, hole madeby the drilling process; that means, that you required a predrilled hole; normally boringprocess is to enlarge the existing hole for that purpose you should have major amountof times some of the special cases it is ok, but normally if you have a existing hole thatis drilled and you can enlarge that hole, that is called as a boring process.Single point cutting tool is called the boring bar which is a along with the chuck. Now ahif you see here this particular thing is nothing, but the boring bar including the tool theboring bar can be rotated or the workpiece can be rotated both things can happen. Ifat all I want to rotate the tool I can rotate it, if I want to rotate the workpiece I canrotate the workpiece also. Normally in case of lathe if you are doing by the boring bythe lathe process the head stock will rotate or evolve. So, the work piece will revolve. The machine tool which rotates the boringbar again as the stationary workpiece are called the boring machines, there are speciallycalled boring machines and also called as boring mills also. So, can be accomplishedin the turning machine also by keeping the stationary boring bar positioned, but theworkpiece can be rotated so; that means, that the boring tool or the boring bar can be heldin the tool post as a stationary and you can rotate your workpiece.So, that you can do this boring process you can see here this is a lathe on which thechuck is a held the workpiece is held in the chuck and the cutting tool, which is calledas a boring bar is stationary and it is drilling happening that is about the boring process.So, existing there was a small hole now I want to enlarge the hole in this particularthing previously may be like this where it can enter, then it is enlarged to this particulardimension ok that is about the boring process. So, if you see the schematic diagram of theboring process. This is the boring bar and this is the work part or the workpiece worktable is there. In the previous case it is workpiece is rotated now the boring bar isrotated. So, that you can get the enlargement of the hole, that is shown here in the schematicdiagram. So, these are the boring bars if you see theboring bar there are different varieties of boring bars which are nothing, but the cuttingtools that are used in the boring process. You can use the HSS single point cutting tool,where you can do the boring bar by using a tool and cutter grinder has per your requirementand all those thing. For that purpose only thing you have to do is you should know howto utilize? How to make particular chuck or the blank that is given by the supplier, whichis a HSS material just you go to the tool and cutter grinder as per your drawing, youcan change to this one commercially available ah boring bars are there just you can usethis to make the bore. So, boring machine types normally there are2 varieties one is a horizontal boring and another one is a vertical boring. So, youcan use horizontal also or vertical also ok. This is about the tool ok. Normally the cuttingfluids, the cutting fluids since it is the machining and machining fluids so, we shouldalso look up at we also should look at the cutting fluids that are used . Normally youcan use both because the boring process can be slightly lower cutting speeds comparedto turning process or some people they may operate depend on the tool material if theyhave a very good high hard stool material they can go for higher speed also.So, you can go for the pure lubricants also as well as emulsion types also in this oneif you see it is looking like a milky color. So, the whatever the cutting fluid they haveused is a cutting fluid emulsion . If you see in the some other cases you cango for the higher amount of a pure lubricant oil with low amount of water. So, the lubricatingproperties will be better in boring process ok. So, this is about ah boring process, nowwe move on to another practical process that is called threading threading is nothing,but ah making of threads internal threads as well as external thread.So, threading is helical shaped groove formed on a cylindrical surface of the workpiece.So, it is a continuously formed helical groove. So, threading cutting operation performedon a lathe to produce a threads by using a tool whose shape will be same that are thethread ok. Assume that I want to make a thread shape.So, you have to have the similar type of shape on the tool also ok. So, external threadsare provided on the bolts screws while the internal threads are incorporated on the nutsand any other machine members this are the 2 varieties; if the functionality of the fastenersare thread for the holding component. Normally if at all I want to hold the componentfor that purpose this threaded components are used . If you see the picture this ishow the thread look like. So, it will have a pitch, it will have a lead, it will havea normally this is the root, pitch, crust to crust is nothing, but pitch there are singlestart multi start threads are also there. So, therefore, thread is there and this isthe crust. So, one crust to another crust it normally the distance is normally knownas a pitch and the lead is nothing, but how much it will move in one rotation ok.If it is a single start thread normally it will move lead equal to pitch if it is a multi-startyou have to multiply by that multi what is the it specified by l. So, helix angle willbe there and the major diameter of the thread minor diameter of the thread under pitch diameteralso will be there this is major diameter and this is the minor diameter of the threadand you will have also the pitch ok. So, you will have the minor diameter majordiameter as well as the pitch diameter. So, this is ah pitch diameter also you can sayit as a mean diameter of that particular threads ok.So, the now we will have also have thread angle normally in this one commonly used arecommonly explained threads are like v threads, where you will have a 60 degrees you can seewhich you can divide into 30 and 30 here. So, the ah you you will have normally singlestart thread multi start thread that was I was talking about and I will explain you whatare the single start multi start and all those thing.So, the thread cutting or the thread manufacturing can be done by various techniques first andforemost basic technique is ah thread cutting using lathe, thread chasing using chasing,die threading, tapping is there thread milling is there thread rolling and thread grinding,thread casting, and thread whirling all these are the varieties of the manufacturing techniquesof this threads. So, whatever you can see here is the simpletechnique that is what I have explained in the previous slide also that is called ahthread cutting by the lathe process, in a lathe machining process you can cut this threads.So, the principle to produce the helical groove on a cylindrical or a conical surface by feedinglongitudinally, when the job is rotating that is how you can generate the threads on thelathe by using a lathe machine . Screw threads there are ah 3 varieties ormulti varieties are there, normally in the common practice will have single start, doublestart, and triple start . So, where ever if you see a single start normally lead equalto pitch, where pitch if you multiply by one normally pitch will be pitch only. So, thatis nothing, but is called single start, if you have lead equal to double of the pitch;that means, that double start and if you have lead equal to multiply by 3 into the pitch;that means, it is called ah triple start thread. Normally why we have to go for single startto triple start the students may know there is about single start threads are there doublestart or triple starts are there, but the practical use of this one is if at all I wantto open certain caps or something. So, if at all I want to put less energy and I wantto get more outcome there you will normally the people go for the double start and triplestart. If you for example, if you see the some ofthe cool drink bottles, if you if you what if at all if you rotate in one go it willmay come some of the bottle may not come. So, those come where ever you just rotatein one go automatically complete it may come out, that is called the technology they mayuse is double start or triple start. So, if you put less energy or one rotationitself it will come out, but if you tighten it also in one rotation itself it will takeperfectly. So, if at all I want to open with less amount of energy and tighten it withless amount of energy you have to go for multi start thread, oh if in a single start threadit will have long time. So, it has to go go go go and go it go on it will be ok.For that purpose normally multi start threads will be used . So, thread manufacturing theanother process is milling process you can also do by the milling cutter, the threadscan be produced by the milling process also that is using the form cutter. So, dependon the shape of the threads that you want your thread cutter you will choose ok. Theform you can choose depend on your requirement of the threads ok. So, the that is why youwill use the form cutter. So, normally when this is suitable is whenproducing external thread which are suitable to cut with a with a tap not with a tap; thatmeans, that if you are unable to cut using the tapping process. The tapping process youcan you will come across in the upcoming slides in this particular class . So, where the ahthreads are not in a position to cut by this tapping process you can cut external as wellas internal. So, I am talking about external in this particularslide if you are unable to cut there you can go for this one. So, normally if you havea very big diameter then you can go for the thread milling process, work that I said onlarge diameters beyond the capacity of a die if I if die is cannot do normally you cango for the thread milling process . So, thread milling it is cold forming processfor making external threads on a cylindrical surfaces and the threads are formed into theblank by pressing the thread rolling against the die or a blank. Normally you can use thisone this is what I am talking is not about the milling it is called the what I am talkingis thread rolling process ok. Rolling process is a cold forming processfor making external threads on a cylindrical surface threads are formed into blank by pressingthe or the rolling against blank. If you see it is a faster method of the production skilledlabors not required . And it is it is a chip less operation there is no chip; that means,that there is no material wastage like in a metal cutting process you will get the chipwastage that is material waste in form a chips. So, here it is a material it is a materialforming process. So, you do not have any chip formation. So, there is no loss of the material,threads are produced by rolling possess good quality and high accuracy. So, whatever thethings are you are going to get will have a better accuracy and ah good quality . Threadrolling increases the tensile as well as fatigue strength of the workpiece material; that means,that whatever the output that I am going to get will have good strength I mean to saytensile strength has well as fatigue strength also .So, for the problem with this thread rolling is it is limited to the ductile materials.Means the material should plastically deform easily, the ductile deformation should bethere if it is a brittle material what will happen it will fracture and it will damagethe workpiece. So, the threads may not form on the particular surface.So, thread rolling you have a 2 type of varieties one is cylindrical, another one is reciprocatingflat die machine. This is called flat die manufacturing processwhere 2 dies are used one is at the bottom die, which remains stationary and other isreciprocating die, what is I mean to say is this is the fixed one and this is the movingone. So, you can reciprocate here. So, that this is your workpiece, the threads are formedon this one by metal forming process where chip is not there and all those thing .The another process is cylindrical die manufacturing, where you will have the die on one side, anotherone is the workpiece will be there at the center then you will have a another supportand you can generate it. Cylindrical die machine uses 2 or 3 dies depend on the requirement,you can use 2 or you can use 3 also . So, in case of 2 die machine as shown in thefigure the blank is supported between the dies and this 2 rollers are rotating you cansee here there is a directional symbol is given here there is a directional symbol isgiven. So, these are rotating against the workpiece that is there here this is the workpieceah threads are formed on the workpiece. So, this is called cylindrical die manufacturing,both this are all metal forming process ok. These are all metal forming process, whichare not metal cutting process that we learnt in the previous lectures are in this particularlecture also that is the only difference you have to make sure about this particular slide. Another method is thread casting method wherecasting all of you may know, because it is a one of the primary manufacturing process,where you can ah take the cavity of the mold then you can ah make it like you just meltit and you just pour it into the cavities the threads are made by the sand cast arerough and not used for except sometimes vises and rough machinery; that means, what I meanto say here is sand casting type of threads if you are somebody is manufacturing thoseare very rough and not used in precision applications, these those are used for rough machinery application.
Video 2: Taping and Knurling ProcessNow, we move on to the taping process. So, where the taping process, if you see the tapingprocess the schematic diagram or the sectional view also you can see here. So, this is thetap and this is the workpiece where you can generate it by the machine or also you cangenerate by the hand also, there are taps hand operated there are the taps the machineoperated also are there. So, one by one we will see introduction tothe taping process taping process is the cutting thread inside a hole. So, that the tap capscrew or can be bolt can be threaded into a hole that means; my prerequisites I requireda hole to make the tapping process. There is no hole I cannot generate the threadingon particular workpiece; that means, that I cannot generate the threadings if thereis no hole. So, I require a hole on which I can generatethe threadings. Taping is done with the tool called which is called tap. So, you can seehere this is called as a tap, the taping operation it can be done by the hand taping lathe machinealso you can use milling machine also you can use and taping machine also, you can usethere are 3 varieties of taps, you can get and the tap is used for internal as well asexternal threadings. So, whatever you are seeing here this is whatis here and this is what the internal threads are generated here? The same time you cansee here 1 2 and 3 these are the tap sets. Whenever somebody want to purchase tap setnormally the people will purchase in a set it will come as a set. Normally you can alsopurchase nowadays, because the materials technology developed. So, you can even go for a singletap, but advisable is you should go for a tap set .So, one can generate the ah external as well as internal this is ah how the external threadingswill be done and this is how internal threads ok. So, thishow the internal as well as external threads are generated ok .So, now we will move on to the ah basic thing that is how the hand held taping process iswork. So, this is how the tap will be normally the tap geometry will be like cutting edgewill be there on edge heel this is particular thing is the land how much width is therethat is nothing, but the land everything here also you will get a relief normally that iscalled chamfer relief and it will also have certain rake angle here and you will alsohave the flute. So, that the chips will come out ah wheneverwhatever generated there it has a provision to send it out. So, you can see the flutehere these are the flutes where through whatever the ah things that are coming here, it willcome then along with the lubricant or along with the cutting fluid that are used here.You can generate 2 types of taps or threading's that is called through threading's also youcan do and bottom tap also you can do where you can terminate at at certain distance itself.So, these are varieties of threadings you can do here; hand taps the first one is thetaper tap. I said there are ah set of taps will be there normally a tap set will contain3, which you have seen in the previous slide . So, among that one whenever I want to generatea particular thread assume that I want to generate m 10, for that particular normallythe prerequisite is you should have a drilled or reaming hole first you do the drillingoperation then, you do the reaming operation then you go and use the first one is tapingtaper tap. So, you may not go for 10 mm hole you cango for 10.8 or 9.7 5 or something. So, that this taper will be there this particular taper,which is there can penetrate at the initial stage. So, that it will once you twist onit will gradually enter into the workpiece ok.Chamfer normally lead 7 to 10 threads at the 5 degrees per side you can see here 7 to 10threads are there, which are chamfer will be there ok; that means, that there will besome taperness will be there. the taper lead distributes the cutting forces over the largearea and the taper shape help the threads to start; that means, that if I have a 9.8mm hole, this taper will help me in positioning at the initial stage ok.Let me position first then you can generate the threads ok. So, used for starting a threadprior to use the second and bottom . So, there are other 2 taps before that one you haveto use it; that means, that I have a 9.8 mm hole, where I use that taper tap and I justgenerated a initial threading before I go for second and third taps ok. Once I completethe taper tap I will move on to the second one that is called plug tap or the secondtap . Which is here instead of 7 there here youwill have 3 to 5 threads will have chamfer and use through holes are also you can generatethe blind holes where the threads are not need to go to the right bottom; that means,that you can also go for the blind holes also where blind holed threads also .And what is the point here to be noted is that you have to use this particular one afteryour taper tap ok. So, taper tap followed by the plug tap then followed by the thirdone that is called bottoming up tap ok. So, chamfer normally here it will be 1 to2 threads and angle of the lead being around 18 degrees per side and used to produce closeto the bottom of the blind holes. Normally if at all I want to generate a perfectly threadsacross the cross section of the workpiece the means that I want a through threads ofthe workpiece completely in that circumstances I have to use this particular thing; thatmeans, first taper will be there then the plug will be there, then bottoming tap willbe there. So, that you will get the perfect throughout M 10; that means that it will haveM 10 generating threads on this one. This is about the 3 varieties in a taps set taperplug and bottoming taps ok . Now, we move on to the ah knurling processwhere knurling is nothing, but embossing of ah diamond cone pattern or some other patternfor the griping purpose ok . Introduction to knurling process normallyprocess of embossing the diamond or straight shaped pattern on to the workpiece that iscalled ah knurling process. It improves the appearance of the workpiece it can gives goodaesthetics to the workpiece at the same time provide better gripping, this is the majoradvantage or major application of the knurling process is to have the grip. Normally wheneveryou see our homes ah locking systems and all those things will also have the gripping ifit is in cylindrical shapes and all those things. So, you can use for those grippingsthe knurling process ok. So, in case of the workpiece diameter when press fit requirednormally if at all I want for the press fit. So, if you can use the knurling process whatwill happen it is a metal defrocking process, because of which the dimensions will slightlychange and then you can fit it perfectly. Special tool that is called knurling toolis used for this particular operation, whatever you are seeing here this is these are allknurling tools ok.
Video 3: Shaping and Planing ProcessNow, we move on to the shaping process. Shaping process is is a different process comparedto the lathe, whatever till now what we have seen is some of the accessories that you canmount on a lathe then you can perform it. Now the shaping process is slightly different,which is some of you know it about this process shaping.Shaping this is the shaping process where you can give the cutting motion is providedto the tool and the feed motion is given to the workpiece. Basically you have a workpiecethis is the workpiece and this will be provided the feed motion; that means, that this typeof motion will be given and the cutter will be reciprocating like this.So, cutter will reciprocate as well as the feed will be given to the workpiece in thatcircumstances the material removal takes place in the forward stroke. These all work underquick return mechanisms, the quick return mechanism is one of the mechanisms that youmay come across in the theory of machines and other courses where in the forward strokeonly it will cut and in the return stroke if there is no material removal and it willcome at very faster rate . There will be 3 forces that is generatingthat is called F c F a and F p where F r is nothing, but the ah in this shaping processthere are 3 forces are generated, which results in F r. So, where F r is a resulting forceor a resultant force F c is the cutting force h a is the feed force as well as F p is theradial force. You can see here F a is in this direction and F c this is the cutting forceand F p which is the radial force and the feed force is in this direction, 3 forcesare there and the cutting velocity will be given to the tool ok.So, the velocity if at all I want to calculate, because there is a quick return mechanismis involved the velocity of forward stroke is different from reverse stroke . That iswhy you have to always be attentive in that circumstances it cannot be l 1 plus l 2 by2 or something. So, you need to take many things here where v equal to ns 1 plus r by2 where S I S nothing, but the stroke length how much stroke it is moving R is the quickreturn ratio and N is the number of strokes per unit time ok. For unit time how many numberof strokes are taking place, these are all will give me the velocity in the shaping process. If you see the shaping process there are manyvarieties of the shapes that one can generate that is called facing on a top, this is theone type of generation facing on a side because this is the top surface . So, it is done onthe facing on the side ways and some of the thing is you can also generate the slots,where you can put the keyways and all those things at the same time you can also generatethe steps also. These are the varieties of applications of the shaping process that onecan generate . Now, move on to the another process that iscalled planar process this is similar to your shaping process. But only the motions arevice versa here the cutting motion will be given to the workpiece and the feed motionis given to the tool ok. So, the planing machines normally used for big workpieces, the shapingnormally uses for the small workpieces that is a only difference if you see the straightand flat surfaces created on both surfaces. Now in this particular slide.If you see here the similarities between shaping and planing is explained, in the both shapingand planing the straight and flat surface is created on the both surfaces interruptedcuttings subjected to tool impact when entering the tool; that means, that when the tool isstarting it is journey what will happen it have some impact on it; that means, that therewill be a impact load on it . So, low cutting speeds are due to the startand stop mechanism, because at the start it will start from 0 and it has to go to 0 velocityfor; that means, normally this particular process will be conducted either shaping ora planing process at lower speeds ok. So, typically tooling single point tools whichmoves linearly relative to the workpiece in the both either, you are giving a cuttingmotion shaping or whether you are giving a feeding motion in the planing both are likelinear motions for the shaping as well as planing .