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Bolt Tightening Conditions
6, 8, 10, 12 x 25 mm (1") Standard bolt
10 x 25
mm
High tensile bolt
k f-cm
(in-lbs)
900
(782)
10 x 25 High tensile bolt
800
(695)
700
(608)
600
(521)
500
(434)
400
(347)
300
(260)
8
200
(174)
100
(87)
6
0
0.1 0.25 0.5 1.0 2.0 3.0 4.0
Tightening time (Sec.)
2) Tightening time
Longer tightening time results in
increased tightening torque. Excessive
tightening, how ever, adds no value and
reduces the life of the tool.
3) Different bolt diameters
The size of the bolt diameter affects
the tight ening torque.
Generally, as the bolt diameter
increases, tightening torque rises
4) Tightening conditions
Tightening torque will vary, even
with the same bolt, according to
grade, length, and torque coefficient
(the fixed coefficient indi cated by the
manufacturer upon produc tion).
(Bolt size : illimeters)
12
10
Bolt
Nut
ightening conditions
* he following bolts are used.
Standard bolt: Strength type 4.8
High tensile type 12.9
Explanation of the strength type
4.8
Bolt yield point
(80% of tensile strength)
48 k f/mm
Bolt tensile strength 60 k f/mm
(85,000psi)
Tightening torque will vary , even
with the same bolting material (e.g.
steel), accord ing to the surface fin-
ish.
Torque is greatly reduced when the
bolt and nut start turning together.
5) Socket play
Torque is lowered as the six-sided
configu ration of the socket of the
wrong size is used to tighten a bolt.
6) Switch (Variable speed control trigger)
Torque is lowered if the unit is used
with the switch not fully pulled out.
7) Effect of Connecting Adaptor
The tightening torque will be lowered
through the use of a universal joint or
a connecting adaptor.
- 9 -
asher
Steel plate
thickness 10 mm (3/8")
asher
Spring washer
(68,000psi)
2
2
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