S3 E8 - Bill Bellows - Genichi Taguchi and Quality - Part 1
Jan 18, 2024
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Bill Bellows, an engineer with experience in the jet engine industry, discusses his introduction to Genichi Taguchi's methods and quality concepts. They explore variability reduction, precision vs accuracy, process capability, and Taguchi's loss function. The conversation compares traditional quality approaches with Taguchi's perspective, using analogies of a dartboard and Deming's red bead experiment.
Genichi Taguchi's view of quality focuses on quantifying loss and variation, rather than just meeting specifications.
Accuracy and precision are key aspects of quality management, with a focus on improving the quality of non-defective items.
Recognizing and addressing the degrees of variation within accepted requirements is crucial for continuous improvement in quality management.
Deep dives
Introduction and Background
In this podcast episode, Bill Bellows, a mechanical engineer with extensive experience in the Deming world, shares his background and journey into the field. He discusses his initial career as a heat transfer engineer in the jet engine industry and his eventual discovery and enthusiasm for the work of Genichi Taguchi and Deming. Bellows highlights his excitement for the broader application of Deming's principles beyond manufacturing and his transition into teaching and consulting roles.
Discovering Taguchi Methods
Bellows recounts his introduction to Taguchi methods during an urgent problem-solving situation with jet engine gears. He explains the concept of fractional factorial experimentation, where multiple factors are changed simultaneously to study their effects. Bellows highlights the shift from black and white thinking to shades of gray, emphasizing the importance of measuring degrees of wear and understanding the concept of variation. This experience sparked his fascination with Taguchi methods, and he realized the potential impact they could have on improving quality.
Understanding Quality as Shades of Gray
Bellows delves into the essence of quality management, which involves two fundamental questions. The first question revolves around whether a characteristic meets requirements, where the answer is either yes or no, representing black and white thinking. The second question focuses on the variability of a quality characteristic within the accepted requirements, recognizing that there can be an infinite number of ways for it to meet those requirements. Bellows emphasizes the importance of addressing both precision and accuracy within the context of quality, highlighting the need to go beyond just reducing variability and striving for improvement in the quality of white beads.
Precision and Accuracy in the Red Bead Experiment
Bellows draws parallels between the red bead experiment and precision and accuracy. He clarifies that the experiment, which involves randomly drawing red and white beads, represents a black and white perspective where red beads symbolize defects and white beads represent non-defective items. Bellows explains that striving for accuracy entails aiming for a cluster of beads closer to the bullseye rather than just reducing the number of red beads. He emphasizes that accuracy and precision in quality management involve understanding variation in good and continuously improving the quality of the white beads.
The Significance of Variation in Good
Bellows expands on the concept of variation in good and its role in quality management. He discusses how Dr. Deming's focus on reducing variation is often misconstrued as solely aiming for precision. However, Bellows stresses that the true essence lies in recognizing the degrees of variation within the accepted requirements and continuously striving for improvement. He equates this understanding to different shades of white in the bead analogy, highlighting the need to focus on enhancing the quality characteristics beyond simply meeting the requirements.
In this first part of a two-part series, I chat with Bill Bellows in this episode. Bill gave us a little history of his introduction to Genichi Taguchi's methods and quality concepts while working as an engineer in the jet engine industry. We explore key ideas around variability reduction, precision vs accuracy, process capability, and Taguchi's loss function. Our conversation looks at the difference between traditional quality approaches focused on specifications and Taguchi's view of quality based on quantifying loss and variation. We riff on analogies using a dartboard and Deming's red bead experiment to clarify Taguchi's perspectives on "loss" and variation even within specification limits. Bill's LinkedIn can be found here:
