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OBJ_BUCH-608-002.book Page 11 Monday, November 23, 2009 8:32 AM
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 accordingly:
– 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.
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-
Standard Screws/Bolts
cording to DIN 267
3.6
M 6
2.71
M 8
6.57
M 10
M 12
22.6
M 14
M 16
M 18
M 20
107
Tips
Before screwing larger, longer screws into hard
materials, it is advisable to predrill a pilot hole
with the core diameter of the thread to approx.
2
/
of the screw length.
3
Belt Clip (see figure D)
With the belt clip 4, the machine can be hung
onto a belt. The user has both hands free and
the machine is always at hand.
Bosch Power Tools
– A spring-loaded seat is given for metal-to-
– A soft seat is given for screw applications,
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.
4.6
5.6
4.8
3.61
4.52
4.8
8.7
11
11.6
13
17.5
22
23
30
37.6
40
36
48
60
65
55
73
92
98
75
101
126
135
143
178
190
The belt clip 4 can be attached and screwed to
either side of the machine.
The belt clip 4 will automatically draw out when
pressing both release buttons. To dismount the
belt clip 4, remove the complete unit by un-
screwing the fastening screw.
Always tighten the fastening screw after mount-
ing the belt clip 4.
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.
e. g., metal on wood or when using lead
washers or fibre washers as backing.
6.6
5.8
6.8
6.9
5.42
6.02
7.22
8.13
13.1
14.6
17.5
19.7
26
29
35
39
45
50
60
67
72
79
95
107
110
122
147
165
151
168
202
227
214
238
286
320
1 609 929 T16 | (23.11.09)
English | 11
High-strength
Bolts
8.8
10.9
12.9
9.7
13.6
16.2
23
33
39
47
65
78
80
113
135
130
180
215
196
275
330
270
380
450
385
540
635
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