−19−
6. Fastening of each portion
Important
A number of bolts are used in each part of this machine. be sure to re-tighten the bolts and nuts, because they may be loosened at the earlier stage of the use.
6-1 Tightening torque
As to the bolts and nuts without any special instruction, tighten them in appropriate tightening torque with proper tool.
Too much tightening may cause the looseness or damage of the screw.
The strength of tightening is determined by types of screws, strength, the friction of thread face or base face and
others.
The table below is for the galvanized or parkerized bolts.
In case that the strength of internal thread is weak, it is not applied.
Do not use rusty or sand attached "screw."
Otherwise, it may cause insufficient tightening even if you apply the specified tightening torque.
The friction of the screw face becomes higher and the tightening torque is canceled out by the friction, therefore sufficient tightening cannot be applied.
If "screw" is wet by water or oil, do not tighten it with normal tightening torque.
If the screw is wet, the torque coefficient will get smaller and it may result in too much tightening.
Too much tightening may cause looseness by the screw stretched or result in damage.
Do not use a bolt experienced too much burden.
Using the impact wrench requires the skill.
Do exercise as much as possible for steady tightening.
General bolt
Strength classification 4.8
Nominal
diameter
N-m
kgf-cm
lb-in
M5
3 - 5
30.59 - 50.99
26.55 - 44.26
M6
7 - 9
71.38 - 91.77
61.96 - 79.66
M8
14 - 19
142.76 - 193.74
123.91 - 168.17
M10
29 - 38
295.71 - 387.49
256.68 - 336.34
M12
52 - 67
530.24 - 683.20
460.25 - 593.02
M14
70 - 94
713.79 - 958.52
619.57 - 831.99
M16
88 - 112
897.34 - 1142.06
778.89 - 991.31
M18
116 - 144
1,182.85 - 1,468.37
1,026.72 - 1,274.54
M20
147 - 183
1,498.96 - 1,866.05
1,301.10 - 1,619.73
M22
295
3,008.12
2,611.05
M24
370
3,772.89
3,274.87
M27
550
5,608.35
4,868.05
M30
740
7,545.78
6,549.74
Heat-treated bolt
Strength classification 8.8
Strength classification 10.9
Nominal
diameter
N-m
kgf-cm
lb-in
N-m
kgf-cm
lb-in
M5
5 - 7
50.99 - 71.38
44.26 - 61.96
7 - 10
71.38 - 101.97
61.96 - 88.51
M6
8 - 11
81.58 - 112.17
70.81 - 97.36
14 - 18
142.76 - 183.55
123.91 - 159.32
M8
23 - 29
234.53 - 295.71
203.57 - 256.68
28 - 38
285.52 - 387.49
247.83 - 336.34
M10
45 - 57
458.87 - 581.23
398.30 - 504.51
58 - 76
591.43 - 774.97
513.36 - 672.68
M12
67 - 85
683.20 - 866.75
593.02 - 752.34
104 - 134
1,060.49 - 1,366.40
920.50 - 1186.03
M14
106 - 134
1,080.88 - 1,366.40
938.21 - 1,186.03
140 - 188
1,427.58 - 1,917.04
1,239.14 - 1,663.99
M16
152 - 188
1,549.94 - 1,917.04
1,345.35 - 1,663.99
210 - 260
2,141.37 - 2,651.22
1,858.71 - 2,301.26
M18
200 - 240
2,039.40 - 2,447.28
1,770.20 - 2,124.24
280 - 340
2,855.16 - 3,466.98
2,478.28 - 3,009.34
M20
245 - 295
2,498.27 - 3,008.12
2,168.50 - 2,611.05
370 - 450
3,772.89 - 4,588.65
3,274.87 - 3,982.95
M22
-
-
-
530
5,404.41
4,691.03
M24
-
-
-
670
6,831.99
5,930.17
M27
-
-
-
1,000
10,197.00
8,851.00
M30
-
-
-
1,340
14,628.78
11,860.34
11 11T
10.9
8
8
T
8.8
M
4
T
4.8
