George Schuetz Director of Precision Gages
What Do You Mean by Accuracy? (20 Years Later)
Nearly twenty years ago, I wrote the column “What Do You Mean by Accuracy?” Since then, new standards have been created or updated to reflect new developments and thinking about what accuracy is. So, has accuracy changed?
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Checking the Performance of Surface Finish Gages
The measurement of surface finish has come a long way in the past 60 years. We have advanced from fingernail scratch pads to microprocessor- and PC-based systems with inductive probes. We even have the choice of optical sensors to evaluate part surfaces.
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Gage Repeatability and Reproducibility Studies
GR&R studies are a way to assess the reliability of gaging results. For these studies, a few gage operators measure a small number of parts, several times each. The results are compiled and reduced to a single number that indicates the total expected spread of measurements for a single part, for all trials, by all operators. This number is expressed as a percentage of the total part tolerance.
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GR&R Studies: Measuring the Measurement
Over the last few columns we’ve been talking about measurement system analysis, or MSA. A key component of this overall analytical process is the GR&R study, officially known as ANOVA GR&R, or “Analysis of Variance Gage Repeatability and Reproducibility.”
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Measurement System Analysis: Using the Data
High-end transducers are available for precision dimensional measurement. These electronic systems can provide incredibly high resolution and accurate readings, but they are also able to transfer data to a data collection device, usually a computer.
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Electronic Gage Heads
Using probes to reduce uncertainty during the electronic gaging process.
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Measurement System Analysis
Range, resolution and accuracy in digital amplifiers and inductive probes.
Read MoreDual Master Air Gaging Systems
Choosing a single master or dual master air gaging system can be difficult. Understanding the similarities and differences--in performance, price and philosophy--can help a user make the best choice for their application.
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Single Master Air Gaging Systems
Choosing a single master air gaging system can be difficult. Understanding the similarities and differences--in performance, price and philosophy--can help a user make the best choice for their application.
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How To Become A Master Of Deviation
In the June 2009 issue, I wrote about how “less” can be “more,” by purchasing lower-grade master rings and discs and using their certified size—their master deviation—to improve the gaging process accuracy. This topic sparked a number of questions and some confusion, primarily because I did not have space to talk about actually applying this technique on the shop floor.
Read MoreComparative Gages and Temperature Compensation
The use of electronic temperature compensation in gaging has become a valuable tool in improving accuracy as well as gage repeatability and reproducibility (GR&R) in harsh manufacturing environments.
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Dealing With Dirty Patches
Gage calibration is a routine process followed by most users of precision gages. How regular a gage needs to be checked and its performance documented is usually defined step by step in a documentation procedure.
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