When ammunition company Precision Ammunition was acquired by RUAG Ammotec USA (Tampa, FL), a division of RUAG Ammotec GmbH, in 2009, the manufacturer’s technologies were combined with facilities in Switzerland, Germany, Sweden and Hungary, leading to increased production volume. Initially, the company handled its inspections visually by using gaging. But as its output grew, the company began to incorporate increasing amounts of automation. RUAG Ammotec USA needed to revamp its quality control system. RUAG Ammotec USA CEO Dan Powers already had a company in mind to help it with the upgrade. In 2007, Powers had witnessed a demonstration of General Inspection’s (Davisburg, MI) high-speed, laser-based sorting and inspection machines. With more than 600 installations worldwide and extensive experience in the ammunition industry, the staff at General Inspection recommended several solutions adapted to different stages of manufacturing. “At the time, Dan and his company were making significant investments in automation machinery,” says General Inspection President Mike Nygaard. “With production quantities that can range up to 500,000 projectiles per day on one shift and 200,000 to 300,000 completed rounds, [RUAG Ammotec] needed inspection systems that could keep up with production volume and guarantee full inspection capability.” THREE AMMUNITION INSPECTION SOLUTIONS A key part of the overhaul was the introduction of General Inspection’s Gi-200 laser gaging sorting system. Designed for inspection of projectiles prior to loading, the system is equipped with a one-profile, single laser measurement module. The totally automated machine measures lengths, diameters and tapers at rates up to 300 parts per minute. It has a 5-minute setup time and userfriendly controls, and measures each individual part and automatically segregates defective units. RUAG Ammotec GmbH also found benefits with the laser-based Gi-360 system. The quantitative measuring system inspects fully loaded rounds and incorporates an array of lasers in a 360-degree configuration. Part characteristics and print tolerances are entered into the machine’s software once, where they are saved for recollection and part changeover. All external part geometries, including overall length, body diameters, tapers, extractor groove diameter, head diameter/height, length-to-shoulder, concentricity, radii and straightness can be measured at up to 300 parts per minute. Designed for cases, cartridges and projectiles, the Gi-360 can inspect 300 parts per minute for small caliber ammunition, 40 to 120 parts per minute for medium caliber ammunition and is utilized after the loading of primer, powder and projectiles. Another machine RUAG Ammotec added to its family was the Gi 6V, which was designed to catch all critical, major and most minor defects. The machine has a case vision inspection module consisting of eight cameras, five ring lights of various sizes and programmable light/dark defect searches. An array of lasers takes measurements 360 degrees around the part circumference. The Mouth Vision option detects cracks and splits on the mouth, and the Primer Vision feature measures head diameter, flash hole presence, head stamp presence and primer pocket diameter. The unit can inspect 300 parts per minute for small caliber ammunition and 40 to 120 parts per minute for medium caliber ammunition. COMPLETE PROFILE INSPECTION RUAG Ammotec GmbH found success when it implemented the LaserLab into its automation processes. This 3-D inspection system is used in both statistical process control (SPC) and lowvolume, high-value part inspections. Like the Gi-360, the LaserLab incorporates an array of lasers positioned around 360 degrees. Designed for parts from 2 to 38 millimeters in diameter, measurement time ranges from 10 to 30 seconds per part. The part is fixtured by hand and remains stationary while undergoing laser scanning. Parameters can be set in two ways: Either an initial part can be fixtured in the system and inspected, thereby creating a template in the LaserLab’s control against which other parts will be measured, or parameters can be input into the control prior to the first inspection. Graphic representations and numerical data are stored in the control memory and can be recalled at any time for future inspections. The 100% profile inspection covers all part characteristics including lengths, diameters, radaii, tapers, minimum/maximum material, thread concentricity and recess depth. Before every scan, the LaserLab automatically calibrates itself via a NIST-traceable calibration device mounted directly on the machine. As a result, quality does not deteriorate over time or with changing environmental conditions. At RUAG Ammotec USA, the LaserLab is used to inspect casings or other components sourced from outside. In-process inspections of projectiles, loaded cartridges and casings are also easily accomplished over the multiple caliber and ammunition types. DRAMATIC RESULTS Powers says he and his staff have seen significant improvements from the new inspection systems. The company enhanced quality on its projectiles by 100%, with a 70% improvement on loaded ammunition, Powers notes. “We’ve also been able to check all values, [which is] extremely important to us,” he says. “For instance, if LaserLab catches an error on our brass casings, we can recheck the dimensional values and correct the situation prior to loading,” he adds. “This has enabled us to improve our performance in preloading by 100%. “In another instance, we were able to catch a problem in the machine setup,” says Powers. “When we detected that one of our loading machines was damaged, we were able to fix the machine, thereby saving a lot of money and time.” Flat surfaces and straight lines are rare among the parts produced at Triumph Fabrications (Shelbyville, IN), which is mainly why the company upgraded its machine tool probe on one of its high-accuracy portal mills to a strain-gage-based Renishaw RMP600. As an aerospace stretch-forming specialist, there is hardly a part or a die in Triumph’s shop that is not sporting a parabolic, compound curved or cone shape. Rapid, precise measurement of machining work on these parts— while the parts are still fixtured on the machine tool—is a core skill the company’s computer aided design (CAD) and computer aided manufacturing (CAM) department developed and refined to facilitate lean manufacturing. But it took an RMP600 straingage probe to bring the refined touch needed for consistent, high-accuracy measurement of small hole diameters, contours and geometric tolerances. With no lobing—or true 3-D triggering characteristic—and a repeatability of 0.00001 inch, the straingage probe delivers high accuracy when triggered from any direction after a one-time calibration routine. The RMP600, combined with Renishaw’s OMV Pro software, gives the company’s Zimmerman CNC 5-axis portal mill coordinate measuring machine (CMM)-like capabilities, allowing measurement results that routinely come within 0.001 inch when double-checked with other devices. As a result, off line checks of work on a true CMM have been eliminated, saving the company many hours of production delays, potential damage and accuracy problems that arise when moving and re-fixturing high-value parts. According to Triumph, it is hard to quantify the time savings, but it can be in the range of five times the cycle time for the part. For example, if a part can be machined in one hour, the extra setups caused by off line measurement can be five hours. The key is that the part is processed in one setup, improving overall cycle time and delivery. KEYS TO SUCCESS Triumph Fabrications’ core capability is the stretch-forming of sheet, extruded, rolled shape and light plate metals for the aerospace industry. The company’s press capacity ranges from 10 to 750 tons, with the ability to stretch-form reverse forms using bulldozer attachments of 150 and 400 tons on its Cyril Bath presses. The company also has unique stretch forming capabilities to support complex single-plane and multiplane forming of a variety of metals. Various types of computer numerical controlled (CNC) machine tools are used to produce features on these formed parts, as well as to shape the forming dies themselves. Supporting this work upstream and downstream is a CAD/CAM department equipped with Catia V4 and V5, Vericut 7.0, Renishaw OMV Pro, AutoCAD, Inventor and other desktop engineering tools. The other key to Triumph’s success is programming the model and geometry. The probing program runs on the CNC to collect the measurement data, which is then evaluated offline in OMV software with CMM-type algorithms. The software compares the measurement data with the map/ model file and produces graphical and numerical reports. The software reports on the deviations from the nominal and will plot a graph to show the ranges. Unlike a conventional machine tool probe, the strain-gage-based RMP600 does not have to be calibrated for each vector, which saves significant cycle time in a 5-axis environment. The RMP600 is fundamentally different from conventional machine tool probes in that its patented Rengage sensing mechanism eliminates lobing, an error inherent to all conventional machine tool probes. If the lobing is excessive and high enough to impact measurement accuracy, operators must compensate by calibrating the probe along each measurement vector. This requires a complex calibration cycle and management of numerous probe offsets. The RMP600 eliminates this. Strain gages measure the contact force applied to the stylus and generate a trigger after the strain threshold is exceeded. This results in low trigger forces, less stylus bending, submicron repeatability, no lobing and a true 3-D triggering characteristic. The RMP600 delivers significantly higher metrology performance, particularly on 3-D surfaces where many sensing directions are used, or in setup, when approach vectors to the workpiece may not be known. Logic inside the probe eliminates unexpected triggers resulting from shock and vibration by determining whether the strains seen at the gages are caused by contact with the part surface or a random event. HIGH CONFIDENCE With its knowledge of the Zimmerman CNC 5-axis portal mill machine’s capabilities, condition and calibration history, Triumph Fabrications believes an inspection on its machine is equal to a CMM inspection. The machine is tested and calibrated to essentially the same requirements as its CMMs, and easily capable of producing part profile accuracies of 0.015 inch. Triumph can verify its metrology performance by probing a known artifact, which has all the features it would encounter in its parts. Because of the high accuracy of this machine and its 5-axis capability, the straingage probe has proven to be a better match for Triumph’s measurement requirements. Periodic double checks against other measurement devices rarely show deviations greater than a thousandth of an inch, giving Triumph a high level of confidence and operational efficiency. BENEFITS RUAG Ammotec USA improved quality on its projectiles by 100% using General Inspections’ inspection machines. Now able to check all of its values, RUAG Ammotec USA has improved its pre-loading performance by 100%. The Gi and LaserLab family of machines feature 360 degree laser inspection. Unlike a conventional machine tool probe, the strain-gage-based RMP600 does not have to be calibrated for each vector. Strain gages measure the contact force applied to the stylus and generate a trigger once the strain threshold is exceeded, resulting in a true 3-D triggering characteristic. The RMP600 delivers significantly higher metrology performance, particularly on 3-D surfaces where many sensing directions are used.
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