Bosch GDS 18 E Professional Original Operating Instructions page 8
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- Original instructions manual (146 pages) ,
- Original instructions manual (97 pages) ,
- Original instructions manual (31 pages)
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OBJ_BUCH-546-001.book Page 8 Friday, November 9, 2007 8:43 AM
8 | English
Screw Applications with Hard, Spring-loaded or
Soft Seat
When in a test, the achieved torques in an impact
series are measured and transferred into a dia-
gram, the result is the curve of a torque charac-
teristic. The height of the curve corresponds with
the maximum reachable torque, and the steep-
ness indicates the duration in which this is
achieved.
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
Reference Values for Maximum Screw/Bolt Tightening Torques
Calculated from the tensional cross-section; utilization of the yield point 90 % (with friction coefficient
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
M 18
M 20
Tips
Torque rods have shanks with precisely calibrat-
ed, reduced diameters. Thus, they act torque-lim-
iting. A torque rod is placed between the impact
wrench and the bit.
Rule of thumb for the application: Core diameter
of the screw/bolt = effective diameter of the
torque rod. The impact duration is to be deter-
mined through practical testing.
The thumbwheel 2 must be set to max. here.
1 609 929 M72 | (9.11.07)
Standard Screws/Bolts
3.6
4.6
5.6
4.8
2.71
3.61
4.52
4.8
6.57
8.7
11
11.6
13
17.5
22
23
22.6
30
37.6
40
36
48
60
65
55
73
92
98
75
101
126
135
107
143
178
190
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 maximum
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 wash-
ers or fiber 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 impact duration
is required.
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
For hanging up, a suspension hook 1 is mounted
at the machine's centre of gravity.
At temperatures below the freezing point, run
the machine for approx. 3 minutes at no-load to
improve its lubricating capacity.
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
Bosch Power Tools
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