June 24, 2017
June 24, 2017
June 28, 2017
Gage capability studies have been widely used in industrial practices for over three decades. They are necessary for any organization to evaluate variation in its measurement processes. Gage capability studies are often required by industrial customers during their quality audits of suppliers. They have been used to study measurement capability for anything from linear dimensions taken by a micrometer to hardness of metals obtained by indentation after thermal processing. Industry practices for studying gage capability have evolved substantially. The early method of studying gage capability was often called the Averages and Ranges Method, or Tabular Method. The heart of this method requires the familiar estimation of standard deviation from range values. Although the Tabular Method is simple to use, it has several disadvantages. Consequently, the later method utilizes Design of Experiment techniques. The Design of Experiment Method requires an Analysis of Variance (ANOVA) with two factors and random effects. Although the Tabular Method is becoming obsolete in industrial practices, it has an extensive history. Many gage capability studies done by the Tabular Method are archived that way and are still presented to industrial customers during quality audits. On that basis, students in a Quality Control and Quality Improvement elective course for seniors are given an assignment to conduct a gage capability study by the Tabular Method. They are provided with repeated measurement data that has been generated by peers and the assignment is made at an early point in the course, shortly after the range estimation of standard deviation has been used to describe process control and process capability. The data is from a small hand-held dimensional measurement device, used on a width feature of small metallic components. Later in the same course, after an introduction to Design of Experiment techniques, those students use the same measurement data to determine gage capability with the Design of Experiment Method. Throughout both assignments, students experience measurement variation first-hand, possibly for the first time. They also experience how industrial practices and associated tools evolve over time. The students gain an appreciation for the effort that is necessary to properly conduct an experiment, including randomization of data collection. Further, they see that for this case, the two methods produce comparable results. The paper will include the measurement data that is provided to the students and a description of how it was generated. The gage capability results from both methods will be provided and compared. The results are also investigated for improvement opportunities or how measurement variation could be reduced in this case study. There will also be a brief assessment of student learning of the variation that occurs in measurement processes.
Sweeney, S. K. (2017, June), Board # 72 : Gage Capability Case Study in a Quality Control Course Paper presented at 2017 ASEE Annual Conference & Exposition, Columbus, Ohio. https://peer.asee.org/27913
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