This project developed an automated back gouging tool that leveraged work done in a previous Navy Metalworking Center (NMC) project that developed a track weld shaver system to remove weld protrusion. That system was first modified to create a prototype tool that was successful in back gouging thin plates requiring a shallow profile depth (¼ to ½ inch).
Bath Iron Works (BIW) manually arc gouges and grinds the Peripheral Vertical Launch System (PVLS) and Anti-Propagation Wall (APW) plates on DDG 1000 to produce the desired weld joint profile and quality. This labor-intensive process is slow, and the repetitive motion causes numerous injury claims, such as carpal tunnel syndrome.
In order to meet the DDG 1000 back gouging requirements for PVLS and APW, a weld shaver was then modified with a larger diameter slotting cutter, a redesigned housing, as well as drive and guide wheels in order to be able to back gouge to a depth of 1-1/2 inches. As a result, a prototype took for thick plate gouging was developed and the Integrated Project Team witnessed the successful deep gouge demonstration and made recommendations for improvements for future tool improvements.
Implementation of the back gouging tool for DDG 1000 has reduced direct labor cost by 75% for APW and PVLS joints. Injury claims associated with manual grinding and carbon arc gouging have been significantly reduced. In addition, reworks of weld joints due to defects discovered during ultrasonic inspection have also been significantly reduced. As a result, BIW has estimated a labor savings of approximately $400K per DDG 1000. The total cost savings for all DDG 1000 production is in excess of $1M. In addition, if mechanized back gouging can be introduced at Ingalls Shipbuilding for LHA, LPD, and NSC applications, an addi¬tional estimated savings of approximately $1.4M may be realized.
The prototype back gouging tool was successfully demonstrated at BIW in August 2010. This was considered the transition event for the technology. This event verified tool life and operational cost, which will enable Ingalls to complete its economic analysis of mechanical back gouging and potentially lead to the implementation of this technology for back gouging applications associated with LHA, LPD, and NSC ship production. The tool was implemented at BIW in October 2010 to support DDG 1000 construction during the fabrication of PVLS and APW components. The tool continues to operate in the demanding shipyard production environment with almost no incidents of breakdown or repair. BIW has completed the training of operators to safely and productively operate the mech¬anical back gouging tool. The tool is fully supported by the commercialization vendor – PushCorp, Inc.
Bath Iron Works
Naval Surface Warfare Center, Carderock Division