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2. Work at a tightening torque suitable
for the bolt under impact
The optimum tightening torque for nuts
and bolts differs with material and size of
the nuts and bolts. An excessively large
tightening torque for a small bolt may
stretch or break the bolt. The tightening
torque increases proportionally to the
operating time. Use the correct operating
time for the bolt.
3. Selecting the socket to be matched
to the bolt
Be sure to use a socket which is matched to
the bolt to be tightened. Using an improper
socket will result not only in insufficient
tightening but also in damage to the socket
or nut.
A worn or deformed hex. or square-holed
socket will not give an adequate tightness
for fitting to the nut or anvil, consequently
resulting in loss of tightening torque.
Pay attention to wear of socket holes, and
replace before further wear has developes.
Matching socket and bolt sizes are shown
in Tables 1 and 2.
The numerical value of a socket designation
denotes the side-to-side distance (S) of its
hex. hole.
4. Holding the tool
Hold the Impact Wrench firmly with both
hands by the body handle and the side
handle. In this case hold the wrench in line
with the bolt.
It is not necessary to push the wrench very
hard. Hold the wrench with a force just
sufficient to counteract the impact force.
5. Confirm the tightening torque
The following factors contribute to a
reduction of the tightening torque. So
confirm the actual tightening torque
needed by screwing up some bolts before
the job with a hand torque wrench.
Factors affecting the tightening torque are
as follows.
(1) Line voltage:
The tightening torque decreases when the
line voltage becomes low. (See Figs. 5, 6, 7,
8 and 9)
(WH16)
M16 × 55 (F10T)
40
(kg-m)
Rating
30
20
10
0
0 2 4 6 8 10 12 14 16
Tightening time
Fig. 6
(WH22)
M16 × 70 (F10T)
70
(kg-m)
60
50
Rating
40
30
20
0
0
2
4
Tightening time
Fig. 7
(WH22)
M20 × 70 (F10T)
70
(kg-m)
Rating 115V
60
50
40
30
20
0
0
2
4
Tightening time
Fig. 8
English
115V
105V
(s)
115V
105V
(s)
6
8
10
105V
(s)
6
8
10
15
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