shaping the future of metrology - Brown & Sharpe

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Paramount, California Gantry CMM Helps Aerospace Contractor Keep Pace Today, there are two constants in the evolving world of aerospace manufacturing—tight design tolerances and even tighter delivery schedules. At Aircraft Engineering Corporation, staying competitive in this tough business means taking advantage of the opportunities that those two challenges offer a seasoned contractor. AEC is a versatile, Small Disadvantaged Business providing engineering, design, numerical control programming, and fabrication support for major assemblies, sub-component assemblies, and tooling to the country’s advanced commercial, military, and space programs. For the past 38 years, AEC has developed and refined an expertise in tool design, machining, welding, composite fabrication, bonding, and structural assembly in both prototype and production atmospheres.The company also supports installations of end item assemblies and large assembly tools, giving customers turnkey support from a single source. AEC’s extensive operations are housed in seven buildings in Paramount, CA, with more than 160,000 square feet of manufacturing space. It’s one of the largest and most advanced facilities of its kind. The company’s commitment to ontime, on-spec production rests on the use of modern production equipment and the experienced personnel to operate it. For example, in the composite fabrication department, a computer controlled autoclave, a vacuum forming machine, a large walk-in freezer for the storage of composite materials, and curing ovens 22 mfg. Shaping the Future of Metrology assure precision manufacturing operations. AEC’s welding department fabricates complex flight hardware, ground support equipment, electro-mechanical, and hydraulic systems.The tooling department is equipped to produce plaster master patterns, fiberglass and carbon fiber lay-up for tooling and production parts, graphite composite tooling, assembly jigs and fixtures, templates, form dies, and router fixtures. AEC’s machined parts/assembly department supports the needs of the fabrication and tooling departments, as well as customers’ needs for machine/assembly work. Coordinating this equipment to meet production schedules is one of the secrets of the company’s success. Some of the largest aerospace components manufactured in the United States are inspected on this Brown & Sharpe DEA DELTA gantry CMM at Aircraft Engineering Corporation. Keeping Pace With Customer Needs Using advanced software systems, AEC has successfully combined computer aided design with manufacturing and inspection operations to accommodate last-minute customer design changes. One of the ways that AEC keeps up with the demand for tighter delivery schedules, even with the last-minute design changes that are frequently part of new programs, is through the integration of computer aided design with the manufacturing and inspection operation. Recently, the company added eight IBM RISC 6000 workstations running CATIA ® Version 4.1.7/FR4.1.7 software developed by Dassault Systèmes, and four Pentium ® Pro workstations operating Unigraphics II design and manufacturing software.These software systems allow AEC engineers to use the customer’s encrypted design data to produce a 3D solid model tool design based on the customer’s requirements. Another recent acquisition is a DELTA gantry-type coordinate measuring machine from Brown & Sharpe DEA.The DELTA CMM at AEC has a measuring envelope of 200" (X), 100" (Y), and 72" (Z) and can accommodate virtually any part or assembly manufactured by AEC.The machine, one of the largest on the West Coast, has undergone testing and qualification at AEC and is certified to Advanced Technology Assembly specifications. This large CMM is being used primarily to prove the accuracy of CNC machining. In a typical application, the CA- TIA software is used to create inspection points based on the information from the part model. These inspection points are used to program the DELTA to determine if the part conforms to machining specifications. CAD Link Reduces Inspection Time The DELTA is equipped with PC- DMIS for WINDOWS geometric measurement software. A special feature of PC- DMIS for WINDOWS allows operators to use the accuracy of original design data to create off-line inspection programs with graphical part models and probe path simulations. At AEC, PC-DMIS for WINDOWS downloads 3D part models from the CATIA system and creates a graphical representation of the part.The CMM operator simply clicks on any surface or feature of the model to create a DCC inspection program. Inspection results can be uploaded directly to the CA- TIA system by IGES and DMIS links. AEC also uses the optional Curves and Surfaces module which imports freeform 3D models from the CATIA system and automatically extracts mathematical surface nominals and direction vectors. When the operator clicks on the surface to be inspected, Curves and Surfaces drives the CMM along the orthogonal surface vectors and collects measurement data.That data is compared to the CAD nominals, and the “fit” of the surface is accurately determined regardless of its complexity.When the user clicks on the program’s interactive graphic model of the part, Curves and Surfaces provides the nominal and actual point deviation.The program also automatically displays the nominal tolerance band over the actual data curve providing clarity of the conformance of a surface to its nominal model. “One of the reasons AEC purchased the DELTA was to allow the inspection program to keep pace with our new high-speed three, four, and five axis machines,” according to Jack Peacock, AEC Quality Assurance Manager. Some of the smaller parts checked can be inspected in as little as three minutes.The larger assemblies and tooling, perhaps having 400 to 500 points to check, take an hour to two hours. “Without the DELTA, that kind of inspection would take us up to a day,” he continued at AEC page 49 mfg. The Brown & Sharpe Publication of Precision Manufacturing 23
AEC cont. from page 23 said, “plus we can measure everything that we machine, from parts that are just a couple of inches square up to anything that’s 200 inches long and 72 inches high.” Stable Temperature Assures Measurement Accuracy The DELTA at AEC is housed in an environmentally controlled room designed to keep the ambient temperature at 68°F ± 2°F. It is mounted on an independent foundation, reinforced with one-inch steel bars and dug 6 feet into the ground to reduce the effects of vibration, and is designed for floor-level loading of the DELTA by lift trucks. “Temperature variation is the culprit when trying to find variant parts from a manufacturing operation that is not environmentally controlled,” Peacock said. Components arrive at the DELTA either right off the machine, or in the case of a production run, after a bench operation to eliminate mismatches and deburr the edges of the part.When a part comes in for inspection, it is “soaked” at 68° for anywhere from a couple of hours to 24 hours before being inspected to assure compliance to engineering specifications.After the inspection process, the component may be sent to an anodizing process, or directly to the customer. “One of our goals is to become a customer-approved acceptance authority in an effort to eliminate the need to have a customer source inspector come in and check every part,” Peacock said. “Quality management is confident that the Delta will assist AEC in providing objective evidence to our customers that we can machine and fabricate parts to engineering specification tolerances consistently to meet the requirements for approved acceptance authority.” o Circle 738 on the READER SERVICE CARD
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