Automated Outer Mold Line (OML) Measurements and Control
Carson Rooms 1 and 2, enter at Carson 1
Ken Vakil - Representing NGAS
Stringent step and gap tolerance requirements are placed upon outer mold line components such as fixed skins, panels and doors. The aircraft design identifies these steps and gaps as key characteristics which must be measured, controlled and improved upon on the production floor. The current processes for achieving these requirements are manual, non-robust and require several iterations of measurements to achieve the desired results – all which add to the product cost and cycle time.
To address this need, Northrop Grumman Aerospace Sector Manufacturing Technology Development organization is developing OML measurement and control system utilizing state-of-the-art metrology technologies. The presentation specifically discusses methodologies used for laser radar method as well as other technologies which are under consideration.
One of the systems tested for this application was the laser radar method in which data was compared with standard calibrated blocks to determine accuracy of the measurements. Composite thickness measurements were made and compared with standard micrometer readings. On the skin and panel assembly, the OML data was compared with the existing method of using hand-held laser gauge.
A test mock-up was created to simulate the gap and step condition encountered during the skin/panel assembly. Measurements were made using the laser radar method along edges and knowing the thickness and cavity depth condition, shim size calculation was computed.
On the aircraft assembly, the system will be designed to predict the shim size and location to achieve OML control based upon composite part thickness and “as built” location of the underlying structure while providing assembly guidance to the mechanics regarding size and location of the shims. The ultimate goal being to implement a robust OML control process that meets required measurement accuracy, is affordable, and provides a “value-approach”.
