 I welcome you all for this session. In the last session, we discussed about the different types of micrometers. Now, we shall continue with that. We will discuss some more types of micrometers available. Now, this is a micrometer of range 25 to 50 millimeter. Now, the specialty of this is we have a counter here, mechanical counter. So, when we rotate the timber, we can the counter will change and then we can directly take the reading from this. This figure shows a digital caliper, wherein we can see there is a digital display. This is a dual type. We have the graduations on sleeve and timber also. We can read this mechanical system as well as the digital system. Now, we can see the various buttons available. This is a button for switching from English system to metric system and then we have on, off button and this is a zero button. At any point of time, we can or at any location of the spindle, we can set zero and from that reference, the readings will be given. So, like this, this can be used as a comparator. We can set the distance between the anvil and spindle using a setting master. For example, say 15 millimeter setting master we use and at a distance of 15 millimeter, we can set zero and we can check the work pieces and then the micrometer will indicate only the deviation from 15 millimeter setting. So, this way we can use this as comparator and you can see using this hold button, we can hold the display and then we have direct data input to computer. That means, from here RS 232C data transmission is possible by connecting suitable cables. We can transmit transfer the data to a computer for statistical process control. Now, this shows a close view of the display and see in this case, we have to put the battery and whenever the battery goes down, we have to recharge and we should use it. Now, recently solar powered micrometers have been developed. So, the light is converted into electricity and that is stored in the battery. So, that way solar powered micrometers are also available. So, this is a special type of micrometer, sheet metal micrometer. We can see the construction, we have a u type body. The distance between you can see the this distance is longer. So, that we can insert the sheet metal or the plates for measurement for thickness measurement purpose and then we have a large diameter dial for easy reading and then again we have a ratchet mechanism. So, there is no over near only one dial scale we have. So, we can take this case the direct reading and the resolution of this is 0.01 millimeter and in different ranges the sheet metal micrometers are available. It is a range of 0 to 25 or range of 0 to 10 millimeter, it is a range of 0 to 12 millimeter. So, we have miniature thickness measuring micrometers are also varying the range will be like 0 to 4 mm, 0 to 5 mm which are used for measurement of paper thickness or thin film thicknesses or for measurement of jewellery. So, such things are possible. Now, this is the close view of the dial. We can see the reading is very easy here, readability of the dial is very very easy where the graduations we can see and then all the numbers are printed and they are very easily readable. Another interesting thing is we can observe the pointer is very close to the dial. So, this is for elimination of the parallax error and then we have another kind of micrometer which is a limit micrometer. You can see this has dual spindle two spindles and two anvils. So, this two spindles can be used for setting the upper limit and lower limit. This is for tolerance setting upper limit can be set in this and the lower limit dimension can be set in this and then we can insert the work piece. So, if it goes and if it does not enter here the work piece is acceptable. Now, let me explain how to use the depth micrometer. First let us see what are the various parts of the depth micrometer. We can see the body of the micrometer, the spindle of the micrometer and then we have the sleeve and the main scale and now we can see the scale is reversed. So, 0 is somewhere here and then 10, 15, 20, 25 like this and then this is the thimble and thimble scale. So, the resolution of this instrument is 0.01 mm and range is 0 to 150 millimeter using these extension rods. Depending upon the depth that is to be measured we can select the appropriate extension rod and we can put the extension rod inside this and then we can use. If there is any 0 error we can rotate this sleeve by using the spanner and then we can make the 0 error 0. Now, how do we check the 0 error of this instrument? So, what we should do is we have to completely withdraw the spindle by rotating the thimble like this and then we have to keep in the after withdrawing the spindle completely in we have to keep the instrument on the surface plate and then we have to rotate the thimble in the other direction. So, that the spindle just touches the surface plate and then we should read the scale. Now, we can see that there is some 0 error. So, we have to rotate the sleeve for making 0 adjustment. Now, we have to take the spanner and we have to rotate this sleeve and then we have to make it 0. Now, we can see the 0 on the thimble is coinciding with this reference line. Now, this is ready for use. Now, how do we use this for measurement of thickness of a workpiece? So, I have a workpiece here I am keeping the workpiece here and then I have to keep the instrument like this and then I have to press this body and then I have to rotate the thimble. So, that the spindle just touches the surface. Now, it is moving towards the workpiece and the surface and now see we should not over pressurize it. Now, we have to operate this ratchet. Now, it is ready for reading. Now, we can see the thimble has just crossed 10 millimeter and it is near 10.5 and then after that we have 0, 1, 2 divisions. That means, the thickness of the workpiece is 10.5 millimeter and then we have to add 2 divisions. 2 divisions means 0.02. So, thickness of the workpiece is 10.52 millimeter. So, this is how we can use depth micrometers for measuring the thickness. Similarly, we can measure the inside diameter and the inside depth whole depth. So, in that case we have to keep the instrument like this and then we have to advance the spindle like this till the spindle just touches the bottom surface datum and then we can lift and again we can take the reading. So, next we have special type of micrometer which is known as laser scan micrometer. You can see the arrangement of the laser scanning. So, one side we have emitter, we have laser source, we have rotating polygon mirror and then optical lenses are there and then we get the laser light, it falls on the receiver side. Again, we have lenses and photo diode. So, from here we can take out the electrical signal and it can be fixed to the digital display. Now, we have to keep the workpieces here for measurement purpose. Now, this shows a laser scan micrometer and this is the place where we have to keep the workpieces and there are some stages workpiece setting stages are available. So, depending upon the requirement, depending upon whether we are measuring the wires or sheets or plates or round bars, cylinders etcetera, we have to choose appropriate stage and we have to fix the stage here and then laser will fall on the workpiece and then the receiver receives it and it is sent to the display unit. Now, I can see one example here. This is diameter and measurement height measurement. So, I can see the component here. So, at a time we can measure all these sizes, all these diameters and other interesting thing is we can also measure the heights. So, at a time we can get a diameter and height measurement. And this shows an x, y, z table wherein we have micrometer heads. So, using micrometer heads we can create stages like x, y stage or x, y, z tables. Now, we have some specifications of laser scan micrometer. 615 nanometer visible laser is used for the measurement purpose and the operating temperature is 0 to 40 degree Celsius. Now, you can see here the measuring ranges in different ranges the laser scan micrometers are available like 0.05 to 10 millimeter and then 1 to 60 millimeter range, 1 to 160 millimeter range and then resolution also I can see it is 0.01 to 10 micrometer for this particular range and for the second range it is 0.05 to 100 and for third range it is 0.1200. So, the 0.01 to 10 micrometer resolution means they are selectable depending upon the accuracy that is needed we can always select the required resolution. So, where very fine precision measurement is required we can go for very fine resolution for medium or precision work we can select the appropriate resolutions. Now, I told you about the adjust the table setting adjustable work station that means between the emitter and receiver we have to place some stages work stations and these there are adjustable work stations vertical adjustable work stations and horizontal work stations are available we can select appropriate work station and we can use them for example. So, we have the laser scan micrometer like this and this is the place where we keep the adjustable work station. So, here this can be moved horizontally and there is arrangement to move this vertically and then say we have we can keep the work pieces here and then laser will fall here and then it receives and then it gives the dimensions. So, like this we are depending upon the work piece we have to select appropriate work stations and then the air blowing is possible to clear the dust for example, say on the window where we get the laser and where we receive the lasers we have windows. So, there should not be any dust particle laying on the windows or lenses. So, for cleaning purpose air blows are possible before we are using the micrometer we have to clean all the surfaces and then we can use it and then for calibration purpose standard calibration gates sets are available along with the micrometer before using we can put that gates set and we can calibrate and then we can use the micrometer and the I told you about the different ranges available and the selectable resolutions that are possible. See the resolution here is 0.01 micrometer such fine resolutions are possible and these micrometers they are capable of providing the repeatability of plus or minus 0.04 micrometer and for this particular range plus or minus 1.4 repeatability. So, there very good repeatability is assured and they also very good accurate measuring measurement is possible for this 0.05 to 10 millimeter range I can see the accuracy is plus or minus 0.5 micrometer that means see we get some result we measure some may be the diameter of the spindle and we get some data. So, that data the true value of the component will be within the this variation plus or minus. So, for example, if we get 8 millimeter as the diameter and then the true value of the workpiece will be 8 millimeter plus or minus 0.005 millimeter such a great accuracy we can get. And then see the these instruments they have very high measurement speed like 3200 scan per second that means if you have conveyor and if the workpieces are moving continuously. So, at a very high speed we can measure the components of a mass production we can use the instruments like this. Now, there are very interesting applications of these laser scan micrometer now in line measurement of glass fiber or fine by this possible. For example, say this is the laser scan micrometer. So, and then we have the glass fiber or some other kind of fine wire. So, the wire is moving in this direction and at the other end we have a receiver receiving roller. So, it will be continuously moving this glass fiber or fine wire will be continuously moving and the laser will be scanning what is the diameter of the fiber. And then that means continuous monitoring of the diameter of wires is possible. So, wherever there is a deviation we can make some adjustments in the settings. So, that we get the wire in within the tolerance and then we have O D measurement, taper measurement and out of roundness measurement of cylinder is possible. For example, say we have a round workpiece like this and we have kept it between the laser emitter and receiver using appropriate work stage. So, the laser will be falling like this, laser is falling like this and here this workpiece obstructs the laser. So, we get like. So, now this distance gives the diameter of the workpiece. So, this is O D measurement and then taper also we can measure for example, we have the workpiece like this. So, and we have the micrometer here and we have the window here to this is receiving side and here it is the laser is emitted. Now, either we can move the micrometer or we can move the workpiece. So, it takes the diameter here and then when we move the workpiece it takes the diameter at the other point. So, like this multiple scannings are possible and then we can this will give by processing the data we can say whether it is a perfect cylinder or any taperness is there that can be checked and then out of roundness also can be checked. For example, we can keep this is the workpiece and we can keep a reference here or a reference gauge and then we have to rotate this workpiece. And laser will be falling like this laser will be falling like this. Now, if there is any variation in the workpiece. So, this gap will vary. So, this gap will vary and that gives the out of roundness of the workpiece. Similarly, this can be used for measurement of thickness of sheets like this we have a reference gauge and then we have the roller on which the sheet is moving paper or some sheet some thin film is moving like this and then see the laser is falling like this. Now, if there is any variation in the workpiece variation if there is any. So, this is the if there is any variation in the sheet thickness. So, this gap will vary and that gives the deviation from the required thickness of the sheet. So, like this the film thicknesses variation of the thicknesses can be measured and then spacing of IC chip heads. For example, we have an IC chip like this and then we have the leads like this. So, this we can keep between the in the micrometer and the laser will be falling like this. So, it will measure the distance between two chip leads. So, if there is any variation we get the measurement result. Then gap between rollers also we can check for example, see in the rolling mills we need to set the distance between rollers very precisely. So, we have two rollers like this and we want very thin sheets varying we have very tight tolerance. So, in that case for setting the distance between rollers we can use this laser scan micrometer. So, this will this distance will give the distance between rollers. So, very precisely we can accurately we can set the distance between two and we can wherever whenever the distance is to be checked we can use this laser scan micrometer. And then measurement of form is also possible whether there is any variation in the cylindrical there whether it is drum shaped or double bell shaped like this barrel shape. So, if the workpiece is like this. So, by scanning multiple scanning will come to know what is the shape of the workpiece. And sometimes the way say we have workpiece is very large large cylinder is there and we want to measure the diameter of that in that cases a dual micrometer arrangement is possible. For example, this is the diameter of the workpiece it is a large workpiece and then we can have two micrometers like this and on the other side receivers. So, now laser will be falling like this we get one reading here and then on the reading here. So, this will give the diameter of the workpiece. So, like this we can use x and y direction x x direction y y direction depending upon the application we can use multiple laser scan micrometers and the data can be required data can be taken. Now, let us move to the whole measuring instruments. There are different kinds of instruments are available like board gauges, two point contact board gauges, three point contact board gauges. And similarly dial caliper gauges are available for quick measurement of the inside dimension of a hole and then inside or internal micro meters are also available where in two point contact micrometers and three point contact micrometers are available. So, we will study some of these things. Now, let us move to the whole measuring instruments in the manufacturing plants we come across with many times we come across with measurement of holes the inside dimension of different sizes. It may be very small hole like 1 millimeter diameter, 2 millimeter diameter or it can be very large hole like 100 millimeters, 200 millimeters, 300 millimeters and then different kinds of instruments are available. Now, let us study some of the instruments board gauge board gauges are available with different ranges and then we have dial caliper gauges for quick measurement of inside dimension and then we have internal micrometers different types of internal micrometers. Now, let us study these things one by one. Let me explain the board gauge, this is the board gauge, this is the gripper part where we have to hold the board gauge you can see an insulating material is provided here. So, that the operator body heat will not flow into the instrument. Now, this is the range of the instrument 18 to 35 millimeter and this is the dial and then we have the measuring portion here. So, we have a round guide here which will make contact with the bore of the workpiece and this is the measuring stylus which will move in and out this is carbide tipped to prevent to reduce the wear and then this is the fixed portion which will make contact with the wall of the hole and again this is the carbide tip is there. So, these are interchangeable anvils depending upon the size of the hole we can remove these anvils and we can replace them. You can see here different anvils are available with different sizes 24 millimeter, 26 millimeter like this and also some washers are available. So, if required we can use these washers to increase the length. Now, I will explain how to use bore gauge for measuring the size of the hole. I have taken an anvil of 22 millimeter and then I will just measure what is the length of the distance between the anvil and spindle. So, the distance between the stylus and this point is as given by micrometer it is 22.79 millimeter. Now, the dial is reading 0 I will just insert the measuring portion in the hole like this. Now, we have to see the pointer is moving in the clockwise direction. Now, we have the zero reference here and then in the clockwise direction it is moving we have to rock or we have to swivel the bore gauge like this. So, that it checks the correct diameter for that we have to take what is the maximum reading that is given by the bore gauge. Now, it is reading 74 divisions that means 0.74. So, now slowly I am removing this. Now, that 0.74 I have to measure the length deduct from the initial setting of 22.79. So, that we will get 22.05 millimeter that means the diameter of this hole is 22.05 millimeter. Now, we have another kind of instrument known as dial caliper gauge. You can see here I have a dial caliper in my hand this is the dial of the dial caliper and we have two legs of the dial caliper and we have a lever here for moving the legs. For zero error checking we can use the setting master and we can check the zero errors and then we can use the instrument. The range of this particular instrument is 10 to 30 millimeter and resolution of this instrument is 0.01 millimeter. Now, let me explain how we can use this dial caliper for measurement of internal diameters. I have a component here and I have to measure the internal diameter of this dial caliper. Now, I have to keep the workpiece on the surface plate and then I have to operate the lever so that the two legs come closer like this and then I have to insert the two legs into the bore of the workpiece into the hole and then we have to swivel like this to and then we should take the minimum reading. Minimum reading will give the diameter of the workpiece and when the caliper is like this we should not read because this will lead to cosine error as shown on the black board. Now, let us move to the internal micrometers. Now, there are different kinds of internal micrometers like 2 point internal micrometer and 3 point internal micrometer. The problem with 2 point internal micrometer is say we have a hole of this shape. So, if we use the 2 point internal micrometer what happens is the contact so this is the micrometer contact will be at only 2 points and to get the mean value of the bore or the hole we have to take at least 3 to 4 readings and then we have to get the mean and that will be the diameter of the hole. If we take only one reading we may get some wrong reading. For example, say there is a probability like this and if we take only one reading it may give a larger diameter. If we take the diameter at this place it will give a smaller diameter so such problem will be there in the 2 point internal micrometer. To avoid that the 3 point internal micrometers have been developed there will be contact at 3 points. So, automatic centering will be there and we get the directly the mean diameter. Now, you can see the 3 point internal micrometer a diagram is written here. So, this is the front view and this is the end view you can see these are the points or sometimes we say pin and sometimes we say anvil. There are 3 anvils separated at an angle of 120 degrees and we have the micrometer unit here. This is the sleeve with the main scale and thimble and we have the thimble scale. So, when we operate this thimble these anvils they move in and move out depending upon the direction in which we rotate the thimble. So, initially what we should do is we have to set this micrometer we have to see whether the setting is correct or not whether micrometer is giving the proper result or not that means whether there is any 0 error. So, setting rings are available along with the micrometer using setting rings we have to check for 0 error if there is any 0 error we have to adjust it and then we can use this micrometer. Now, different ranges are available like 6 to 8 millimeter range 8 to 10 millimeter range and 10 to 12 millimeter range they are also available from 100 to 300 millimeter in steps of 25 millimeter. Now, we have to insert this micrometer inside the hole and then we have to operate the thimble. So, the pins will move out and they will come in contact with the inner wall of the bore and then we can directly take the reading. So, like this we can use 3 point internal micrometers and the such instruments they are capable of a very good accuracy of plus or minus 2 micrometer at the lower ranges. Now, let us see the internal micrometers. Now, we can see the 3 internal micrometers are available here the range is 6 to 8 millimeter then 8 to 10 millimeter and then 10 to 12 millimeter. Now, we can see the pins here anvils. So, there will be 3 anvils now you can see 3 anvils are there at 120 degree apart and then this is the scale on the thimble. So, 0 to 50 50 divisions are there and then this is the vernier 10 gradations are there for the vernier scale. So, the resolution of this instrument is 0.001 millimeter. And main scale we can see here on the sleeve this is the main scale the range of this instrument is 6 to 8 millimeter. Similarly, we have another internal micrometer with this range 8 to 10 millimeter and then the main scale on this sleeve and then vernier scale and then thimble scale and then thimble scale. Similarly, we have one more internal micrometer 3 point internal micrometer 3 anvils are there and then the range of this is 10 to 12 millimeter and then we have the main scale here on the sleeve and then vernier scale and the scale on the thimble. So, again the resolution of this instrument is 1 division is equal to 0.001 millimeter. Sometimes if the hole is very deep then we can use this extension rod we can fix this extension rod here and then the deeper holes can be check for fixing this extension rod. You can see here at both the ends we have threaded ends this is a threaded end as well as we have threads here and then initially before using we should clean the anvils. So, that the dust and oily layer is removed and then we have to check for 0 error for that masters are given. So, this is 10 millimeter master and this is 7.996 millimeter that is 8 millimeter master is given using these masters we have to check for 0 error and then we can use the instrument for hole measurement. Now, let me explain how to measure the diameter of this hole I am taking this internal micrometer of 8 to 10 millimeter range and then I am rotating the thimble. So, that the anvils are withdrawn now anvils are moving in all the anvils now they have moved in and now I have to insert the instrument inside and then we have to rotate the thimble. Now, the anvils are coming out they make contact with the internal wall of the hole and then we should put the ratchet operate the ratchet now this is ready for reading. Now, you can see the 10th graduation is just visible that means, thimble has crossed 9.5 millimeter and now we have to take the reading 0 references here and the the graduation on thimble 40, 41, 42, 43, 44. So, that means, we have 44th graduation on the thimble is coinciding here that means, the reading is 0.44 millimeter and then we have to look for which one is coinciding coinciding division. So, in this case the 44th reading itself is coinciding here 0 0 graduation is coinciding here. So, the if we add the 0.44 with 9.5 the reading will be 9.94. So, the diameter of this hole is 9.94 millimeter like this we have to take the readings. Let us conclude this session in this session we discussed about different types of micrometers like the digital micrometer and then sheet metal thickness micrometer and then depth micrometer and also the laser scan micrometers and what are the various applications of laser scan micrometers? What are the specifications of laser scan micrometers? Those things we studied also we discussed about the different hole measurement devices like bore gauges and dial caliper gauges and then internal micrometers. In the next session we will continue with linear measuring instruments. Thank you.