INSTRUMENT CALIBRATION PROCEDURE GAGE BLOCKS

Transcription

1 TECHNICAL MANUAL MD-185 INSTRUMENT CALIBRATION PROCEDURE GAGE BLOCKS STYLES 1 (RECTANGULAR) AND 2 (SQUARE); B GRADES: 00, 0, AS1 AND AS2, GGG-G-15C: 0.5, 1, 2 AND 3; TO 20 INCHES THIS PUBLICATION SUPERSEDES NAVAIR 17-20MD-185 DATED 1 SEPTEMBER 2005 DISTRIBUTION STATEMENT C. DISTRIBUTION AUTHORIZED TO U.S. GOVERNMENT AGENCIES AND THEIR CONTRACTORS TO PROTECT PUBLICATIONS REQUIRED FOR OFFICIAL USE OR FOR ADMINISTRATIVE OR OPERATIONAL PURPOSES ONLY. OTHER REQUESTS FOR THIS DOCUMENT SHALL BE REFERRED TO MEASUREMENT SCIENCE DEPARTMENT, CORONA DIVISION, NAVAL SURFACE WARFARE CENTER, P.O. BOX 5000, CORONA, CA MD-185 DESTRUCTION NOTICE - FOR UNCLASSIFIED, LIMITED DOCUMENTS, DESTROY BY ANY METHOD THAT WILL PREVENT DISCLOSURE OF CONTENTS OR RECONSTRUCTION OF THE DOCUMENT. PUBLISHED BY DIRECTION OF COMMANDER NAVAL AIR SYSTEMS COMMAND 1 APRIL 2006

2 LIST OF EFFECTIVE PAGES The purpose of this list is to identify the pages in this document affected by any technical content changes made since the previous release of the document. NOTE: On a revised page, with the exception of the Title, the A, the i pages, the technical changes are indicated by a vertical line in the outer margin of the page. Page No. ** Revision* Page No. ** Revision* Page No. ** Revision* Title 0 A 0 i 0 1 to 17 0 A-1 0 B-1 to B-3 0 C-1 to C-3 0 D-1 0 *Zero in this column indicates an original page. R in this column indicates a revised page. **All pages not listed are blank pages. A

3 TABLE OF CONTENTS Section Page 1 Introduction Description Equipment Requirements Preliminary Operations Calibration Process Test (0.010 to 4 Inches) Test (4 to 20 Inches) Tests (0.010 to 4 Inches) Calibration (4 to 20 Inches) Navy Calibration Checklist Appendix A: Sample Certificate of Calibration... A-1 Appendix B: Sample Report of Calibration... B-1 Appendix C: Federal Specification GGG-G-15 ANSI B (Short Blocks, English)... C-1 Appendix D: Representative Test Instruments... D-1 ILLUSTRATIONS Figure Page 1 Comparator Setup (0.010 to 4 Inch Gage Blocks) Comparator Setup (4 to 20 Inch Gage Blocks) Check Using Monochromatic Light Test Setup (Long Blocks) Points of Reference (Short Gage Blocks) Points of Reference (Long Blocks) TABLES Table Page 1 Calibration Description Equipment Requirements... 2 i

4 SECTION 1 INTRODUCTION AND DESCRIPTION 1.1 This procedure describes the calibration of Style 1 (rectangular) Style 2 (square) Gage Blocks manufactured to GGG-G-15 B specifications for Gage Block grades: 0.5, 1, 2, 3 00, 0, AS1, AS2 respectively: through 20 inches. The instrument being calibrated is referred to herein as the TI (Test Instrument). 1.2 All comments concerning this procedure should be directed to the Measurement Science Department, Corona Division, Naval Surface Warfare Center, P.O. Box 5000, Corona, CA This procedure includes tests of essential performance parameters only. Any malfunction noticed during calibration, whether specifically tested for or not, should be corrected. TI Characteristics Table 1. Calibration Description Performance Specifications Gage block flatness 1 Tolerance Grade: 0.5 Tolerance Grade: 1 Tolerance Grade: 2 Tolerance Grade: 3 Tolerance Grade: 00 Tolerance Grade: 0 Tolerance Grade: AS1 Tolerance Grade: AS2 Gage block length parallelism 1 Tolerance Grade: 0.5 Tolerance Grade: 1 Tolerance Grade: 2 Tolerance Grade: 3 Tolerance Grade: 00 Tolerance Grade: 0 Tolerance Grade: AS1 Tolerance Grade: AS2 Test Method The gage blocks are verified for flatness using an optical flat with monochromatic light in conjunction with fringe pattern interpretation. The gage blocks are verified for length parallelism by comparison to transfer stards with an electronic gage block comparator. 1 Tolerance grades based on ANSI B Federal Specification GGG-G-15. The Federal Specification has been cancelled ANSI B89.1.9M equivalent tolerances have superseded the Federal Specification. SECTION 2 EQUIPMENT REQUIREMENTS NOTES Minimum use specifications are the principal parameters required for performance of the calibration, are included to assist in the selection of alternate equipment, which may be used at the discretion of the using laboratory. Satisfactory performance of alternate items shall be verified prior to use. All applicable equipment must bear evidence of current calibration. The instruments utilized in this procedure were selected from those known to be available at Navy calibration facilities the listing by make or model number carries no implication of preference, recommendation, or approval for use by other agencies. It is recognized that equivalent equipment produced by other manufacturers may be capable of equally satisfactory performance in this procedure. 1

5 Item 2.1 Temperature humidity recorder Required Components: Table 2. Equipment Requirements Minimum Use Specifications See required components Calibration Equipment Hart Scientific 1620H Readout NA Hart Scientific Sensor Temperature range: 67.5 to 68.5 F Uncertainty: ±0.25 F Humidity range: 20 to 45% RH Uncertainty: ±3% RH Hart Scientific 2626S 2.2 Cheesecloth 36 wide, 10 yard, unbleached Local supply 2.3 Wash tray (2 required) Plastic, 24 x 12 x 4 in (alcohol resistant) Local supply 2.4 Insulated forceps 10 inches long minimum with insulated tips Local supply 2.5 Turco soap 1 gallon container Local supply 2.6 Washing brush Round, 1 in diameter, utility Local supply 2.7 Hling tray (2 required) 16 x 16 x 1 in for storing gage blocks during calibration 2.8 Dust cover (2 required) Plexiglass, 16 x 16 x ¼ in (required for item 2.7) 2.9 Thermometer Range: 19 C to 21 C Uncertainty: ±0.1 C 2.10 Electronic gage block comparator Resolution: 0 to 50 µin Range: 0 to 20 in Uncertainty: ±1 µin 2.11 Soaking platen Aluminum (or equivalent), 24 x 12 x 1 ¾ in adjustable legs, smooth finish with anodized coating (see Figure 1) 2.12 Gage block set 121 piece, style 1, 0.1 to 4 in Uncertainty: Grade 2 (NIST traceable) 2.13 Gage block set 112 piece, style 1, 0.01 to 4 in Uncertainty: Grade 2 (NIST traceable) 2.14 Gage block set 36 piece, styles 1 2, grade 2, Uncertainty: Grade 2 (NIST traceable) 2.15 Gage block set 88 piece, styles 1 2, 0.05 to 4 in Uncertainty: Grade 2 (NIST traceable) 2.16 Gage block set 88 piece, styles 1 2, 0.05 to 4 in Uncertainty: Grade 2 (NIST traceable) 2.17 Gage block set 8 piece, style 1, 5 to 20 in (long blocks) Uncertainty: Grade 2 (NIST traceable) 2.18 Monochromatic light Helium light source: Range: 11.6 µin/fringe 2.19 Rough deburring stone Type: Arkansas or equivalent Size: 3 x 1 x 5 in Local supply Local supply Taylor Environmental 21001, p/o Mahr Federal Products 130B16, 130B24 or 130B38 Local supply Doall 121R Starrett, LS, RS112MA1 Starrett, LS, RS36A1 Starrett, LS, RS88A1 Starrett, LS, RC88.AAX Starrett, LS, SS8A1X Van Keuren L-1A or equivalent Local supply 2

6 Item Minimum Use Specifications 2.20 Fine deburring stone Type: Arkansas or equivalent Size: 8 x 2 x 1 in, lapped flat (required for gage blocks) Local supply Calibration Equipment 2.21 Plano-interferometer Aperture: 5 in Uncertainty: 1/10 fringe 2.22 Optical flat Size: 3 inch diameter x 1 ¼ inches thick Uncertainty: 2 µinches (flatness) 2.23 Dusting brush Camel s hair Local supply 2.24 H syringe Rubber, surgical #3 Local supply 2.25 Chamois skin Grade B, class 1, 16 x 21 in Local supply 2.26 Gage block preservative Non-corrosive, spray such as Do All Cat. No , Starrett LS Cat. No. M1.01 or equivalent Davidson Optronics D309 3INDIASSM or equivalent Local supply SECTION 3 PRELIMINARY OPERATIONS 3.1 PRELIMINARY OPERATIONS AND ENVIRONMENTAL CONSIDERATIONS Ensure that the laboratory temperature humidity recorder (item 2.1) is functioning properly is located as close as practical to where the calibration will be performed Ensure that the gage block calibration area is as small as possible with no windows or exterior walls. The laboratory environmental system, should provide sufficient cooling /or heating capacity to maintain a uniform reference temperature of 68 F (20 C). The indicated room temperature variations should not exceed ±0.5 F during the calibration Ensure that the humidity is controlled between 20% RH 45% RH. Additionally, ensure that there are no drafts in the room. Draft shields can be fabricated, as needed from plywood or plexiglass. NOTES Drafts cause temperature differences in a gage room. Temperature differences in the comparator st, the TI, or the transfer stard will cause erroneous readings in the calibration of the TIs. The degree of environmental control required for gage block calibration is highly critical due to the extremely stringent tolerances repeatability requirements. The length of a gage block is defined at precisely 68 F. The temperature control is crucial because steel gage blocks have a thermal expansion coefficient of 6.4 ppm / F /inch. In some cases, this change may be greater than the uncertainty of the gage block Ensure that the laboratory temperature remains stable for a period of 8 hours prior to the calibration during the calibration of gage blocks Inspect each individual TI in the test set for proper identification. The serial number, the nominal size the manufacturer s trademark must be displayed. 3

7 3.1.6 Ensure that the marking on the TI is permanent, legible is made in a manner as to not affect the accuracy of the TI. NOTES Tolerance grades 0.5, 1 2 must display an identification number. This practice is optional but recommended on tolerance grade 3 blocks. Such numbers should be the serial number of the set. Wear blocks must have unique serial numbers. The middle one-third of the gaging surface must be free of marking. Each gage block must be marked with a code that identifies the material, if it is not positively identified as being a part of the set of one material. The symbol code is as follows: CC: Chromium Carbide, CP: Chromium Plated, SS: Stainless Steel TC: Tungsten Carbide. No code symbol is required for steel. CAUTION IF THE TIs ARE NOT PROPERLY IDENTIFIED, THE ENTIRE SET SHOULD BE REJECTED WITHOUT FURTHER INSPECTION IN ACCORDANCE WITH FEDERAL SPECIFICATION GGG-G-15 AND/OR ANSI B CLEANING AND PREPARATION Place a clean piece of cheesecloth (item 2.2) in a clean plastic wash tray (item 2.3) Use the insulated forceps (item 2.4) place the TIs on top of the cheesecloth. Start with the smallest TI progress to the largest Cover the TIs with turco soap (item 2.5) approximately 1/4 in over the highest block Gently wipe the TIs with clean cheesecloth Clean the TIs in an ultrasonic cleaner, with a washing brush (item 2.6) or by rubbing them on the cheesecloth in the plastic wash tray Apply the turco soap to a clean piece of cheesecloth, gently wipe the gaging surfaces of each TI Place the TIs in the clean hling tray (item 2.7) containing clean cheesecloth, place a dust cover (item 2.8) over the tray. NOTES Calibration of style 1 blocks with style 1 stards style 2 blocks with style 2 stards is recommended to minimize transfer error temperature differences related to size. Ceramic gage blocks should be used cleaned with the same care as steel gage blocks. The primary difference is that ceramic gage blocks will not rust do not require preservative after use. Ceramic gage blocks may be cleaned using the same method currently used for steel gage blocks. Ceramic gage blocks are also subject to the same types of damage, i.e. scratches, burrs, chipping. They should be kept clean hled with significant care at all times. Ceramic gage blocks should be cleaned prior to returning to the storage case. Do not use a preservative on ceramic gage blocks. Gage block preservative should be used on all steel gage blocks to prevent rust corrosion. The preservative must be removed by approved cleaning methods, prior to use of steel gage blocks. The TI temperatures must be allowed to normalize to their staging platforms prior to use. (Refer to the Note following step.) 4

8 3.2.8 Clean the gage block transfer stards as required or as instructed for the TIs in steps through Place the transfer stards TIs in a temperature-controlled area allow all blocks to normalize to the reference temperature using the following table for recommended nomalization formula guidelines. NOTE It is not recommended to soak gage blocks to temperature on a granite surface plate. Granite is a very poor conductor of heat. While the granite may feel cool to the touch, it may localize the heat from the gage block on the surface of the granite insulate the block from its environment. Steel Normalization Time On a Soaking Platen In Open Air Given by the formula: Given by the formula: Time (minutes) = 4L +7 Time (minutes) = 30L +50 Where L = of gage block (inches) Where L = of gage block (inches) However, time should not be less than 8 minutes or greater than 60 minutes. However, time should not be less than 60 minutes or greater than 300 minutes Gage block materials have different thermal values of conductivity, therefore will have different normalization times than steel. For gage blocks made from materials other than steel, multiply the recommended normalization time in the above table by the values indicated in the following table. Material Relative Thermal Conductivity (Factor) Croblox (chrome-carbide) 1.2 Tungsten-carbide 1.5 Ceramic Suspend the thermometer (item 2.9) next to the electronic gage block comparator (item 2.10) for temperature observations. NOTES The operator should have on a long-sleeved, lint free shop coat before continuing with the calibration. The coat will help prevent radiated body heat from being absorbed by the blocks measuring equipment. Stable temperatures in the measurement area shall be maintained for a minimum of 8 hrs prior to performing the calibration of gage blocks Place the test gage blocks on a soaking platen (item 2.11) place a dust cover on the soaking platen Position the transfer stards (items 2.12 to 2.17) as required depending on the size tolerance grade of TI being calibrated with the smallest size in front then uniformly progressing to the largest in the back Allow all blocks to normalize to platen temperature. 3.3 BURR AND WRINGABILITY CHECK Start with the smallest TI progress to the largest TI. Ensure that the faces edges of each TI are free from damage such as dents, nicks, or scratches that would impair the wringability of the test gage blocks. 5

9 3.3.2 Turn on the monochromatic light (item 2.18) If a visual inspection shows excessive dents or nicks on edges of the test gage block, remove excessive material with a rough deburring stone (item 2.19) a fine deburring stone (item 2.20), as required Rub the individual faces of each TI on a lapped deburring stone to ensure that the wringing faces are free of burrs. The face of the test gage block should wring to the deburring stone if no burrs exist Ensure that the TI will wring to the optical flat (item 2.22) Re-clean deburr the TI if the TI does not wring properly. If the TIs will not wring to the optical flat, repeat steps through NOTE Blocks that have lost their wringing qualities should be replaced. 3.4 COMPARATOR SETUP Turn on the electronic gage block comparator allow it to warm up for 30 minutes Set up the electronic gage block comparator with a suitable anvil gage stylus for the type of gage blocks to be calibrated. NOTE Ensure that the comparator electronic amplifier is located at a safe working distance from the gage block comparator to prevent any errors in the readings due to the heat generator by the amplifier Utilization of dual gage point contact comparator is recommended for either style 1 or style 2 test gage blocks. The lower gage head spindle shall be suspended within the main structure of the comparator, providing highly sensitive, point-to-point contact If applicable, place the computer monitor, the digital readout unit, the electronic gage block comparator meter to the immediate left of the operator for easy quick reference (See Figure 1). NOTES The amplifier should be located no less than 6 inches from the comparator. The electronic gage block comparator shall be in front of the operator the soaking platen to the right as shown in Figure 2. The comparator may be installed in a plexiglass enclosure to achieve improved temperature stability. When setting up the long gage block comparator (greater than 4 inches), mount the meter to the immediate left of the operator to facilitate easy reference. 6

10 Figure 1. Comparator Setup (0.010 to 4 Inch Gage Blocks) Figure 2. Comparator Setup (4 to 20 Inch Gage Blocks) 7

11 SECTION 4 CALIBRATION PROCESS 4.1 FLATNESS TEST (0.010 TO 4 INCHES) NOTE Since the majority of tolerance grade 2 3 blocks under inch (2.54 mm) in length are not precisely flat in their free state, the test for parallelism is considered sufficient (Federal Specification GGG-G-15C ANSI B ) Using the monochromatic light (See Figure 3) or the plano-interferometer (item 2.21) perform the following steps: Figure 3. Check Using Monochromatic Light Position one side of the TI under the plano-interferometer or the optical flat as applicable. Examine the optical flat or the plano-interferometer interpret the fringe pattern to determine the flatness value for the length width of the TI. NOTE If the TI is a thin block (less than inch) hold the thin gage blocks flat to the testing surface during this test. (Thin blocks are sometimes warped must be held flat during flatness calibration.) Examine the opposite face with the optical flat or the interferometer, observe the fringe pattern interpret the flatness for the TI surface. 8

12 NOTES If the fringe pattern on the TI consists of many lines when examined under the monochromatic light, the TI face may have dust particles or burrs on its surface. If the TI has no lines, then the optical flat is stuck to the TI must be broke free reset on the TI. The out-of-flatness condition of the contact surfaces shall be measured by optical interference methods along lines midway between the sides both across the width along the length of the surfaces; however on style 1 blocks, the measurement along the length shall not include 0.02 inch (0.5 mm) of surface nearest each end. On some blocks, the out-of-flatness along one of the diagonals is appreciably larger than midway between the edges as evidenced by a fan-shaped distribution of interference bs. In such cases, this error is measured along a diagonal If the TI has dust particles on its surface, brush the surface of the questionable TI with a dusting brush (item 2.23) to remove the dust particles, then repeat steps ; otherwise, skip to step If the fringe pattern remains questionable, deburr the questionable face using the applicable gage block deburring stone, repeat steps Record the out-of-flatness values for length width as the flatness deviations for the TI examined (out-of-tolerance blocks only) Verify that the TI flatness values are within specified tolerances. Refer to the applicable specifications in Appendix C, if necessary. NOTE The tables in Appendix C reflect tolerances from Federal Specification GGG-G-15 ANSI B The tolerances are indicated compared to the old federal classifications in the tables. The tables in Appendix C are provided for reference purposes only may not apply to every calibration. Customer requirements may also be taken into consideration when providing out-of-tolerance data. If it is determined that 10% of the gage blocks in the set exhibit excessive out-of-flatness deviations, the set shall be rejected without proceeding further. 4.2 FLATNESS TEST (4 TO 20 INCHES) Using the monochromatic light (see Figure 4), complete the following steps: 9

13 Figure 4. Test Setup (Long Blocks) Position one face of the TI upward under the monochromatic light, position the optical flat on the surface Observe the fringe pattern interpret the out-of-flatness condition for the length width of the TI. NOTES If the fringe pattern on the TI consists of many lines when examined under the monochromatic light, the TI face may have dust particles or burrs on its surface. If the TI has no lines, then the optical flat is stuck to the TI must be broke free reset on the TI. The out-of-flatness condition of the contact surfaces shall be measured by optical interference methods along lines midway between the sides both across the width along the length of the surfaces, however on style 1 blocks the measurement along the length shall not include 0.02 inch (0.5 mm) of surface nearest each end. On some blocks, the out-of-flatness along one of the diagonals is appreciably larger than midway between the edges as evidenced by a fan-shaped distribution of interference bs. In such cases, this error is measured along a diagonal If the TI has dust particles on its surface, brush the surface of the questionable TI with the dusting brush to remove the dust particles. The h syringe (item 2.25) can also be used to blow off dust particles Repeat steps If the fringe pattern is still questionable, deburr the questionable face on the applicable gage block deburring stone Examine the opposite face with the optical flat, observe the fringe pattern interpret the flatness for the TI surface Record, as appropriate, the largest deviations from a plane determined for the length width of both surfaces as the flatness deviations for the TI Verify that the flatness values are within the specified tolerances. (Refer to Appendix C.) 10

14 NOTE If it is determined that 10% of the gage blocks in the set exhibit excessive out-of-flatness deviations, the set shall be rejected without proceeding further Repeat steps through for each TI. 4.3 LENGTH AND PARALLELISM TESTS (0.010 TO 4 INCHES) NOTE Insulated forceps must be used at all times for hling gage blocks during calibration. Do not use gloves alone for they may not provide adequate heat insulation. Each stard or TI should be wiped, as necessary, with a clean chamois skin (item 2.25) just before placing the block under the stylus. Figure 5. Points of Reference (Short Gage Blocks) NOTES Ensure that the comparator electronic amplifier is at a safe working distance from the gage block comparator to prevent any errors in the readings due to the heat generated by the amplifier. Blocks under inch shall not be marked in the vicinity of reference point A. However, blocks so marked shall be utilized until replacement blocks with the correct marking are obtained. When TIs under inch are marked in the vicinity of reference point A, reference point D shall be used for the length measurements on style 2 gage blocks. The measured length of a style 1 gage block shall be the perpendicular distance from one contact surface to a central point midway between the edges of the opposite surface (reference point A). The measured length of a style 2 TI shall be the perpendicular distance from one contact surface to a central point on the opposite surface midway between the hole or outer edge of the countersink the edge of the block. Reference point A is nearest the size marking. 11

15 NOTES (CONTINUED) Metric gage blocks are measured in essentially the same manner as those made in English units. Unless an alternate meter readout in nanometers/micrometers is available, it will be necessary to record deviations in µinches convert to metric units when reporting to the customer activity Set the electronic gage block comparator for point-to-point calibration Set the RANGE control knob ±500 MILLIONTHS. Set the THOUSANDTHS STEPS switch to zero TENTHS OF THOUSANDTHS STEPS switch to Insert a stard gage block of the same nominal size as the first TI to be calibrated Lower the comparator vertical column until the stylus contacts the gage block stard the electronic meter indicates an on-scale indication When gaging stylus contact is established, set the RANGE control knob to ±50 MILLIONTHS adjust the amplifier ZERO CONTROL until the meter pointer indicates the actual deviation (+ or ) of the transfer stard from nominal, as recorded on the last valid calibration data sheet. (See sample calibration data sheet on page B-2.) Remove replace the gage block stard under the gaging stylus three times to verify the repeatability of the readings within ±1 µin. NOTE Repeatability of readings is most critical. If the reading cannot be repeated within ±1 µinch, the source of error must be found to ensure a reliable calibration of the TIs. For example, if the temperature at the comparator has increased by 0.1 C or more, it may be advisable to step away from the operation until the effect of body heat has dissipated Adjust the gage block comparator amplifier ZERO CONTROL until the digital readout indicates the actual deviation of the transfer stard from nominal Remove the transfer stard, replace it with a TI of the same nominal size. Refer to Figure 5 for reference point locations Note the reading of the TI at reference point A on the digital readout. Remove the TI, wipe both faces with a chamois skin reinsert it to take a second reading If the second reading is within 1 µin of the first, record the value of the second reading on the calibration data sheet. If the second reading differs from the first by 2 µinches, record the average of the two values to the nearest µinch If the second reading differs from the first by more than 2 µinches, repeat the operations to re-check the readings. If the difference is again greater than 2 µinches, the gage block may be defective it should be inspected to determine if it has to be rejected Verify that the second reading at reference point A repeats the first reading at reference point A within ±1 µin to ensure a reliable calibration of the TI Take readings at reference points A, B, C. Include reference point D if the TIs are style 2. NOTE On a base triangle, take readings at three equidistant points, as appropriate. On an extension arm, take one reading at the midpoint. 12

16 Record the readings for reference points A, B, C on the calibration data sheet. (See sample on page B-2.) Include reference point D if the TIs are style 2. If the difference exceeds the length tolerance for the TI per Appendix C, record the OOT value in the DEVIATION column under the applicable reference point in the calibration data sheet Determine the maximum difference between readings A, B, C D if applicable. If the difference exceeds the parallelism tolerance for the TI per the Federal Specification GGG G 15 or ANSI B89.1.9, record the OOT value in the PARA column of the calibration data sheet. (See sample sheet page B-2.) Verify that the grade classification parallelism length value for each TI per tolerance indicated in Appendix C. If the TI is metric, refer to the metric tolerance table in Appendix C Repeat steps through for each TI, as necessary The TI calibration uncertainty shall be calculated when: (1) the uncertainty of the stards used has changed, (2) the repeatability of the gage block comparator has changed appreciably, or (3) a different calibration method is adopted The TI calibration uncertainty can be estimated from the following equation: Where: T u = ± [R+ S u ] T u = TI calibration uncertainty (µin) R = Comparator repeatability (µin) S u = Calibration uncertainty of the stard used (µin) If not performing the length parallelism tests for long gage blocks (4 to 20 inches), skip to step LENGTH AND PARALLELISM CALIBRATION (4 TO 20 INCHES) NOTES Strong insulated forceps must be used at all times for hling long gage blocks during calibration. Do not use gloves only, as they may not provide adequate heat insulation. Each stard or TI should be wiped, as required, with a clean chamois skin just before placing the block under the stylus. Ensure that the comparator electronic amplifier is at a safe working distance from the gage block comparator to prevent any errors in the readings due to the heat generated by the amplifier. The measured length of a style 1 gage block shall be the perpendicular distance from one contact surface to a central point midway between the edges of the opposite surface (reference point A). See Figure 6. The measured length of a style 2 TI shall be the perpendicular distance from one contact surface to a central point on the opposite surface midway between the hole or outer edge of the countersink the edge of the block. Reference point A is nearest the size marking metric gage blocks. Metric gage blocks are measured in the same manner as those made in English units. Unless an alternate meter readout in nanometers/micrometers is available, it will be necessary to record deviations in µinches convert to metric units when reporting to the customer. 13

17 Figure 6. Points of Reference (Long Blocks) Set the electronic gage block comparator for point-to-point calibration Refer to Figure 6 for reference point locations Set the RANGE control knob to ±500 MILLIONTHS. Set the THOUSANDTHS STEPS TENTHS OF THOUSANDTHS STEPS switches to zero Set the adjustable reference arm at a height of 0 to 0.1 inch above the nominal size of the first TI (minimum length in set) to be calibrated lock the arm into position. NOTE When calibrating metric gage blocks, set the adjustable reference arm at a height to the nearest tenth of an inch division above the equivalent height of the metric length in inch units. For example, the equivalent height of a 125 mm block is approximately 5 inches; therefore, the arm is set at the 5.0 inch mark. A small label listing the mm to inch equivalents may be attached to the comparator for easy reference Place a stard gage block of the same nominal size as the first TI in position for measurement. Turn the knob of the reference contact until the stylus touches the block When stylus contact is established, set the RANGE control knob to ±50 MILLIONTHS adjust the amplifier ZERO CONTROL until the comparator meter pointer indicates the actual deviation (+ or ) of the gage block stard from nominal, as recorded on the last valid calibration data sheet (see sample on page B-2) Remove replace the stard gage block under the gaging stylus three times to verify repeatability within ±1 µinch. 14

18 NOTE Repeatability of readings is most critical. If the reading cannot be repeated within ±1 µinch, the source of error must be found to ensure a reliable calibration of the TI. For example, if the temperature at the comparator has increased by 0.1 C or more, it may be advisable to step away from the operation until the effect of body heat has dissipated Remove the gage block stard replace it with a TI of the same nominal value Note the reading of the TI at reference point A on the comparator meter. Remove the TI, wipe both faces with a chamois skin re-insert it to make a repeat reading If the second reading is within 1 µinch of the first reading, record the value of the second reading on the calibration data sheet. If the second reading differs from the first by 2 µinches, record the average of the two values to the nearest µinch If the second reading differs from the first by more than 2 µinches, repeat the operations to re-check the readings. If the difference is again greater than 2 µinches, the gage block may be defective it should be inspected to determine if it has to be rejected Take readings at reference points B C. Include reference point D if the TIs are style Record the readings for reference points A, B, C on the calibration data sheet. Include reference point D if the TIs are style 2. If the difference exceeds the length tolerance for the TI per Federal Specification GGG-G-15 or ANSI B89.1.9, record the OOT value in the DEVIATION column under the applicable reference point in the calibration data sheet Determine the maximum difference between readings A, B, C D, if applicable. If the difference exceeds the parallelism length tolerance for the TI, record the value in the PARA column of the calibration data sheet Verify that the TI is within tolerance per Federal Specification GGG-G-15 or ANSI B89.1.9, as applicable. If the TI is metric, refer to the metric tolerance table in Appendix C Repeat steps through for each TI to be calibrated The TI calibration uncertainty must be calculated when: (1) the uncertainty of the stards used has changed, (2) the repeatability of the gage block comparator has changed appreciably, or (3) a different calibration method is adopted The TI calibration uncertainty can be determined from the following equation: Where: T u = ± [R+ S u ] T u = TI calibration uncertainty (µin) R = Comparator repeatability (µin) S u = Calibration uncertainty of the stard used (µin) Record on the Report of Calibration (ROC) or Certificate of Calibration (COC) form, as required, all pertinent data relating to the calibration of the TIs such as the method of measuring length, flatness parallelism, the uncertainty of the length measurements Annotate the ROC or COC with all the temperature humidity values obtained from the temperature humidity recorder Clean the TI case wipe each TI with clean cheesecloth, coat with non-corrosive gage block preservative (item 2.26) place it in the case. 15

19 Wipe each stard gage block with cheesecloth lubricate replace the stard gage block into the hling tray Clean secure the remaining equipment as necessary Attach a black-on-white CALIBRATED label to the TI case Unless other MEASUREMENTS are to be performed, turn all power switches to off or stby disconnect the equipment from the TI. 16

20 CALIBRATION CHECKLIST TEST INST (S) Various manufacturers, Grades 0.5, 1, 2 3 Gage blocks PROC. NO. NA 17-20MD-185 MFR MODEL SER. NO. PROCEDURE MEASURED VALUES OUT STEP FUNCTION TESTED NOMINAL FIRST RUN SECOND RUN OF CALIBRATION TOLERANCES NO. TOL (1) (2) (3) (4) (5) (6) (7) 3.1 Preliminary operations environmental considerations ck ( ) 3.2 Cleaning Preparation ck ( ) 3.3 Burr wringability check ck ( ) 3.4 Comparator setup ck ( ) 4.1 Test (0.010 to 4 in) Record out-of-flatness value ck ( ) Verify TI flatness within tolerance Refer to Appendix C 4.2 Test (4 to 20 in) Record out-of-flatness value ck ( ) Verify TI flatness within tolerance Refer to Appendix C 4.3 Calibration (0.010 to 4 in) Verify repeatability 0 µin Verify repeatability 0 µin 0 to 1 µin Record OOT value in calibration data sheet ck ( ) Record OOT value in calibration data sheet ck ( ) Verify tolerance Refer to Appendix C 4.4 Calibration (4 to 20 in) Verify repeatability 0 µin 0 to 1 µin Record value, record average 0 µin 2 µin (average max) Record OOT value in calibration data sheet ck ( ) Record OOT value in calibration data sheet ck ( ) Verify tolerance ck ( ) Refer to Appendix C Record pertinent data ck ( ) Record temperature values ck ( ) Page 1 of 1 17

21 APPENDIX A SAMPLE CERTIFICATE OF CALIBRATION DEPARTMENT OF THE NAVY Naval Aviation Depot Operations Center Navy Calibration Laboratory (COM) XXX/XXX-XXXX (DSN) XXX-XXXX (FAX) XXX/XXX-XXXX Manufacturer: Description: Model: The Navy Calibration Laboratory certifies that this instrument meets or exceeds the manufacturers specification as published in the users hbook. The measurement uncertainties of this instrument will be well within the 1 Sigma limits of the Calibrators being tested a report of errors, or corrections, is not required. Stards used by the Navy Calibration Laboratory are directly traceable to stards defined, maintained disseminated by the National Institute of Stards Technology (NIST). AMBIENT TEMP: CERTIFICATION DATE: RELATIVE HUMIDITY: DUE DATE: METROLOGIST: APPROVED BY: A-1

22 APPENDIX B SAMPLE REPORT OF CALIBRATION MFG: Starrett Webber MODEL: SS8AAX SERIAL: DEPARTMENT OF THE NAVY NAVAL AIR DEPOT NORTH ISLAND NAVY PRIMARY STANDARDS LABORATORY (COM) (DSN) (FAX) Report Of Calibration For Gage Block Set Submitted By: Kuwait Air Force NAVAIR Liaison Office, North Isl The gage blocks were compared against NIST calibrated master gage blocks using an electro-mechanical comparator. The deviations in length from nominal size at degrees C (68 degrees F) are given on the following pages along with the total uncertainty of the measurements. A minus sign indicates the length is shorter than nominal a plus sign indicates the length is longer than nominal. CALIBRATION RESULTS ARE ATTACHED Stards used by the Navy Primary Stards Laboratory are directly traceable to stards defined, maintained disseminated by the National Institute of Stards Technology. This report shall not be reproduced except in full, without the written approval of the Navy Primary Stards Laboratory. Ambient Temperature: 68 0 F Calibration Date 31 May 2005 Relative Humidity: 36% Due Date: 31 May 2006 Metrologist: A.M. Miller Approved By: D.A. Giesenschlag Physical Metrology Manager B-1

23 APPENDIX B SAMPLE CALIBRATION DATA SHEET Nomenclature: Gage Block Set Manufacturer: Starrett Webber Model: SS8AAX Serial Number: Calibration Date: 31 May 2005 Due Date: 31 May 2006 Serial Nominal Deviation from Total Number Nominal Deviation Uncertainty (inches) (micro-inches) (micro-inches) (micro-inches) R8V R8V R8V R8V R8V R8V R8V R8V The assigned total uncertainty reported for each block in this report, is the exped uncertainty using a coverage factor of k =2. Total uncertainty is the uncertainty the reported values are expected to remain within for the duration of the calibration interval. END - This report shall not be reproduced except in full, without the written approval of the Navy Primary Stards Laboratory. - END B-2

24 APPENDIX B APPROPRIATE STATEMENTS FOR NAVY STANDARDS LABORATORY REPORT OF CALIBRATION (SELECT STATEMENTS THAT ARE APPLICABLE) 1. This report forms a part of the Report of Calibration accompanying the above stards. 2. Transfer stards used during calibration Set Ser #. 3. errors of 4 µinches or less are not reported. 4. The measured length is the perpendicular distance from one contact surface to a central point midway between the edges of the opposite surface for style 1 blocks or to a central point on the opposite surface midway between the hole or outer edge of the countersink the edge of the block for style 2 blocks. 5. The measured length applies at the reference temperature of 20 C (68 F) stard air pressure of mb ( in. Hg.). 6. All values are reported in International Inches. 7. This activity recommends the replacement of the following gage blocks due to nonconformity in size, flatness /or visual finish (see ANSI B or GGG-G-15). 8. was not certified due to the variables noted above. 9. This activity does not recommend the following blocks for use other than grade B stards due to nonconformity in size, flatness visual finish. (See B or Fed. Spec. GGG-G-15.) 10. Visible scratches are not detrimental to reported size. 11. Stards should normalize a minimum of 5 minutes per inch of length at 20 C prior to use. 12. This activity does not recommend the following gage blocks for use other than spacer blocks, due to nonconformity in size, flatness surface finish. (See ANSI B or Fed. Spec. GGG G 15.) B-3

25 Nom. Size (in) Tol. Grade 0.5 Formerly (Grade AAA) (µin) APPENDIX C FEDERAL SPECIFICATION GGG-G-15 AND ANSI B (SHORT BLOCKS, ENGLISH) Tol. Grade 1 Formerly (Grade AA) (µin) Tol. Grade 2 Formerly (Grade A+) (µin) Tol. Grade 3 Formerly (Compromise between A+B) (µin) 1 ±1 1 ±2 2 +4, , ±2 1 ±4 2 +8, , ±3 1 ± , , ±4 1 ± , , ANSI B LENGTH AND PARALLELISM TOLERANCE (SHORT BLOCKS, METRIC) Tol. Grade 0.5 (µm) Tol. Grade 1 (µm) Tol. Grade 2 (µm) Tol. Grade 3 (µm) Nom. Size (mm) 10 ± ± , ± ± , ± ± , ± ± , ± ± , C-1

26 Nom. Size (in) APPENDIX C FEDERAL SPECIFICATION GGG-G-15 AND ANSI B LENGTH AND PARALLELISM TOLERANCES (LONG BLOCKS, ENGLISH) Tol. Grade 0.5 Formerly (Grade AAA) (µin) Tol. Grade 1 Formerly (Grade AA) (µin) Tol. Grade 2 Formerly (Grade A+) (µin) Tol. Grade 3 Formerly (Compromise between Grades A+B) (µin) ± , , ± , , ± , , ± , , ± , , ± , , ± , , ± , , Nom. Size (mm) ANSI B LENGTH AND PARALLELISM TOLERANCES (LONG BLOCKS, METRIC) Tol. Grade 0.5 (µm) Tol. Grade 1 (µm) Tol. Grade 2 (µm) Tol. Grade 3 (µm) ± , , ± , , ± , , ± , , ± , , ± , , ± , , ± , , C-2

27 APPENDIX C ANSI B SIZE TOLERANCES (ENGLISH AND METRIC) Size Grade 00 Grade 0 Grade AS1 Grade AS2 Thru in (0.5 mm) ±4 µin (±0.10 mm) ±6 µin (±0.14 mm) ±12 µin (±0.30 mm) ±24 µin (±0.60 mm) Thru in (10 mm) ±3 µin (±0.7 mm) ±5 µin (±0.12 mm) ±8 µin (±0.20 mm) ±18 µin (±0.45 mm) Thru in (25 mm) ±3 µin (±0.07 mm) ±6 µin (±0.10 mm) ±12 µin (±0.30 mm) ±24 µin (±0.60 mm) Thru in (50 mm) ±4 µin (±0.10 mm) ±8 µin (±.20 mm) ±16 µin (±0.40 mm) ±32 µin (±0.80 mm) Thru in (75 mm) ±5 µin (±0.12 mm) ±10 µin (±0.25 mm) ±20 µin (±0.50 mm) ±40 µin (±1.0 mm) Thru in (100 mm) ±6 µin (±0.15 mm) ±12 µin (±0.30 mm) ±24 µin (±0.60 mm) ±48 µin (±1.2 mm) Thru in (125 mm) ±8 µin (±.20 mm) ±16 µin (±0.40 mm) ±32 µin (±0.80 mm) ±64 µin (±1.6 mm) Thru in (150 mm) ±8 µin (±.20 mm) ±16 µin (±0.40 mm) ±32 µin (±0.80 mm) ±64 µin (±1.6 mm) Thru in (175 mm) ±10 µin (±0.25 mm) ±20 µin (±0.50 mm) ±40 µin (±1.0 mm) ±80 µin (±2.0 mm) Thru in (200 mm) ±10 µin (±0.25 mm) ±20 µin (±0.50 mm) ±40 µin (±1.0 mm) ±80 µin (±2.0 mm) Thru in (250 mm) ±12 µin (±0.30 mm) ±24 µin (±0.60 mm) ±48 µin (±1.2 mm) ±104 µin (±2.4 mm) Thru in (300 mm) ±14 µin (±0.35 mm) ±28 µin (±0.70 mm) ±56 µin (±1.4 mm) ±112 µin (±2.8 mm) Thru in (400 mm) ±18 µin (±0.45 mm) ±36 µin (±0.90 mm) ±72 µin (±1.8 mm) ±176 µin (±3.6 mm) Thru in (500 mm) ±20 µin (±0.50 mm) ±44 µin (±1.1 mm) ±88 µin (±2.2 mm) ±176 µin (±4.4 mm) C-3

28 APPENDIX D REPRESENTATIVE TEST INSTRUMENTS TIs that may be calibrated with this procedure include, but are not limited to, the following: Model Manufacturer Tolerance Grade 112M2 Doall Co. Grade 2 121R Electrovac Grade 3 (Ceramic) 54R Starrett, L.S. Co. Various Grades 88 Colt Ind, Operating Corp, Pratt Whitney Manufacturing Grade 2 RC88AA Starrett, L S, Co, Webber Gage Div Grade 2 RS88A1 Starrett, L S, Co Brown Sharp Manufacturing 8M Doall Co. 8S Various Grades SS8A1X Starrett, L S, Co, Webber Gage Div Grade 2 D-1