18
6. FACTORS THAT AFFECT
TIGHTENING TORQUE
1. Voltage
If the battery reaches the margin of complete
discharge level, voltage drops and tightening
torque is lowered.
2. Operating time
The longer the operating period, the greater
the tightening torque will become, but only to
a certain level. Extending the operating peri-
od cannot cause the level to be transcended.
The appropriate tightening torque required
for a screw or a bolt differs according to the
material, size and grade of the screw/bolt.
Be sure to apply an operating period and
torque that are suitable for the screw/bolt. If
an excessively large torque is applied to a
small screw or bolt, it may stretch or break.
3. Diameter of screw/bolt
•
Screws/bolts with different diameters have
the different torque coefficient (A coeffi-
cient determined by finished conditions of
the bolt. Indicated by bolt manufacturers).
Even in the same grade, screws/bolts with
different diameter require different tighten-
ing torque.
•
Even with the same diameter, the required
tightening torque differs according to its
torque coefficient (A coefficient deter-
mined by finished conditions of the bolt. In-
dicated by bolt manufacturers), grade or
length.
4. Workpiece
When a bolt is tightened into wood or anoth-
er type of soft material, tightening torque is
reduced significantly compared with the
case where the bolt is tightened into an iron
frame or other type of hard material.
5. Bit
Inappropriate selection of a bit that is not
suitable for screw or bolt reduces tightening
torque.
6. Trigger switch
Slightly pulling the trigger switch (not full
power) reduces tightening torque.
<If the tool stops unexpectedly during opera-
tion>
When battery power drops to a certain discharge
level, the control circuit is activated and the tool
stops automatically.
Once the control circuit is activated, you cannot
continue operation. (The tool stops again even if
it is operated for a short period of time.) Install a
charged battery pack.
•
Do not leave the battery pack attached if
the control circuit has been activated.
If a discharged battery pack is left for a long pe-
riod of time, it may become damaged. Charge
the battery pack immediately if the control cir-
cuit has been activated.
CAUTION
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