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Chapter 7-Measurement (eChapter) Image

Chapter 7-Measurement (eChapter)

Author(s)/Editor(s): Charles L Caristan, PhD
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Published: 08/14/2003
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Measurements play a key role in automation, supervisory control, troubleshooting, and process improvement to increase productivity, quality and, hopefully, profitability. They involve the collection of input and output data to be processed into information rather than relying on anecdotal reporting. Information is analyzed to derive executable actions to improve and control operations. The integrity of the executable actions depends on the objectivity demonstrated at all steps of the measurement process, from selection of which data to collect, how these data are sampled and processed, to the analysis criteria used. Imprecise and inaccurate measurements are the only things worse than no measurement at all. For this reason, gages must be regularly tested for calibration, repeatability, and reproducibility. Measurements would not be necessary if laser-cutting operations could produce perfect products, specified by perfect customers, with perfect material, by perfect employees, with a perfect laser-cutting method, and a perfect machine. Inputs in the 6M categories (material, man, method, measurement, machine, and Mother Nature) must be ranked by order of importance by the team managing a laser-cutting operation. Output data to be measured include part-contour accuracy and edge-quality parameters such as dross height, cut-edge roughness, angle of striations on cut edge roughness, cut-edge taper, and kerf width at the top and bottom, along with supervisory control data such as machine uptime versus idle time, cycle time, and scrap rate.