Hitachi WH 14DMR Technical Data And Service Manual page 21

7-3-3. Bolt tightening torque characteristics
Figures 5-1 and 5-2 show 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. 8-3, "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 Figs. 5-1 to 5-4, the screws are being tightened directly into a steel plate;
accordingly, the torque goes up very abruptly in comparison with ordinary bolt tightening conditions.
•
Model WH 14DMR
kgf . cm
N . m
(in-lbs.) M10 x 30
160
1600
(1389)
140
1400
High-strength bolt
(1215)
120
1200
(1042)
100
1000
(868)
800
80
(694)
Ordinary bolt
600 60
(521)
400 40
(347)
200
20
(174)
0
0
0 1
Tightening time: sec.
(Steel plate thickness
t = 10 mm))
* The following bolts were utilized:
Ordinary bolt; strength grade 4.8
High-strength bolt; strength grade
kgf . cm
(in-lbs.)
1600
(1389)
1400
(1215)
1200
(1042)
1000
(868)
800
(694)
600
(521)
400
(347)
200
(174)
0
3
2
12.9
N . m
M12 x 45
160
High-strength bolt
140
120
100
80
Ordinary bolt
60
40
20
0
0
1 2 3
Tightening time: sec.
(Steel plate thickness
t = 25 mm))
Fig. 5-1
--- 18 ---
Strength grade is read as follows:
4.8
Yield point or durable force:
(45,500 psi)
Tensile strength of the bolt:
(56,900 psi)
kgf . cm
N . m
M14 x 50
(in-lbs.)
160
1600
High-strength bolt
(1389)
140
1400
(1215)
120
1200
(1042)
100
1000
Ordinary bolt
(868)
800
80
(694)
600 60
(521)
400 40
(347)
200
20
(174)
0
0
0 1
Tightening time: sec.
(Steel plate thickness
t = 25 mm))
2 3