Prototype friction stir welding machine at NMC facilities in Johnstown, Pennsylvania. Navy Metalworking Center photo
The objective of this project is to develop a low-cost friction stir welding machine and to demonstrate its operation at a shipyard supporting the Lockheed Martin Team LCS construction. Working with the project Integrated Project Team (IPT), the Navy Metalworking Center (NMC) designed, built, and demonstrated a transportable friction stir welding system that will be transitioned to production use at the shipyard. In operation, the machine essentially serves as an aluminum panel line, forming stiffened panels from edge-welded extrusions.
The Littoral Combat Ship (LCS) incorporates significant amounts of aluminum. Friction Stir Welding (FSW) is an ideal joining process for aluminum and provides vast improvements over conventional marine aluminum construction methods because it offers decreased distortion, improved joint properties, and reduced production costs.
The project is a two-phased approach. Phase one designed the low-cost machine and evaluated the costs and benefits of implementation. The tooling for the process was developed and demonstrated on existing equipment. Phase two will procure the low-cost machine, perform welds for certification, perform demonstrations at the implementing shipyards and other potential programs, final delivery of the machine for production, and training and support for the final operator.
By limiting the design’s functionality to the specific needs of extrusion welding, the machine is less costly and provides a quicker return on investment. The simpler machine requires minimal site preparation and is sized for mobility among and within shipyards. By locating the FSW operation at the construction yard, the benefits of FSW are more fully realized because the panels are built to the size needed for construction, rather than being limited to a panel sized for transportation from a remote site. The machine’s simplified controls and operation also reduce the skill set and technical support required for the operator. The low capital costs and proven design will enable industry to readily scale-up for multi-ship construction, and do so at a much lower capital cost.
Negotiations are ongoing among Bollinger, Lockheed Martin Space Systems (LMSS), Lockheed Martin Maritime Systems and Sensors, the LCS Program Office and NMC regarding an earlier transition to LMSS Michoud facility. The dual-use machine design is available through NMC or the Defense Technical Information Center (DTIC) for other programs or industries in need of flat, thin, stiffened aluminum panel production.