Original Date: 10/20/1997
Revision Date: 01/18/2007
Best Practice : Factory Process Modeling and Simulation
Northrop Grumman’s Simulation and Virtual Manufacturing Tools team developed Factory Process Modeling and Simulation for some sections of the F/A-18 C/D assembly line. Through modeling and simulation, the company can continuously make improvements in quality and productivity, and evaluate new ideas, methods, and actions. Simulation tools can develop utilization profiles for resources; allow Integrated Product Teams to plan and analyze possible scenarios; predict production system behavior without disrupting ongoing operations; and identify processes where lean manufacturing practices will have the greatest impact.
As a test case, the team modeled the production operations of Cost Center 2510 (the Aft Center Fuselage Assembly). First, the team developed an assembly precedence model using Microsoft project. This model identified critical paths and opportunities for shortening the process cycle. Next, the model was fine tuned via input from the mechanics working on the production line. Then the model was exported from Microsoft Project, translated, and imported into the Autosimulations Autosched software. A graphic simulation model of the Center was developed in the Autosched software (see Figure 2-2). To populate the model, data was downloaded from 35,000 lines of production scheduling and the Integrated Management, Planning, and Control for Assembly system. Other types of data used in the simulation included operator data such as quality certifications, efficiency/experience, difficulty of tasks, and job preference qualifications. The team devised and ran numerous simulation experiments to vary the parameters (e.g., operator efficiency, number of operators, work shift hours, number of nonconformances, quality assurance processing time).
Through this modeling and simulation effort, Northrop Grumman identified opportunities for a 10% cost reduction in the Center’s operation. Simulations were also used to determine the best course of action to deal with part shortages occurring at the Center. The company was able to define and analyze possible scenarios for handling the shortages in a three-hour timeframe. Northrop Grumman is now applying its Factory Process Modeling and Simulation to other production areas within the company. A detailed simulation model of the Composites Center has already been developed.
Figure 2-2. Simulation Model of Assembly Area 2510
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