HEIDENHAIN ND 1200T - Manual (Page 82)

Chapter 3 Setup
3-30
Error Correction
Linear, segmented linear and non-linear error correction methods
can be used with the TC200. Linear and segmented linear error
corrections are provided with every TC200. system and non-linear
error correction is provided as an option. Each method compen-
sates for encoder and machine travel variations using error cor-
rection coefficients developed by comparing actual measurements
of a standard to the standard’s nominal values.
Linear error correction (LEC) uses one correction coefficient for
each axis to compensate for variations along the axis. For ex-
ample, a linear error correction coefficient of 0.0002 “/inch ap-
plied to a 6” measurement along the X axis would produce a mea-
surement result of 6.0012”.
Segmented linear error correction (SLEC) divides each axis into up
to 7 segments. Each segment uses one error correction coeffi-
cient to compensate for variations within the segment. Each axis
also includes a machine zero offset to refer the position of the
standard’s datum to the machine zero reference. The standard’s
nominal and measured segment values must be specified during
the setup process. The machine zero offset for each axis must
also be specified. When SLEC is used, the stage must be moved to
cross a reference mark/hard-stop on each axis upon system startup
to initialize SLEC.
Non-linear error correction (NLEC) uses a standard that divides the
entire measurement area into a grid of up to 30 X 30 cells. Each
cell uses error correction coefficient for each axis to compensate
for variations within a cell. The standard’s nominal and measured
X and Y values must be specified for the positions of each cell
during the setup process. The machine zero offset to the grid
datum must also be specified. When NLEC is used, the stage must
have a repeatable
machine zero defined on startup to initial-
ize NLEC.
NOTE NOTE NOTE NOTE NOTE
Y
Y Y Y You must set the machine zero by crossing reference marks on ou must set the machine zero by crossing reference marks on ou must set the machine zero by crossing reference marks on ou must set the machine zero by crossing reference marks on ou must set the machine zero by crossing reference marks on
the X and Y encoders before calibrating the SLEC and NLEC error the X and Y encoders before calibrating the SLEC and NLEC error the X and Y encoders before calibrating the SLEC and NLEC error the X and Y encoders before calibrating the SLEC and NLEC error the X and Y encoders before calibrating the SLEC and NLEC error
corrections.
corrections. corrections. corrections. corrections.