Automated weld seam facing on DDG 1000 ships will reduce costs due to decreased injury claims and direct labor. This tool is shown undergoing testing on DDG 51. Bath Iron Works photo
This Navy Metalworking Center (NMC) project has developed a portable tool that automatically faces the weld reinforcement, substantially reducing the amount of hand grinding and associated injury claims, labor costs and production costs.
DDG 1000 Class ships have a substantial requirement for hull surface fairness both above and below the waterline. The requirement is much more stringent than for past ship construction projects. Butt welding exterior ship hull and deck panels produces a weld protrusion that exceeds DDG 1000 fairness requirements. As a result, approximately 23,000 feet of weld reinforcement must be hand ground flush. Manual weld removal is slow, which increases shipbuilding costs, and the repetitive nature of hand grinding causes frequent injuries and costly medical expenses.
The tools are expected to achieve a cost reduction of $2.77M for the DDG 1000 Program based on three ships. Average reinforcement removal rate was verified to be well in excess of 40 feet per hour compared to the present rate of 3 feet per hour. The tool can operate in flat, vertical, horizontal, and overhead orientations.
The final preproduction tools were delivered to BIW and NGSB-GC in June 2009. The use of the preproduction tools will enable the shipyards to begin to take advantage of their benefits, identify potential tool enhancements for future production tool acquisitions and identify other processes that can leverage this technology. Currently, a modified version of the tools is being considered for back gouging at both BIW and NGSB-GC.