Selection guide for screwdrivers, Tightening torque – Bosch 1375-01 User Manual

Page 24

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47

46

0,1

0,5

1

5

10

50

100

500

1000

Torque for hard screwdriving application as per ISO 5393 (Nm)

Hardness
class per
DIN 267

8.8

10.9

M 2.5

0.7

1.0

M 3

1.2

1.7

M 4

2.9

4

M 5

5.5

8

M 6

9.7

13.6

M 8

23

33

M 10

47

65

M 12

80

113

M 14

130

180

M 16

196

275

M 18

270

380

M 20

385

540

M 22

510

715

M 24

650

910

M 27

960

1345

M 30

1300

1830

Tightening
torque

Guideline values for maximum
bolt/screw tightening torques in
Nm. Assumed friction below head
mges. = 0.12, calculated from the

stressed cross sections: yield point
usage 90 %. Valid for shaft screws
with standard metric thread as per
DIN 13, BL 13; heads as per
DIN 931, 933.

When you select a screwdriver, you
must consider not only the re-
quired torque – as a function of
the pretensioning force required
from the bolted connection – but
also the torque accuracy as a func-
tion of the bolting event. This
information has been compiled in
tables 1 and 2 in order to facilitate
the selection from among the
various bolting systems. The fixed
torque values provided apply to
“hard” bolted connections. The
maximum values are lower for
“soft” bolted connections (e.g.
spring washers, rubber washers,
etc.)

Order number

0 602 485 1..

0 602 488 1..

0 602 486 2..

0 602 489 0..

0 602 487 0..

0 602 442 0..

0 602 443 0..

0 602 440 0..

0 602 433 1..

0 602 438 0..

0 602 435 0..

0 602 439 0..

Screwdrivers with adjustable cut-off clutch

For screw connections with high torque accuracy

Torque upper range limited by reaction torques

Further advantages: low noise, low wear, long service life,
the user has no influence on the torque

Impact Wrenches

For large screw / bolt diameters with high torque

Virtually free of reaction torque, therefore no upward limitation

Torque is a decisive parameter for
controlling the pretension force
applied. The table provides an over-
view of the recommended torques
for common bolt and nut sizes. The
recommended maximum torques
apply to untreated, oil-lubricated
screws (coefficient of friction =
0.125). The torques correspond to
approx. 62 % of the yield point.

Torque accuracy

with automatic

shut-off

Torque accuracy

with overload

disengaging clutch

Torque accuracy

with percussion

mechanism

Torque

Torque

Torque

Torque

Torque

Rotation

Rotation

Rotation

Rotation

Rotation

Rotation

up to
approx.
30°

up to
approx.
60°

over 60°

angle of
rotation
not
definable

very good

good to very good

satisfactory –
depending upon
the degree of
accuracy required

somewhat
unsatisfactory

satisfactory –pro-
vided only a low
level of accuracy
is required

satisfactory

satisfactory

good to very good

good to
satisfactory

satisfactory

satisfactory

good

good – provided
cut-out function
is still operative

good – provided
cut-out function
is still operative

good – provided
cut-out function
is still operative

good – provided
cut-out function
is still operative

good

good – provided
that the function
is still operative

Bolting event

Angle of

rotation

to M

d

max.

Torque accuracy depending
on screwdriver system and
screwdriving type

The torque that can be achieved for
a screw connection depends on the
type of screwdriving / bolting situa-
tion. To achieve a balanced basis for
assessment, all data on screwdrivers
is based on unbending, or “hard”
screw connections (30° angle of
rotation). In the case of flexible or
“soft” screw connections, achievable
values are, in part, considerably
below the nominal values. Further-
more, torque variance increases. Due
to the wide variety of possibilities,
specifications with absolute values
are not possible. If in doubt, use a
trial and error system. The table
offers an overview of the advantages
and achievable torque accuracy of
the individual screwdriver systems
with various characteristic screw-
driving applications.

Torque

SELECTION GUIDE FOR SCREWDRIVERS.

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