Gedore

Tensioning Forces & Tightening Values

The tightening forces given below (P_v) and the suggested torques (M_A) are guideline values for metric standard threads or metric fine threads as per DIN 13, and head dimensions as per DIN 912, 931, 934, 6912, 7984 and 7990 as well as inch threads coarse (UNC) and fine (UNF) They mean using the bolt's limit of elasticity up to 90%. A coefficient of friction of 0.14 (new bolt, without treatment, unlubricated) was taken as a basis for the calculations.

Please Note : Only use this table if no manufacturers' specifications are available and when this high stressing of the bolt can not damage other parts such as flanges, seals, etc. The individual calculation of the torque from the desired tensioning force, taking into account any deviating frictional values is urgently recommended (see table below) Lubrication using MOS₂ for example, requires a reduction of the torque by approx. 20%.

	Bolt with metric standard thread DIN 13 Sheet 13, Friction value mges.=0,14													Factor X [m] for calculating the tightening value MA
	4,6		5,6		6,9		8,8		10,9		12,9
	Tightening Force = P_n (F_m), Torque = M_A
	P_n N	M_A Nm	P_n N	M_A Nm	P_n N	M_A Nm	P_n N	M_A Nm	P_n N	M_A Nm	P_n N	M_A Nm
N2 M2.3 M2.6	284 407 525	0,123 0,196 0,284	378 544 701	0,162 0,265 0,373	731 1049 1353	0,314 0.510 0.726	863 1245 1598	0,373 0,598 0,863	1216 1755 2246	0,520 0,843 1,206	1461 2099 2697	0,628 1.010 1,451	4 4,5 5	0,00043 0.00048 0,00054
N13 M3.5 N4	726 971 1255	0,441 0,677 1.000	966 1294 1677	0,588 0,902 1,344	1863 2501 3226	1,128 1,736 2.599	2206 2962 3825	1,344 2,060 3,040	3109 4168 5374	1,883 2,893 4,315	3727 5001 6453	2,256 3,481 5.148	5,5 6 7	0,00061 0.00070 0,00080
M5 M6 M7	2059 2903 4236	1.961 3,432 5,590	2736 3864 5649	2,648 4,511 7,453	5286 7543 10885	5,099 8,728 14,220	6257 8836 12945	6.031 10,300 17,162	8806 12405 18191	8,483 14,710 24,517	10591 14906 21771	10,200 17.625 28.439	8-9 10 11-12	0,00096 0,00118 0,00131
MB M10 M 12	5315 8473 12356	8.238 16,67 28,44	7090 11278 16475	10.787 21,575 38,246	13680 21771 31773	21,575 42,168 73,550	16230 25791 37657	25,497 50,014 87,279	22751 36284 52956	35,304 70,608 122.60	27360 43541 63547	42.168 85,317 147,10	13-14 15-17 19-21	0,00155 0,00195 0,00232
M14 M16 M18	16965 23340 28341	45,11 69,63 95,12	22653 31087 37853	60,801 93,163 127,50	43639 60016 72961	116,70 178,50 245,50	51681 71196 86494	138,30 210,80 289,30	72667 100027 121602	194,20 299,10 411,90	87279 120131 146118	235,40 357,90 490,30	22-23 24-26 27	0,00270 0,00300 0,00335
MBO M22 M24	36481 45601 52563	135,3 182,4 230,5	48641 60801 70019	180,45 245,16 308.91	93849 117189 135331	384.10 470,70 598,20	111305 139254 160338	411.90 559,00 711,00	156415 195642 225552	578.60 784,50 1000	187796 234378 270662	696,30 941,40 1196	30 32 36	0,00370 0,00400 0,00440
M27 M30 M33	W235 84043 104931	343,2 465,8 632,5	92280 112286 139744	460,90 622,72 848,30	177990 215745 269682	887,50 1206 1628	210842 255952 319695	1049 1422 1932	296159 359902 449142	1481 2010 2716	355980 432471 539363	1775 2403 3266	41 46 50	0,00497 0,00550 0,00605
M36 M39 M42	123073 148080 169164	814,0 1059 1304	164261 197113 225552	1089 1412 1746	316753 380496 435413	2099 2716 3364	374612 451104 515827	2481 3226 3991	527595 633506 725688	3491 4531 5609	632526 760992 870826	4197 5443 6727	55 60 65	0,00664 0,00715 0,00771
M45 M48 M52	198093 222610 267720	1638 1981 2540	264778 297140 356960	2177 2683 3393	509943 573686 688423	4207 5080 6541	604087 679597 815909	4992 6021 7747	850232 956144 1147372	7012 8473 10885	1019886 1147372 1377827	8414 10150 13092	70 75 8O	0,00836 0,00895 0,00961
M56 M60 MM	308908 360883 407955	3168 3932 4737	411877 481504 544266	4227 5247 6306	793354 927704 1049306	8149 10101 12160	940453 1098339 1245438	9650 11964 14416	1323891 1544540 1750478	13582 16867 20300	1588669 1853447 2098612	16279 20202 24320	85 90 95	0,01032 0,01098 0,01169
M68 M72 M76	467836 531574 599377	5780 6917 8194	668338 759392 856253	8257 9882 11706	1203008 1366905 1541255	14863 17787 21071	1425787 1620036 1826672	17615 21081 24973	2005013 2278175 2568758	24771 29645 35118	2406016 2733810 3082510	29725 35575 42141	100 105 110	0,01235 0.01301 0,01367
M80 M90 M100	671244 868696 1091549	9618 13953 19425	958921 1240994 1559355	13741 19934 27750	1726057 2233789 2806839	24733 35880 49950	2045697 2647453 3326624	29314 42525 59200	2876762 3722982 4678066	41222 59801 83250	3452115 4467578 5613679	49467 71761 99900	115 130 145	0,01432 0,01606 0,01779

The given tightening forces P_v are guideline values for metric standard and fine threads as per DIN 13, Sheet 13. They are calculated using comperative tensions and mean that the limit of elasticity is used up to 90%.

The factor X contains all values resulting from the thread geometry, and the head dimensions as per DIN 912. 931. 934. 6912. 7984. 7990, the coefficient of friction has been taken into account m_ges.= 0.14

The factor X was calculated according to this formula
X=0,001 [0.159.P+m_ges. ( 0.578.d_2+Dm/2)]

For other coefficients of friction, please insert the appropriate value from the table for m_ges. Coefficients of friction differing greatly from one another may require up to 20% difference in the torque!

Vickers hardness	Brinell hardness	Rookwell hardness ²]		Tensile strength
HV 30	HB 30	HRB	HRC	sB N/mm²
85 85 90 95	80,7 85 90 95	36,4 42,4 47.4 52,0	- - - -	270 290 310 320
100 105 110 115	100 105 110 115	56,4 60,0 63,4 66,4	- - - -	340 360 380 390
120 125 130 135	120 125 130 135	69;4 72,0 74,4 76,4	- - - -	410 420 440 460
140 145 150 155	140 145 150 155	78,4 80,4 82,2 83,8	- - - -	470 490 500 520
160 165 170 175	160 165 170 175	85,4 86,8 88,2 89,6	- - - -	540 550 570 590
180 185 200 195	180 185 190 195	90,8 91,8 91,5 94.0	- - - -	600 620 640 660
200 205 210 225	200 205 210 214	95,0 95,8 96.6 96,6	- - - -	670 680 710 720
220 225 230 235 240	220 225 230 235 240	98,2 99,0 - - -	- - 19.2 20,2 21.2	730 750 760 780 800

What torque is required to achieve a certain tightening force?

The factor X makes the calculation of the required torque
[M_A] for a given tightening force [P_n]

M_A = P_n.X

Example A screw connection is to be tightened at
P_n= 60.000 N.A bolt, M 16, production class 6.9, is selected from the table. The factor X is read off as 0.003 m.
M_A= 60.000 . 0,003
M_A= 180 Nm
Table of Comparisons of the Vickers, Brinell, and
Rockwell Hardnesses and Tensile Strength ¹)

Vickers hardness	Brinell hardness	Rookwell hardness ²]		Tensile strength
HV 30	HB 30	HR B	HRC	sB N/mm²
24B 250 255 260	245 250 255 260	- - - -	22,1 23,0 23,8 24,6	820 830 850 870
265 280 275 280	265 266 275 280	- - - -	25,4 27,1 26,9 27,6	880 900 920 940
285 290 295 300	2S5 290 295 300	- - - -	28,3 29,0 29,6 30,3	950 970 990 1010
310 320 330 340	510 320 330 340	- - - -	51,5 32,7 33.8 34.9	1040 1080 1110 1140
350 360 370 380	S50 359 368 376	- - - -	36,0 37,0 38,0 38,9	1170 1200 1230 1260
390 400 410 420	5S5 392 400 408	- - - -	39,8 40,7 41,5 42,4	1290 1320 1350 1380
430 440 450 460	415 423 430	- - - -	43,2 44,0 44,8 45,6	1410 1430 1460 -
470 480 490 500 510	- - - - -	- - - - -	46,3 47,0 47,7 48,3 49,1	- - - - -

Which tightening force is attained at a preselected tightening
value for a certain bolt?

The factor X makes it possible to calculate the
tightening force [P_n] at a given tightening value for a
certain bolt [M_A]

P_{n = MA / X}

Example A M 16 bolt is tightened to 135 Nm.

P_n = 135 / 0,003 = 45.000 N

All hardness values determined by various hardness
testing methods in various materials are only approxi-
mately comparable.

The Rockwell values given to one decimal point are
only for interpolation, and in the end result should be
rounded off to whole numbers.

Vickers hardness	Brinell hardness	Rookwell hardness ²]		Tensile strength
HV 30	HB 30	HR B	HRC	sB N/mm²
520 530 540 550	- - - -	- - - -	49,7 50,4 51,0 51,6	- - - -
560 570 580 590	- - - -	- - - -	52,2 52,8 53,3 53,9	- - - -
600 610 620 630	- - - -	- - - -	54,4 55,0 55,5 56,0	- - - -
640 650 660 670	- - - -	- - - -	56,5 57,0 57,5 58,0	- - - -
680 690 700 720	- - - -	- - - -	58,5 59,0 59,5 60,4	- - - -
740 760 780 800	- - - -	- - - -	61,2 62,0 62,8 63,6	- - - -
820 840 860 880	- - - -	- - - -	64,3 65,0 65,7 66,3	- - - -
900 920 940	- - -	- - -	66,9 67,5 68,0	- - -