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9-18
Application Notes
Dynamic sizing
Sizing recommendation
Normal Operation
In normal operation, using the holding brake for clamping of an axis
standstill, the brake`s static torque (M4) rating in the data sheets applies
directly as static friction (M4) – stiction (friction coefficient µ
Fault Condition (EMERGENCY STOP)
In fault conditions (i.e., EMERGENCY STOP), where the holding brake
is used to stop a moving axis, the "dynamic braking torque", or sliding
friction (friction factor µ
G
The dynamic braking torque is reduced in comparison to the indicated
static holding torque M4. Therefore, note the following description of
dynamic sizing.
The load torque must be lower than the minimum dynamic torque which
the brake can provide. Otherwise the dynamic brake torque is not
sufficient to stop the axis.
If a mass is to be decelerated in a defined time or in a defined way, the
additional moment of inertia of the whole system must be taken into
account.
Further important aspects for sizing:
The holding brake is not a safety brake (see DIN EN 954 / 03.97 and
vertical axis data sheet SMBG). Due to uncontrollable influencing factors
such as a rust film on the brake surface, the brake holding torque can be
reduced. Additionally, excessive voltages and temperatures can weaken
the permanent magnets and the brake.
Bringing these factors together, the following recommendations can be
given for sizing the holding brakes to the axles.
The necessary holding torque required for the application must not
exceed a maximum of 60% of the static holding torque (M4) of the
used holding brake.
Note:
Holding torque reduction and premature wear occur when
braking moving axles!
Do not use the holding brake to stop a moving axle! This is
permitted for EMERGENCY STOP situations only. In this
situation, the specified rated torque of the holding brake (M4)
is reduced to the value of the available dynamic braking
torque. Complete deterioration of brake holding capability can
be expected after approximately 20,000 revolutions of the
brake when clamped.
Observe the instructions on commissioning holding brakes as described
in chapter 12 "Startup, Operation, and Maintenance".
) applies.
DOK-MOTOR*-MAD/MAF****-PR03-EN-P
Rexroth IndraDyn A
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