Elementi filettati, standardizzazione
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Recommended torque
 
Threaded elements / Recommended torque

When an assembly is made, a torque (Cs) is applied to the screw or bolt and nut system, so that the force (Fo) generates a clamping force on the entire assembly. For a given torque (Cs) applied, the Fo value is dependent on the system’s friction coefficient (µ).

The table here after (extract from the NF E 25-030 standard: Screw or bolt elements – Screwed assemblies – Design, calculation and assembly conditions) shows maximum recommended torque (in accordance with the assembled screw or bolt and nut elements).

Couples de serrage - Forces
  Screw or
bolt Ø
3 4 5 6 8 10 12 14 16
Pitch 0.5 0.7 0.8 1 1.25 1.5 1.75 2 2
Grade µ Dimension
across-flats
5.5 7 8 10 13 16 18 21 21

6.8

Rm = 600 N/mm²
Re = 480 N/mm²

0.10 Cs (Nm) 0.71 1.65 3.25 5.6 13.6 27 46 75 115
Fo (N) 1724 2988 4885 6896 12647 20128 29339 40280 55356
0.15 Cs (Nm) 0.91 2.09 4.14 7.1 17.4 34 59 95 148
Fo (N) 1556 2696 4414 6226 11432 18206 26550 36463 50216
0.20 Cs (Nm) 1.06 2.42 4.81 8.3 20 40 69 111 174
Fo (N) 1399 2422 3970 5598 10283 16382 23895 32822 45248

8.8

Rm = 800 N/mm²
Re = 640 N/mm²

0.10 Cs (Nm) 0.95 2.20 4.34 7.5 18.2 36 62 99 153
Fo (N) 2298 3985 6514 9195 16863 26838 39119 53707 73808
0.15 Cs (Nm) 1.21 2.78 5.5 9.5 23 46 79 127 198
Fo (N) 2075 3594 5836 8302 15242 24275 35401 48618 66955
0.20 Cs (Nm) 1.41 3.22 6.4 11.1 27 53 92 148 232
Fo (N) 1866 3230 5293 7464 13710 21843 31860 43763 60331

10.9

Rm = 1000 N/mm²
Re = 900 N/mm²

0.10 Cs (Nm) 1.40 3.23 6.3 11 26 52 91 145 225
Fo (N) 3376 5853 9568 13506 24768 39418 57457 78882 108406
0.15 Cs (Nm) 1.79 4.09 8.1 14 34 67 116 187 291
Fo (N) 3048 5279 8645 12194 22388 35655 51995 71408 98340
0.20 Cs (Nm) 2.07 4.74 9.4 16.3 39 78 136 218 341
Fo (N) 2740 4744 7774 10962 20137 32082 46795 64277 88611

12.9

Rm = 1200 N/mm²
Re = 1080 N/mm²

0.10 Cs (Nm) 1.64 3.78 7.4 12.6 31 61 106 170 263
Fo (N) 3951 6849 11196 15805 28984 46128 67236 92309 126858
0.15 Cs (Nm) 2.09 4.79 9.5 16.4 40 79 136 219 341
Fo (N) 3567 6178 10116 14269 26198 41724 60845 83563 115079
0.20 Cs (Nm) 2.43 5.5 11 19.1 46 92 159 255 399
Fo (N) 3207 5552 9098 12828 23565 37542 54760 75218 103964

Rm = tensile strength
Re = elastic strength

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