(API: Rockville, MD) -- Northrop Grumman Corp. has successfully deployed the Volumetric Error Compensation (VEC) service from Automated Precision Inc. (API) to achieve higher accuracies on its large volume machine tools. Seeking greater machine-tool accuracy for the F-35 Joint Strike Fighter production, the military aircraft and defense systems integrator and manufacturer selected VEC to achieve the high-tolerance machined parts.
“API’s Volumetric Error Compensation is a true game-changing technology for anyone with large and complex machine tools,” says Dave Maxham, global marketing director at API. “Older technology considers each machine axis separately, stacking errors from three or more individual coordinate systems. This limits the mapping of errors to three linear axes and 21 error parameters, which has proven challenging for large, five- and six-axis machine tools. We recommend the innovative VEC process to the entire F-35 supply chain.”
The VEC service uses a unique, global, free-form error model to allow error mapping of every point with its six degrees of freedom (6DOF) in the machine’s entire working volume, regardless of the number of axes or machine complexity. This holistic approach results in machine-tool compensation done in real time, improving the tool center-point accuracy between four and tenfold on most quality-built machine tools.
An exhaustive battery of on-machine testing and evaluation at Northrop Grumman’s facility in Palmdale, California, has shown that VEC achieved the desired tolerances for F-35 production and completed the task in less than one day.
“The biggest advantage of VEC is achieving these impressive accuracies in a fraction of the time it would take using a 21-error parameter model,” notes Maxham. “Some of the larger and more complex five- and six-axis machines used to take weeks to compensate; but now most can be done in less than a day, virtually eliminating thermal drift in the measurements.”
Wayne Bromiley, a Northrop Grumman facilities engineer, is pleased with the VEC results. “API’s VEC improved our machine tool performance considerably,” says Bromiley. “It reduced the calibration times for these machines from one week of 12- and 14-hour days down to one eight-hour shift. This improvement saved us a major amount of downtime and made the machines more available for production use.”
The VEC process is the heart of the volumetric accuracy for large machine tools (VALMT) project funded by the National Center for Manufacturing Sciences (NCMS). Automated Precision’s work on the project was recognized in December 2009 with the Defense Manufacturing Excellence Award given out annually by the National Center for Advanced Technologies .
“The innovative VALMT project will save the Department of Defense millions while ensuring weapon systems are mission-ready and available for our war fighters when they need them,” says NCMS vice president, Chuck Ryan. “This technology will also pave the way for reducing the manufacturing costs of commercial ships and aircraft, benefiting both government and industry.”
