Laser encoders allow 40m-long composite parts to be machined accurately over lengthy cutting cycles

摘要

Flow International Corporation's Composites Machining Center (CMC) 'hits the mark' for single-set-up processing of long composite wing skins; and one of the keys to holding long-axis accuracy during week-long machining cycles is the use of laser encoders. Measuring distance with the precision of a laser interferometer, the HS10 and HS20 laser encoders from Renishaw plc, Wotton-under-Edge (www.renishaw.com) - together with their 'companion' RCU10 real-time compensation unit - deliver a 'micron level' positioning accuracy on the CMC's X axis. The laser encoders also eliminate variables that had to be compensated for when using a physical scale attached to the machine. Flow's CMC is one of the new machine tools developed to meet the aerospace industry's need to produce 'large monolithic parts' with minimal dimensional variation. Mark Saberton, Flow's director of aerospace, says: "Reduced variation in parts is an industry-wide goal. The objective is reduced assembly time, effort and tooling. The OEMs want to eliminate assembly shimming, which adds weight to the product and time to the process. They also want parts to meet the specified tolerances when they arrive on the assembly floor, rather than using fixtures and shims to bring them into assembly tolerance. Weight is also an issue; less variance on a plane's parts ensures better control of the aircraft's final weight."