Siemens SINUMERIK Series Function Manual

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K3: Compensations4.4 Interpolatory compensationExtended Functions238 Function Manual, 03/2013, 6FC5397-1BP40-3BA1Compensation value at reference pointThe compensation table should be structured such that the compensation value at thereference point is "zero".4.4.2 Compensation of leadscrew errors and measuring system errors4.4.2.1 Measuring system error compensation (MSEC)Leadscrew and measuring system errorsThe measuring principle of "indirect measurement" on NC-controlled machines is based onthe assumption that the lead of the ball screw is constant at any point within the traversingrange, so that the actual position of the axis can be derived from the position of the drivespindle (ideal case). However, manufacturing tolerances result in dimensional deviations ofvarying degrees of severity on spindles (so-called leadscrew errors).Added to this are the dimensional deviations (differences in reference division) caused bythe measuring system as well as its mounting on the machine (so-called measuring systemerrors), plus any machine-dependent error sources.CompensationWith "measuring system error compensation" (referred to below as MSEC), the base andcompensation axes are always identical. It is therefore an axial compensation for which adefinition of the base axis and compensation axis in the compensation table is notnecessary.NoteThe leadscrew error compensation (LEC) is part of the measuring system errorcompensation.The principle of the MSEC is to modify the axis-specific position actual value by the assignedcompensation value in the interpolation cycle and to apply this value to the machine axis forimmediate traversal. A positive compensation value causes the corresponding machine axisto move in the negative direction.The magnitude of the compensation value is not limited and is not monitored. In order toavoid impermissibly high velocities and accelerations caused by compensation, smallcompensation values must be selected. Large compensation values can cause other axismonitoring functions to output alarms (e.g. contour monitoring, speed setpoint limitation).If the axis to be compensated has a 2nd position measuring system, a separatecompensation table must be created and activated for each measuring system. The correcttable is automatically used when switching between measuring systems.