Publicidad
Idiomas disponibles
Idiomas disponibles
22 | English
Working Advice
Apply the power tool to the screw/nut only
when it is switched off. Rotating tool inserts
can slip off.
The torque depends on the impact duration. The
maximum achieved torque results from the sum
of all individual torques achieved through im-
pact. The maximum torque is achieved after an
impact duration of 6–10 seconds. After this du-
ration, the tightening torque is increased only
minimally.
The impact duration is to be determined for
each required tightening torque. The actually
achieved tightening torque is always to be
checked with a torque wrench.
Screw Applications with Hard, Spring-loaded
or Soft Seat
When in a test, the achieved torques in an im-
pact series are measured and transferred into a
diagram, resulting in the curve of a torque char-
acteristic. The height of the curve corresponds
with the maximum reachable torque, and the
steepness indicates the duration in which this is
achieved.
Reference Values for Maximum Screw/Bolt Tightening Torques
Calculated from the tensional cross-section; utilization of the yield point 90 % (with friction coeffi-
cient μ
= 0.12). As a control measure, always check the tightening torque with a torque wrench.
total
Property Classes ac-
cording to DIN 267
M 6
M 8
M 10
M 12
M 14
M 16
2 609 140 816 | (26.10.10)
Standard Screws/Bolts
3.6
4.6
5.6
2.71
3.61
4.52
6.57
8.7
11
13
17.5
22
22.6
30
37.6
36
48
60
55
73
92
A torque gradient depends on the following fac-
tors:
– Strength properties of the screws/nuts
– Type of backing (washer, disc spring, seal)
– Strength properties of the material being
screwed/bolted together
– Lubrication conditions at the screw/bolt con-
nection
The following application cases result accord-
ingly:
– A hard seat is given for metal-to-metal screw
applications with the use of washers. After a
relatively short impact duration, the maxi-
mum torque is reached (steep characteristic
curve). Unnecessary long impact duration
only causes damage to the machine.
– A spring-loaded seat is given for metal-to-
metal screw applications, however with the
use of spring washers, disc springs, studs or
screws/nuts with conical seat as well as
when using extensions.
– A soft seat is given for screw applications,
e. g., metal on wood or when using lead
washers or fibre washers as backing.
For a spring-loaded seat as well as for a soft
seat, the maximum tightening torque is lower
than for a hard seat. Also, a clearly longer im-
pact duration is required.
4.8
6.6
5.8
4.8
5.42
6.02
11.6
13.1
14.6
23
26
29
40
45
50
65
72
79
98
110
122
High-strength
Bolts
6.8
6.9
8.8
7.22
8.13
9.7
17.5
19.7
23
35
39
47
60
67
80
95
107
130
147
165
196
Bosch Power Tools
10.9
12.9
13.6
16.2
33
39
65
78
113
135
180
215
275
330
Publicidad
