Metrology for NCSX
Steve Raftopoulos and the NCSX
– Two laser trackers:
• Leica LTD 500 (Interferometer and ADM unit) upgraded to EmScon interface
• Faro Tracker X (ADM unit only)
– Three Romer articulating arms – 12 ft length.
– Verisurf CAD-based 3D inspection software running on all hardware
platforms. Metrology software built on top of MasterCam CAD?CAM
software. Allows manipulation of CAD data and creation of layers for
organization of metrology data.
– Leica AXYZ and EmScon software available for interfacing and
Diagnostics for Leica Laser Tracker.
– Faro Utilities software for interfacing with Faro Laser Tracker
Coil winding and Initial Coordinate System
• Coordinate system of coil is
established during coil winding
phase with the coil in a vertical
position in the ring.
• Approximately 10,000
measurement points (taken with
Romer Arm) on winding form are
best fit to CAD geometry.
• Coil is wound using this reference
• Unfortunately, the coils are NOT
rigid bodies – they flex under their
own gravity load when the
support system is changed.
Field Period Assembly (FPA) Preliminary
• Coil is placed on horizontal fixture
for measurements prior to sub-
assembly of 3 coils.
• The coil is deformed using
wedge/lifting plates in order to re-
create the shape measured in the
coil winding fixture.
• Reshaping error must be less than
0.005” (~0.12 mm)
• Once acceptable reshaping is
achieved, the flange faces and
tooling balls (fiducial points) are
FPA Measurements (continued)
• In order to characterize the entire
coil, at least three laser tracker
positions are required.
• A set of Global Fiducial points is
used to re-align to the coil. These
Global points were established
immediately after alignment to the
coil coordinate system.
• Re-alignment error (to global
points) must be less than 0.002”
Integrity of Measurements
• Laser trackers are checked
daily by performing two-face
• Laser tracker accuracy is
verified by measuring a
N.I.S.T. traceable length
• Measurement data is validated
by re-measuring alignment
points after data collection.
This verifies that the coil and
laser tracker remained stable
• Currently we are working with individual components.
• Alignment to known fiducial points on the measured part defines the
• Deflection of the part is a major concern.
• We fiducialize monuments surrounding the part and use these
monuments to “leapfrog” around the part to obtain complete scan.
• In the future assembly of these components we will establish the
machine coordinate system in the assembly hall and move the parts
to the correct position.
• Deformation of the assembly of parts as well as deformation of the
assembly hall will be important concerns.