Original Date: 07/21/2003
Revision Date: 01/18/2007
Best Practice : Advanced Plate Processing System
Electric Boat Corporation, Quonset Point Facility constructed a new facility around a highly advanced Automated Plate Processing System. This system is specifically designed to optimize material flow in conjunction with the Laser Marking System, Statistical Process Control, and CATIA data to create highly accurate parts for kitting and marking. This allows the fabrication of complex assemblies without the need for detailed 2-D fabrication drawings.
The primary material used in submarine construction is metallic plates that are cut, bent, or formed into shapes, then welded together into complex assemblies. Traditional plate processing methods are labor intensive, rely extensively on forklifts and overhead cranes, have little control of the storage of remnants, and material flow is multi-directional on the shop floor.
Electric Boat Corporation, Quonset Point Facility’s (EBQP’s) advanced Automated Plate Processing System produces highly accurate pieces that are kitted and marked for the fabrication of complex assemblies without the need for detailed 2-D fabrication drawings. These pieces are cut and kitted when required in the shipbuilding process, which minimizes the indefinite staging of cut pieces. This world-class facility incorporates unique processes developed by EBQP and utilizes the most advanced equipment and technologies available. Capabilities include double-sided marking, cutting, and forming of plates up to 15' wide x 50' long and range in thickness between 0.375" and 1.500". With the Virginia Class submarines being the first U.S. Navy ships fully designed electronically, EBQP designed and built a plate processing facility that optimizes material flow and takes advantage of the efficiencies of the design database. This plate processing system is also integrated with laser marking, cutting tools, and statistical process control (SPC) to produce high quality assemblies. The automatic nesting system is also used in the blasting and cutting processes to minimize waste, using only the material required.
The process begins when a plate is received from the plate yard and placed on the conveyor. The work package for the plate is scanned, which initializes the Direct Numerical Control (DNC) programs and establishes the parameters for the blasting and marking operation. The plate proceeds into an abrasive blast machine where only those areas designated by the cutting program are blasted. It is then advanced to the marking queue where alignment holes are drilled, and then forwarded to the laser marker which automatically aligns itself on the indexing holes using CATIA to transform data to mark each part. The laser marker etches on the near side of the plate and when the near side markings are completed, the system automatically turns the plate, re-indexes, and performs whatever marking operations have been specified for the far side of the plate. When all marking operations are complete, the plate is moved to the appropriate station for optimal cutting by an overhead magnetic crane for magnetic plates or a vacuum coupling crane for non-magnetic plates. A water jet, plasma, or laser cutting machine, as appropriate for the part and material, is then used to cut and bevel the part. Fumes from the cutting operation are captured by dampers under the cutter, filtered, and re-circulated into the shop without emissions. Parts are cut in a kit-type sequence and then delivered to the consuming work center. The delivered part contains all the information needed for fit-up and welding, and is completely ready for installation or assembly. Bar codes control the cutting and routing of the part in process.
All handling, marking, sequencing, scheduling, and cutting of the plate are controlled from a central control station. The process is designed to maximize automation in the material handling, as well as control the blasting, marking, and cutting of all plates. This process eliminates several independent operations by integrating them into a cutting line capable of being operated by three individuals who deliver completed kits that are marked and prepped for assembly. This process, integrated with the laser marking system, the computer model database, and SPC, results in an overall reduction of 47% in per-part labor hours and 26% in structural fabrication labor hours downstream. Additionally, all six components in the plate processing system were produced by the same vendor; therefore, parts such as motors and controls are common, which has eased maintenance requirements.
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