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2. Tightening torque inspection prior to operation
As described and shown in page 7, the output tightening torque of the Models WH 14DCAL and WH 14DY
may exceed the rated tightening torque of certain bolts and screws. Accordingly, if the tightening time is
prolonged for such bolts and screws, the screws or the bolts may be damaged or sheared off. (This
phenomenon is common to all existing impact drivers.)
Particularly when tightening M6 (1/4") or smaller screws, tightening time must be kept extremely short: 0.5
seconds or less. The customer should be advised to carry out several screw tightening operations and
adjust the tightening time as necessary by measuring the tightening torque with an appropriate torque
wrench or driver before commencing continuous operation.
3. Tightening torque variation
The tightening torque of the cordless impact drivers or wrenches may vary slightly in accordance with the
factors described below. Salespersons are requested to advise the customers to confirm that the
appropriate tightening torque is obtained by measuring the torque with an appropriate torque wrench or
torque driver at the beginning of the tightening operations, and as necessary during the tightening
operations. In addition, the torque values shown in page 6 above are useful as a handy reference, and may
be utilized as tentative standards.
(1) Voltage of battery
The tightening torque is affected by the voltage output of the battery. The tightening torque decreases
as the number of bolts tightened increases. This phenomenon is caused by the decline in voltage output
of the battery due to the increasing number of bolts tightened. In particular, the tightening torque
decreases rapidly just before the overdischarge protection circuit is activated. As this phenomenon is an
inherent drawback in any cordless impact driver/wrench, salespersons are requested to ensure that the
customers are fully aware of and understand this characteristic.
Precautions for use of the Type BCL 1430 lithium-ion battery
The Type BCL 1430 lithium-ion battery is equipped with a protective function that automatically stops
output to extend the battery life. The motor may stop automatically even though the switch is depressed
continuously when the remaining battery level is low (about 8 V or lower). This is because the protective
function is activated and the battery is not faulty. Charge the battery immediately in such case.
(2) Effects of low ambient temperature
The tightening torque required may be reduced at low ambient temperature under the influence of
grease and different torque coefficients (depending on manufacturing and finishing processes, and
specified by bolt manufacturers).
(3) Different bolt diameter
Difference in bolt diameter may cause variation of the required levels of tightening torque. Generally,
high tightening torque is required for large bolts.
(4) Different materials tightened
When a bolt is tightened into a soft material such as aluminum, plastic, wood, etc., the tightening torque
is considerably low in comparison with the tightening torgue reguired for tightening a bolt into a hard
material such as steel.
