1 Scope
This standard specifies the measuring method for friction coefficient of screw thread pair of automobiles.
This standard is applicable to measure the friction coefficient of bolt-nut screw thread pair of automobiles by using special automatic operation test devices.
2 Normative references
The following normative documents contain provisions which, through reference in this text, constitute provisions of this standard. For dated references, subsequent amendments (excluding corrections), or revisions, of any of these publications do not apply to this standard. However, parties to agreements based on this standard are encouraged to investigate the possibility of applying the most recent editions of the normative documents indicated below. For undated references, the latest edition applies.
GB/T 16823.3 Method of tightening test for threaded fasteners (eqv JIS B1084: 1987)
3 Test conditions
3.1 The surface of the test piece shall be clean and free of lubricating medium, and each test piece can only be used once. The standard backing plate for test can be reused only after being processed to meet the requirements of clause 5.
3.2 Bolts matched with test piece nuts and nuts matched with test piece bolts shall not have surface coating, and the surface shall be clean and free of lubricating medium.
3.3 The ambient temperature of test: 23℃±5℃.
3.4 The ambient humidity of test: 65％±10％.
3.5 The screw engagement length of steel nuts shall be greater than or equal to the nominal diameter of thread + pitch.
Foreword i
1 Scope １
2 Normative references １
3 Test conditions １
4 Test devices ２
5 Standard backing plate for test ２
6 Measuring method for friction coefficient ２
7 Test results ２
