--- 13 ---
Fig. 6
6-2-3. Bolt tightening torque characteristics
Figure 6 shows relationships between time and tightening torque for individual bolt types and sizes. While the
data are useful for handy reference, actual tightening torque will vary depending on tightening conditions and
other variables. For details, please refer to Para. 7-3, Tightening Torque Variation.
(Note)
The term "tightening time" indicates the impact time after the lower surface of the bolt has come in contact with
the material into which it is being tightened.
In the tightening conditions shown in Fig. 6, the screws are being tightened directly into a steel plate;
accordingly, the torque goes up very abruptly in comparison with ordinary bolt tightening conditions.
* The following bolts were utilized:
Ordinary bolt; strength grade 4.8
High-strength bolt; strength grade 12.9
Bolt
Strength grade is read as follows:
4.8
Yield point or durable force:
(45,500 psi)
Tensile strength of the bolt:
(56,900 psi)
Nut
Steel plate
thickness: t
0
1
2
3
(sec.)
M10 x 30 (3/8" x 1-5/32")
Tightening time
[Steel plate thickness t= 10 mm (3/8")]
High-strength bolt
Ordinary bolt
0
20
40
60
80
100
120
140
160
0
200
400
600
800
1000
1200
1400
1600
(174 in-lbs.)
(347 in-lbs.)
(521 in-lbs.)
(694 in-lbs.)
(868 in-lbs.)
(1042 in-lbs.)
(1215 in-lbs.)
(1389 in-lbs.)
(kgf•cm)
(N•m)
200
400
600
800
1200
1000
1400
(in-lbs.)
0
0
1
2
3
(sec.)
M12 x 45 (15/32" x 4/3")
Tightening time
[Steel plate thickness t= 25 mm (1")]
High-strength bolt
Ordinary bolt
0
20
40
60
80
100
120
140
160
0
200
400
600
800
1000
1200
1400
1600
(174 in-lbs.)
(347 in-lbs.)
(521 in-lbs.)
(694 in-lbs.)
(868 in-lbs.)
(1042 in-lbs.)
(1215 in-lbs.)
(1389 in-lbs.)
(kgf•cm)
(N•m)
200
400
600
800
1200
1000
1400
(in-lbs.)
0
0
1
2
3 (sec.)
M14 x 50 (9/16" x 1-15/16")
Tightening time
[Steel plate thickness t= 25 mm (1")]
High-strength bolt
Ordinary bolt
0
20
40
60
80
100
120
140
160
0
200
400
600
800
1000
1200
1400
1600
(174 in-lbs.)
(347 in-lbs.)
(521 in-lbs.)
(694 in-lbs.)
(868 in-lbs.)
(1042 in-lbs.)
(1215 in-lbs.)
(1389 in-lbs.)
(kgf•cm)
(N•m)
200
400
600
800
1200
1000
1400
(in-lbs.)
0
