ROHM Safety instructions and guidelines for the use of power-operated clamping devices - Manual (Page 5)

I. Qualifications of operating personnel
Personnel lacking any experience in the handling of clamping
fixtures are at particular risk of sustaining injury due to
incorrect handling and usage, such injuries emanating in
particular from the clamping movements and forces involved
during setup work. Clamping fixtures should therefore only
be used, set up or repaired by personnel specially trained or
instructed for this purpose and / or who have long years of
experience. Chuck functionality should be tested after
mounting prior to commissioning.
Two important points are:
Clamping force: The clamping force specified for the
clamping medium (+15%) should be achieved at max.
actuation force / pressure.
Stroke monitoring: The clamping piston stroke should have a
safety range in the front and rear end position. The machine
spindle should only start if the clamping piston has passed
through the safety range. Only limit sensors should be used
for monitoring the clamping distance, and these should meet
the requirements for safety limit sensors specified in VDE
0113 / 12.73 Section 7.1.3.
II.Injury risks
This module can, for technical reasons, consist in part of
individual components with sharp edges and corners. Any
tasks involving this module should be carried out with
extreme care to prevent risks of injury!
1.Integrated energy storage
Moving parts which are pretensioned with pressure
springs, tractive springs and other springs, or other flexible
elements, are a potential source of risk, due to the intrinsic
energy stored. Underestimation of this can lead to serious
injury caused by uncontrolled, flying parts being propelled
through the air. This stored energy must be dissipated
before work can be continued. Clamping fixtures which
are to be dismantled should be inspected for such
sources of danger with the assistance of the respective
assembly drawings.
The fixture should be dismantled by authorised RÖHM
personnel if it should prove impossible to ”safely” dissipate
this stored energy.
2.Maximum permissible speed
The max. permissible speed may only be set with applied
max. actuation force and clamping chucks which are
functioning perfectly. Failure to observe this basic principle
can lead to a loss of residual clamping force and, conse
quently, workpieces being thrown out of the chuck and the
risk of injury associated with this. The clamping fixture
should only be used at high speeds under an adequately-
dimensioned safety guard.
3.Exceeding the permissible speed
This equipment is intended for revolving operation.
Centrifugal forces created by excessive speed and / or
peripheral speed can result in individual parts loosening
and becoming potential sources of danger for personnel
or objects in the near vicinity. In addition to this, clamping
media which are only designed for use at lower speeds
but are operated at high speeds can result in unbalance
which adversely affects safety and the machining results
achieved. Operation at speeds higher than those permit-
ted for these units is prohibited for the above-mentioned
reasons. The max. speed and actuation force / pressure
are engraved on the body and should not be exceeded.
This means that the max. speed of the machine being
used should not exceed that of the clamping fixture
1. Safety instructions and guidelines for the use of
power-operated clamping devices
(i.e. it should be limited accordingly). Even a singular incident
where the permitted values are exceeded can lead to damage
or injury and represent a hidden source of risk, even if not
immediately detected. The manufacturer should be informed
immediately in such cases so that an inspection of functional
and operational safety can be conducted. Further safe
operation of the clamping unit can only be guaranteed in
this manner.
4.Unbalance
Residual risks can emanate from insufficient rotary compensa-
tion, see § 6.2 No. e) EN 1550. This applies in particular where
high speeds are involved, when machining asymmetrical
workpieces or when using different top jaws. The chuck should
be dynamically balanced with the workpiece mounted in accor
dance with DIN ISO 1940 to prevent any resulting damage.
5.Calculating the required clamping forces
The required clamping forces and / or permissible maximum
speed for the chuck should be determined for a specific task
in accordance with VDI Guideline 3106 (governing the
determination of permissible speeds for rotary chucks (jawed
chucks)). High centrifugal forces associated with special clam-
ping inserts which, due to their design, are heavier or larger
than the clamping inserts allocated to the clamping medium
should be taken into consideration when determining the
required clamping force and permissible speed.
6.Use of other / additional clamping sets / workpieces
VDI Guideline 3106 governing the determination of permissi-
ble speeds for rotary chucks (jawed chucks) should always be
consulted when using clamping inserts / workpieces.
1.Use of other / additional clamping inserts
The operator must rule out use of the chuck at an inordinately
excessive speed and, consequently, the generation of
excessive centrifugal force if clamping inserts other than
those intended for this clamping fixture are used. A risk
exists otherwise that the workpiece will not be adequately
clamped. The chuck manufacturer and / or designer should
therefore be consulted in all such cases.
2.Danger due to ejection
So as to protect the operator against ejected parts and in line
with DIN EN 12415 a separating protective equipment must
be fitted to the machine tool, the resistance capability of
which is specified in so-called resistance classes. Should
new clamping sets be used on the machine, their approved
suitability must first be checked. This also includes clamping
sets and / or parts thereof manufactured by the user himself.
This approved suitability is influenced by the resistance
class of the protective equipment, the mass of the possible
ejected parts (determined by calculation or weighing), the
max. possible chuck diameter (measure) as well as the max.
possible speed of the machine. In order to reduce the possi-
ble impact force to the permissible value, the permissible
mass and RPM must be determined (e.g. enquiry at the
machine manufacturer) and then the max. RPM of the
machine restricted (if required). However, the parts of
the clamping set (e.g. top jaws, workpiece supports, face
clamping claws etc.) should be designed to be as light
as possible.
3.Clamping other / additional workpieces
Special clamping sets designed for use with this clamping
fixture (jaws, clamping inserts, locating fixtures, aligning
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23021-k001-004_005 06.09.2006 11:14 Uhr Seite 5