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Author Topic:   Mythology (Not quite Joseph Campbell, but...)
Marc Smith
Cheech Wizard

Posts: 4119
From:West Chester, OH, USA
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posted 08 May 1999 01:41 PM     Click Here to See the Profile for Marc Smith   Click Here to Email Marc Smith     Edit/Delete Message   Reply w/Quote
Date: Thu, 6 May 1999 11:12:49 -0400
From: Daniels Beverly
Subject: "Famous" Mythological(?) Studies

Myth #1: For years I have heard reference to a "famous" study done Ford (?) on transmissions(?). One version of the story goes: Ford and Mazda were both using an identical (in design) transmission. However, Ford had far more complaints about the performance of their transmission than Mazda reportedly did. Some at Ford thought the difference was due to perception; consumers just thought that Mazda had a better transmission and so they didn't complain as much. Others thought there might be a physical difference. So they obtained several of each transmission and proceeded to measure various dimensions. To Ford's surprise, their transmissions had all measured dimensions in tolerance, however, the variation took the entire tolerance range in every case. The Mazda parts were uniformly distributed very tightly around the target - the Mazda parts showed very little variation. Ford thus concluded that it wasn't simply conformance to tolerances but reduced variation around the target that caused high quality and happy customers. (This story is also promoted as one of the seeds for the six sigma movement)

Although I have heard this story innumerable times, I have never seen the published study. I have seen references to references, etc. My question is: Is this just one of those "myths" or "parables" that gets handed down and around or did this study ever actually occur? If so, where was it published?

Myth #2: I also recall a similar story concerning televisions. The players are usually sited as being Sony and some American manufacturer (GE perhaps?)

Myth # 3: And while I'm at it: there is also a paper that supposedly was published by someone at Motorola that stated that product that was reworked had a much higher failure rate in the field than product that was "built right the first time" or at least never rejected and repaired. ( This is also touted as a beginning of the six sigma movement)

I appreciate any light that any one can shed on these myths. Are they real? If so, where were they published?

Bev Daniels
bd1042@warn.com
danielsb@warn.com

----------snippo----------

Date: Fri, 7 May 1999 09:36:50 -0400
From: Jay Warner
Subject: Re: "Famous" Mythological(?) Studies

Daniels Beverly wrote:

> Myth #2: I also recall a similar story concerning televisions. The
> players are usually sited as being Sony and some American manufacturer
> > (GE perhaps?)

This one is not a myth. Genichi Taguchi reported pieces of it in different books, including "The little Green book": Taguchi, Genichi, Introduction to Quality Engineering, UNIPUB, Kraus International Publications, White Plains, Asian Productivity Organization, 1986, perhaps his magnum opus 2 vol. set., Taguchi, Genichi; Clausing, Don, Technical Editor, Tung, Louise Watanabe, English Translator, System of Experimental Design: Engineering Methods to Optimize Quality and Minimize Costs, UNIPUB, Kraus International Publications, White Plains, NY 10601, 1987 If it's in there, it's in the first volume. Also in Taguchi, Genichi; Wu, Yu-in, Introduction to Off-Line Quality Control, Central Japan Quality Control Association, 1979. There is a technical biography of Taguchi which I believe has something on it.

As I tried to pull it out just now, I found it only in Wu, Yu-In & Moore, Wille Hobbs, _Quality Engineering: Product and Process Design Optimization_ (Based on the works of Genichi Taguchi), (c) assigned to Ford Motor Company and American Supplier Institute, 1985. I'm sure that ASI could give you complete refs.

Yu-In Wu refs. the Asahi Newspaper, April 17, 1979. I've never found the exact ref. for myself, nor have I seen a translation.

Sony had 2 plants, which made the same picture tube. A key performance parameter, "color density," had a tolerance range from (coded numbers) 9 to 14, nominal 10. Tokyo plant had a distribution with +3 - -3 sigma inside the tolerance, clearly a normal dist. What we would call a Cpk ratio of 1. 3/1000 parts outside the tolerance. Meanwhile, a Sand Diego plant built the identical tube, assembled into identical sets. Their distribution showed NO parts outside tolerance, but they used nearly the whole range. Now you have to realize that if you see a TV set by itself, your eye cannot tell whether the color density is near a 10, or 9 without training. You must put them side by side to tell, and then you need some help, I believe. So it is hard to detect consciously the difference between a TV which is nominal and one near the tolerance limit. As it should be. Which TV sets were preferred by the customers? Answer: The Japanese ones, by a wide margin. Even though NO US tubes were out of specification, and 0.3% of the Tokyo sets were out of spec.

Why? For one, it turns out that the measure is actually the color resolution. Go talk to your local TV station engineer. It is hard to get, and they pay extra for high color res monitors. People can unconsciously tell something is different with the set, even if they can't tell you what it is. This seems to translate into concern for the set's performance, which means more complaints.

Why? An easier way to deal with this is to use Taguchi's loss function to determine that the US made sets have a loss value some 12 times that of the Tokyo made sets. Now tell the engineers, anything they can do to reduce the loss value is a good thing, and they will start to build better tubes.

Now the above is mostly what I found in various Taguchi refs. The color resolution I got from a TV engineer I met. Amazing what you find out talking to people behind the camera.

But the story isn't over. In 1988 I was talking at a conference with an employee of a large high tech firm that used a lot of computers. He was in charge of checking out the new models, responsible for many of them. Some time before he had seen the first models of a new unit with a high res screen on it. Clarity was a big issue for this new model. Sony was to supply these monitors, with tubes from the US plant (closer to the market, I suspect). "It was obvious," he said. "You set the thing on your desk, and it looked fuzzy!" Eventually, the computer maker issued a letter, saying they would not accept tubes made from the offending plant.

In 9 or ten years the plant had not learned to make its own product. Now do you see why I am so frustrated? I know exactly the logic, the procedure, to follow for product improvement, yet managers will tell me that 5% rejects is OK, that a little fuzz is OK, that customers don't want machines to last over 3 years. Then when the rejection letter arrives, we wonder why. Can you say 'system'? There are causes for effects. We _can_ make improvements. Engineers don't have to know how to achieve the improvements. Certainly managers don't need to know how. Manager only have to know that the procedure for getting there exists. The engineers always get excited when I and they together work through to a solution. We don't need motivation. We need permission and support.

Sorry, I got on my soap box again.

While I was digging out the refs for the tale above, I found what may be the ref for the first 'myth.' The question went as follows:

Myth #1: For years I have heard reference to a "famous" study done Ford

(?) on transmissions(?). One version of the story goes: Ford and Mazda

were both using an identical (in design) transmission. However, Ford had far more complaints about the performance of their transmission than

Mazda reportedly did. Some at Ford thought the difference was due to perception; consumers just thought that Mazda had a better transmission and so they didn't complain as much. Others thought there might be a physical difference. So they obtained several of each transmission and proceeded to measure various dimensions. To Ford's surprise, their transmissions had all measured dimensions in tolerance, however, the variation took the entire tolerance range in every case. The Mazda parts were uniformly distributed very tightly around the target - the Mazda parts showed very little variation. Ford thus concluded that it wasn't simply conformance to tolerances but reduced variation around the

target that caused high quality and happy customers. (This story is also promoted as one of the seeds for the six sigma movement)

Although I have heard this story innumerable times, I have never seen the published study. I have seen references to references, etc. My question is: Is this just one of those "myths" or "parables" that gets handed down and around or did this study ever actually occur? If so, where was it published?

In Ross, Phillip J., Taguchi Techniques for Quality Engineering, McGraw-Hill Book Company, New York, NY, 1988, p 16. Ross refs. Ford Motor Company, 1987. His relating of it is a little different. The product was automatic transmissions, Mazda's were "made more consistently..." Apparently Mazda had a stdev about half that of Ford. Mazda achieved the improvement by use of a more expensive grinder. The added cost in mfg was recovered in reduced warranty claims. Ross concludes, that thanks to this information, the Ford plant (Batavia) improved their "quality substantially and, in the first quarter of 1987, surpassed the Mazda level."

Ross uses this example to do some hypothetical calculations designed to show how the Loss function works. Which it does. It can be well used to translate the distant, vague customer into dollars (or yen) related directly to product dimensions and performance. This makes it much easier to determine which changes are improvements, and by how much they improve.

Now, were either of these items precursors to six Sigma? I doubt it. Neither involved a product Motorola manufactured. The person who told me the tale of the TV's was not in at the inception of 6S, I think. 6S development preceded the time frames cited here, no? Most of the 6S justification is made on piece parts and % rejects, is it not? The examples above get below the % rejects, to the distribution, and how adjusting this controls the % rejects. Can we say 'system' again?

The concept of variance reduction, which is one of Taguchi's major points, serves equally well when dressed up in 6S. Or A2Q, for that matter (see yours truly web site, address below). I can easily see that a presenter of any methodology would like to claim these examples as sources of inspiration. So long as no one is fooled or hurt, I suppose it is OK. But what we really need to work on is getting down to the core logic, apply it, and find the solution. If you buy a program that is not applied well to your plant and product (i.e., is applied mechanically), or that your managers do not want to adapt/adopt the system, you will not get the sizzle you paid for.

Jay
--
Jay Warner
Principal Scientist
Warner Consulting, Inc.
4444 North Green Bay Road
Racine, WI 53404-1216
USA

Ph: (414) 634-9100
FAX: (414) 681-1133
email: quality@a2q.com
Power to the data!

----------snippo----------

Subject: Re: "Famous" Mythological(?) Studies
Author: CGLEASON at USNC01
Date: 05/07/1999 9:57 AM

In regards to the third question about "mythological" studies, I can't answer to an actual study at Motorola (hopefully someone else can) but I can speak from several years of quality engineering experience in computer hardware manufacture. I would advise that individuals be VERY cautious about extending what is generally accepted to be true about electronics rework to other industries and products. Why? Rework on electronics typically involves a secondary soldering operation. The heat from soldering operations unquestionably affects the reliability of many electronic components and absolutely affects the reliability of the printed circuit board connections at the point of soldering. Add this to the HUGE amount of variability in hand soldering operations, and the impossibility of truly inspecting the impacts of the results, and you have a recipe for early product mortality.

Many years ago, it was common to do solder touch-up to products with cosmetic machine-solder defects. This practice was eliminated when the rework/reliability effect was understood. Other changes to improve reliability, such as reducing hand-soldered components and implementation of Engineering Changes by revising board designs rather than adding wires, also resulted from this knowledge.

Before extending this result to other rework processes, the potential failure modes and mechanisms must be understood. There are undoubtedly many rework operations that would not affect the reliability of the finished product, just as there are many that would. Elimination of rework is always a valid goal regardless as it reduces product costs (cost of poor quality), but reliability impacts can greatly increase the justification to pursue a rework-free quality level.

Carla Gleason
Raychem Corp.
cgleason@raychem.com
web: http://www.a2q.com

---------snippo----------

Date: Thu, 6 May 1999 12:37:15 -0400
From: "L. H. Garlinghouse"
Subject: Re: "Famous" Mythological(?) Studies

Re Myth #1:

> Myth #1: For years I have heard reference to a "famous" study done Ford
> (?) on transmissions(?). One version of the story goes: Ford and Mazda
> were both using an identical (in design) transmission.
<< snippity snipp snipp>>
-------------

Some input on source on this one. I first encountered this story in one of the Transformation of American Industry (copyright PQSystems) videos (c.1985). The story was done on video by David Scwhinn, P.E. (then a Stat/Eng. guy for FORD) and the US transmission plant was given as being Batavia, OH (?). This was, I think, around module 7 or 8 of the TOA series. Ing. Scwhinn went on to become a principal in PQSystems, which is still very much in business so if one was really interested one might contact him/them.

I also think I recall reading of the same study in perhaps a Wheeler or a Myron Tribus paper/publication or elsewhere, but at the moment I don't really recall where. In my mind the study is legitimate and should be removed from myth status.


<< All opinions, statements, &c are my own>>
L.H. Garlinghouse, C.Q.E.
Pocahontas AR U.S.A.
(870) 892-4586 ext 7659
garlinghou@waterlooindustries.com

----------snippo----------

Subject: Batavia study
Date: Sat, 08 May 1999 07:47:34 +0000
From: Marc Smith
Organization: Cayman Systems
To: quality@PUCC.PRINCETON.EDU

The transmission study was real. It was the Batavia (Cincinnati) transmission plant. It had to do mostly with surface roughness of machined parts (shafts, gears) which interfaced. The Batavia transmissions were failing at better than 20% in warranty while the Japanese built ones were rock solid. Transmissions from each were dissected at Batavia. Batavia's measurement indicators for things like shaft roundness and surface roughness could not measure the minute variations of the Japanese tooled surfaces however they had no problem detecting the irregularities on the Batavia shafts and gears. The instrument manufacturers were brought in and - long story short Batavia did not buy indicators as sensitive as Mazda did. Ford's surface roughness indicators could not even measure the irregularities in the Mazda machined shafts while Ford's shafts looked like sandpaper. It was shown that the Japanese had scheduled frequent tooling changes and such (predictive methodologies were utilized), and they went beyond the 'requirements' - Mazda also focused on achieving the center of the spec while Batavia was content to keep within spec ("They're running high today, George, but they're technically in spec so keep the line going full blast!").

I've never seen this story told in regard to 6 Sigma, however.

Ford produced a video of the experiment for training within Ford but many tapes quickly got out. For a number of reasons Ford had a hernia and went after every tape they could find and destroyed them. Last time I saw someone with a pirated tape was back about 1987 - doubt there are many left out there by now. Yes, Virginia! It was a real experiment! I saw the actual Ford training tape back in 1987 (my friend with the pirated tape).

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