Fig. 2. A point cloud view of the surface is shown.
three measurement planes, each rotated over 120 degrees around the C axis.
Te laser scanner produces visible
light at a 662 nm wavelength. To ensure correct identification of the location of laser light projected on the surface of the casting, the casting surface is prepared to prevent light reflection, absorption or transmission. Te part surface is cleaned and coated in a dull white non-reflective finish. An even white color minimizes any extraneous
Fig. 3. Here is a close-up view of the point cloud.
data that might be collected from the fixturing used to locate and hold the part, which can be covered in black cloth, as well. Te type of fixturing used for
inspection is based on its ability to hold the casting so all of the tooling points, or datum targets, are visible within the given field of view (FOV) based on the articulation of the scanner on the CMM. Normally, one surface of the casting will face the surface plate. To collect data on this bottom facing
Fig. 4. Multiscan passes have unique colors.
surface, the casting must be reposi- tioned to put the unscanned surface in a visible orientation. When the scanner is used in conjunction with the CMM, the data collected from a single part orientation has a common X-Y-Z origin. Even though the scanner may have to be rotated many times to see all the surfaces of the casting, all of the scan passes will have a single origin to locate all of the point cloud data. Data collected from other types of laser scanning device may require alignment
20 | METAL CASTING DESIGN & PURCHASING | Nov/Dec 2013
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