Metrology Lab -Manual

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<p>Metrology lab manual. Metrology Laboratory</p> <p>1</p> <p>Subject code:</p> <p>Duration of Exam: 3Hours</p> <p>1. Calibration of micrometer using slip gauge or height master. 2. Calibration of Vernier caliper using slip gauge or height master. 3. Calibration of height gauge using slip gauge or height master. 4. Calibration of straight edge by Wedge method. 5. Measurement of dovetail angle and checking the taper angle of taper plug. 6. Angle measurement using Combination sets, Universal bevel protector, Optical bevel protector, Sine bar and Since Center. 7. Screw thread measurement using Two wire method, three wire method, Pitch gauge and Profile projector. 8. Auto Collimator 9. Gear tooth measurement using Gear tooth Vernier Caliper, Constant chord method 10. Calibration of Height gauge 11. Profile Projector andTool Maker Microscope 12. Study and measurement of surface finish by surface finish tester, 13. Roundness or Circularity testing.</p> <p>Ravi.K, Dept. of I&amp;P Engg., PESCE, Mandya, Karnataka</p> <p>Metrology lab manual. Expt. No 01 CALIBRATION OF MICROMETER Theory:</p> <p>2</p> <p>Write brief theory about slip gauges; classification, specification, uses and care to be taken before and after using. A micrometer is used to measure the external diameter of small cylinders, sphere etc. It has a V shaped structure to which a handle is attached. Two anvils are fixed to the inner surface of the block. The job to be measured is placed between the anvils and held in position by rotating the handle. The end of the screw forms one measuring tip and the other measuring tip is constituted by a stationary anvil in the base of the frame. The screw is threaded for certain distance and plain for the remaining distance. The screws plain portion is called sleeve and its end is the measuring surface.</p> <p>Procedure:1. Find out the least count of the given instrument. 2. Clean the micrometer stand so that there are no burrs on the anvils. Clean the measuring faces of micrometer with a cleaning cloth. 3. Fix the micrometer to the stand horizontally, to avoid manual errors during handling. 4. Check for zero errors of micrometer by closing the micrometer to 0 and note down the zero error, if any (ex.: -0.01mm or + 0.01mm) 5. The selected (values) standard step gauges are taken and cleaned with a cloth and arranged in such a way that there would be no gap (wringing phenomenon) and placed between the anvils. 6. The readings shown by the micrometer are noted and compared with the actual reading of slip gauges. 7. Error and percentage error are calculated results and calculations are tabulated in the tabular column. 8. The experiment is repeated for different readings of slip gauges (minimum 10 readings). Note: Always complete the entire range of the instrument by selecting appropriate values unless specified</p> <p>Ravi.K, Dept. of I&amp;P Engg., PESCE, Mandya, Karnataka</p> <p>Metrology lab manual.</p> <p>3</p> <p>Aim: To calibrate the given Micrometer using slip gauges.</p> <p>Apparatus Used: Slip gauge set, Micrometer, Micrometer stand, cleaning cloth</p> <p>Least count</p> <p>= =</p> <p>Distance moved/rotation of thimble Total No. of divisions on thimble</p> <p>LC = Zero Error =</p> <p>______mm ______mm</p> <p>Tabulation Sl.No Actual Reading Micrometer Reading Error Percentage Error</p> <p>Specimen calculation: Actual reading of slip gauge (x) Micrometer reading Error = Micrometer reading - Actual reading Percentage error =Error Actual reading</p> <p>Ravi.K, Dept. of I&amp;P Engg., PESCE, Mandya, Karnataka</p> <p>Metrology lab manual. Expt. No 02 CALIBRATION OF VERNIER CALIPER</p> <p>4</p> <p>Aim: To calibrate the given Vernier calipers using given slip gauges.</p> <p>Theory: Vernier calipers are used to measure the outside diameter as well as inside diameter of cylinders. All parts of the instrument are made of good quality steel. It is commonly used in machine shop to measure the diameters of work piece. Apparatus: Vernier Caliper, Slip gauges, cleaning cloth Procedure:9. Find out the least count of the given instrument. 10. Clean measuring faces of Vernier caliper with a cleaning cloth. 11. Check for zero errors of Vernier caliper by closing the micrometer to 0 and note down the zero error, if any (ex.: -0.02mm or + 0.02mm) 12. The selected (values) standard step gauges are taken and cleaned with a cloth and arranged in such a way that there would be no gap (wringing phenomenon) and placed between the jaws. 13. The readings of Vernier are noted and compared with the actual reading of slip gauges. 14. Error and percentage error are calculated results and calculations are tabulated in the tabular column. 15. The experiment is repeated for different readings of slip gauges (minimum 10 readings). Note: Always complete the entire range of the instrument by selecting appropriate values unless specified L.C. = = Zero Error Tabulation Sl No Actual Reading Reading of Caliper Error Percentage Error = 1 M.S.D 1 V.S.D. (consider the coinciding divisions of main and Vernier) _______mm ______mm</p> <p>Specimen Calculation: Error = Reading of caliper - Actual reading</p> <p>Ravi.K, Dept. of I&amp;P Engg., PESCE, Mandya, Karnataka</p> <p>Metrology lab manual. Percentage error =Error Actual reading</p> <p>5</p> <p>Sl. No</p> <p>Actual (m)</p> <p>Instrument reading in (mm)</p> <p>Error</p> <p>% Error</p> <p>M.S.D Given</p> <p>V.S.D.</p> <p>T.R Given Given cal given cal 1</p> <p>Calculated from Vernier</p> <p>Ravi.K, Dept. of I&amp;P Engg., PESCE, Mandya, Karnataka</p> <p>Metrology lab manual.</p> <p>6</p> <p>CALIBRATION OF CALIPERS Procedure: 1. The least count of the instrument is calculated 2. Standard slip gauges of known values are taken cleaned properly and arranged in such a way that these should be no air gap between them. 3. The micrometer readings are noted and compared with actual results. 4. Reading are tabulated in the tabular column 5. Procedure is repeated for different values gauges.</p> <p>CALCULATIONS: Least count of Dial Gauge =1 rotation(or ) No of divisions made on main scale No of divisions moved on dial scale</p> <p>= 1/100 = 0.01mm Least count of calibration tester = Dis tan ce moved on main scale No of divisions on micrometer dis rotations = 0.5 = 0.001mm 500</p> <p>Actual Disc Reading = Dial Gauge Reading x L.C Correct disc reading (Instrumental Reading)= Micrometer disc reading Instrumented error given in chart Error = Actual Reading Instrumental Reading % Error = Sl. No Dial gauge Reading x LC mmError x100 Actual reading</p> <p>Micrometer disc reading x LC (0.001) mm</p> <p>Instrumental Error from chart</p> <p>Instrumental reading</p> <p>Error</p> <p>% Error</p> <p>Ravi.K, Dept. of I&amp;P Engg., PESCE, Mandya, Karnataka</p> <p>Metrology lab manual. Exp. No: 03 CALIBRATION OF DIAL GAUGE AIM: - Calibration of dial gauge using dial indicator. Apparatus: - Dial gauge, dial calibration tester.</p> <p>7</p> <p>Theory:- Dial indicators are instruments used for making and checking linear measurements. These require less skill than other precision instruments for their usage, like plug gauges, gap gauges, micrometers and Vernier scales etc. Dial indicators are smaller indicating devices containing a graduated dial lever magnification system. These are generally used as comparators is compare a part to a master setting. Some indicators known as dial micrometers or dial thickness gauge are however, also used for actual measurements when dial indicator is used as an essential part in the mechanism of any set up for compassion measurement purposes it is referred to as dial gauge. Most of the dial indicators take the form of a circular or semicircular scale upon which a pointer fives a direct indication of the movements of a contact arm or a spindle small changes of dimensions of the component in contact with the spindle are made to assume large proportions to scale by employing some mechanical reading to be obtained. A dial indicator by it self is not of much use unless it is properly mounted and set before using for inspection purpose. By mounting a dial Indicator on any suitable base and with various attachments it can be used on thousands of special gauges which manufacturers them selves design to meet the requirement of the job. Procedure: 1. The L.C of the dial indicator is calculated 2. The L.C of calibration tester is calculated. 3. Rotate the dial tester circular disc to touch the points of contact of dial indicators &amp; lock the spindle. 4. Now loosen the 3 screws under the disc of dial tester and make the disc reading zero and again tighter the screws. 5. Now make the reading of dial indicator zero. 6. Fix the pointer to some specified reading and take the disc reading. 7. Rotate the disc for 10mm displacement and take the disc reading.</p> <p>The instrument error is noted from the chart and total error is calculated.</p> <p>Ravi.K, Dept. of I&amp;P Engg., PESCE, Mandya, Karnataka</p> <p>Metrology lab manual.</p> <p>8</p> <p>Experiment No 4 CHECKING OF STRAIGHT EDGES BY WEDGE METHOD</p> <p>Aim: To check the straightness of the straight edge by wedge method. Apparatus : Straight edge with blade width not less then 6mm, surface plate to accommodate the straight edge, slip gauges, dial indicator, support blocks. Theory Straight edges: These are used for checking the straightens and flatness of parts in conjunctions with the surface plates, spirit levels and the flatness of a surface background or by a light coat of prussian blue on the work surface. These may be made of steel or cast iron. Steel straight edges are available up to 2 m length and may be rectangular in section with beveled edge. C. I straight edges, are made up to 3 m length and widely used for testing machine tool slide ways. They are heavily ribbed and bowshaped (camel back construction) to prevent distortion. These are provided with feet for rest when they are idle to prevent distortion. Feet are placed at points of minimum deflection. According to IS: 2220 1962, straight edges are of two grades; Grade A for inspection and Grade B for workshop purposes. These are of rectangular cross section and the side faces of the straight edge are straight parallel and also square with the working surfaces. When the straight edge is supported at minimum natural deflection points (Airy points) over the span, i.e., at a distance of 2/9 total length of straight edge from each end or 0.5541 span, the error in the straightness of the working faces over its whole length should not exceed (2 + 101) microns for Grade A and (5 + 101) microns for Grade B; where is the length in meters.</p> <p>The straight edges are classified as follows: 1. Tool makers straight edge. 2. Wide edge straight edge, 3. Angle straight edge.</p> <p>Procedure: The distance of support points is calculated (i.e., 2/9 of total length of straight edge from each end, or 0.5541 span). The straight edge is divided into convenient equal number parts (measuring accuracy increases with maximum number of parts), which contains the support points also. TheRavi.K, Dept. of I&amp;P Engg., PESCE, Mandya, Karnataka</p> <p>Metrology lab manual.</p> <p>9</p> <p>surface plate, straight edge and support blocks are cleaned. The straight edge is supported over the blocks at the calculated distance. Any convenient intended slope (by allowing, say 0.05 mm difference in height for each point) is introduced at the support points using slip gauges. If the surface is flat and the straight edge is having true edges, then the gap between the successive points will vary by the intended difference in height. Slip gauge for the required dimension for the start point is set below the straight edge so that the gauge is inserted with free force. Repeat this at each point (by increasing the height of gauges with respect to the slope set earlier) throughout the length of the straight edge. If any difference is noted at any point, the value of slips may increase or decreased. The difference between the nominal and measured difference in heights at various points is the error. In another method, dial gauge is set below the straight edge so that the plunger is in its middle position and the readings were taken at each point. The measurements were made throughout the length of the straight edge. The difference between the nominal and measured difference in heights at various points is the error. Position Nominal Slips (mm) Actual Slips (mm) Error</p> <p>Error ()</p> <p>+</p> <p>Position (mm)</p> <p>Ravi.K, Dept. of I&amp;P Engg., PESCE, Mandya, Karnataka</p> <p>Metrology lab manual. 10</p> <p>Experiment - 5 Measurement of External TaperAim Apparatus : To measure the external taper angle of given specimen : Tapered specimen (preferably a plug gauge), Surface plate, Slip gauge set, Standard rollers of equal size, Vernier caliper / Micrometer. L.C of the instrument (Vernier caliper /Micrometer) : _____________________</p> <p>Procedure</p> <p>:</p> <p>Clean the specimen surface with a clean cloth and place it on the surface plate.</p> <p>Select 2 set slip gauges (each set of equal size) of different height and two equal size standard rollers. Position the slip gauges at each side of upper end (h 1 ) of specimen and place the rollers. Note down the reading over the rollers. Repeat the above step at lower end (h 2 ) of the specimen with another set of slip gauge. Now using the equation given below, calculate the taper angle of the specimen. Select another set of slip gauges, which ranges between the first 2 sets. Keeping one of the first set readings as first reading, take the second reading with this set of slip gauges and rollers. Calculate the angle to prove that the taper of the specimen is uniform and more accurate.</p> <p>tan</p> <p>l l = 1 2 2 2(h 1 h 2 )</p> <p>l1 Standard rollers</p> <p>h1</p> <p>Plug gauge 2 l2</p> <p>h2</p> <p>Slip gauge</p> <p>Ravi.K, Dept. of I&amp;P Engg., PESCE, Mandya, Karnataka</p> <p>Metrology lab manual. 11</p> <p>Measurement of Dovetail AngleAim : To Determine the Included Angle of an Internal Dovetail</p> <p>Apparatus : Tapered specimen (dovetailed), Surface plate, Slip gauge set, Standard rollers of equal size, Vernier caliper / Micrometer.</p> <p>L.C of the instrument (Vernier caliper /Micrometer) :</p> <p>l2 Std. Rollers Slip gauges h A l1 B A</p> <p>C</p> <p>In dovetail, the sloping sides act as guide and prevent the lifting of the female mating part during mating operation. The angle which the sloping face makes with an imaginary vertical centre plane is important in case of dovetail. For measuring this angle we require two pins of equal size, slip gauges and micrometers. First the two pins are placed touching both the sides of dovetail as shown in fig. above and distance l 1 is measured across pins with a micrometer. Then the pins are raised on two sets of equal slip gauge blocks. Here care should be taken that the pins do not extend above the top surface of dovetail. Again distance l 2 across the pins is measured. Let the height of the slip gauges be h.BC Then tan A= = AC</p> <p>l 2 l1 2 h</p> <p>Thus knowing l 2 , l 1 and h, the angle A can be calculated. This method is also suitable for measuring the angle of a taper plug gauge or any round or flat tapered work which can be placed on a surface.</p> <p>Ravi.K, Dept. of I&amp;P Engg., PESCE, Mandya, Karnataka</p> <p>Metrology lab manual. 12 EXPERIME...</p>