ROHM mandrels - Handbuch (Seite 12)

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R ÖHM GmbH, Schwarzwaldstr. 5, 78112 St. Georgen/Schwarzwald, GERMANY, Tel. (49)7724-9468-0
The following table applies:
Tightening torque in Nm
Quality M5 M6 M8 M10 M12 M14 M16 M18 M20 M22 M24
8.8 5.5 9.5 23 46 80 130 190 270 380 510 670 Nm
10.9 8.1 13 33 65 110 180 270 380 530 720 960 Nm
12.9 9.5 16 39 78 140 220 330 450 640 860 1120 Nm
Attention: The values in the table do not apply when the
tightening torque is expressly specified elsewhere.
Screw quality 12.9 should be selected in cases of doubt when replacing original
screws. 12.9 quality should be selected in all cases involving fixing screws for
clamping inserts, top jaws, fixed stops, cylinder covers and similar elements.
All fixing screws which, due to the purpose for which they are intended, are loosened
frequently and must then be tightened again (e.g. during conversion work) should
have their threads and the bearing surface of their heads coated with a lubricating
medium every six months (grease paste).
Even securely tightened screws can become loose under adverse outside conditions
such as, for instance, vibrations. In order to prevent this happening, all safety-related
screws (clamping fixture fastening screws, clamping set fastening screws etc.) must
be checked and tightened at regular intervals.
Injury risks
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 authorized Röhm personnel if it should prove
impossible to "safely" dissipate this stored energy.
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, consequently, 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.