1、 WORLDWIDE FASTENER STANDARD Date: 2002-06-11 WZ 101 Steel Metric Threaded Fasteners Torque/Clamping Force Performance Printed copies are uncontrolled. Page 1 of 8 1. SCOPE This Worldwide Standard provides two test programs for determining the torque/clamping force performance of lubricated finishes
2、 on ISO Metric coarse threaded steel fasteners tested at room temperature as specified in ISO 1. (a) With thread sizes M3 to M24 inclusive. (b) With strength requirements in accordance with WA 950 or WE 952. (c) With dimensions as specified in the Worldwide Product Standards. Substance restrictions
3、imposed by law, regulations or Ford apply to the materials addressed by this document. The restrictions are defined in Engineering Material Specification WSS-M99P9999-A1. NOTE: Set screws and similar threaded fasteners not under tensile stresses, screws that form a mating thread, and threaded fasten
4、ers having additional self locking features are excluded from the provisions of this specification. 2. PURPOSE To establish a referee test method for determining the torque/clamping force performance of fastener finishes consisting of either a surface-applied lubricant or an integral lubricant on IS
5、O metric coarse threaded steel fasteners. There are two basic test programs. 2.1 SPECIFIC FASTENER/FINISH (TEST PROGRAM A) - To test the torque/clamping force performance of a specified fastener/finish combination under uniform test conditions. This test may be used where it is necessary to control
6、the frictional properties of both the fastener and the finish. 2.2 PROCESS CONTROL OF FINISH (TEST PROGRAM B) - To test the torque/clamping force performance of a specified finish under uniform test conditions. This test program may be used as a process control tool of the frictional performance of
7、the finish. The results obtained by these tests are relevant to the test conditions only and should not be utilized for determining the torque specification of specific applications. 3. REFERENCES ISO 1 - Standard Reference Temperature for Industrial Length Measurement. ISO 1302 - Technical Drawing
8、- Method of Indicating Surface Texture on Drawings. ISO 965/1 - General Purpose Metric Screw Threads - Tolerances - Part 1: Principles and Basic Data. ASTM A 109/109M - Standard Specifications for Steel, Strip, Carbon, Cold-Rolled. WA 900 - Dimensional Requirements for Hexagon and Flanged Hexagon Bo
9、lts and Screws, and Hexagon Screw and Washer Assemblies WA 950 - Material Requirements and Mechanical Properties of Bolts, Screws, Studs and Screw and Washer Assemblies. WE 950 - Prevailing Torque-Type Steel Hexagon Nuts and Hexagon Flange Nuts -Mechanical and Performance Properties. WE 952 - Mechan
10、ical Properties of Nuts with Specified Proof Load Values. WX 100 - Finish Specifications. WSD-M13P7-A - Torque/Clamping Force Control WSS-M99P9999-A - Substance Restrictions WORLDWIDE FASTENER STANDARD Date: 2002-06-11 WZ 101 Steel Metric Threaded Fasteners Torque/Clamping Force Performance Printed
11、copies are uncontrolled. Page 2 of 8 4. DEFINITIONS 4.1 CLAMPING FORCE, F - The clamping force is the axial tension acting on the bolt shank or the compression applied by the bearing face of the fastener on the clamped members after application of a specified tightening torque. 4.2 TIGHTENING TORQUE
12、, T - The tightening torque is the overall applied torque to the fastener during tightening. It is commonly called the wrenching torque or applied torque. 4.3 TORQUE COEFFICIENT, K - The torque coefficient is determined from the torque/clamp force relation using the following formula: K = T/(Fd) whe
13、re d is the nominal thread diameter 4.4 COEFFICIENT OF TOTAL FRICTION, tot- The coefficient of total friction is determined from the tightening torque/clamp force ratio using the following formula: (T/F) (P/2) tot= 0.578d2 + 0.5DbDo+ dhwhere P is the thread pitch, d2is the basic pitch diameter and D
14、b= 2 where Do is the outer bearing diameter and dhis the nominal clearance hole diameter The formula for the coefficient of total friction is based upon the assumption that the coefficient of friction between the threads and between the bearing surfaces are equivalent. 5. TORQUE/CLAMPING FORCE CONTR
15、OL LUBRICANTS 5.1 SURFACE-APPLIED LUBRICANTS Unless otherwise specified, surface-applied lubricants shall be in accordance with the requirements of WSD-M13P7-A and shall meet the torque/clamping force requirements specified in Table 1. 5.2 INTEGRAL LUBRICANTS Integral lubricants shall meet the torqu
16、e/clamping force requirements outlined in the individual material/performance standards or those specified on the engineering drawing. 6. TORQUE/CLAMPING FORCE PERFORMANCE REQUIREMENTS 6.1 SPECIFIC FASTENER/FINISH (TEST PROGRAM A) To determine the torque/clamping force performance of a specific fast
17、ener/finish combination, the torque/clamping force test shall be conducted at room temperature (See ISO 1) using the test equipment specified in Clause 7, the appropriate test material specified in Clause 8, and the test procedure specified in Clause 9. WORLDWIDE FASTENER STANDARD Date: 2002-06-11 W
18、Z 101 Steel Metric Threaded Fasteners Torque/Clamping Force Performance Printed copies are uncontrolled. Page 3 of 8 6.2 PROCESS CONTROL OF FINISH (TEST PROGRAM B) To determine the torque/clamping force performance of a specific finish process, the torque/clamping force test shall be conducted at ro
19、om temperature (See ISO 1) using the test equipment specified in Clause 7, a surrogate bolt as specified in Clause 8.4, the appropriate test nut and test plate specified in Clause 8, and the test procedure specified in Clause 9. 7. TEST EQUIPMENT 7.1 TORQUE MEASURING DEVICE The torque measuring devi
20、ce shall be a strain gage torque transducer. The accuracy of the torque measurement shall be within 2.0% of the torque being read. 7.2 CLAMPING FORCE MEASURING DEVICE The force measuring device shall be a tension test fixture with a strain gage load cell. The accuracy of load measurement shall be wi
21、thin 2.0% of the load being read. The bolt clearance hole in the backing plate shall be the same diameter and tolerance as the test plate. The face against which the test plate bears shall be smooth, flat within 0.1/100 and square with the axis of the test bolt within a tolerance of 0.1/100. The axi
22、s of the test bolt and test plate must be aligned so as to avoid contact between the fillet radius of the bolt and the hole in the test plate. 7.3 DATA COLLECTION DEVICE The data collection device shall have the capability to simultaneously record torque and tension. The sampling rate and frequency
23、response of the recording system shall be such that, at the test speeds (RPM) specified in Clause 7.4, the measurements of torque and load shall meet the accuracies specified in Clauses 7.1 and 7.2. 7.4 DRIVE TOOL The drive tool shall be capable of producing torques greater than the requirements of
24、the parts to be tested and must be able to maintain a continuous speed for the duration of the test. Unless otherwise specified, the initial tightening speed shall be 30 10 RPM for sizes M3 to M16 and 10 5.0 RPM for sizes greater than M16. Sockets shall not be allowed to contact the test plate durin
25、g the rundown. WORLDWIDE FASTENER STANDARD Date: 2002-06-11 WZ 101 Steel Metric Threaded Fasteners Torque/Clamping Force Performance Printed copies are uncontrolled. Page 4 of 8 8. TEST MATERIAL 8.1 TEST BOLT FOR NUT TESTING Test bolts shall correspond in size and property class to the nut to be tes
26、ted. The bolts shall conform to the general requirements of ISO 4014 with the exception of the across flats dimension and heat treated in accordance with ISO 898/1. Decarburization of the threads shall be within the limits defined in ISO 898/1, Class 3/4 H. Bolts shall be uncoated, clean, dry, and l
27、ubricant free. Threads shall be in accordance with ISO 965/1 with a Tolerance Class of 6g. Threads on all test bolts shall be produced by rolling. The thread surface shall be free of burrs or other contamination that might affect an accurate determination of the performance of the nut. The bolt leng
28、th shall be such that a minimum of two full form threads protrude through the nut when the nut is fully seated against the test plate. The thread length shall be such that a minimum of two full form threads are exposed within the grip length after the nut is fully seated. Refer to Figure 1. A new te
29、st bolt and test plate shall be used for testing each nut. 8.2 TEST NUT FOR BOLT TESTING Test nuts shall correspond in size and property class to the bolt to be tested. The nuts shall conform to the general requirements of ISO 4032 with the exception of the across flats dimension and heat treated in
30、 accordance with ISO 898/2. Nuts shall be uncoated, clean, dry, and lubricant free. Threads shall be in accordance with ISO 965/1 with a Tolerance Class of 6H. Threads on all test nuts shall be produced by tapping. The thread surface shall be free of burrs or other contamination that might affect an
31、 accurate determination of the performance of the bolt. A new test nut and test plate shall be used for testing each screw. 8.3 TEST PLATE Test plates shall conform to the dimensional, metallurgical, mechanical and finish requirements given in Table 2. Test plates must be designed such that when ass
32、embled into the test equipment, rotation of the plate is prevented during tightening of the nut or bolt. Any device used to prevent rotation shall not intrude into a diameter equal to the maximum bearing face diameter of the nuts or bolts to be tested. Alternatively, multi-hole test strips may be us
33、ed provided the above requirements are satisfied. A new test plate shall be used for each test sample.WORLDWIDE FASTENER STANDARD Date: 2002-06-11 WZ 101 Steel Metric Threaded Fasteners Torque/Clamping Force Performance Printed copies are uncontrolled. Page 5 of 8 8.4 SURROGATE BOLT Surrogate bolts
34、shall be of M10 X 1.5 size and of property Class 8.8. The bolts shall conform to the general requirements of ISO 4014 with the exception of the across flats dimension and heat treated in accordance with ISO 898/1. Decarburization of the threads shall be within the limits defined in ISO 898/1, Class
35、3/4 H. The finish to be evaluated shall be uniformly applied using normal production processes and equipment and shall meet all requirements of the individual finish specification. Threads shall be in accordance with ISO 965/1 within a Tolerance Class of 6h . The threads may be undersized to allow f
36、or the thickness of the coating, but shall not be undersized below the 6e Tolerance Class. Threads on all test bolts shall be produced by rolling. The thread surface shall be free of burrs or other contamination that might affect an accurate determination of the torque/clamping force performance of
37、the finish. The bolt length shall be such that a minimum of two full form threads protrude through the nut when the bolt is fully seated against the test plate. The thread length shall be such that a minimum of two full form threads are exposed within the grip length after the bolt is fully seated.
38、Refer to Figure 1. A new test nut and test plate shall be used for testing each bolt. 9.0 TEST PROCEDURE Loosely assemble by hand the test sample, the appropriate mating test part and the test plate into the test fixture. The parts are to be installed such that the test sample can be driven by the d
39、rive tool and its bearing surface rotates against the punch entry side of test plate. The test plate must be prevented from turning during the rundown. Adjust the grip length of the test fixture such that when the parts are fully seated, the screw protrudes a minimum of two full form threads through
40、 the nut. A suitable fixture is shown in Figure 1. Set the power tool to shut off at a torque 2.0 to 5.0% greater than the maximum torque at clamp value (typically the clamp value is 75% of the proof load for the externally threaded fastener) allowed for the test sample. Alternatively the tool may b
41、e set to shut off on a tension value approximately 1.0% greater than the clamp value. This method is preferred if this test is performed in conjunction with prevailing torque testing. Tighten the joint by driving the test sample with the power tool at the appropriate speed for the sample being teste
42、d. Both torque and tension are to be recorded during the rundown. WORLDWIDE FASTENER STANDARD Date: 2002-06-11 WZ 101 Steel Metric Threaded Fasteners Torque/Clamping Force Performance Printed copies are uncontrolled. Page 6 of 8 10. DATA ANALYSIS 10.1 SAMPLE SIZE The sample size shall be as specifie
43、d or as agreed to between manufacturer and purchaser. 10.2 TEST RESULTS The torque shall be statistically analyzed to produce mean and 3 sigma limits at the specified tension. The torque necessary to develop the specified tension shall meet the applied torque requirements specified in Table 1 or the
44、 individual finish specification. Table 1 - Test Requirements Clamping Force, kN Applied Torque, Nm Hexagon Hexagon Flange Property Class 8.8/8 10.9/10 8.8/8 10.9/10 Nom. Dia. 8.8/8 10.9/10 Mean Mean Mean Mean M3 M4 M5 M6 M8 2.2 3.8 6.2 8.7 15.9 3.1 5.5 8.9 12.9 22.8 2.9 5.7 9.8 23.8 0.5 1.1 1.9 4.5
45、 4.2 8.3 14.6 34.2 0.8 1.5 2.7 6.3 6.3 10.7 25.8 1.2 2.0 4.8 9.0 15.9 37.0 1.7 3.0 6.9 M10 M12 M14 M16 M18 25.3 36.7 50.0 68.2 86.2 36.1 52.5 71.6 97.5 119 46.3 80.8 127.7 196.5 8.7 15.1 24 37.4 66.1 115.6 182.9 280.9 12.3 21.6 34.3 54.2 50.9 88.9 140.9 218 9.7 16.9 26.7 42 72.7 127.2 201.7 311.6 13
46、.7 24.1 38.4 60.1 M20 M22 M24 110 136 159 152 189 220 396.6 684.4 75.6 130.4 548.1 947.0 104.4 180.4 NOTES: 1. The Clamping Forces specified are equal to 75% of the Proof Load of the Property Classes of bolts as specified in WA 950. 2. The Applied Torque values are based upon a totvalue of 0.14 0.03
47、. 3. Where values of Applied Torque are not provided, the equation for totin Clause 4.4 shall be used to calculate the applied torque for the specific part geometries to be tested. 4. The Applied Torques may not be suitable for assembly torques. 5. For surrogate bolt testing, 3-sigma limits must mee
48、t the range specified. WORLDWIDE FASTENER STANDARD Date: 2002-06-11 WZ 101 Steel Metric Threaded Fasteners Torque/Clamping Force Performance Printed copies are uncontrolled. Page 7 of 8 Table 2 - Test plates Nominal Diameter of Test Bolt Hole Diameter dh Maximum Minimum Width w Minimum Thickness s M
49、inimum M3 M4 M5 M6 M8 3.58 4.68 5.68 6.82 9.22 3.4 4.5 5.5 6.6 9 7.9 10.2 11.6 16.4 19.4 0.45 0.7 0.9 1.4 1.4 M10 M12 M14 M16 M18 11.27 13.77 15.77 17.77 20.33 11 13.5 15.5 17.5 20 22.4 29.0 32.1 35.8 1.8 2.3 2.3 2.7 2.7 M20 M22 M24 22.33 24.33 26.33 22 24 26 42.3 55.2 2.7 2.7 3.7 NOTES: 1. All dimensions are in millimeters 2. Material shall be cold rolled carbon steel strip to ASTM A 109/109M, temper No. 1 hard except hardness to be 200 to 250 HV. 3. Both faces of the test plate shall be uncoated, clean, dry and lubricant free unless
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