Original Date: 10/20/1997
Revision Date: 01/18/2007
Best Practice : Wiring Harness Master Assembly Jig Tooling
Historically, the design of aircraft wiring harnesses involved a laborious manufacturing process where fabricators built a prototype based on 2-D drawings, and then fitted and curved the apparatus to meet internal aircraft specifications. Fabricators had to rely on tape measures and note pads to calculate the bends and curvatures of the wiring harness for incorporation into the aircraft’s fuselage. In many instances, wiring harnesses required additional modification even as the latest changes were being incorporated into the aircraft’s design. These trial-and-error obstacles would either stall the fabrication process or require the creation of a new wiring harness. Today, numerous computer software programs exist to assist engineers in designing aircraft wiring harnesses.
Northrop Grumman chose the Common Electrical Electronic Data Systems (CEEDS) software to design and develop its aircraft wiring harnesses in relationship to electrical systems, wiring diagrams, cable assemblies (build-to packages), circuit configurations, and jig board tooling of the F/A-18 E/F program. This choice allows the company to integrate its Unigraphics 3-D geometrical data with the CEEDS wiring data to create an electrical wiring harness jig board master layout and ensure that the 3-D drawing agrees with the wiring harness tooling. The CEEDS software also defines the wiring data required including wire length, diameter, breakouts, connector clocking, and braid stops. In addition, the Unigraphics 3-D modeling allows the designer to add dimensional requirements and spacing/routing configurations (i.e., component identification in the style of connectors used) to create wiring harness jig board master tooling layouts. Northrop Grumman can update the wiring harness jig board master through engineering change approvals of the 3-D geometric drawing package, thereby maintaining configuration control.
With the advent of wiring harness jig board master tools, all installation and design considerations are taken into account, and a pattern jig can be developed for fabricating electrical wiring harnesses. The jig board highlights the application of the routing for wiring flow, interconnects, and even braid stop locations. Fabricators can identify the layout of the wiring harness, as it relates to the aircraft, without ever performing a trial fit. Additional wiring harness jigs can be developed based on production requirements.
By using the wiring harness master assembly jig tooling, Northrop Grumman has realized major cost savings, especially in expended hours. Scheduled implementation time has been reduced from 36 months to 11 months due to the design-development-to-installation time of wiring the harness into the aircraft. Northrop Grumman is also investigating a laser marking process for the wires used in the wiring harness. Laser marking equipment, manufactured by Vektonics Incorporated Laser Marker, will allow the wire to be inscribed with nomenclature at the rate of 200 feet per minute at three-inch spacing increments. Although cost savings associated with the laser marking process have not been determined, Northrop Grumman anticipates an increase in convenience of rework/repair identification and configuration control.
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