Notes on tightening operations
0
Check your local voltage
Using a power source with ten percent
less than the nameplate voltage will cause
a
sharp drop in tightening torque.
Check your voltage when using an exten-
sion cord.
~
Socket Size
(Across hex f l a t s )
0
Socket selection and installing capacity
Use the right
size
socket for bolts and
nuts.
A different size socket will result in poor
tightening torque.
Metric
inch
Screws (I SO)
Screws
kg
cm
19
21
22
23
4,000
3,000
2,000
1,000
0
1
2
3
4
5
6
7
6
12 mm
7/16"
-
1 /2"
-
14
m m
-
9/16"
second
0
Tightening time in terms of the kindhize of bolt
Tightening torque increases with time and varies with the kind and
size
of bolt.
Tightening
a
small-diameter bolt too long can ruin it. Fasten, keeping in mind your
bolt
-
Do not tighten too long or too short.
Check bolt or nut for looseness
A loose bolt or nut will merely spin and the proper torque will not be possible. If the
socket keeps spinning, stop and check the bolt or nut for looseness.
0
Manner of holding wrench affects performance
Grip the handle and side grip lightly, keeping the wrench pointed straight
a t
the nut or
bolt. Be careful not to tip the tool
a t
an angle or place the weight of the tool on the
socket. This can markedly reduce the tightening torque.
Do
not apply undue pressure
on
a
nut or bolt with the tool itself.
Factors affecting tightening torque
1. Voltage
A
drop in voltage causes
a
reduction in motor speed, the force and number of impacts,
and tightening torque.
"The tightening time affects the number of impacts. Thus, the torque increases with
time of tightening.
"
Long tightening eventually means no more increase in tightening torque, since the
tool hammer's tightening force and the force of the bolt or nut cancel each other
out.
2. Tightening time
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