[mech eng.] tightening torques

2000 by Bossard T.035

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Preload andtightening torques

Metric coarse threadMaximum permissible preload and tightening torques forscrews of property classes 3.6–12.9 at 90% utilization of theyield point ReL or Rp0,2

Maximum preload Fv [N] Maximum tightening torque MA [Ncm]

Property class according to ISO 898 / 1 Property class according to ISO 898 / 15.6 5.6

3.6 4.6 4.8 5.8 8.8 10.9 12.9 3.6 4.6 4.8 5.8 8.8 10.9 12.9M 1,6 0,100 185 200 250 330 575 810 970 4,5 5 6,5 8,5 15 21 25 0,026

0,125 175 190 240 310 545 770 920 5 5,5 7,5 9,5 17 24 29 0,0310,140 165 180 230 300 530 745 895 6,5 6 8 10 18 25 30 0,034

M 1,8 0,100 220 230 295 380 680 955 1150 5,5 6 8 10 18,5 26 32 0,0270,125 205 220 280 360 645 905 1090 6,5 7 9,5 11,5 21 30 36 0,0330,140 200 215 275 350 625 880 1050 7 7,5 10 12,5 23 32 38 0,036

M 2 0,100 310 335 420 540 960 1350 1620 9,5 10,5 13,5 17 31 44 52 0,0320,125 295 320 400 520 910 1280 1530 11,5 12 15,5 19 35 50 60 0,0390,140 285 305 385 500 880 1240 1490 12 13 16,5 21,5 38 53 64 0,043

M 2,5 0,100 515 560 700 910 1600 2250 2700 20 21 28 36 63 89 107 0,0400,125 490 530 665 860 1520 2140 2560 23 25 32 39 73 102 123 0,0480,140 475 510 645 830 1470 2070 2480 25 27 34 43 78 109 131 0,053

M 3 0,100 790 855 1070 1390 2440 3430 4120 35 38 49 63 111 157 188 0,0460,125 770 815 1020 1320 2320 3270 3920 42 44 56 72 128 180 215 0,0550,140 730 785 985 1280 2250 3170 3800 44 47 60 78 137 192 230 0,061

M 3,5 0,100 1050 1140 1430 1850 3270 4600 5520 54 59 75 96 171 240 290 0,0520,125 1000 1080 1360 1760 3120 4380 5260 63 68 86 110 196 275 330 0,0630,140 970 1050 1320 1710 3020 4250 5100 67 73 92 119 210 295 395 0,070

M 4 0,100 1370 1480 1850 2400 4230 5950 7140 82 88 112 144 255 360 430 0,0600,125 1300 1400 1760 2280 4020 5660 6790 94 102 128 166 290 410 495 0,0730,140 1260 1360 1710 2220 3900 5480 6580 100 108 137 177 310 440 525 0,080

M 5 0,100 2250 2410 3020 3920 6910 9720 11650 160 170 220 280 500 705 845 0,0720,125 2140 2300 2880 3740 6580 9260 11100 180 200 250 320 575 810 970 0,0870,140 2000 2230 2790 3620 6380 8980 10800 190 210 270 340 615 865 1040 0,096

Maximum tightening torque MA [Nm]M 6 0,100 3200 3400 4270 5550 9760 13700 16450 2,8 3 3,8 4,8 8,6 12 14,5 0,00087

0,125 3050 3240 4060 5270 9290 13050 15650 3,2 3,4 4,3 5,6 9,9 14 16,5 0,001060,140 2960 3150 3940 5120 9010 12650 15200 3,5 3,7 4,6 6 10,5 15 18 0,00117

M 8 0,100 5870 6260 7830 10170 17900 25200 30200 6,8 7,2 9,1 11,7 21 29 35 0,001150,125 5590 5960 7460 9690 17050 24000 28800 7,9 8,3 10,5 13,6 24 34 40 0,001400,140 5420 5780 7230 9390 16550 23200 27900 8,4 8,9 11 14,5 26 36 43 0,00155

M 10 0,100 9350 9960 12450 16180 28500 40100 48100 13,5 14,4 18 23,4 42 58 70 0,001450,125 8900 9480 11850 15400 27100 38200 45800 15,5 16,6 21 27 48 67 81 0,001750,140 8640 9200 11500 14900 26300 37000 44400 17 18 22 29 51 72 87 0,00195

M 12 0,100 13600 14520 18150 23500 41500 58400 70000 24 25 31 41 72 101 121 0,001750,125 13000 13840 17300 22400 39600 55600 66800 27 29 36 47 83 117 140 0,002100,140 12600 13400 16800 21800 38400 54000 64800 29 31 39 50 89 125 150 0,00230

M 14 0,100 18700 19900 24900 32300 57000 80100 96200 37 40 50 47 114 160 193 0,002000,125 17800 19000 23800 30900 54300 76400 91700 43 46 58 74 132 185 220 0,002400,140 17300 18400 23100 30000 52700 74100 89000 46 50 62 81 141 198 240 0,00270

M 16 0,100 25700 27400 34300 44500 78300 110000 132000 57 60 76 98 174 245 295 0,002200,125 24500 26100 32700 42500 74700 105000 126000 66 70 88 115 200 285 340 0,002700,140 23800 25300 31700 41200 72600 102000 122500 71 76 95 124 215 305 365 0,00300

M 18 0,100 31300 33300 41700 54200 95300 134000 161000 79 83 105 135 240 340 405 0,002500,125 29800 31700 39700 51600 90900 128000 153500 91 95 121 155 275 390 470 0,003000,140 28900 30800 38600 50100 88200 124000 149000 97 105 130 171 295 420 500 0,00340

M 20 0,100 40200 42800 53500 69500 122500 172000 206000 111 120 148 195 340 475 570 0,002800,125 38300 40800 51100 66400 117000 164000 197000 128 135 170 219 390 550 660 0,003300,140 37200 39600 49600 66400 113500 159000 191500 138 146 184 238 420 590 710 0,00370

M 22 0,100 50100 53400 66800 86800 153000 215000 258000 149 160 199 260 455 640 765 0,003000,125 47900 51000 63800 82900 146000 205000 246000 173 183 230 298 530 745 890 0,003600,140 46500 49600 62000 80600 142000 199500 239500 186 198 250 322 570 800 960 0,00400

M 24 0,100 57800 61600 77100 100200 176000 248000 297000 191 203 255 330 580 820 980 0,003300,125 55200 58800 73600 95680 168000 236000 284000 220 235 295 382 675 950 1140 0,004000,140 53600 57100 71400 92800 163500 230000 276500 235 251 315 408 725 1020 1220 0,00440

M 27 0,100 76000 81200 101500 131900 232000 326000 391000 280 300 375 488 855 1210 1450 0,003700,125 72600 77400 96800 125800 221000 311000 374000 325 348 435 566 995 1400 1680 0,004500,140 70600 75200 94100 122300 215000 302000 363000 350 376 470 610 1070 1510 1810 0,00500

M 30 0,100 92500 98800 123500 160500 282000 396000 475000 380 405 510 658 1160 1640 1970 0,004100,125 88300 94000 117500 162700 269000 378000 454000 445 470 590 763 1350 1900 2280 0,005000,140 85700 91600 114500 148800 261000 367000 441000 475 504 635 818 1450 2050 2450 0,00550

M 33 0,100 115000 122800 153500 199500 351000 494000 592000 515 552 690 898 1570 2210 2650 0,004500,125 110000 117200 146500 190400 335000 472000 566000 600 645 800 1045 1830 2580 3090 0,005500,140 107000 114000 142500 185200 326000 458000 550000 645 685 865 1110 1970 2770 3330 0,00600

M 36 0,100 135000 144000 180000 234000 412000 579000 695000 665 705 885 1145 2030 2850 3420 0,004900,125 129000 137600 172000 223600 394000 553000 664000 775 825 1030 1340 2360 3310 3980 0,006000,140 125500 134000 167500 217700 382000 538000 645000 830 885 1111 1435 2530 3560 4280 0,00660

M 39 0,100 162500 173500 217000 282100 495000 696000 835000 860 920 1150 1495 2620 3680 4420 0,005300,125 155000 165600 207000 269100 473000 665000 798000 1000 1075 1340 1750 3050 4290 5150 0,006500,140 151000 160800 201000 261300 460000 646000 776000 1080 1155 1440 1880 3290 4620 5550 0,00720

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With MA = FV.X, the tightening torque can be calculated for every ot-her preload.

Attention: For the threaded fastener calculation procedure,see VDI guidelines 2230.

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Bossard AG Schrauben Tel. 041 749 66 11 Fax 041 749 66 22


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Metric fine thread


Maximum permissible preload and tightening torques forscrews of property classes 8.8–12.9 at 90% utilization of theyield point ReL or Rp0,2

Preload FV max [N] Tightening torque MA max [Nm]Thread µ total

1) Property class according to ISO 898 / 1 Property class according to ISO 898 / 18.8 10.9 12.9 8.8 10.9 12.9

0,100 19500 27500 33000 22 30 36M 8 x 1 0,125 18600 26200 31500 25 35 42

0,140 18100 25500 30600 27 38 450,100 30500 42900 51500 42 59 71

M 10 x 1,25 0,125 29100 40900 49100 49 68 820,140 28300 39800 47700 52 73 880,100 46600 65500 78500 76 105 130

M 12 x 1,25 0,125 44600 62500 75000 88 125 1500,140 43300 61000 73000 95 135 1600,100 63000 88500 106000 120 165 200

M 14 x 1,5 0,125 60500 85000 102000 140 195 2350,140 58500 82500 99000 150 210 2500,100 85000 120000 144000 180 250 300

M 16 x 1,5 0,125 81500 114000 137000 210 295 3500,140 79000 111000 133000 225 315 3800,100 111000 156000 187000 260 365 435

M 18 x 1,5 0,125 106000 149000 179000 305 425 5100,140 103000 145000 174000 325 460 5500,100 140000 197000 236000 360 510 610

M 20 x 1,5 0,125 134000 189000 226000 425 600 7200,140 130000 183000 220000 460 640 7700,100 172000 242000 291000 480 680 810

M 22 x 1,5 0,125 165000 234000 279000 570 800 9600,140 161000 226000 271000 610 860 10500,100 197000 277000 332000 610 860 1050

M 24 x 2 0,125 188000 265000 318000 720 1000 12000,140 183000 257000 309000 780 1100 1300

1) For explanation of µ total see page T.032

Polyamide 6.6 (20 °C, moisture absorbed)

Thread M3 M4 M5 M6 M8 M10 M12 M14 M16Screws MAmax [Nm] 0,1 0,2 0,5 1 2 3 4 6 7,5Nuts MAmax. [Nm] 0,1 0,3 0,6 1,5 3 4 5 7,5 9



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Screws made from austenitic stainlesssteel A1 / A2 / A4: maximum permissible preload and tightening torquesat 90% utilization of yield point Rp0,2

Preload Fv (kN) Tightening torque MA (Nm)Thread µ total Property class Property class

50 70 80 50 70 800,1 0,4 0,55 0,6 0,1 0,1 0,2

M 1,6 0,2 0,3 0,35 0,4 0,1 0,2 0,350,3 0,2 0,3 0,35 0,2 0,25 0,450,1 0,5 0,6 0,8 0,15 0,2 0,3

M 2 0,2 0,4 0,5 0,6 0,25 0,3 0,40,3 0,25 0,36 0,4 4 0,4 0,550,1 0,65 0,9 1 0,25 0,45 0,6

M 2,5 0,2 0,4 0,5 0,85 0,45 0,6 0,650,3 0,3 0,3 0,6 0,6 0,75 0,80,1 0,9 1 1,2 0,85 1 1,3

M 3 0,2 0,6 0,65 0,95 1 1,1 1,60,3 0,4 0,45 0,7 1,25 1,35 1,850,1 1,08 2,97 3,96 0,8 1,7 2,3

M 4 0,2 1,12 2,4 3,2 1,3 2,6 3,50,3 0,9 1,94 2,59 1,5 3 4,10,1 2,26 4,85 6,47 1,6 3,4 4,6

M 5 0,2 1,83 3,93 5,24 2,4 5,1 6,90,3 1,49 3,19 4,25 2,8 6,1 80,1 3,2 6,85 9,13 2,8 5,9 8

M 6 0,2 2,59 5,54 7,39 4,1 8,8 11,80,3 2,09 4,49 5,98 4,8 10,4 13,90,1 5,86 12,6 16,7 6,8 14,5 19,3

M 8 0,2 4,75 10,2 13,6 10,1 21,4 28,70,3 3,85 8,85 11 11,9 25,5 33,90,1 9,32 20 26,6 13,7 30 39,4

M10 0,2 7,58 16,2 21,7 20,3 44 580,3 6,14 13,1 17,5 24 51 690,1 13,6 29,1 38,8 23,6 50 67

M12 0,2 11,1 23,7 31,6 34,8 74 1000,3 9 19,2 25,6 41 88 1170,1 18,7 40 53,3 37,1 79 106

M14 0,2 15,2 32,6 43,4 56 119 1590,3 12,3 26,4 35,2 66 141 1880,1 25,7 55 73,3 56 121 161

M16 0,2 20,9 44,9 59,8 86 183 2450,3 17 36,4 48,6 102 218 291

Preload Fv (kN) Tightening torque MA (Nm)Thread µ total Property class Property class

50 70 80 50 70 800,1 32,2 69 92 81 174 232

M18 0,2 26,2 56,2 74,9 122 260 3460,3 21,1 45,5 60,7 144 308 4110,1 41,3 88,6 118,1 114 224 325

M20 0,2 33,8 72,4 96,5 173 370 4940,3 27,4 58,7 78,3 205 439 5860,1 50 107 143 148 318 424

M22 0,2 41 88 118 227 488 6500,3 34 72 96 272 582 7760,1 58 142 165 187 400 534

M24 0,2 47 101 135 284 608 8100,3 39 83 110 338 724 9660,1 75 275

M27 0,2 61 4210,3 50 5030,1 91 374

M30 0,2 75 5710,3 61 6800,1 114 506

M33 0,2 94 7790,3 76 9290,1 135 651

M36 0,2 110 9980,3 89 11890,1 162 842

M39 0,2 133 13000,3 108 1553

Fasteners with hexagon and hexalobular socket and flat heads

Maximum tightening torques MA max. [Nm]ISO 4026 / DIN 913

ISO 4027 / DIN 914

Screwtype ISO 4028 / DIN915

DIN 6912 DIN 7984 BN 1206BN 9524 ISO 7379 DIN 7991 ISO14581 DIN 7991 ISO 7380BN 6404 ISO 7380 ISO 4029 / DIN916

Thread 8.8 A2–70 8.8 A2–70 10.9 8.8 12.9 10.9 8.8 A2–70 10.9 8.8 A2–70 45 H1) A2A4–70 A4–70 A4–70 A4–70 A4

M 3 1 0,6 1 1 0,5 1 1 0,5 0,5 0,2M 4 2 1 2 1,2 2 2 2 2 1 2 2 1 1 0,5M 5 6 4 4 2,5 5 5 4 5 5 2,5 4 4 2 3 1,5M 6 9 5 8 5 5 5 9 9 9 4,5 8 8 4 5 2,5M 8 20 12 12 7 10 10 25 15 8 12 12 6 10 5M10 40 24 35 21 18 40 40 20 30 15 20 10M12 65 40 50 30 70 65 33 60 30 45 22M14 110 66 100 50 45 22M16 180 110 110 66 200 110 55 90 45M18 140 70M20 280 170 200 120 400 150 75 140 70M22 220 110M24 390 235 400 200 220 110

1) The mechanical characteristics and property classes according to ISO 898, part 5 are valid for headless screws not subjected to tensile forces.

Fasteners made from these steels tend to erode during fitting. Thisrisk can be reduced through smooth, clean thread sufaces (rolledthreads), lubricants, molykote smooth varnish coating (black), lownumber of revolutions of the screwdriver, or continuous tightening wi-thout interruption (impact screwdriver not recommended). For coeffi-cients of friction, see T.032.



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Preload andtightening torquesLocking screws and nuts,

flange screws and nuts (according to manufacturer's specifications)

Tightening torques MAmax. [Nm]Class Counter-material M5 M6 M8 M10 M12 M14 M16

steel 11 19 42 85 130 230 330Inbus-Ripp screws Rm < 800 N /mm2

Verbus-Ripp screws 100 steel 10 18 37 80 120 215 310and nuts 10 Rm = 800–1100 N /mm2

grey cast iron 9 16 35 75 115 200 300

Tensilock screws 90 steel 9 16 34 58 97 155 215and nuts 8 grey cast iron 7 13 28 49 83 130 195

Tightening torques MA max for VERBUS-RIPP , INBUS-RIPP and TENSILOCK screws and nuts at 90% utilization of the yield point Rp0,2

Preload FVmax for VERBUS-RIPP , INBUS-RIPP and TENSILOCK : The tightening torques inthe above chart result in the preloads listed below.

Preload FVmax [N]Class M5 M6 M8 M10 M12 M14 M16Inbus-Ripp screwsVerbus-Ripp screws 100 9000 12600 23200 37000 54000 74000 102000Tensilock screwsand Verbus-Ripp nuts 10Tensilock screws 90 6350 9000 16500 26200 38300 52500 73000and nuts 8

Tightening torques MAmax for pan washer head screws with hexagonsocket and pressed-on flange (black, property class 10.9)

Tightening torques MAmax. (Nm)M3 M4 M5 M6 M8 M10 M121 3 6 11 27 52 100

Tightening torques MAmax eco-fix screws made from steel (zinc plated,property class 4.8) and stainless steel A2

Tightening torques MAmax. (Nm)M2,5 M3 M4 M5 M6 M80,5 0,9 2 4,1 6,9 17

0 To ensure good locking action, screws (or the nuts) should be tightened to the recommended MA where possible.

0 For high dynamic stresses, Inbus-Ripp or Verbus-Ripp screws are recommended.



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Preload andtightening torquesHigh-strength structural steel bolts

according to DIN 6914(HV sets according to DIN 6914 / 15 / 16)

Dimensioning, design and manufacture of fasteners with high-strength structural steel bolts are regulated in DIN 18800,parts 1.

The strength of high-strength structural steel bolts correspondsto the value stipulated in DIN 267, respectively ISO 898:

– ISO 898, part 1 for bolts DIN 6914

– DIN 267, part 4 for nuts DIN 6915

– Washers DIN 6916, 6917, 6918 of steel hardened to 295-350HV 10

1 2 3 4 5 6 7 8 9Screw prestressed according to the

Torque procedure Impact Angle of rotation procedureprocedure

Screw Required Tightening torque MA Preload Pre-tightening Clamping Angle of rotation ordiameter preload FV to be applied to be torque to length number of revolutions

in the screw lubricated with lightly applied be applied MoS2 1) oiled FV

2) MA2) lk

3) ϕ 2) U2)

mm kN Nm Nm kN Nm mm1 M 12 50 100 120 60 102 M 16 100 250 350 1103 M 20 160 450 600 1754 M 22 190 650 900 2105 M 24 220 800 1100 2406 M 27 290 1250 1650 3207 M 30 350 1650 2200 390 2008 M 36 510 2800 3800 5609 M 12 see 0 to 50 180° 1/2

10 to lines 51 to 100 240° 2/311 M 36 1–8 101 to 240 270° 3/4

1) Since the values MA are highly dependent upon the thread lubricant, observance of these values must be confirmed by the screw manufacturer.2) Does not depend on the lubrication of the thread and the contact surfaces of nut and screw.3) For screws M12 to M22 with clamping lengths 171 to 240 mm, an angle of rotation ϕ 360° and U = 1 must be used.

To apply a partial preload force ≥ 0,5 · FV, half the values of columns 3 to 5 and 8 or 9 and hand-tightening according tocolumn 6 is sufficient.

The following methods are available for applying preload to thebolt:

– with hand operated torque wrench (torque process)

– with power screwdriver which must be regulated to a well de-fined torque (angular torque)

– angle of rotation process, in which after having applied a cer-tain preload, the nut or bolt is retightened with a well definedangel of rotation.

50

100

Table 1, which is taken from DIN 18800 part 7, shows the necessary preloads, torques and tightening angles. The screwsmay be tightened either by the nut or by the screw.


[mech eng.] tightening torques

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