1、 WORLDWIDE FASTENER STANDARDWA 970 Date: 2010 07 20 Printed copies are uncontrolled Copyright 2010, Ford Global Technologies, LLC Page 1 of 4 Performance Requirements for Bolts with Plastic Prevailing Torque Feature 1. SCOPE: This specification gives the prevailing torque performance requirements fo
2、r bolts with a plastic prevailing torque feature incorporated in the threads. The prevailing torque feature on bolts covered by this specification will be adversely affected by temperatures above 120oC or below -50oC. 1.1 REFERENCE. ISO 1 Standard reference temperature for industrial length measurem
3、ent. WSD-M13P7-A Lubricant-torque/clamping force control. 2. GENERAL: All performance requirements apply to the finished product as received by Ford (i.e., after the application of any specified protective finish). Any protective coating applied to bolts may be affected by the heating process used t
4、o bond the plastic prevailing torque feature. This is considered acceptable only if the effect on the corrosion resistance and color is confined to the threads. The lubrication for torque/clamping force control must not be affected by the bonding process. The patched portion of the thread shall be a
5、ble to pass through a hole in a test plate of thickness not less than 6 pitches. The hole diameter shall be in accordance with ISO 273 Fine series. 3. MATERIAL, DIMENSIONS AND POSITION: 3.1 MATERIAL: The material of the feature and the method by which it is incorporated in the bolt is optional provi
6、ded that all the requirements of this specification are met. 3.2 DIMENSIONS AND POSITION: The dimensions of the feature shall be as specified in Figure 1. The position of the feature shall be as specified in the Ford utility part drawing. Figure 1. No prevailing torque feature material permitted in
7、areas marked * WORLDWIDE FASTENER STANDARDWA 970 Date: 2010 07 20 Printed copies are uncontrolled Copyright 2010, Ford Global Technologies, LLC Page 2 of 4 4. PERFORMANCE REQUIREMENTS 4.1 TORQUE/CLAMPING FORCE: The torque/clamping force requirements of products required to meet this specification sh
8、all be in accordance with WZ 101. 4.2 PREVAILING TORQUE PERFORMANCE: The prevailing torque test shall be conducted at room temperature as specified in ISO 1. All prevailing torque measurements shall be taken with the bolt in motion and with the full length of the prevailing torque feature in contact
9、 with the test nut thread. Using a suitable test spacer or spacers (see Clause 4.2.2) assemble the sample bolt in the test nut (see Clause 4.2.3). The bolt shall be advanced in the nut until all prevailing torque feature threads are in full contact with the test nut thread. The highest torque occurr
10、ing while the bolt is being advanced through the next 360 of rotation shall be measured. For the bolt to be acceptable this torque shall not exceed the maximum prevailing torque value as specified for the applicable bolt in Table 1. Tightening shall be continued until the bolt is seated against the
11、test spacer and the tightening clamp force in Table 1 is achieved. The thickness of the test nut shall be such that seating of the bolt occurs when the feature is still fully in contact with the test nut thread. The test spacer shall be prevented from turning during bolt tightening. The bolt shall t
12、hen be slackened by the application of reverse torque until the tensile load has been reduced to zero. The highest torque occurring while the bolt is being removed through the next 360 of rotation shall be measured. For the bolt to be acceptable, this torque shall not be less than the first removal
13、prevailing torque specified for the applicable bolt in Table 1 nor greater than the maximum prevailing torque. After the first removal prevailing torque has been measured, the bolt shall be backed off until the feature is disengaged from the nut thread. The bolt shall then be reassembled to the spec
14、ified tightening clamp force and removed two more times. On each removal, the feature shall be disengaged from the nut thread. During the third removal, the highest torque occurring while the bolt is being removed through the first 360 of rotation shall be measured. For the bolt to be acceptable, th
15、is torque shall be not less than the third removal prevailing torque value as specified in Table 1. In addition, at no time during these two subsequent tightening and slackening shall the torque exceed the maximum prevailing torque value specified in Table 1. To avoid overheating of the test assembl
16、y, sufficient time shall elapse between the torque application cycles. Speed of installation and removal of the nut shall not exceed 30 rpm. and shall be continuous and uniform. The test spacer shall be cleaned and examined for compliance with the requirements of Clause 4.2.2 for each new sample bol
17、t. 4.2.1 TORQUE MEASURING DEVICE: The torque measuring device (torque wrench or power device) shall be accurate to 2% of the maximum specified torque range of the device. For referee purposes, the measuring device shall be chosen so that all readings fall within the upper half of its torque range. W
18、ORLDWIDE FASTENER STANDARDWA 970 Date: 2010 07 20 Printed copies are uncontrolled Copyright 2010, Ford Global Technologies, LLC Page 3 of 4 4.2.2 TEST SPACERS: Test spacers shall be made from carbon steel quenched and tempered to a surface hardness of 500-600HV and a core hardness of 450-490HV and s
19、hall be unplated. The inside diameter shall be in accordance with Table 2. The faces shall be flat and parallel within a tolerance zone of 4% of the specified minimum thickness. The surface roughness of both abutment faces shall not exceed N8 to ISO 1302. 4.2.3 TEST NUT: The test nut shall be proper
20、ty class 10 (ISO 898/2) or made from steel hardened to 450HV minimum at the surface. The test nut shall have sufficient thread to ensure that the feature engagement requirements specified in Clause 4.2 are achieved. Threads shall have a 6H tolerance class. Test nuts shall not be plated or lubricated
21、. NOTE: The test nut shall not be re-used. Table 1 - Performance Requirements Tightening Clamp Force 4.8 8.8 and 10.9 kN Maximum Minimum P/T Maximum Minimum P/T 4.8 8.8 10.9 P/T Removal P/T Removal Nominal (Property Class) 1st 3rd 1st 3rd Diameter Nm Nm Nm Nm M4 1.5 3.8 5.5 0.7 0.15 0.1 1.2 0.15 0.1
22、 M5 2.4 6.2 8.9 1.25 0.25 0.15 2.1 0.25 0.15 M6 3.4 8.7 12.9 2.4 0.4 0.25 4 0.4 0.25 M8 6.2 15.9 22.8 4.8 0.7 0.45 8 0.7 0.45 M10 25.3 36.1 14 1.2 0.8 M12 36.7 52.5 21 1.8 1.2 M14 50 71.6 31 2.4 1.6 M16 68.2 97.5 42 3.3 2.2 M18 86.2 119 56 4.4 3 M20 110 152 72 5.7 3.8 M24 159 220 106 9 6 Prevailing
23、torque figures are test requirements and shall not be used as parameters for statistical evaluation. Table 2 - Spacer Dimensions Nominal Size Internal Diameter Spacer Thickness Max Min Min M4 4.9 4.5 2 M5 5.9 5.8 2 M6 7.1 6.9 3 M8 9.5 9.3 4 M10 11.5 11.3 5 M12 14 13.8 6 M14 16 15.8 6 M16 18 17.8 6 M
24、18 20.5 20.3 6 M20 22.7 22.5 6 WORLDWIDE FASTENER STANDARDWA 970 Date: 2010 07 20 Printed copies are uncontrolled Copyright 2010, Ford Global Technologies, LLC Page 4 of 4 M24 26.7 26.5 6 5. SUMMARY OF REVISIONS 2010 07 20 - 2. Deleted references to lubricant usage - 4.1 Deleted Clause 6 reference -
25、 4.2 Revised text and changed fifth off references to third off - 4.2.3 Revised test nut description - Table 1 Revised column heading and Tightening Forces NOVEMBER 2005 - Deleted “The test nut shall be cleaned between tests so as to ensure all prevailing torque feature material and lubricant is removed.”
