Assembly Planbook - April 2008 - (Page 48) Fastening Test Results for Combined Joints Tool Type Torque wrench Adjustable shut-off nutrunner Cordless impact tool with control Transducerized pulse tool Shut-off pulse tool Stall pulse tool Mean Torque 82.2 48.2 69.2 70.2 35.5 79.5 Torque Torque Standard Percent Capability Range Deviation (Six Sigma Scatter) 81 to 84 42 to 55 55 to 83 56 to 84 26 to 43 64 to 94 1.1 2.6 5.3 5.6 3.9 7.8 8% 33% 46% 48% 65% 59% This table shows the combined results of the tests on medium and soft joints. Torque values are in newton-meters. The capability value represents total variation in applied torque. If expressed as a ± value, it should be cut in half. which produces almost no variation in applied torque, was included in the program: to check the accuracy of our measurement process. We then calculated the mean and standard deviation for each set of measurements. Capability, defined as six standard deviations as a percent of the mean torque, was calculated for each joint and for the combined joints. This is essentially the evaluation procedure described in ISO 5393. The most accurate tool was the manual torque wrench, with a capability of 5 percent on the soft joint, 9 percent on the medium joint, and 8 percent for both. This is very accurate and indicates that our test approach of measuring residual torque was reliable. We calculated that a random error of only ±1 newton-meter would produce a capability of 6 percent, and an error of only ±0.5 newton-meter would produce a capability of 4 percent. Our measurements were made in increments of 1 newton-meter. The next best tool was the adjustable shut-off nutrunner. On individual joints, the capability was about 25 percent. This is a much higher scatter than this tool would have produced on the ISO 5393 test rig, on which it yields a capability of approximately 10 percent. The additional scatter is probably because the tool is handheld instead of fixtured and because it’s tested on a fastener instead of torsion Linear Synchronous Motor Transport Systems QuickStick® LSM transport systems move product faster for increased throughput, require less maintenance and provide these built-in functions: ❑ Accurate positioning and indexing ❑ Independent control of many vehicles ❑ Constant vehicle ID and tracking ❑ Automatic advancement/anti-collision ❑ Bi-directional travel Contact us today to build your automation system of the future. (978) 461-5090 x223 • info@magnemotion.com www.magnemotion.com New MagneMoverTM Automation Transport System Based on QuickStick LSM Technology And Featuring Electro-magnetic Switching See us at ATX East, Booth 3023 48 ASSEMBLY / April 2008 www.assemblymag.com http://www.magnemotion.com http://www.magnemotion.com http://www.assemblymag.com
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