Machinery's Handbook, 31st Edition
HELICAL COIL SCREW THREAD INSERTS 1755 Torque Test Method: The torque test shall consist of a 15-cycle, room temperature test. A new bolt or screw and new tapped hole shall be used for each complete 15-cycle test For each of the 15 cycles, bolts shall be assembled and seated to the assembly torque specified in Table 5. Bolts shall be completely disengaged from the locking coils of the insert at the end of each cycle. The test shall be run at less than 40 rpm to yield a dependable measure of torque and avoid heating of the bolt. Maximum Locking Torque: Maximum locking torque shall be the highest torque value encountered on any installation or removal cycle and shall not exceed the values specified in Table 5 . Maximum locking torque readings shall be taken on the first and seventh instal lation cycles before the assembly torque is applied and on the 15th removal cycle. Table 5. Self-Locking Torque ANSI/ASME B18.29.2M-2005 (R2017)
Maximum Locking Torque Installation or Removal, N-m
Maximum Locking Torque Installation or Removal, N-m
Minimum Breakaway Torque, N-m
Minimum Breakaway Torque, N-m
Nominal Thread Size M18 × 1.5 M18 × 2 M18 × 2.5 M20 × 1.5 M20 × 2 M20 × 2.5 M22 × 1.5 M22 × 2 M22 × 2.5 M24 × 2 M24 × 3 M27 × 2 M27 × 3 M30 × 2 M30 × 3 M30 × 3.5 M33 × 2 M33 × 3 M36 × 2 M36 × 3
Nominal Thread Size
42 42 42 54 54 54 70 70 70 80 80 95
5.5 5.5 5.5
0.12 0.22 0.44 0.68
0.03 0.06 0.1 0.12 0.16 0.3 0.4 0.6
M2 × 0.4 M2.5 × 0.45 M3 × 0.5 M3.5 × 0.6 M4 × 0.7 M5 × 0.8 M6 × 1 M7 × 1 M8 × 1 M8 × 1.25 M10 × 1 M10 × 1.25 M10 × 1.5 M12 × 1.25 M12 × 1.5 M12 × 1.75 M14 × 1.5 M14 × 2 M16 × 1.5 M16 × 2
7 7 7 9 9 9
0.9 1.6 4.4 3 6 6
0.8 0.8 1.4 1.4 1.4 2.2 2.2 2.2
11 11 12 12 14 14 14 16 16 18 18 18 20
10 10 10 15 15 15 23 23 32 32
95 110 110 110 125 125 140 140 140 150 150
3 3
4.2 4.2
… … …
… … …
… M36 × 4 … M39 × 2 … M39 × 3
20 Minimum Breakaway Torque: Minimum breakaway torque shall be the torque required to overcome static friction when 100 percent of the locking feature is engaged and the bolt or screw is not seated (no axial load). It shall be recorded at the start of the 15th removal cycle. The torque value for any cycle shall be not less than the applicable value shown in Table 5. Acceptance: The inserts shall be considered to have failed if, at the completion of any of the tests and inspection, any of the following conditions exist: a) any break or crack in the insert b) installation or removal torque exceeds the maximum locking torque value in Table 5 c) breakaway torque less than the values in Table 5 d) movement of the insert beyond 90 ° relative to the top surface when installing or removing the test bolt e) seizure or galling of the insert or test bolt f) tang not broken off, which interferes with the test bolt at installation g) tang breaks off during insert installation
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