Hitachi WH 12DAF2 Instrucciones De Manejo página 15

(2) Operating time
The tightening torque increases when the operating
time increases. But the tightening torque does not
increase above a certain value even if the tool is
driven for a long time. (See Fig. 18 and 19)
(3) Diameter of bolt
The tightening torque differs with the diameter of the
bolt as shown in Fig. 18 and 19. Generally a larger
diameter bolt requires larger tightening torque.
(4) Tightening conditions
The tightening torque differs according to the torque
ratio; class, and length of bolts even when bolts with
the same size threads are used. The tightening torque
also differs according to the condition of the surface
of workpiece through which the bolts are to be
tightened. When the bolt and nut turn together, torque
is greatly reduced.
(5) Using optional parts (WR12DAF2)
The tightening torque is reduced a little when an
extension bar, universal joint or a long socket is
used.
〈 WH12DAF2 〉
kgf cm N m
• •
M8 × 30
1000 100
800 80
High tension bolt
600 60
400 40
200 20
Ordinary bolt
0 0
0 1
Tightening time: sec.
(Steel plate thickness
t = 10 mm)
kgf cm N m
• •
1000 100
800 80
600 60
400 40
200 20
0 0
2 3 0
Tightening time: sec.
(Steel plate thickness
t = 10 mm)
(6) Clearance of the socket (WR12DAF2)
A worn or deformed hex. or a square-holed socket
will not give an adequate tightness to the fitting
between the nut or anvil, consequently resulting in
loss of tightening torque.
Using an improper socket which does not match to
the bolt will result in an insufficient tightening torque.
(7) Tightening torque varies, depending on the battery's
charge level. (WR12DAF2)
Fig. 21 show examples of the relationship between
tightening torque and the number of tightenings, for
WR12DAF2. As shown, tightening torque gradually
weakens with the increase in the number of
tightenings. In particular, as the torque decreases
very close to the complete discharge ("a" margin in
graph), the unit's impact weakens, the number of
time impacts declines and tightening torque drops
off abruptly. If this occurs, check torque level, then
recharge the battery if necessary.
kgf
M10 × 30
High tension bolt
Ordinary bolt
1 2 3
Fig. 18
cm N m
• •
M12 × 45
1200 120
High tension bolt
1000 100
800 80
600 60
Ordinary bolt
400 40
200 20
0 0
0 1 2
Tightening time: sec.
(Steel plate thickness
t = 25 mm)
English
3
14