Backlash Compensation; Description Of Functions - Siemens SINUMERIK 840D sl Function Manual

K3: Compensation

5.3 Backlash compensation

5.3 Backlash compensation
5.3
5.3.1

Description of functions

Mechanical backlash
When force is transmitted between a moving machine part and its drive (e.g. ball screw),
there is normally a small amount of backlash because adjusting mechanical parts so that
they are completely free of backlash would result in too much wear and tear on the machine.
Thus, backlash (play) can occur between the machine component and the measuring
system.
Effects
In the case of axes/spindles with indirect measuring systems, mechanical backlash falsifies
the traversing path. For example, when the direction of movement is reversed, an axis will
travel too much or too little by the amount of the backlash.
Positive backlash (normal case)
The encoder leads the machine part (e.g.
table). Since the actual position acquired by
the encoder also leads the real actual
position of the table, the table travels too
short a distance.
Backlash compensation
To compensate for backlash, the axis-specific actual value is corrected by the axis-specific
backlash amount specified when commissioning (MD32450, see "Backlash (Page 353)")
every time the axis/spindle changes direction.
Activation
Backlash compensation is always active in all operating modes after reference point
approach.
352
Negative backlash
The encoder lags behind the machine part
(e.g. table). The table travels too far as the
actual position of the table leads the actual
position detected by the encoder.
Function Manual, 09/2009, 6FC5397-1BP20-0BA0
Extended Functions