NJC Initiates New Joining Development Projects
To Support Navy Platforms

The Navy Joining Center (NJC), operated by Edison Welding Institute, has been awarded several new joining development projects from the US Navy’s ManTech office to address materials joining issues for new weapons platform systems. Projects recently initiated are: Weld Development of Large Structures for Hull Integration, Improved Hull Fabrication and Assembly Welding, Structure Fabrication Weld Improvement, and Improved Affordability of Sheet Metal Products. These projects are in support of the next generation destroyer (DDX) and Virginia class submarines (VCS).

Weld Development of Large Structures for Hull Integration: Current design concept for the multi-role surface combatant includes a number of large structures for each ship that are to be fabricated from thick-section high-strength steel. The heavy structures are to be manufactured in modular form and brought shipside for erection with the hull. The cost to integrate the large modules into the ship hull will be excessively high and production cycle times will be very long without significant improvements in manufacturing technology to replace current welding practices presently available for this work.

The goal of this project is to develop mobile, high productivity, welding technology for integration of the heavy thick-section modules to the hull of the DDG 1000. The development will investigate several processes to facilitate out-of-position erection welding. Robust welding procedures will be developed with the preferred processes, and the integration of weld mechanization to maximize first time quality. These advancements are targeted to reduce welding labor hours and assure first time quality.

Improved Hull Fabrication and Assembly: The need for continuous improvement in manufacturing costs of Virginia Class submarines (VCS) is of high importance for the Navy and its shipbuilders. The shipyards are focusing on reducing construction costs from $2.4 billion to $2 billion per hull. The specific goal is to achieve a 20% reduction in welding costs by focusing on those operations that have been identified to have the greatest potential for savings. One objective is to reduce construction time from 84 months to 60 months by 2009. Development opportunities have been identified by the U.S. Navy and its subcontractors to apply new manufacturing processes and technologies to reduce the costs of welding hull cylinders and subassemblies. The objective of this project is to reduce construction costs for VCS by developing and applying technology to reduce welding costs for hull fabrication and assembly.

Initial reviews of hull welding operations have identified a number of opportunities to improve welding processes and equipment to reduce ship construction labor costs. As a result of the review this project will address: 1) Horizontal butt welds, i.e., ships-position C-seams, 2) High heat input welding, 3) Welding hull inserts and penetrations, and 4) Adaptive mechanized butt welding.

Structure Fabrication Weld Improvement: In follow-on activity to support the need for continuous improvement for VCS, operations involved with the production of structural fabrications have been identified as major contributors to construction costs. Specific fabricated structural elements include tank internals, mid-span bulkhead structures, main propulsion foundations, manhole liners, and penetrations. Preliminary assessments have identified opportunities to improve the accuracy of weld preparations, component assembly and fit-up, preheating, welding processes, and equipment, as well as increased use of fixtures, positioning, automation, and mechanization.

This project will be performed in two phases addressing: 1) Mechanized welding of structures, 2) Reducing the cost of preheating weldments, and 3) Developing an improved welding method for fill and vent holes. Phase I activity will determine the requirements and supporting business cases for implementation of new technology. Phase 2 will develop mechanized equipment and procedures to increase weld productivity. The developed systems will be demonstrated at NJC and moved to the shipyards for performance evaluations.

Improved Affordability of Sheet Metal Products: Significant fabrication of sheet metal products, such as electrical enclosures, racks, lockers, HVAC ducting, etc., is utilized in submarine construction. Because of the distinctive design of submarines and the necessity to maximize space, these products represent many common features but comprise a wide variety of sizes and shapes. In many instances, they are custom built for a particular boat. The variations in design and size of these components have necessitated significant hand fitting and fabrication, which is costly. Of particular interest is the manual joining techniques that are used for this construction, manual gas tungsten arc welding and upsetting rivets. Both processes involve significant labor and, applied to the current product forms, are not easily adapted to more efficient manufacturing techniques.

The primary objective of the project will be to identify alternate joining techniques that enable greater efficiency and affordability in sheet metal construction. The Navy Joining Center will investigate adhesive bonding, gas metal arc welding, ultrasonic spot welding, laser welding, and resistance spot welding.

For more information, contact Larry Brown at 614.688.5080 or email larry_brown@ewi.org.