Butt welding exterior ship panels together produces a weld protrusion that exceeds DDG1000 fairness requirements. As a result, approximately 23,000 feet of weld reinforcement must be hand ground flush with the hull. The manual weld removal is slow, which increases shipbuilding costs, and the repetitive nature of hand grinding causes frequent injuries and costly medical expenses. A Navy Metalworking Center (NMC) project is developing a tool that automatically faces the weld reinforcement, substantially reducing the amount of hand grinding and associated injury claims, labor costs and production costs. The tool is expected to remove 80% of the weld reinforcement height at 20 feet/hour, versus the current rate of 3 feet/hour, as well as operate in a flat, vertical, horizontal and inverted orientation.
Based on their shipyard assessments, NMC and the Integrated Project Team developed the tool requirements and evaluated metal removal technologies, including grinding, milling and shaving. NMC generated and validated a concept using a commercially available weld shaver from PushCorp, Inc. An Alpha version of the tool was developed by PushCorp, Inc., and tested at Bath Iron Works (BIW) in January 2009, showing that the tool is capable of meeting or exceeding all performance requirements. Improvements are being incorporated into a Beta version, which will be tested at Northrop Grumman Shipbuilding-Gulf Coast (NGSB-GC) in March 2009. A Gamma tool will be further developed for shipyard implementation.
Implementation and Technology Transfer:
BIW and NGSB-GC will implement the technology by July 2009 during DDG 1000 construction. This tool has applications beyond shipbuilding and will be the basis of a commercially available tool developed by PushCorp, Inc.
- Cost reduction of $650K/hull due to decreased injury claims and labor
- Removal of 80% of the weld reinforcement height above the panel at a rate of 20 feet/hour, versus the current rate of 3 feet/hour
- Technology being considered for weld removal on lifting lugs for DDG 1000 and other ships as well as windmill and vessel construction
- The weld seam facing track could potentially be used for burning, welding and back-gouging operations
- No harmful airborne particles or debris
- Metal shavings can be recycled
- DDG 1000 Program Office
- Bath Iron Works
- Northrop Grumman Shipbuilding – Gulf Coast
- General Dynamics Electric Boat
- Naval Surface Warfare Center Carderock Division
- PushCorp, Inc.
- Navy Metalworking Center