Siemens SINUMERIK 840Di Function Manual page 157

Overload factor
The overload factor restricts step changes in the machine axis velocity at block ends. So that
the velocity jump does not exceed the maximum load on the axis, the jump is derived from
the acceleration of the axis.
The overload factor indicates the extent by which the acceleration of the machine axis, which
is set in machine data
MD32300 MAX_AX_ACCEL (axis acceleration),
may be exceeded for an IPO cycle.
The velocity jump is the product of the axial acceleration * (overload factor -1) * interpolator
cycle.
The factor is set in machine data:
MD32210 MAX_ACCEL_OVL_FACTOR
(overload factor for axial velocity jumps).
Factor 1.0 means that only tangential transitions with finite velocity can be traversed. For all
other transitions, the velocity is reduced to zero by changing the setpoint. This behavior is
equivalent to the function "Exact stop with interpolator end". This is undesirable for
continuous-path mode, so the factor must be set to greater than 1.0.
For startup and installation, please note that the factor must be reduced if the machine is
likely to be subject to vibrations during angular block transitions and rounding is not to be
used.
Set machine data:
MD20490 IGNORE_OVL_FACTOR_FOR_ADIS
to smooth block transitions irrespective of the programmed overload factor.
Selection and deselection of velocity reduction
Continuous-path mode with velocity reduction according to overload factor can be selected
modally in every NC part program block by means of program code G64.
Continuous-path mode G64 can be
• Interrupted non-modally by selecting exact stop G09
• Deselected by selecting exact stop G60
• Deselected by selecting rounding G641
Continuous-Path Mode, Exact Stop, LookAhead (B1)
Function Manual, 08/2005 Edition, 6FC5397-0BP10-0BA0
Detailed Description
2.3 Continuous-path mode
2-9