IFI-524-1996.pdf
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1、1. Scope. INDUSTRIAL FASTENERS INSTITUTE 1717 East 9th St., Suite 11 05 Cleveland, Ohio 441 14 USA 1.1 This Standard establishes a conformance test procedure for the performance of metric Nonmetallic Resistant Element Type Prevailing Torque Screws (hereinafter called REPT screw), in nominal thread d
2、iameters M1.6 thru M36. The prevailing torque values given in this Standard are conformance requirements of test conditions described in the performance test procedure (4.1). If the conditions of the actual service application differ from those of 4.1 (e.g., internally threaded hole in a different m
3、aterial, length of thread engagement, class of internal thread tolerance, speed of driving, different plating or coating on screw or mating part), the prevailing torque values may differ. Such values can only be determined through testing the REPT screw in its specific application. This Standard is
4、not concerned with dimensional features such as head styles, or with other mechanical or performance capabilities such as strength properties, corrosion resistance, sealing, suitability for use in high or low temperatures, and/ or consistency of torque-to-tension relationships during assembly. Such
5、features and properties are covered in other standards and specifications and must be referenced when specifying a REPT screw to assure that all of the service conditions of the particular engineering application are properly met. (Note: The application of some nonmetallic elements requires heating
6、of an isolated area in the screw thread to approximately 6OOpF which may have an adverse effect on the mechanical properties of some products.) 1.2 While the requirements of this Standard apply to REPT screws, it is not the intent to preclude alternate types of screws which totally satisfy the requi
7、rements of this Standard. 1.3 Definitions. 1.3.1 A prevailing-torque REPTscrew is an externally threaded fastener which is frictionally resistant to rotation due to a self-contained prevailing-torque feature, and not because of a compressive load developed against the under head bearing surface of t
8、he screw or a tensile load developed in the shank of the screw. 1.3.2 REPT screws are metallic screws to which have been added a nonmetallic insert or fused nonmetallic substance in their threaded length. The design of the prevailing-torque feature shall be in accordance with the practice of the man
9、ufacturer. Depending upon the amount of friction present because of surface finish and lubricants, the dimensional characteristics of the nonmetallic element may vary to achieve the performance requirements stated in Table 1. 1.3.3 For purposes of this Standard, “lot“ means a quantity of fasteners o
10、f one part number fabricated by the same production process from the same coil or heat number of metal as provided by the fastener manufacturer and submitted for inspection and testing at one time. 2.0 Property Classes. 2.1 Property Classes. This Standard covers only steel REPT screws produced to me
11、et the mechanical strength requirements of one of four basic property classes, 8.8,9.8,10.9 and 12.9 as specified in ASTM F568. The standard sizes of REPT screws for each of the four property classes are given in Table 1. 3.0 Requirements. 3.1 Finish. REPT screws shall be furnished plain or with a p
12、rotective coating as specified by the purchaser. If tolerancing differs, see “Scope“ paragraph 2. At the option of the manufacturer, screws may be provided with a supplementary lubricant. I lFl-524 I FI STANDARD I TEST PROCEDURE FOR THE PERFORMANCE Revised: October 1996 OF METRIC NONMETALLIC RESISTA
13、NT ELEMENT Industrial Fasteners PREVAILING-TORQUE SCREWS titute of Cleveland, OH 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 or the user of the product, and the IF1 is not
14、 responsible for any loss, claim, or damage arising therefrom. In formulating and approving standards and specifications, the IF1 has not investigated and will not investigate patents which may apply to the subject matter. Prospective users of the standards and specifications are responsible for adv
15、ising themselves of and protecting themselves against any patent infringement liability which may arise out of such use. O INDUSTRIAL FASTENERS INSTITUTE 1996 Copyright Industrial Fastener Institute Provided by IHS under license with IFILicensee=IHS Employees/1111111001, User=Wing, Bernie Not for Re
16、sale, 06/12/2007 02:48:22 MDTNo reproduction or networking permitted without license from IHS -,-,- INDUSTRIAL FASTENERS INSTITUTE 1717 East 9th St., Suite 11 05 Cleveland, Ohio 441 14 USA Clamp Load (1) Nom kN Screw Size and Thread Pitch Property Class of Screw 8.8 9.8 10.9 12.9 M1.6 x 0.35 _ 0.6 -
17、 0.9 M2 x 0.4 -_ 1 .o -_- 1.5 M2.5 x 0.45 -_ 1.6 _- 2.5 M3 x 0.5 - 2.4 _- 3.7 M3.5 x 0.6 _ 3.3 _-_ 4.9 M4 x 0.7 _-_ 4.3 _ 6.4 M5 x 0.8 _-_ 6.9 8.8 10 M6 x 1 _-_ 9.8 12 15 M8 x 1.25 _ 18 23 27 M10 x 1.5 - 28 36 42 M12 x 1.75 - 41 52 61 M14 x 2 _ 56 72 84 M16 x 2 -_- 76 98 110 M20 X 2.5 110 - 150 180
18、M24 x 3 160 _-_ 220 260 M30 x 3.5 250 - 350 41 O M36 x 4 370 _- 51 O 590 Table 1 - Prevailing Torques for Nonmetallic Resistant Element Screws First Removal Prevailing Torque Prevailing Torque max min Nam N .m 0.10 0.01 0.20 0.02 0.40 0.05 0.60 0.14 0.90 0.22 1.2 0.26 2.3 0.36 3.0 0.45 10 0.90 14 1.
19、8 21 2.6 30 3.6 40 5.0 60 8 .O 90 13 120 19 150 28 Fifth Removal Prevailing Torque - I 0.004 0.03 0.01 1 0.23 0.30 I 0.58 7 1 5.5 8.5 13 18 l.2 Threads. l.2.1 Thread Tolerances. Threads of REPT screws hall be tolerance class 6g as specified in ASME 11.13M, except that the portion of the threaded mgt
20、h containing the nonmetallic element need not onform. If tolerancing differs, see “Scope“ paragraph 1.2.2 Thread Start. REPT screws, except those :overed in 3.3.2, shall assemble a minimum of one full Jrn by the fingers into any mating internally threaded :omponent that has threads acceptable to Gag
21、ing jystem 21 of ASME B1.3M. 1 . 3 Performance 3.3.1 The prevailing torque of REPT screws occurring during any installation or removal shall not exceed the maximum prevailing torque specified in Table 1 when tested as specified in 4.1. In addition, the highest prevailing torques developed by REPT sc
22、rews during first and fifth removal shall not be less than the minimum first and fifth removal torques, respectively, specified in Table 1 when tested in accordance with 4.1. In addition, the lowest prevailing torque developed by REPT screws during the fifth removal shall not be zero, when tested in
23、 accordance with 4.1. 3.3.2 REPT screws which are too short or which have thread lengths too short to permit testing in accordance with 4.1 shall have their prevailing-torque requirements and test procedure established by agreement between the purchaser and manufacturer. lF1-524 Issued: 1982 Revised
24、: October 1996 TEST PROCEDURE FOR THE PERFORMANCE OF METRIC NONMETALLIC RESISTANT ELEMENT ished and issued by Industrial Fasteners PREVAILING-TORQUE SCREWS tute of Cleveland, OH All standards and specifications are advisory only. Their use by anyone is entirely voluntary. Reliance thereon for any pu
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