The objective of this project was to implement Electron Beam Welding (EBW) of the Virginia Class Submarine (VCS) 1st reduction gear, providing better distortion control and reduced manufacturing costs. EBW would allow for narrow, single-pass, single-sided, full-penetration welds.
Current welding processes used in the manufacture of the first reduction gear on the VCS require multiple passes in complex sequencing, with some joints requiring double-sided welding to ensure full penetration.
The project will reduce fabrication time by incorporating single-pass, full-penetration welds; utilize narrow welds that improve fit-up and simplify machining operations on fabricated gears by reducing rim-to-shaft distortion; eliminate the need for closing plates on gear fabrication; and reduce Magnetic Particle Testing requirements due to single-sided welds.
The implementation of EBW for the fabrication of VCS 1st reduction gears has several potential cost/performance benefits. EBW will:
• Reduce fabrication time by incorporation of single-pass, full-penetration welds
• Narrow welds will improve fit-up and simplify machining operations on fabricated gears by reducing rim-to-shaft distortion
• Reduce part count by eliminating the need for closing plates
• Reduce Mag Particle Testing requirements due to single-sided welds
The total estimated manufacturing cost avoidance from using EBW was $88K per hull. The Navy plans to procure an additional 22 subs after the target hull number. If the project results are ready in time for implementation on the target hull, there will be a total of 23 subs with EB-welded 1st reduction gears. This will result in a total manufacturing cost avoidance of more than $2M over the life of the program.
The integrated project team will seek other potential EB welding applications on the VCS and other naval weapon systems during the execution of this project.