Leadscrew Error And Measuring System Error Compensation; Measuring System Error Compensation (Msec) - Siemens SINUMERIK 840D sl Function Manual

Supplementary conditions
Compensation value at reference point
It is recommended that a compensation table be structured in such a way that the
compensation value has the value "0" at the reference point of the axis.
5.4.2

Leadscrew error and measuring system error compensation

5.4.2.1

Measuring system error compensation (MSEC)

Leadscrew and measuring system errors
The measuring principle of "indirect measurement" on NC-controlled machines is based on
the assumption that the lead of the ball screw is constant at any point within the traversing
range, so that the actual position of the axis can be derived from the position of the drive spindle
(ideal case). However, manufacturing tolerances result in dimensional deviations of varying
degrees of severity on spindles (so-called leadscrew errors).
Added to this are the dimensional deviations (differences in reference division) caused by the
measuring system as well as its mounting on the machine (so-called measuring system errors),
plus any machine-dependent error sources.
Compensation
With "measuring system error compensation" (referred to below as MSEC), the base and
compensation axes are always identical. It is therefore an axial compensation for which a
definition of the base axis and compensation axis in the compensation table is not necessary.
Note
The leadscrew error compensation (LEC) is part of the measuring system error compensation.
The principle of the MSEC is to modify the axis-specific position actual value by the assigned
compensation value in the interpolator clock cycle and to apply this value to the machine axis
for immediate traversal. A positive compensation value causes the corresponding machine
axis to move in the negative direction.
The magnitude of the compensation value is not limited and is not monitored. In order to avoid
impermissibly high velocities and accelerations caused by compensation, small compensation
values must be selected. Large compensation values can cause other axis monitoring
functions to output alarms (e.g. contour monitoring, speed setpoint limitation).
If the axis to be compensated has a 2nd position measuring system, a separate compensation
table must be created and activated for each measuring system. The correct table is
automatically used when switching between measuring systems.
Extended Functions
Function Manual, 10/2015, 6FC5397-1BP40-5BA3
K3: Compensations
5.4 Interpolatory compensation
267