Quality Magazine - April 2009 - (Page 33) tive to the axis of the part. Part and feature diameters are indicated as a series of connected points or dots, and measurement computations are made with this calculated image of the part. Because of the low resolution, small features are harder to measure. The use of high-resolution matrix array, or CCD cameras, is more recent and has been made possible by advances in computer processor technology. While faster than other measurement methods, matrix measurements can still be slightly slower than a line sensor due to the larger amount of data to be processed or the number of places where camera images need to be taken. On the other hand, many different measurements can be completed from a single image. Higher resolution makes measurements more stable and accurate, and allows measurement of much smaller features than the calculated image of a line scan. The best matrix systems virtually eliminate all operator influence and, to ensure the highest possible accuracy, take multiple images per measurement. Because matrix array technology uses an actual, highly magnified image of the part, any dirt or problems with the part are instantly visible. While this can be slightly disconcerting— line scan images appear to clean the part rather effectively, and it is a reminder that good measurements require clean parts. Whether or not a universal shaft measurement system is right for the application depends on the careful analysis of several factors, including the size and weight of the part, the number produced per shift and per run, the number and type of checks required, the current means of doing these checks and—in the case of CMMs—whether there are other demands for those systems. Q Patrick Nugent is vice president metrology systems and Dewey Christy is product manager, precision length metrology, for Mahr Federal Inc. (Providence, RI). For more information, call (800) 343-2050, e-mail information@mahr.com or visit www.mahr.com. The use of high-resolution, matrix array or CCD cameras is more recent and has been made possible by advances in computer processor technology. This system can complete many different measurements from a single image. Higher resolutions make measurements more stable and accurate, and allow for measurement of much smaller features than the calculated image of a line scan. Source: Mahr Federal Inc. Quality Quick Clicks 412 at qualitymag.com Visit us at QMC, Booth 25 www.qualitymag.com April 2009 | QUALITY 33 http://www.mahr.com http://www.qualityrevolution.com http://www.qualityrevolution.com http://www.qualitymag.com http://www.qualitymag.com
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