November 15, 2024

Bolt tightening torque calculation and tightening torque standard



The bolt tightening torque is an important basis for the selected bolt type and pattern. For standard bolts, there is a fixed range of bolt tightening torques. Bolts can be selected based on this range.



In general, the tensile strength and shear strength of the screw are constant. In actual use, the tightening force should be calculated based on the specific connection stress, and then the appropriate size of the screw bolt should be selected.



Bolt tightening torque calculation



T=KFd



T: torque to tighten the nut



K: torque coefficient ( approximate 0.2)



F: Preload



d: Bolt diameter



Remark: The general connection steel bolt connection recommended by the following relationship to determine



Carbon Steel: F<=(0.6~0.7) Os A1



Alloy steel: F<=(0.5~0.6) Os A1



Os : Yield Limit of Bolt Material



A1 : Bolt Hazardous Section Area



Ordinary bolt tightening torque standard



































bolt


strength


level



yield


strength


N/mm 2



screw   bolt   public   Said   straight   path   Mm



6



8



10



12



14



16



18



20



screw   tight   force   Moment    Nm



4.6


5.6


6.8


8.8


10.9


12.9



240


300


480


640


900


1080



4-5


5-7


7-9


9-12


13-16


16-21



10-12


12-15


17-23


22-30


30-36


38-51



20-25


25-32


33-45


45-59


65-78


75-100



36-45


45-55


58-78


78-104


110-130


131-175



55-70


70-90


93-124


124-165


180-201


209-278



90-110


110-140


145-193


193-257


280-330


326-434



120-150


150-190


199-264


264-354


380-450


448-597



170-210


210-270


282-376


376-502


540-650


635-847




































bolt


strength


level



yield


strength


N/mm 2



screw   bolt   public   Said   straight   path      Mm



twenty two



twenty four



27



30



33



36



39



screw   tight   force   Moment     Nm



4.6


5.6


6.8


8.8


10.9


12.9



240


300


480


640


900


1080



230-290


290-350


384-512


512-683


740-880


864-1152



300-377


370-450


488-650


651-868


940-1120


1098-1464



450-530


550-700


714-952


952-1269


1400-1650


1606-2142



540-680


680-850


969-1293


1293-1723


1700-2000


2181-2908



670-880


825-1100


1319-1759


1759-2345


2473-3298


2968-3958



900-1100


1120-1400


1694-2259


2259-3012


2800-3350


3812-5082



928-1237


1160-1546


1559-2079


2923-3898


4111-5481


4933-6577




Metric bolt tightening torque standard



















material



45 , 35CrMo or equivalent



Nominal thread diameter ( mm )



Range Nm(kgfm)



Target Nm (kgfm)



M6


M8


M10


M12


M14


M16


M18


M20


M22


M24


M27


M30


M33


M36


M39



8.8-14.7 (0.9-1.5)


14.7-34 (1.5-3.5)


34-74 (3.5-7.5)


54-123 (5.5-12.5)


84-196 (8.5-20)


147-309 (15.0-31.5)


201-427 (20.5-43.5)


319-608 (32.5-62.0)


471-829 (48.0-84.5)


588-1030 (60-105)


883-1470 (90-150)


1130-1910(115-195)


1470-2450 (150-250)


1860-3040 (190-310)


2260-3630 (230-370)



12(1.2)


25(2.5)


54(5.5).


89 (9.0)


137(14)


230 (23.5)


315 (32)


460(47)


650 (66.5)


810 (82.5)


1180(120)


1520 (155)


1960 (200)


2450 (250)


2940 ( 300 )




The bolt tightening torque is an important basis for the selected bolt type and pattern. For standard bolts, there is a fixed range of bolt tightening torques. Bolts can be selected based on this range.



In general, the tensile strength and shear strength of the screw are constant. In actual use, the tightening force should be calculated based on the specific connection stress, and then the appropriate size of the screw bolt should be selected.



Bolt tightening torque calculation



T=KFd



T: torque to tighten the nut



K: torque coefficient ( approximate 0.2)



F: Preload



d: Bolt diameter



Remark: The general connection steel bolt connection recommended by the following relationship to determine



Carbon Steel: F<=(0.6~0.7) Os A1



Alloy steel: F<=(0.5~0.6) Os A1



Os : Yield Limit of Bolt Material



A1 : Bolt Hazardous Section Area



Ordinary bolt tightening torque standard

























bolt


strength


level



yield


strength


N/mm 2



screw   bolt   public   Said   straight   path   Mm



6



8



10



12



14



16



18



20



screw   tight   force   Moment    Nm



4.6


5.6


6.8


8.8


10.9


12.9



240


300


480


640


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