Ergonomics - Atlas Copco

EXTERNAL LOAD
For evaluation purposes, it is assumed that
the tool is operated by a female operator at
a sitting workstation. The tool is supported
in a balancer. The tightening torque used
at this workstation is 3 Nm which is
experienced as a dorsal flexion. The grip
surface has good friction so the grip force
will not limit the torque capacity. In most
applications the push force required is low.
No trigger force is experienced. The tool has
a push-to-start function.
WEIGHT
Screwdrivers are often used for repetitive
tasks. The dynamic motion of the tool mass
is therefore important. The tool weight is
0.7 kg, giving a score of 6.
TEMPERATURE
Even if the tool is used for repetitive work,
high or low temperature is not a problem.
A typical tightening time is 2 seconds.
In an 8-hour working day, the tool running
time is usually 2 hours, resulting in a work
cycle time of 8 seconds. If the machine runs
on a test joint at 4.5 Nm (range 0.5-4.5 Nm)
in a “6 sec. rest, 2 sec. run” sequence, the
temperature in the handle will be 17ºC, giv-
ing a factor evaluation of 3.
SHOCK REACTION
The shock reaction depends on the force of
the impulse entering the machine dur-
ing tightening. Since this tool has a fast
clutch, the impulse is primarily due to the
stiffness of the joint, the torque level and
power of the motor, and the inertia of the
machine. The impulse from this straight
machine, measured in accordance with
ISO 6544 at 3 Nm, is 2.0 Ns, giving a
score of 4.
VIBRATION
The declared vibration value is