SMW Autoblok AP-D 170 Manuel D'utilisation page 20

The screws must always be tightened with a torque wrench set accor-
ding to the clamping couples shown in the following table.
Minimum class request 12.9
Dimensions of screw Tightening torque (N.m)
M6 12
M8 30
M10 45
M12 70
4.2.6 The clamping jaws should not extend beyond the diameter of the
chuck. In the rare occasions when jaws are used which extend beyond
the diameter of the power chuck, great care should be exercised in CNC
programming and machining, in order to avoid collisions with the tools
and prevent injury to the operator during machine operation.
4.2.7 NEVER use jaws higher than twice the height of standard jaws.
For special applications with greater heights, it is necessary to use
chucks with tongue and groove master jaws.
4.2.8 The maximum height of the component
to be clamped must NEVER be higher
than 3 times the height of the clamping
jaws.
Components with greater heights must
be supported by a tailstock or by a self-
centering work rest.
4.3 SUGGESTIONS ON HOW TO USE TOP JAWS.
4.3.1 A constant clamping force, the draw coupling applied to the workpiece
increases with the clamping diameter. Therefore always clamp the
component on the greatest diameter possible.
4.3.2 The clamping force is reduced with the increase of the height to which it
is applied; therefore, reduce the height of the clamping jaws as much as
possible.
4.3.3 When good axial tolerance is necessary, do not reference the workpie-
ce on the jaws, because they are deformed by the clamping. In this
case, the axial reference of the workpiece must be done by means of
fixed supports on the chuck body or on the front flange; these points
undergo less axial deformation (fig.7A). It is also possible to have the
axial support on the top jaws when the clamping diameter is medium-
small in case of internal clamping medium-large in case of external
clamping anyway, close to the clamping area (see fig. 7B)
4.3.4 IMPORTANT: When positioning the jaws, the first mounting screw
(A) must be positioned as far as possible away from the fulcrum (C) of
reaction at the gripping coupling thereby incresing the arm (b
reducing the draw force (F1) on the screw itself, and consequently its
stress and deformation.
External clamping: The screw (A) must be as close as possible to the
center:
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INSTRUCTIONS AND SAFETY REGULATIONS
Minimum class request 8.8
Dimensions of screw Tightening torque (N.m)
M16 170
M20 300
M24 500
M30 950
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Internal clamping: The screw (A) must be in the most external position
possible.
4.3.5 We advise the use of collet chucks for
clamping bar stock. If a power chuck is
used for clamping a bar, we suggest
mounting carbide inserts with diamond
clamping areas on the jaws. These
inserts increase the friction coefficient
and compensate for the deformation of
the top jaws.
4.4 INSTRUCTIONS TO TURN SOFT TOP JAWS.
To obtain the best concentricity between the clamping diameter and the
machined one, it is necessary, to take up the clearance and deformation
of the chuck before grinding the soft top jaws. This is done by clamping
a ring (A) or a tool (B) in the same direction as the workpiece (internal or
external).
A) External clamping:
B) Internal clamping:
4.5 "T" NUTS.
4.5.1
Worn out or damaged T nuts must be replaced with original SMW-
AUTOBLOK components. The SMW AUTOBLOK guarantee is void if
non-original "T" nuts are used. The use of substitute components can
>b) and
cause breakage in the chuck and/or in the clamping.
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IMPORTANT. T-nut wear causes deformation in the master jaws
and an increase in the friction between the sliding surfaces. This can
cause seizure or breakage of the master jaws.
4.5.2 When attaching the top jaws to the master jaws, there must be at
least 2 mounting screws and the T nut must not protrude from the "T"
slot in the master jaw.
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