Original Date: 02/26/2001
Revision Date: 01/18/2007
Best Practice : Rapid Prototyping
Rapid prototyping at the unit level has enabled General Dynamics Armament Systems to realize significant time and money savings in the development of Line Replaceable Units. Other advantages of this process include quality improvement of the product and the production of visual aids.
In the past, the mechanical design process involved designing castings, gears, sprockets, shafts, and miscellaneous parts; developing multiple drawings over a six- to twelve-month period; and then producing the parts in metal. Today, General Dynamics Armament Systems (GDAS) utilizes concurrent engineering in the mechanical design process to shorten its design lead times. Rapid Prototyping (RP) allows the company to identify potential problems and determine the needs of casting, machining, and assembly processes prior to the manufacturing phase. This approach drastically reduces tooling costs. GDAS also uses Rapid Prototyping to verify proof of concept and produce visual aids for its customers and suppliers. As a result, the company ensures compliance before major investments are made in the development of an actual product. Rapid Prototyping also assists in the selection of a foundry by allowing potential suppliers to bid on development by using a model.
All development programs as well as casting development now use Rapid Prototyping to build hardware. Full-size working models are built from piece-part models to generate workable Line Replaceable Units (LRUs) for proof of concept and design reviews. These units verify the working relationships between parts that make up the unit and draw attention to mechanical deficiencies which need corrective action before the actual build. Limited quantities of spares can also be produced for customers where tooling is no longer available.
In identifying a rapid prototyping (RP) process to suit its needs, GDAS used an equipment selection process which took cost, usage, accuracy, material, environmental, and health concerns into consideration. The Stratasys FDM 2000 was selected. This fused deposition modeling (FDM) process has a 10 x 10 x 10-inch envelope; utilizes the Quickslice software to view and generate parts; and has enabled the company to generate hundreds of in-house models for design concepts, fit checks, and analysis.
The KTX-2 Program’s A-50 Gun Ammunition Transfer Unit demonstrates the benefits gained from Rapid Prototyping. Previously, this project would have required the fabrication of two large complex castings as well as six gears, seven sprockets and shafts, and 32 miscellaneous parts and hardware to populate the unit. The 20 drawings would also have taken ten weeks to be produced. Overall development time would be about 12 months to obtain the castings and produce the parts in metal. By using Rapid Prototyping, GDAS only needed three weeks to produce the parts in plastic and assemble them. As a result, interference and assembly problems were corrected in weeks rather than months, and saved the company time and money in rework.
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