Correlation of CMM Data with Flexible Fixturing

To correlate data collected at multiple sites when using flexible fixturing to position parts for a CMM (Coordinate Measurement Machine), there are additional factors to consider and coordinate than when using CMM Holding Fixtures.

When measuring sheet metal with hard gages or using CMM holding fixtures at multiple sites, the following factors must be considered:

1. 1)
   Datums must be coordinated
2. 2)
   Part orientation must be common with respect to gravity
3. 3)
   Clamp sequence must be the same
4. 4)
   Measurement points and approach angles must be identical

When measuring sheet metal with flexible fixturing, such as a DEA System 5 (Manufactured by DEA Brown & Sharpe), at multiple sites, additional factors come into play:

1. 5)
   The locations of the programmable sheet metal supports (commonly called bowling pins) must be alike and positioned at, or as close as possible to, the same datums
2. 6)
   Clamping devices generally are not necessary
3. 7)
   The alignment points must be alike
4. 8)
   The quantity of iterations and acceptance criteria used for best fit must be the same
5. 9)
   Alignment points must be output in the measurement report

This paper will describe and demonstrate the importance of all of these factors and focus on the ones, which are unique to flexible fixturing systems, such as the DEA System 5.