 Welcome back to the lecture series on Metrology, we will start module 11, lecture number 2. In this lecture we will be covering the following topics, practical tests on late, in the previous lecture number 1 we discussed about various alignment test, static test. In this lecture we will be covering some aspects of practical test conducted on engine lead and then we will move on to test on pillar type drilling machine, under this we will be covering alignment test and then the practical test and then we will cover general inspection of machine tools. Now we will discuss about the practical tests conducted on engine lead, so in which a workpiece is mounted in the chuck or faceplate mounted on the nose of the lead spindle and machining operations such as turning and facing and threading are performed and the machining accuracy is tested. In this diagram we can see a workpiece of length 300 millimetre is mounted in the trija chuck or faceplate, the diameter of the workpiece is 1 4th to 1 6th of swing over bed, if the swing over bed is 100 millimetre then we can take the workpiece of diameter of 25 millimetre and we can fix it to the work holding device and we can turn it. So length of turning is 300 millimetre, as we can see here the two diameters are machined with width maximum 30 millimetre, the workpiece material is it can be free cutting steel or cast iron and two diameters are turned using a single point cutting tool. After that circularity error is measured using roundness tester on both the diameters and the circularity error should not exceed 0.03 millimetre and then consistency of machined diameter variation is also checked what is the diameter is the first diameter and what is the diameter at the second place and then what is the variation that is measured, the error the diameter variation should be less than 0.05 millimetre per 300 millimetre length. Now in the second test facing operation is performed, we can see here workpiece is mounted in a charcoal face plate, the diameter of the workpiece is it should be greater than half of a swing over bed, if swing over bed is 100 millimetre then the diameter of the workpiece should be greater than 50 millimetre and D max should be 1000 millimetre if swing over bed is more than this particular size and then the material workpiece material can be free cutting steel or cast iron. A facing operation is performed using a single point cutting tool, the tool moves perpendicular to the spindle axis and the facing is performed as shown here and then surface flatness is measured using the straight edge and slip edges. The deviation in flatness should be less than 0.03 millimetre for a diameter of 300 millimetre and deviation is allowed only in concave direction and all the important test that is practical test that is conducted is threading operation on a cylindrical workpiece, workpiece of sufficient length is placed between the centres and a screw thread is cut for a length of 300 millimetre. The diameter and pitch of the that is cut should be close to the lead screw and again the material workpiece material can be free cutting steel or cast iron and after cutting the thread it is checked for cumulative error over 300 millimetre thread that is cut using cumulative error is checked using screw thread measurement techniques. Error cumulative error should not exceed 0.06 millimetre over 300 millimetre or 0.02 millimetre over 50 millimetre length. The screw thread that is cut should be clean without flats or babylens. Now let us start the discussion on various test conducted on filler type vertical drilling machine. In this photograph we can see the appearance of filler type vertical drilling machine. So this is the pillar around column which supports the various parts of the drilling machine and this is the base on which the vertical pillar is mounted. Now this is the machined base surface. We can also see the t-slots for mounting the workpieces and then we have the machined table surface and then the knee which supports the table and there is a clamp for clamping the table. By loosening this clamp we can rotate the table and we can move this button down to accommodate workpieces of different sizes and for moving the knee up and down we have the rack and there is a lever to move the knee up and down and this is the drill head and this drill head can be moved up and down over the vertical pillar and this drill head houses the spindle, the electric motor which is used to rotate the spindle and the cone pulleys or gearbox are housed in this drill head. To accommodate the workpiece of different height either we can move this knee and table up and down or we can also move up and down this drill head. If we have very large workpieces we can rotate this table and knee to the other side and then we can directly mount the workpieces on the machined base surface and we can perform the drilling operation. Now various tests are conducted to check whether alignment is proper or not. Some tests are whether the machined base surface is flat or not and the machined table surface is flat or not or if there is any error whether it is concave or convex whether the movement of the spindle is perpendicular to the table surface or base surface whether the running of the spindle is true or not whether the movement of the drill head is parallel to the spindle axis. So such things are tested in alignment test conducted on a drilling machine. Now we will discuss about leveling of the drilling machine. Before conducting any alignment test it is very essential to check whether the machine is properly leveled or not. For leveling for to check the level a spirit level and straight edges are used table and knee are locked in mid position and then the straight edge is placed on the table surface over which a spirit level is placed and then the drilling is taken. Similar procedure is repeated on the base machined surface and measurement is taken in a plane of symmetry of the machine as shown here and then in a plane perpendicular to the plane of symmetry and passing through the spindle axis as shown in figure B. In both the planes the error should not exceed 0.03 per 300 mm. Now if the error exceeds this value we can always insert shin plates below the base plate and we can adjust the level. If machine is not leveled properly what happens is the pillar will deflect and undesirable stresses are introduced in the pillar which is not desirable. Now to conduct the flatness of the table surface also the flatness of the base plate of the machine. Base plate of the machine this is the machined surface we can also see these slots and this is the pillar. Now we have to check whether this base machine base is flat or not. For machining the flatness we can use precision level which is shown here or we can use straight edge and gauge blocks along with filler gauges. These instruments can be used to check the flatness. The test is performed by placing the precision level at different positions along the x direction as also y direction and we can note down the reading which will indicate whether the base plate is flat or not. We can also use straight edge and gauge blocks. Gauge blocks can be placed on the machined surface like this over which we can place the straight edge and then these gaps can be filled by inserting the filler gauges which will give the flatness of the base surface. The similar procedure is repeated on the table surface also. Now the error flatness error should not exceed 0.03 millimeter for any measuring length of 300 millimeter and the surface should be flat or if there is any deviation the surface should be concave only the surface should be like this. If the surface is convex then when we place the workpiece on the convex machined table that base plate and when we clamp it due to the clamping force the workpiece will tilt it may tilt like this or it may bend like this. To avoid this the error should be concave only if there is a convex shape and again the remissioning is done so that the table surface or base surface becomes flat. Now another important test that is conducted is a true running of spindle internal taper you can see here we have the spindle of the drilling machine this is the spindle and inside there will be tapered bore this is the axis of spindle. Now the spindle internal bore or internal taper should run through this we insert the drill bit in the taper so if this internal taper is not true then the drill tool will wobble it will wobble and we don't get the proper drill hole there may be unevenness in the hole that is drilled or the hole size increases because of the wobbling of drill tool so the true running of internal taper of spindle is very very essential. To test the true running we have to use a mandrel test mandrel of maybe 200 millimeter or 300 millimeter then we have to insert the test mandrel into the tapered bore and then the dial indicator lunger should touch the the mandrel and the magnetic stand of the test dial test indicator should be placed on the table. The spindle is rotated slowly and the readings are noted down at two places one near the spindle and then away from the spindle the distance of L. Now the error true running error should not exceed 0.02 millimeter near the spindle nose for and 0.035 millimeter at a distance of 200 millimeter. If we use a 300 millimeter mandrel then near the spindle nose the error should not exceed 0.025 millimeter and at a distance of 300 millimeter error should not exceed 0.05 millimeter. Now we will discuss about palism of spindle axis with its vertical movement spindle we move up and down for feeding the drill tool into the workpiece the movement vertical movement of the spindle should be parallel to its axis if the axis this is the spindle axis and the spindle movement is at some inclination then what happens is when we feed the tool we get a hole at some inclination alpha we do not get the drill hole perpendicular to the surface of the workpiece we get it will the hole will be drilled at some angle. So in order to avoid this the spindle axis the movement of the spindle should be parallel to its axis that we can check using the test metal and dial indicator test metal is fixed into the tapered hole of the spindle the dial gauge is fixed on the table as shown here the plunger of the dial indicator should touch the metal as shown here spindle is adjusted in the middle position of its travel and then the dialed readings are noted when the spindle is moved in upper and lower directions from the middle position. So when the spindle is moved up what is the reading and when the spindle is moved down from the middle position what is the reading that we have to note down and this experiment should be repeated in both the directions in plane A in planes of symmetry of the machine and in plane B in the plane perpendicular to the plane of symmetry in both the planes error should not exceed 0.1 per 300 millimeter movement of the spindle. Now you can see the operator is checking whether the movement of spindle is parallel to its axis or not the plunger dial indicator plunger is in contact with the spindle and dial indicator is mounted on the machine table now the operator is slowly retracting the spindle and he is noting down the readings from the dial gauge. Now we will discuss about another test that is normally conducted straightness of the pillar and squareness of the spindle axis to the table surface and base plate surface the pillar should be straight otherwise when we move the spindle or knee or spindle head to accommodate what pieces of different height then the if the pillar is like this then because of this error in straightness when we move the spindle head it moves like this and then the axis spindle axis will not be perpendicular to the table surface because of this we get holes at some angle instead of getting holes perpendicular to the surface of the work pieces. So, before using or accepting any machine tool that is drilling machine we should check for straightness of pillar also the squareness of the spindle axis to the table whether the spindle axis is perpendicular to the table surface or base surface but also we should check if it is not perpendicular again we get holes inclined to the top surface we do not get holes perpendicular to the surface. Now let us see how we can check the straightness and squareness of the spindle axis the dial gauge and straight edges are used for conducting this test. Straightness checking shall be carried out at a number of positions equally spaced between the extreme positions of the table. I can see here the table and knee can be moved to different positions to accommodate work pieces of different sizes. So, it is necessary that we should conduct this experiment at different positions of knee and table. While taking the readings it is essential that table and knee should be locked and then we should move the table and knee to a particular position say one. The dial indicator stand is mounted on the spindle and we should see that the plunger of the dial is touching the straight edge surface kept on the table surface or the base surface and then slowly we have to rotate the spindle to 180 degree and again we should take the reading. So, this proceeds the difference in reading from reading at place one and reading at place two. This difference gives the squareness of the spindle axis to the table surface as well as to the base surface. Checking this squareness we have to move the spindle head to the middle position and then it should be locked and then the squareness test can be conducted. So, this is possible if the machine is having the elevating spindle head facility and measurement should be taken in two planes in a plane of symmetry of the machine and in the plane perpendicular to the plane of symmetry and error should not exceed 0.06 millimeter per 300 millimeter. So, this 300 millimeter is the distance between two points touched that is distance between this point and this point is 300 millimeter and in the case of plane of symmetry of the machine that is in this position the angle the angle between the table surface or the straight edge surface and the spindle axis should be less than 90 degree or equal to 90 degree. The reason is if it is if alpha is equal to 90 degree then we get holes perpendicular to the surface of the workpiece like this we get perpendicular holes. Now, if the angle is if there is any error if there is any error in the squareness the angle should be less than 90 degree that means the front edge of the table should be upwards like this. So, this is the table surface or the base surface the front edge should be upwards. The reason is when during the drilling process because the forces the front edge it tilts like this and error is minimized. Also other reason is when due to the cutting the force of drilling forces this spindle head tends to bend upwards tends to bend upwards like this and then it tends to reduce the squareness error because of that the alpha should be less than 90 degree or equal to 90 degree. Now, another test is squareness of the table surface to the vertical movement of the spindle. Now, again the dial gauge strided and squares are used to conduct this squareness test. Now, this is the spindle axis and the spindle will be moving vertically up and down. Now, this movement vertical movement of the spindle should be perpendicular to the table surface. If there is any error again we do not get the holes perpendicular to the surface of the workpiece. Now, while conducting this experiment table and knee are locked in mid position the table and knee should be moved to the middle position of the pillar and they should be locked. Also spindle head should be locked in mid position for machines having an elevating spindle head. The spindle head also should be moved nearer to the mid position and then it should be locked. The straight edge is placed on the table machine table over which the square is placed and the magnetic stand of the spindle is placed on the spindle and the dielectricated plunger should touch the vertical surface of the square. Initially the reading is taken in this position number one and slowly the spindle is moved up and then at a distance of 300 millimeter again the second reading is taken. The difference gives the squareness error. The measurement is taken in two planes in a plane of symmetry of the machine in this position and in a plane perpendicular to the plane of symmetry and passing through the spindle axis. Now error should not exceed 0.1 millimeter per 300 millimeter in both the planes and again the alpha this angle alpha should be less than or equal to 90 degree. The reason we explained in the previous test. Now the squareness of the table surface to the vertical movement of the spindle head. So, some machines will be having this facility elevating the spindle head. So, wherein the spindle head can be moved up and down on the pillar. So, this movement of the spindle head there should be perpendicular or should be square with the table surface. In order to check this dial gauge straight head and the square are used. The straight head is placed on the table surface over which the square is placed as shown here and the magnetic stand of the dial gauge is placed on the spindle and the plunger should touch the surface of vertical surface of the square. While taking reading table and knee are locked in the mid position and spindle head should be locked while taking the readings. That means spindle is moved to position number one and the plunger is adjusted to zero and then it is unlocked, spindle head is unlocked and it is slowly moved up and then again it is locked and then second reading is taken. So, the distance between position one and position two is normally 300 millimeter. So, measurement is again taken in the two planes in the plane of symmetry of the machine and in the plane perpendicular to symmetry of the machine. The error should not exceed 0.1 per 300 millimeter in both the planes and this alpha angle alpha should be equal to 90 degree or less than 90 degree reason we have already explained. Now, let us discuss about the camming of the rotating table. Some machines will have this rotating table facility. Now, when this rotation is required whenever we want to drill holes in a circular pattern, this is the rotating table of the drilling machine. Say we have kept a workpiece on which we want to drill some holes in circular pattern like this. So, during that time there should not be any camming or wobbling of the table. If there is a camming of the table then the geometrical accuracy of the holes at the pattern will be lost. So, in order to conduct in order to check whether there is camming or not we use dial gauge and straight edge. We have to keep the straight edge on the table as shown here and then the magnetic stand of the dial indicator is kept on the spindle head. The plunger of the dial indicator is touching the straight edge. So, it will touch like this and we have to take a reading at point A and then we have to rotate the table but unclamp before taking the readings we should clamp the table. We should clamp the table and we should take the reading here then unclamp the table and rotate the table through 180 degrees. Now the plunger will touch the straight edge on point B. The difference in readings will indicate whether there is camming or not. This procedure is repeated setting the straight edge in another plane perpendicular error should not exceed 0.05 millimeter for D is equal to 300 mm where D is the table diameter. If there is any camming we have to remission the hole which guides the table. Now let us discuss about a practical test that can be conducted on a billet type drilling machine. We can actually measure the deflection of spindle axis from its position square with the table under an axial force applied to the spindle. For conducting this experiment we use a dial gauge and a load gauge. So, we have to keep the load gauge on the table of the drilling machine as shown here. Load gauge should be coaxial with the spindle axis. This load gauge is capable of measuring what is the axial force applied and it will also apply the axial force onto the spindle nose and then a special equipment A which is shown here is mounted directly on the spindle nose. The spindle nose is like this and a special equipment A which looks like this is mounted on the spindle nose. So, this is special equipment A. There is a provision for mounting the equipment A on to the spindle nose. And now it is mounted on the spindle nose and then we use a dial gauges for measurement of deflection. So, we have to keep the magnetic stand on the machine table and the plunger should touch the special equipment A. And now we apply the axial force onto the spindle because the axial force the spindle head will deflect like this. So, along with that the special equipment A will also deflect like this. And now what is the reading of this dial gauge and what is the reading of this dial gauge can be noted down. The difference gives the deflection of the spindle. So, this experiment is conducted in two planes in a plane symmetry of the machine as shown here. And again another plane which is perpendicular to the plane of symmetry as shown in B and that particular plane will pass through the spindle axis. During the measurement we have to arrange the drill head at the table in the middle position and they should be clamped properly. The error the deflection should not exceed 2 mm per 1000 mm in both the cases. Apart from conducting alignment test and practical test on machine tools while purchasing new equipment, new machine tools, we have to do some general inspection of the machine tools that we will discuss now. We should examine for the mechanical defects in the machine tool whether all parts are in good condition whether any broken parts are there that we have to check. If there are broken parts we have to arrange for replacing them. Then whether the gears all the gears and cone pulleys run quietly at all the specified speeds. We have to arrange all the settings combinations for gears as well as for cone pulleys and we have to run them and we should see whether the running is smooth or not. Is the machine free from vibration when we have to actually conduct the cutting experiment? We have to mount the workpiece and tool and we have to cut the workpieces to check whether any vibration is there or not. If there is any vibration so we have to check the settings, alignments so that the vibration level is reduced. Then we should see whether all the listed speeds and feeds are available. You can see many the spindle speeds like 1070 rpm, 385 rpm and lower speeds such as 165 rpm, 90 rpm they are mentioned in the display. We should actually do the settings of gears and we should run the spindle and we should use an appropriate speed testing device to check whether the spindle is running at the specified speeds and we should also check whether all the listed speeds are available. Similarly we should check for the availability of the different feed rates as mentioned in the manual or in the display. For example, the feed rate of 0.373 millimeter per revolution is mentioned and 0.606 millimeter per revolution is mentioned. So we should actually do the required settings and then we should check physically whether the saddle or cutting tool is moving at the specified speed and similarly we should do some thread cutting operation to check whether we get the specified pitch values or not. Now is the machine adequately guarded, guarding of the machine tool also we should check. We can see different kinds of guardings are used on the machine tool. It is the guard provided for lathe, another type of guard transparent guard provided on the lathe. This is the guard provided for pillar type drilling machine and the guards for milling machine. So we should check whether machine tools are properly guarded and whether visibility of the cutting operation is proper or not. Also we should check for reachability of various switches provided and color coding whether proper color coding is used in the switches. For example, the reachability of the emergency button on or off button such things we should check whether they are easily reachable by the operator and we should also check whether proper color coding is used or not. And then we should also check for the reachability of various levers and operating wheels we can see here in this particular lathe. On the saddle many wheels are provided for moving the saddle and then many levers are provided on the headstock and then the levers are provided on the feed box. Now we should check whether all these levers and operating wheels are easily reachable by the operator and all the levers and operating wheels can be operated smoothly or not that we should check. The easiness to operate so for all the levers we should check. Now are the rapid traverses functioning properly and whether auto traverse is working or not. If such facilities are provided on the machine tools we should check for functioning of rapid traverse and auto traverse and whether the lubricating system is working properly or not what if the pump capacity is used whether it is adequate to pump the oil and whether any leakage is there in the pipeline all such things we should check and our safety devices we tend to prevent serious breakdowns safety devices such as emergency button limit switches we should check whether they're properly working and whether the high holes are properly capped or not that we have to check otherwise the dust particles may enter into the hole and the performance will be affected and do the traverses cover the specified dimensions various traverses are provided on the machine tool and whether all the traverses cover the specified dimensions we should actually run and check for this specified availability of the traverses and does all auxiliary equipment fit the machine the auxiliary equipment such as indexing mechanism and study rates whether they are properly fitted whether they are present or not such things we should check and do the operating levers clear each other in all positions you can see here this particular mission tool many levers are provided many wheels are provided whether they are clear each other in all the operating positions or whether there is any whether levers are touching at some positions that we have to check and whether electrical equipment or proper cooling arrangement is made for restrictive equipment whether there is any overheating of the electrical equipment such as motors that we have to check now sometimes we can use a checklist to check the machine for to conduct the general inspection of the machine tools one such checklist is provided here for risky parts of the machinery so this will indicate whether the proper guarding is provided or not or all dangerous parts of the machinery guarded not if the guarding is proper we can check here put a tick mark here if they are not provided we can put a tick mark here if a particular question is not applicable we can put tick mark here so like this we should check for all the items or all guards of good construction adequate strength and well maintained whether guarding provided ease of adequate strength or not that we have to check do guards permit an adequate view of operation where it is necessary whether transparent guards are provided or not for proper visibility is it difficult to bypass or disable guards so sometimes the operators disable the guards and try to run the machine which is very dangerous for such things we should check can the machinery only be started when a specific labeled start device is used and is it impossible to start the machine just by resetting a safety device and is there a readily accessible stop device which stops the machinery in a safe way accessible stop device such as emergency button button the positioning of the button the color coding the button such things we should check where appropriate is there a prominent easily accessible emergency stop device provided can controls be operated safely and easily and all controlling levers wheels whether they are easy to operate whether they are safe to operate is there any system of work which ensures that nobody is in a dangerous position when the machinery is about to be started so such things we should carefully check by using the checklist now with the general inspection of the machine tools we will conclude module 11 lecture 2 in this lecture number 2 we discussed about the following topics practical tests are conducted on lathe and various tests normally conducted on the pillar type drilling machine alignment test we discussed and the practical test conducted on pillar type drilling machine that also we discussed and apart from that we also discussed about the general inspection of machine tools one should do on machine tools with this we will conclude this lecture thank you