1717 East Ninth Street, Suite 1105 • Cleveland, Ohio 44114 USA
1.0
Scope.
feature, and not because of a compressive loaddeveloped against the underhead bearing surface ofthe screw or a tensile load developed in the shank ofthe screw.
1.3.2REPT screws are metallic screws to which havebeen added a nonmetallic insert or fused nonmetallicsubstance in their threaded length. The design of theprevailing-torque feature shall be in accordance with thepractice of the manufacturer. Depending upon the amountof friction present because of surface finish and lubri-cants, the dimensional characteristics of the nonmetallicelement may vary to achieve the performance require-ments stated in Table 1.
1.3.3For purposes of this standard, \"lot\" means aquantity of fasteners of one part number fabricated bythe same production process from the same coil orheat number of metal as provided by the fastenermanufacturer and submitted for inspection and test-ing at one time.2.0
Property Classes.
1.1This standard establishes a conformancetest procedure for the performance of metricNonmetallic Resistant Element Type Prevailing-Torque Screws (hereinafter called REPT screw), innominal thread diameters M1.6 thru M36.
The prevailing-torque values given in this
standard are conformance requirements of test con-ditions described in the performance test procedure(5.1). If the conditions of the actual service applica-tion differ from those of 5.1 (e.g., internally threadedhole in a different material, length of thread engage-ment, class of internal thread tolerance, speed ofdriving, different plating or coating on screw or mat-ing part), the prevailing-torque values may differ.Such values can only be determined through testingthe REPT screw in its specific application.
This standard is not concerned with dimen-sional features such as head styles, or with perfor-mance capabilities such as strength properties, cor-rosion resistance, sealing, suitability for use in highor low temperatures, and/or consistency of torque-to-tension relationships during assembly. Such fea-tures and properties are covered in other standardsand specifications and must be referenced whenspecifying a REPT screw to assure that all of theservice conditions of the particular engineering ap-plication are properly met.
(Note: The application of some nonmetallic
elements requires heating of an isolated area in thescrew thread to approximately 316ºC which mayhave an adverse effect on the mechanical proper-ties of some products.)
1.2While the requirements of this standard applyto REPT screws, it is not the intent to precludealternate types of screws which totally satisfy therequirements of this standard.1.3
Definitions.
2.1Property Classes. This standard coversonly steel REPT screws produced to meet the me-chanical strength requirements of one of four basicproperty classes, 8.8, 9.8, 10.9 and 12.9 as specifiedin ASTM F568.
The standard sizes of REPT screws for each
of the four property classes are given in Table 1.3.0
Referenced Standards.
All standards are latest issue unless otherwise
agreed between manufacturer and purchaser.3.1
ASME Standards.
These may be obtained from ASME; Three
Park Avenue; New York, NY 10016-5990.
•B1.3M Screw Thread Gaging Systems for
Dimensional Acceptability – Inch and Metric ScrewThreads, (UN, UNR, UNJ, M and MJ)
1.3.1A prevailing-torque REPT screw is an exter-nally threaded fastener which is frictionally resistantto rotation due to a self-contained prevailing-torque IFI
STANDARD ®
Published and issued bythe Industrial FastenersInstitute of Cleveland, OH
TEST PROCEDURE FOR THE PERFORMANCE OFMETRIC NONMETALLIC RESISTANT ELEMENT
PREVAILING-TORQUE SCREWS
IFI-524
Page 1 of 5
Issued: 1982
Revised: July 2002
All standards and specifications are advisory only. Their use by anyone is entirely voluntary. Reliance thereon for any purpose by anyone is at the sole risk of that person orthe user of the product, and the IFI is not responsible for any loss, claim, or damage arising therefrom. In formulating and approving standards and specifications, the IFI hasnot investigated and will not investigate patents which may apply to the subject matter. Prospective users of the standards and specifications are responsible for advisingthemselves of and protecting themselves against any patent infringement liability which may arise out of such use. © INDUSTRIAL FASTENERS INSTITUTE 2002
INDUSTRIAL FASTENERS INSTITUTE
1717 East Ninth Street, Suite 1105 • Cleveland, Ohio 44114 USA
Table1Prevailing-TorquesforNonmetallicResistantElementScrewsClampLoad(1)kNPropertyClassofScrew8.8M1.6×0.35M2×0.4M2.5×0.45M3×0.5M3.5×0.6M4×0.7M5×0.8M6×1M8×1.25M10×1.5M12M14M16M20×1.75×2×2×2.5—————————————1101602503709.80.61.01.62.43.34.36.99.81828415676————10.9——————8.812233652729815022035051012.90.91.52.53.74.96.4101527426184110180260410590Prevailing-TorqueMaxN•m0.100.200.400.600.901.22.33.010142130406090120150FirstRemovalPrevailing-TorqueMinN•m0.010.020.050.140.220.260.360.450.901.82.63.65.08.0131928FifthRemovalPrevailing-TorqueMinN•m0.0040.010.030.060.110.160.230.300.581.11.52.33.45.58.51318NomScrewSizeandThreadPitchM24×3M30×3.5M36×4(1) Clamp loads equal 75 percent of the proof loads specified for the property class in ASTM F568.
•B1.13M Metric Screw Threads – M Profile
3.2
ASTM Standards.
At the option of the manufacturer, screws
may be provided with a supplementary lubricant.4.2
Threads.
These may be obtained from ASTM; 100 Barr
Harbor Drive; West Conshohocken, PA 19428-2959.•ASTM F568M Carbon and Alloy Steel Exter-nally Threaded Metric Fasteners4.0
Requirements.
4.2.1Thread Tolerances. Threads of REPT screwsshall be tolerance class 6g as specified in ASMEB1.13M, except that the portion of the threadedlength containing the nonmetallic element need notconform.
4.2.2Thread Start. REPT screws, except thosecovered in 4.3.2, shall assemble a minimum of one fullturn by the fingers into any mating internally threadedcomponent that has threads acceptable to GagingSystem 21 of ASME B1.3M.
4.1Finish. REPT screws shall be furnishedplain or with a protective coating as specified by thepurchaser. IFI
STANDARD ®
Published and issued bythe Industrial FastenersInstitute of Cleveland, OH
TEST PROCEDURE FOR THE PERFORMANCE OFMETRIC NONMETALLIC RESISTANT ELEMENT
PREVAILING-TORQUE SCREWS
IFI-524
Page 2 of 5
Issued: 1982
Revised: July 2002
All standards and specifications are advisory only. Their use by anyone is entirely voluntary. Reliance thereon for any purpose by anyone is at the sole risk of that person orthe user of the product, and the IFI is not responsible for any loss, claim, or damage arising therefrom. In formulating and approving standards and specifications, the IFI hasnot investigated and will not investigate patents which may apply to the subject matter. Prospective users of the standards and specifications are responsible for advisingthemselves of and protecting themselves against any patent infringement liability which may arise out of such use. © INDUSTRIAL FASTENERS INSTITUTE 2002
INDUSTRIAL FASTENERS INSTITUTE
1717 East Ninth Street, Suite 1105 • Cleveland, Ohio 44114 USA
4.3
Performance.
to two thread pitches shall project through the top ofthe test nut. During this first installation, the highestprevailing-torque (first on torque) occurring while theREPT screw or test nut is in motion and prior todevelopment of any axial load shall be measured andrecorded.
Tightening shall be continued until an axial
tensile clamp load equal to the load as specified inTable 1 for the applicable screw size and propertyclass is developed.
The axial tensile clamp load in the REPT
screw shall be reduced to zero by backing the turnedmember off until the test washer is free to move by thefingers. Following a pause (it is generally necessaryto change the wrench to one of a lower torque capac-ity), removal shall be continued and the highest torque(first removal torque) occurring while the REPT screwor test nut is being backed off throughout the next360 deg of rotation shall be measured and re-corded. The REPT screw and test nut shall bedisassembled and then reassembled and disas-sembled two more times. On each reassembly theREPT screw shall be assembled with the test nutuntil the turned element is seated against the testwasher, but no tensile load shall be induced in theREPT screw. During the third removal, the highesttorque (third removal torque) occurring while theREPT screw or test nut is being backed off through-out the first 360 deg of rotation shall be measuredand recorded. At no time during this 360 deg ofrotation shall the torque be zero.
At no time during the two additional installa-tions and removals should the prevailing-torque ex-ceed the maximum prevailing-torque as specified inTable 1.
(Note: The intent of this preceding require-ment is to demonstrate that galling between thesample REPT screw and test nut has not oc-curred. With certain designs of REPT screws theremay be an increase in the prevailing-torque dur-ing the three assembly cycles and in rare in-stances the specified maximum prevailing-torquemay be exceeded. In such instances the manufac-turer, when requested, shall give evidence thatgalling was not a contributing factor.)
4.3.1The prevailing-torque of REPT screws occur-ring during any installation or removal shall not exceedthe maximum prevailing-torque specified in Table 1when tested as specified in 5.1. In addition, the highestprevailing-torques developed by REPT screws dur-ing first and fifth removal shall not be less than theminimum first and fifth removal torques, respectively,specified in Table 1 when tested in accordance with5.1. In addition, the lowest prevailing-torque devel-oped by REPT screws during the fifth removal shallnot be zero, when tested in accordance with 5.1.4.3.2REPT screws which are too short or whichhave thread lengths too short to permit testing inaccordance with 5.1 shall have their prevailing-torquerequirements and test procedure established by agree-ment between the purchaser and manufacturer.4.4When REPT screws are altered in any mannerby any source following shipment by the manuacturerto a purchaser, the screw manufacturer shall not beheld responsible for failures of the screws to meetdimensional or performance requirements traceable tothe alteration.5.0
Performance Test.
5.1Test Procedure. The sample REPT screwshall be assembled with a test washer (5.1.6) and atest nut (5.1.3) in a load measuring device (5.1.1)with the test washer located adjacent to the compo-nent to be turned. During the complete performanceof the test, either the REPT screw or the test nut shallbe turned. When the REPT screw is turned, therestraining mechanism shall be such that it impartsno radial distortion to the test nut. The REPT screwor test nut shall be advanced until its bearing surfaceis seated against the test washer. The total thicknessof spacer material in the test assembly shall beselected so that at seating, the mid-length of thenonmetallic element of the screw shall coincide asclosely as practical with the mid-thickness of the testnut, and a minimum length of REPT screw equivalent
IFI
STANDARD ®
Published and issued bythe Industrial FastenersInstitute of Cleveland, OH
TEST PROCEDURE FOR THE PERFORMANCE OFMETRIC NONMETALLIC RESISTANT ELEMENT
PREVAILING-TORQUE SCREWS
IFI-524
Page 3 of 5
Issued: 1982
Revised: July 2002
All standards and specifications are advisory only. Their use by anyone is entirely voluntary. Reliance thereon for any purpose by anyone is at the sole risk of that person orthe user of the product, and the IFI is not responsible for any loss, claim, or damage arising therefrom. In formulating and approving standards and specifications, the IFI hasnot investigated and will not investigate patents which may apply to the subject matter. Prospective users of the standards and specifications are responsible for advisingthemselves of and protecting themselves against any patent infringement liability which may arise out of such use. © INDUSTRIAL FASTENERS INSTITUTE 2002
INDUSTRIAL FASTENERS INSTITUTE
1717 East Ninth Street, Suite 1105 • Cleveland, Ohio 44114 USA
Sufficient time shall elapse between torquing
cycles to prevent overheating of the test assembly.
Speed of driving shall not exceed 30 RPM.5.1.1Tensile Load Measuring Device. The tensileload measuring device shall be an instrument capableof measuring the actual tension induced in the REPTscrew as it is being tightened. The device shall beaccurate within plus or minus 5 percent of the tensileclamp load to be induced. Diameter of the REPTscrew clearance hole in the backing plate shall bethe REPT screw nominal size plus 0.4 mm for screwsizes M5 and smaller, plus 0.8 mm for sizes M6 toM24 incl., and plus 1.6 mm for sizes M30 and M36.5.1.2Torque wrenches shall be accurate withinplus or minus 2 percent of the maximum of thespecified torque range of the wrench.
5.1.3Test Nut. The test nut shall conform to di-mensions given in Table 2. Alternately, a test blockmay be used as long as its thickness and countersinkcomply with Table 2. Nuts or test blocks shall bemade of carbon steel, and shall have proof loadstrengths equal to or greater than the minimumspecified ultimate strength of the screw being tested.Test blocks shall meet the same mechanical require-ments as test nuts.
5.1.4Thread Tolerance. All test nuts shall beClass 6H when testing screws with Class 6g or Class4g6g.Test nuts shall be free of rust and dirt and shallhave a plain finish with light oil coating. The screwshall be assembled into the countersunk side of thenut. Alternate testing using a gage block shall beused only by agreement of purchaser and supplier.
Test blocks must meet the same thread tolerance astest nuts.
5.1.5Usage. A new test nut shall be used fortesting each screw. Prior to the usage of a test nut, itsthreads shall be gaged and shall be acceptable to therequirements of Gaging System 21 of ASME B1.3M.Alternate testing with test block shall require gagingprior to usage and gaging after each screw test to therequirements of Gaging System 21 of ASME B1.3M.5.1.6Test Washer. Washers shall be steel withdimensions, hardness and finish at option of testingagency.6.0
Inspection.
6.1Inspection Procedure. REPT screws shallbe inspected to determine conformance with therequirements of this standard.
Unless otherwise specified, from each lot
of REPT screws the following number of tests shallbe conducted to determine the acceptability toeach of the requirements:
LotSize(pieces)to5051to500501to35,000over35,000No.ofTests2358Alternate inspection procedures may be
specified by the purchaser on the purchase orderor engineering drawing.
IFI
STANDARD ®
Published and issued bythe Industrial FastenersInstitute of Cleveland, OH
TEST PROCEDURE FOR THE PERFORMANCE OFMETRIC NONMETALLIC RESISTANT ELEMENT
PREVAILING-TORQUE SCREWS
IFI-524
Page 4 of 5
Issued: 1982
Revised: July 2002
All standards and specifications are advisory only. Their use by anyone is entirely voluntary. Reliance thereon for any purpose by anyone is at the sole risk of that person orthe user of the product, and the IFI is not responsible for any loss, claim, or damage arising therefrom. In formulating and approving standards and specifications, the IFI hasnot investigated and will not investigate patents which may apply to the subject matter. Prospective users of the standards and specifications are responsible for advisingthemselves of and protecting themselves against any patent infringement liability which may arise out of such use. © INDUSTRIAL FASTENERS INSTITUTE 2002
INDUSTRIAL FASTENERS INSTITUTE
1717 East Ninth Street, Suite 1105 • Cleveland, Ohio 44114 USA
Table2DimensionsofTestNutsNominalSizeM1.6M2.0M2.5M3.0M3.5M4.0M5.0M6.0M8.0M10.0M12.0M14.0M16.0M20.0M24.0M30.0M36.0WidthAcrossFlatsMax3.204.005.005.506.007.008.0010.0013.0016.0018.0021.0024.0030.0036.0046.0055.00Min3.023.824.825.325.826.787.789.7812.7315.7317.7320.6723.6729.1635.0045.0053.80WidthAcrossCornersMax3.704.625.776.356.938.089.2411.5515.0118.4820.7824.2527.7134.6441.5753.1263.51Min3.414.325.456.016.587.668.7911.0514.3817.7720.0323.3526.7532.9539.5550.8560.79NutThicknessMax1.301.602.002.903.303.805.105.707.509.3012.0014.1016.4020.3023.9028.6034.70Min1.051.351.752.653.003.504.805.407.148.9411.5713.4015.7019.0022.6027.3033.1090°–120°CountersinkDiaMax1.842.302.8753.454.0254.605.756.758.7510.8012.9615.1217.2821.6025.9232.4038.88Min1.602.002.503.003.504.005.006.008.0010.0012.0014.0016.0020.0024.0030.0036.00 *Nut sizes M1.6 thru M2.5 are based on ASME B18.2.4.1M Style 1.(1)Nut sizes M3.0 thru M36 are based on ASME B18.2.4.2M Style 2.
IFI
STANDARD ®
Published and issued bythe Industrial FastenersInstitute of Cleveland, OH
TEST PROCEDURE FOR THE PERFORMANCE OFMETRIC NONMETALLIC RESISTANT ELEMENT
PREVAILING-TORQUE SCREWS
IFI-524
Page 5 of 5
Issued: 1982
Revised: July 2002
All standards and specifications are advisory only. Their use by anyone is entirely voluntary. Reliance thereon for any purpose by anyone is at the sole risk of that person orthe user of the product, and the IFI is not responsible for any loss, claim, or damage arising therefrom. In formulating and approving standards and specifications, the IFI hasnot investigated and will not investigate patents which may apply to the subject matter. Prospective users of the standards and specifications are responsible for advisingthemselves of and protecting themselves against any patent infringement liability which may arise out of such use. © INDUSTRIAL FASTENERS INSTITUTE 2002
因篇幅问题不能全部显示，请点此查看更多更全内容