English | 7
Bosch Power Tools 3 609 929 D01 | (7.3.14)
Determining the Impact Duration
The diagrams (examples) indicate that the tightening torque
[Nm] depends on the impact duration [s]:
For a hard seat
For a soft seat.
The data are mean values and vary depending on the applica-
tion. As a control measure, always check the tightening
torque with a torque wrench.
Diagram for GDS 24
The highest torque is achieved:
– for a hard seat after approx. 10 seconds of impact
– for a soft seat after approx. 22 seconds of impact
Diagram for GDS 30
The highest torque is achieved:
– for a hard seat after approx. 6 seconds of impact
– for a soft seat after approx. 26 seconds of impact
For reference values for the maximum tightening torques of
commercially available screw/bolts, see the following table.
Reference Values for Maximum Screw/Bolt Tightening Torques
Calculated from the tensional cross-section; utilization of the yield point 90 % (with friction coefficient μ
total
= 0.12). As a control
measure, always check the tightening torque with a torque wrench.
Examples for Determining the Impact Duration
(GDS 30)
Screw/bolt size M 24 of property class 8.8 = Screw/bolt tight-
ening torque 650 Nm
For 650 Nm, the GDS 30 diagram reveals an impact duration
of 0.8 seconds. (Diagram for GDS 30 see page 7)
Tips
Torque rods have shanks with precisely calibrated, reduced
diameters. Thus, they act torque-limiting. 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 determined through practical testing.
Property Classes ac-
cording to DIN 267
Standard Screws/Bolts High-strength Bolts
3.6 4.6 5.6 4.8 6.6 5.8 6.8 6.9 8.8 10.9 12.9
M 8
6.57 8.7 11 11.6 13.1 14.6 17.5 19.7 23 33 39
M 10
13 17.5 22 23 26 29 35 39 47 65 78
M 12
22.6 30 37.6 40 45 50 60 67 80 113 135
M 14
36 48 60 65 72 79 95 107 130 180 215
M 16
55 73 92 98 110 122 147 165 196 275 330
M 18
75 101 126 135 151 168 202 227 270 380 450
M 20
107 143 178 190 214 238 286 320 385 540 635
M 22
145 190 240 255 290 320 385 430 510 715 855
M 24
185 245 310 325 370 410 490 455 650 910 1100
M 27
275 365 455 480 445 605 725 815 960 1345 1615
M 30
370 495 615 650 740 820 990 1110 1300 1830 2200
OBJ_BUCH-550-002.book Page 7 Friday, March 7, 2014 1:03 PM
To Next Page
Loading...
