shaping the future of metrology - Brown & Sharpe

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Wichita, Kansas Aerospace Shop Soars Over Measurement Bottlenecks B usiness has been brisk for L & S Machine Company Inc., an aerospace machine shop in Wichita, Kansas. The company machines 500 different aerospace part numbers a year.This is a dramatic increase from approximately 250 part numbers just two years ago. Growth has placed a tremendous load on the company’s dimensional measurement capabilities. A Division of Tru Circle Corporation, L & S Machine employs about 160 people. For the fiscal years ’97 and ’98, sales bookings have increased by approximately 25 percent and 30 percent respectively.This very healthy growth rate is due, in part, to the company’s willing- 16 mfg. Shaping the Future of Metrology If a manufacturing non-conformity is found, PC- DMIS for WINDOWS can display dimensional data on the computer’s screen, along with a drawing of the part. Analysis of the drawing helps engineers pinpoint process problems. ness to take on the manufacturing of 100 percent more part numbers. Along with this opportunity has come the responsibility to set up, trouble-shoot, and validate twice as many manufacturing processes. Rather than buy more measurement equipment and double its inspection staff, L & S has kept pace with the increased dimensional measurement work by relying on PC-DMIS for WINDOWS graphicscoupled CMM software to improve measurement capabilities and throughput.The software has also made a significant contribution to the company’s overall improvements in productivity and adherence to production schedules during the past three years. The parts are typically complex 3, 4, and 5-axis components with true position tolerances down to .001". They are used in a wide range of assemblies and subassemblies for commercial and military aircraft, including structural members, landing gear and wing flaps. For many years, inspection had been the number one bottleneck in the manufacturing process. Before installing PC- DMIS for WINDOWS, in-process inspection was complicated. Operators had to memorize numerous codes to access the various programming and measurement features. Even performing rough, in-process checks was time consuming because every specific set of points measured required its own program. According to Skip Steely, Quality Assurance Manager, inspection was laborious, and training CMM operators was difficult. Improving Programming Throughput Now, instead of memorizing codes, operators use a screen drawing of the part to select dimensions that need to be measured, and measurement parameters are entered quickly by filling out simple menus. PC-DMIS software displays the drawing based on an IGES file supplied by the customer.Typically the IGES file is used as-is. However, if the customer supplies a complex, multi-layered drawing (e.g. in CATIA ® ), this can be easily reduced to the essentials needed for measurement using a program called CAMAX ® . Steely said that writing a conventional CMM part program used to take about 40 to 80 hours. “Now we have that down to about 16 to 40 hours depending on the complexity of the part.We’ve essentially cut our initial part programming time in half,” he said. With PC-DMIS, separate programs are not required for rough, in-process checks. The operator can select any set of points on the screen drawing, and PC-DMIS will automatically measure them.The disparity between finished part and rough part tolerances are handled simply by entering appropriate values in a pop-up menu. Since there is no longer a programming time penalty to do rough checks, they are performed more frequently. Fast, rough checks have helped L & S reduce in-spec PC-DMIS for WINDOWS, retrofitted to this LK G 80C coordinate measuring machine, has helped L&S Machine Company improve inspection throughput without the need for additional equipment. Because inspection routines are much faster now, machine tools average 95 percent utilization. variation on some parts, and this translates to improved quality and productivity in assembly. L & S has three measurement systems, one manufactured by Brown & Sharpe and two by LK. Since PC-DMIS software is common to all three, only one program needs to be written per part, no matter how many machines it will be measured on.That also results in a reduction in programming man-hours. While conventional programming is typically performed as a teach-and-learn operation at the CMM, an offline version of PC-DMIS makes it possible to perform all of the programming on a personal computer. L & S has two off-line licenses for PC-DMIS which assures that measurement will no longer be an obstacle. Part programming can now begin before the first piece has been manufactured, and CMMs are more frequently “We’ve essentially cut our initial part programming time in half.” available for measuring parts, since they are not required for part programming. Optimizing CMM Operator Productivity L & S is managing substantial increases in production with only a modest increase in inspection personnel.This is fortunate because experienced people are hard to find. “We try to hire the best CMM operators we possibly can,” said Steely, “but unfortunately, Wichita is a Boeing, Lear Jet, and Cessna town. Most of the talent is locked into positions with those other companies. PC-DMIS allows us to bring in inspectors who have had limited CMM experience and train them to be proficient.” Using this philosophy, L & S recently increased the number of CMM operators on staff from four to six. “If they are used to the WINDOWS mfg. The Brown & Sharpe Publication of Precision Manufacturing 17
environment in some other type of software,that’s half the battle. If they know how to inspect parts on a surface plate, with a week’s worth of training they will also understand how to operate the CMMs using the PC-DMIS point and click operator interface.Then we give them a little bit of coaching over the next few weeks and they are off and running,” Steely said. There are a great many parts that run automatically in an hour or less. It only takes a few minutes for the operator to swap in a new part and begin inspection. While the CMM is in operation, the operator can be performing conventional measurements on a surface plate or writing more CMM programs on a PC-DMIS off-line station. Maximizing Production Machine Uptime L & S Machine has made a concerted effort to improve up-time for production manufacturing equipment.Where 60-75 percent uptime was not uncommon several years ago, today most production equipment is averaging 95 percent utilization. PC-DMIS has helped. 18 mfg. Shaping the Future of Metrology Steely said, “Because we use our CMMs more efficiently, we have been able to reduce hard gaging in the shop. Operators used to set the parts up on hard gages for first-piece inspection.This was very timeconsuming. Now the operators are just responsible for some simple hand measurements—wall thicknesses, radii, holes and a visual.Then the parts come directly to inspection, and we run them quickly on the CMM.While we are doing this, the machine operator runs a proven part that has already been set up on a pallet. So, very little time is lost.” Steely said a typical first-piece inspection on the CMM will check hundreds of features in about a half an hour. Checking 50 features in the shop with a hard gage used to take about four hours. Customers are frequently on hand for the first-piece inspection of critical parts. PC-DMIS can automatically change the feature numbers to match the bubble numbers on the part drawing.The customer can look down at the inspection re- Using PC-DMIS for WINDOWS software with this Brown & Sharpe MicroXcel CMM, L & S Machine Company has reduced time required for first-piece inspection. A typical first-piece inspection…will check hundreds of features in about a half an hour. sults and know exactly what has been measured. Finally, Steely noted that PC-DMIS is an excellent tool for problem solving. “When manufacturing finds a nonconformity, they will frequently request additional data.We bring up the part drawing on our PC and visually determine where we need to measure.We will take those measurements, and the results will be right on the screen. Once we blow that up, they can see where the surface actually is in relation to the CAD drawing. Before, when we gave manufacturing tabular data, there were frequently discussions about where the measurement was actually taken. PC-DMIS has eliminated that. Our manufacturing people just go and fix the problem. It’s really clean.” o Circle 706 on the READER SERVICE CARD
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