Oct 5 2020
20 years ago, Honda stood out through its reputation for quality. Outsiders were studying Honda’s approach and Youtube now offers several videos shot at that time about it. Today, quality is no longer the differentiator among carmakers that is used to be but the practices of a company like Honda — past and present — remain a worthwhile object of study.
Sep 26 2020
The post on Does Toyota Use SPC? elicited many comments on LinkedIn. Some suggested that it was scoping SPC too narrowly when contrasting it with Toyota’s approach. In fact, SPC as referenced in the post is the body of knowledge described in the American literature on quality and taught in professional courses.
As to why Toyota is not using SPC, the answer is simple: SPC is about process capability and the quality problems Toyota addresses in 2020 are not due to lack of process capability. In industries that lack process capability, modern data science outguns the old SPC toolkit but that is a different discussion. The most vital question raised in the comments was why we have been not learning Toyota’s approach to quality. In the past 30 years, American industry has learned “Lean Six Sigma” instead.
The comments also enriched the public sources of information cited in the post with corroboration by current and former employees of Toyota.
Sep 21 2020
As part of a discussion started by Lance Richardson on LinkedIn, I stated as a fact that SPC was not part of the Toyota Production System (TPS), which prompted several contradictors to tell me I didn’t know what I was talking about. The “evidence” they provided, however, does not refute my statement. It confirms it instead.
Nov 4 2019
“The ability to react to process changes is more important than protecting yourself from occasional false alarms. […] So do not worry so much about straining out the gnats of false alarms that you end up swallowing the camels of undetected process changes.”
Sourced through Quality Digest
Michel Baudin‘s comments:
The people of the Honda plant in Anna, OH, claim to make the best engines in the world. On the floor, there is neither a single control chart nor any engineer trained in SPC.
Of course, we should fact-check their claim. Rankings of engine quality are not readily googleable. The closest I could find is a ranking of engine reliability from 2014 in a UK blog called The Car Expert, based on data from Warranty Direct, a UK provider of extended warranties. According to them, Honda indeed made the most reliable engines:
“Only one in every 344 Honda owners have had engine trouble, with second-placed rival Toyota notching up just 1 in 171.”
According to Anna engineers, their machine tools can hold tolerance ten times tighter than necessary. The few quality problems they do have are due to operators picking the wrong parts in assembly. Control charts in the machine shop would produce nothing but false alarms. With the charts crying wolf, the alarms would lose credibility and nobody would react when a real one hit.
In this kind of situation, Wheeler’s statement can be reversed. The ability to protect yourself against false alarms that send your engineers on wild goose chases is more important than detecting changes that hardly ever happen. You do want to detect changes in the process but control charts are too crude a tool for this purpose.
Jul 16 2019
A conversation with Franck Vermet about problem-solving tools for factory operators caused me to revisit the 7 tools of QC from 50 years ago and ponder how they should be updated with current data science.
Data Science for Operators, as a book, remains to be written. If you google this phrase today, what comes up is training courses offering to “change your career” by attending a “data science bootcamp.” TIBCO Spotfire has “Workflow Operators” but these are programs, not people.
So the following are tentative answers to questions that haven’t been asked before.
Mar 12 2021
Process capability
The literature on quality defines process capability as a metric that compares the variability of its output with tolerances. There are, in fact, two different concepts:
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By Michel Baudin • Tools 6 • Tags: Cpk, First-pass Yield, Quality, Rolled Throughput Yield, Run-by-Run, SPC, Yield