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  Maryland Metrics: Introduction to torque control

Click for µ = 0,10 Tightening torques for phosphated or zinc plated fasteners with thorough lubrication
Click for µ = 0,15 Tightening torques for black or zinc plated fasteners with minimal lubrication


= 0.20
Tightening torques for coated or bright fasteners fitted dry
( = average frictional coefficient)


ISO 272 Strength classes for steel bolts per ISO 898-1
diameter
pitch
wrench
Ø mm ISO mm mm Cs Fo Cs Fo Cs Fo Cs Fo Cs Fo Cs Fo Cs Fo
1,6** 0,35 3,2 0,086 210 0,12 294 0,137 335 0,183 447 0,206 503 0,269 657 0,315 769
2** 0,4 4 0,183 349 0,256 488 0,293 558 0,39 744 0,439 837 0,573 1 093 0,671 1 279
2,5** 0,45 5 0,383 582 0,536 815 0,612 931 0,816 1 242 0,918 1 397 1,2 1 824 1,4 2 134
3 0,5 5,5 0,66 874 0,92 1 224 1,06 1 399 1,41 1 866 1,6 2 099 2,07 2 740 2,43 3 207
4 0,7 7 1,51 1 514 2,11 2 120 2,42 2 422 3,22 3 230 3,66 3 635 4,74 4 744 5,5 5 552
5 0,8 8 3 2 481 4,2 3 473 4,81 3 970 6,4 5 293 7,27 5 958 9,4 7 774 11 9 098
6 1 10 5,2 3 498 7,2 4 893 8,3 5 598 11,1 7 464 12,57 8 392 16,3 10 962 19,1 12 828
8 1,25 13 12,6 6 426 17,7 8 997 20 10 283 27 13 710 30,62 15 423 39 20 137 46 23 565
10 1,5 16 25 10 238 35 14 334 40 16 382 53 21 843 61 24 575 78 32 082 92 37 542
12 1,75 18 43 14 934 60 20 908 69 23 895 92 31 860 105 35 849 136 46 795 159 54 760
14 2 21 69 20 514 97 28 719 111 32 822 148 43 763 167 49 142 218 64 277 255 75 218
16 2 24 108 28 280 152 39 592 174 45 248 232 60 331 262 67 944 341 88 611 399 103 694
18 2,5 27 149 34 324 209 48 054 239 54 919 330 75 421     469 107 549 549 125 856
20 2,5 30 213 44 188 298 61 863 341 70 700 471 97 253     667 138 456 781 162 023
22 2,5 34 293 55 298 411 77 418 470 88 478 648 121 574     920 173 269 1 077 202 762
24 3 36 366 63 630 513 89 083 586 101 809 809 140 084     1 148 199 376 1 343 233 313
27 3 41 544 83 910 762 117 474 871 134 257 1 201 184 517     1 706 262 920 1 997 307 672
30 3,5 46 737 101 914 1 032 142 679 1 180 163 062 1 628 224 292     2 311 319 331 2 704 373 685
33 3,5 50 1 004 127 210 1 406 178 094 1 607 203 536 2 216 279 953     3 148 398 593 3 684 466 438
36 4 55 1 288 149 174 1 803 208 844 2 060 238 679 2 840 328 236     4 036 467 413 4 723 546 973
39 4 60 1 677 179 487 2 348 251 282 2 683 287 179 3 697 394 919     5 255 562 393 6 150 658 119
42** 4,5 65 2 070 205 323 2 898 287 452 3 312 328 516 4 554 451 710     6 486 643 344 7 590 752 849
45** 4,5 70 2 596 240 641 3 635 336 897 4 154 385 025 5 712 529 410     8 136 754 008 9 520 882 350
48** 5 75 3 130 270 321 4 383 378 449 5 009 432 514 6 887 594 706     9 809 847 006 11 478 991 177
52** 5 80 4 041 324 763 5 657 454 668 6 465 519 620 8 889 714 478     12 661 1 017 590 14 816 1 190 797
56** 5,5 85 5 034 374 739 7 048 524 635 8 054 599 582 11 075 824 426     15 773 1 174 182 18 458 1 374 043
60** 5,5 90 6 266 438 337 8 772 613 672 10 026 701 340 13 785 964 342     19 634 1 373 457 22 976 1 607 237
64** 6 95 7 533 495 676 10 546 693 947 12 052 793 082 16 572 1 090 488     23 603 1 553 119 27 620 1 817 480

*Class 8-8a up to Ø 16 mm, 8-8b for Ø 18 mm and above. ** Values per Fr. Std. E 25-030.

Tensile load (Fo)
The force in newtons (N) which maintains pressure contact between assembled components.

Tightening torque (Cs) [ values are in N·m ]
The product of a force and the leverage length at which it is applied: Torque (N·m) = Force (in newtons) x Length (in metres).

Note: per european conventional usage; the comma ( , ) is used as the decimal point ( . ) in these charts

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