Luminescent Quality

It is no coincidence that Astronics-Luminescent Systems Inc. (LSI) is a prominent supplier of aerospace lighting systems in three aircraft markets: commercial transport, military and business jets. For nearly a decade, Astronics has focused on expanding their product line to become a major provider of complete lighting systems for the cockpit, cabin and exterior of an aircraft, in addition to electrical power and distribution systems for cabin and airframe power. Located in Lebanon, NH, LSI operates under the umbrella of Astronics Corporation. This year, Astronics was named number one on Fortune Small Business Magazine's 2008 list of America's 100 fastest-growing small public companies.

From intricate, contoured parts, to reflective materials, LSI is no stranger to solving tough design and engineering challenges. The company manufactures components for the cockpit including illuminated display panels, control panel assemblies, keyboards, floodlights, map lights, caution/indicator panels, ambient light sensors, and a range of power supplies and dimmer units needed to control the lighting system. The company also designs emergency egress lighting systems to help airline passengers identify aircraft exits in case of an emergency. To date, LSI provides escape path lighting to more than 200 airline operators around the world. They also create reading lights, passenger signage and general area lighting.

In terms of exterior lighting, LSI designs systems for navigation, anti-collision and landing/taxi, including night vision compliant products. The company also produces special formation lights used for military aircraft when flying in close proximity to one another. In fact, LSI exterior lighting products can be found on every type of military aircraft from single seat fighters, to cargo aircraft, to attack helicopters. Their innovative use of high reliability LED (Light Emitting Diode) and HID (High Intensity Discharge) lighting technology has secured contracts to design exterior lighting systems for many new aircraft.

Maintaining Quality

Getting to the top of the marketplace requires teamwork and management leadership to set the gold standard in aerospace lighting. To maintain a high level of part quality, LSI began the search for a high precision measurement system that would enable them to verify, on-the-fly, the thousands of parts manufactured in-house or arriving at their doorstep each day. Their quality assurance technician would need to capture 3D data from all critical aspects of a part, and conduct a CAD model-to-part comparison. The search led the company to a ROMER articulating arm (ROMER, Inc., Wixom, MI) and PowerInspect inspection software (Delcam plc, UK). This portable CMM has long been used to ensure part quality and manufacturing productivity in industries such as automotive, aerospace, ship/boat building, and more.

John Hamel, LSI quality assurance Manager, states, "Our business is changing and developing. To compete successfully in this aerospace lighting market, we needed to change with the market. Our new designs primarily use LED and HID lighting sources that are intended to be highly reliable with long service intervals. These systems require new thinking in terms of directing light using multiple parabolic curves and reflectors. These surfaces can not be measured with 2D measuring systems, and this need lead us to this particular articulating arm technology."

The ROMER INFINITE 1.0 arm operates very much like a human arm, but uses Zero-G counterbalance that offsets the weight of the arm and probe allowing onehanded operation from any position. The counterbalance works equally well from any position in the arm's reach, above and below the midline. The patented infinite rotation of the principal axes enables inspection of hard-to-reach areas and avoids damaging the arm against rotational hard stops. The carbon fiber arm enables high precision probing and optional scanning capabilities.

Originally, LSI relied heavily on their suppliers for quality assurance. In some cases, suppliers missed the mark, and parts were sent back. Hamel made a swift move to gain oversight of the process, "to make sure we were getting what we were paying for, and they were producing to our spec." At first, they sourced their quality control to a company specializing in industrial metrology. But eventually, they purchased the same portable CMM used by the metrology services firm, which was the ROMER arm. Since the purchase of the arm, it has not set idle for a single day, according to Hamel. "We use it eight hours a day. Our business is booming, and our customers require quality products. In order for us to hit their requirements, we are obligated to buy and implement the best metrology solution for our QA."

Manufacturing and QC Converge

LSI handles millions of parts for their lighting systems. While some are manufactured in-house, and others are bought from distributors, the majority of components are produced by contract manufacturers. LSI brings all of these parts together under a quality management system, inspects them to specified criteria, then puts those parts into their innovative, custom lighting designs.

For every component inspected with the ROMER arm, there is an equivalent CAD file originating from one of LSI's design engineers.

The place where manufacturing and quality converge is Jared Demers' work area, which consists of the CMM on a granite table, a computer, fixtures and magnets to help lock items into place for measurement. Demers, a quality assurance technician, has been using the measuring arm for nearly two years. He was originally trained to use an X, Y machine to gather 2D measurements. There were similar features in the new PowerInspect 3D inspection software, which he was quick to learn. During the learning curve, he invested time into devising ways to position parts on the table so the arm could reach all areas, some requiring two setup programs.

Each day LSI's incoming inspection department receives parts from vendors or from their sister company. Three samples are taken from each part run requiring CMM verification and sent to Demers for analysis. For every component inspected, there is an equivalent CAD file originating from one of LSI's design engineers. An IGES file is requested from the owner engineer, as well as a blueprint denoting the areas for inspection such as critical curves or reflectors, or the side of an encap or hole locations. If it is a special component, there is lots of dialogue between Demers and the engineer.

Jared Demers uses a ROMER articulating arm to gather point data from a sample part for CMM verification.

As Demers gather's points from a part's surface, the software lets him visualize if the point is good or bad. Green data is good, while red and blue points denote under or over tolerance. Once the session is completed, he generates a report and prints out model views in a PDF format for documentation. If the inspection goes well, parts go forward. If not, a non-conformance report is written and heads to engineering for rectification. In essence, the buck stops at Demers's desk, where a part run either passes or fails.

Engineering Entwines with Metrology

During the product development phase, LSI design engineers send Demers new parts and the related CAD models to see how close they are getting to the final iteration. Demers states, "The organic shapes created by our engineering team are certainly the most challenging aspect of inspection, and most often require surface data to help with dimensional verification."

David Breault, LSI design engineer, creates both external LED-based and HID-based lighting systems. On a daily basis, he could be generating initial concepts of a new customer product or interacting with quality assurance. Breault was the first engineer to work closely with Demers after the implementation of the 3D CMM. To begin the process, he would create a CAD model that would be exported into an IGES file from Solidworks or PRO-Engineer, their in-house CAD systems. In the quality assurance department, Demers would import the 3D data into the inspection software program. If there were any problems, Breault would jump in to troubleshoot the process.

"In the ramp up period, Jared and I worked through many projects and inspection routines," Breault states. "It was a highly-interative process. I would provide a CAD model, and he would take the measurements based on our discussions. He would come back with questions on certain part features, and ask for particular data points in specific locations. I would export this data for another round of inspection. With odd contoured parts, I would also have to create surfaces for best fit calculations."

Before and After Portable Metrology

"With many of our lighting products today, conventional measurement tools are just not feasible anymore," Breault continues. "With a height gage, we would have to completely fixture a part with multiple angles or orientations. With the portable arm, within one or two setups, all points can be reached (including under the part) and studied. Until about four years ago, our products had been easier to inspect with gages, etc. Now we build parts that would be impossible to inspect without an arm. A major advantage of working with the 3D measurement system is I do not have to create multiple page drawings with many views. The data is all there in the CAD file and can be transferred easily into the inspection system, which includes GD&T dimensioning and more. Jared sets up inspection programs using my CAD models and targets a relatively even set of points. He can generate a data report and a visual reference showing points and their compliance with our set tolerances."

Hamel concludes, "Our lighting systems have reflectors critical in mass that have to meet requirements set by a regulatory agency or the FAA. And to comply with those standards, we need to measure those items. We have parts with scalloped shapes that push light into a fan pattern. Our engineers focus on the critical nature of the shape of those parts, and we have to closely scrutinize those surfaces. The arm's versatility sold itself. Our 3D measurement capability sped up our inprocess inspection and delivery has increased. If I had to describe its value, well, it is just invaluable, because at LSI, it all boils down to customer satisfaction."