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What is quality
6

What is quality

What is quality

(OP)
Although quality is easy to talk about in generalities, it's difficult to define in specifics.

It was Aristotle who said: "Quality is not an act. It is a habit."

Think for a minute what quality, or the lack of it, means to you, objectively as well as subjectively, and let us learn from your opinions.

RE: What is quality

My brother is a carpenter and a perfectionist.  He is always spending too much time a job's money, but refuses to leave a job until its "perfect".

Once he was lamenting that he spent so much time on fine details of a job, that he made only 4 per hour at the end.  I said there is a difference between doing a $2000 job for $500 vs. giving a person the best $500 job possible for $500.

The point: perfectionism is not quality.

I could be the world's greatest underachiever, if I could just learn to apply myself.
http://www.EsoxRepublic.com-SolidWorks API VB programming help

RE: What is quality

Well quality is defined in ISO 9000 as reaching a stated failure rate (something which is often forgotten by managers who insist that all vendors much be ISO 9000).  So if you state that you aim for a maximum failure rate in a component of 98% on post manufacture testing is OK, and you achive 97%, then you've got a quality manufacturing process...

For me quality is "doing what it says on the tin"- it is a cheap and cheerful one shot disposable product that does the job once, for example.  Or the guy that tells me I can get a rough draft by friday and produces a report by the deadline that has good technical content but lots of spelling errors, poor formatting and no pictures has produced a quality piece of work.

RE: What is quality

For me, quality is how well something meets (or exceeds) my expectations (which sometimes change with time just like any customer).  This is a purely subjective measure unless I have made those expectations known up front.  If the expectations are known and accepted, you at least then can establish an objective measurement of quality.  From there you can attempt to influence or control it.

Lack of quality simply to me means problems.

Regards,

RE: What is quality

This was a significant topic in the 1980's.  One cheer leader was Phillip Crosby.  His definition of quality was conformance with the requirements.

This is big.  In other words, if you need basic transportation, then an inexpensive but reliable car is a quality car.  A Mercedes or BMW exceeds your requirements.  A used Mustang may be just fine.

This is big because you must define your requirements in specifications, references to applicable codes and standards, detailed drawings, etc.  Specify that something must work.  This seems basic but is not.

For the QA departments it is all about documentation and procedures.  QA may not care whether something works so long as quality procedures exist, proper material documentation exists, the paper trail is suitable.

John

RE: What is quality

Some thoughts, for what they are worth.

"Quality" is, of course, relative, much like "fast".  A quality product is one that is superior to, or at least equals that of your competitors.

Quality, these days, appears to be very closely aligned to "continuous improvement".  So, in DrillerNic's example above, 98% may be satisfactory in year 1, but might not be in year 2.

Quite often, quality implies that a certain minimum or required standard has been reached.  Improvements beyond this that have a cost implication may prove to make a company uncompetitive.

The 'Quality triangle' indicates that there is a direct correlation with cost and time.

Finally, a company or product with the word 'quality' in the name is usually missing the word 'poor'. "Quality speaks for itself."

RE: What is quality

For an interesting read on quality and its elusive definition, read ZEN AND THE ART OF MOTORCYCLE MAINTENANCE by Robert Pirsig.

RE: What is quality

(OP)
Concerning the posts I've read in the meantime, I'll transcribe herebelow some paragraphs from an article I had the chance to read on this subject.

...A goal of zero errors or defects may be the only way. Jeff Dewar of QCI International once said:

If we accept 99.9% as our goal, we'd have to accept the following conditions:

• 2 unsafe plane landings per day at O'Hare airport
• 16,000 pieces of mail lost by the USPS every hour
• 22,000 checks deducted from the wrong account  
   every hour
• 20,000 incorrect drug prescriptions each year
• 32,000 missed ehartbeats person per year

That puts quality goal in perspective. Thus perfection should be the aim every way every day...

...Speaking of products an services, there is no need to be a prophet to predict that in the years ahead, technology won't win the war. The competitive difference in industry wil be the people who attend to quality.

Would anyone like to comment ?

RE: What is quality

25362
 Quality is how well something fits your specifications.
Chevrolets and Mercedes Benze cars have equal levels of quality, Godiva chocolate and Hershey bars have the same level of quality.
They all have different standards and specification but they all were made to meet those standards.
A Rolex and a free watch from Burger King have the same level of quality.  The pilot on your next airline trip will probably not be using a Sponge Bob watch made in China. Both watches met the standards of quality for the markets they were made for.
Higher standards usually cost more. Were willing to spend the money to prevent accidents at O'Hare but if your kids Sponge Bob watch is 10 minutes off per day, who cares.
You might want to read thread 765-98263. IMO it was a clear example of not having a standard and in turn not getting the quality for the ruquired job.

RE: What is quality

3
Wow, 61 bpm AVERAGE over a yr; now, that's quality!

Being in systems engineering, I'd like to warn everyone to not get hung up over specs.  As with pornography, you know it when you see it, but defining it is a tenuous proposition.

>  Most customers haven't a clue how to specify what they want, so specifications are sometimes irrelevant to the actual operational requirements of the product

>  Writing a good specification is tricky.  All requirements should be quantifiable and testable

>  But, requirements verification can be like a science project.  No one might have enough money to pay for verifying systems with complex requirements.  

>  Case in point, military systems generally have specifications that include sections with environmental conditions and reliability requirements.  An exhaustive verification of a million-dollar system against ALL its environmental and reliability requirements could cost $25-million and more than a year to cover the all the units that are destructively tested and labor/facilities required.

Personally, I'd define quality as a product that works in the intended application and exceeds customer expectations.  

Down with software that deny the possibility of working in any intended application!

TTFN

RE: What is quality

BJC
  The examples you listed may be true as far as the manufacturer is concerned, but how individuals perceive that "quality" is much different.  You forget to mention  that "quality" is a highly subjective term.  I would definitely prefer the Mercedes, Godiva chocolate and a rolex watch over the alternatives, if I could afford them.  Why?  Because, to me, they are of higher "quality".  For example, high quality chocolate will melt in your mouth very quickly.  Hershey chocolate has to be masticated a bit (or left in a warm place) before it will melt, and even then it doesn't compare.  The feeling of a high quality chocolate in your mouth is something you will not experience with the waxy confections made by Hershey.

RE: What is quality

(OP)

BJC, I read Thread765-98263 which dealt with lawn mowers and ended with specifications, and you know what they say about that: An elephant is a mouse built to government specifications. Building elephants seems to be a very unprofitable product line...

From the standpoint of the manufacturer, as John L. McCaffey said: "... You have to make some stuff and sell it to somebody for more than it cost you. That's about all there is to it,...except for a few million details."

So, it appears that quality should be nothing but... continued attention to details. True?

RE: What is quality

The question that eludes many companies is, "which details?"

Consider WalMart and K-Mart, similar names, similar businesses.  K-Mart has been dying a slow death and WalMart has more clout that some countries.

The second issue is that some of the details are conflicting.  Is it even possible to make something perfectly safe?  If so, can it even be built or sold at a reasonable price?  Does the customer even care; since he probably is more interested in sharpness and durability in a knife than its safety?

TTFN

RE: What is quality

The classic answer to the question of "what is quality?" is it is very hard to define, but you know it when you see it.

A lot of replies here regarding reject or failure rate.

When you aim for perfection, do you actually achieve it?

What would you expect to achieve if you aim for less than perfection?

Several replies regarding meeting expectations (specifications).

If I ask you to provide me a product that fails to perform as intended 76% of the time, requires twenty hours of maintenance for each hour of use, and, when it does work, 50% of the product produced must be rejected and you provide me exactly that, have you provided a quality product?

RE: What is quality

ewh
Once you decide what charesterics a product should have quality is not subjective.  A Hershey bar may be good enough for a break at work but not good enough for your sweety on her birthday. Godiva has higher standards that result in better chocolate, maby they use only fresh milk and Hershey uses powered, maby Godiva uses only  cocoa from Ghana grown at elevatons of 1000 meters and Hershey may use cocoa bought on the spot market.  Godiva is better is better because they have higher standards for every ingredinet and step in production.
Getting quality on a project is a matter of writing tight specifications and seeing that they are delivered and installed they way want.  The use of the project is a key factor in the specifications.  If your doing the electrical system in a K-mart it not as tight as the electrical system in a data center.  The K-mart the Hershey, the data center is the Godiva.   On "9" is OK for a K-Mart, you need 6 "9"s for a data center.
Sometimes conditions or circumstances may force you to make a product or process that conformz to standrds that are nearly impossible, thats when engineering gets fun.  

RE: What is quality


Quality:  One of the most misused and misundersood words in the English language.  The level of quality must be quantified for it to mean anything. For example, the phrase "We manufacture and sell a quality product" to most people means that it is a good or reliable product.  The manufacturer however, ommited to say that it was a product of poor or average quality due to the level of quality control.
Let's say we have two widget factories manufacturing the identical product....same method of manufacture, same material etc., both flying their ISO 9000 certification banners.  To get certification, they "say what they do and do what they say" and later, the ISO auditers are satisfied that they are meeting their requirements.  The difference being that factory A randomly inspects 10 out of 100 widgets.  Factory B on the other hand, inspect 100% of theirs, scrap the deficient ones and only perfect widgets go to market.  This of course having a vast difference in the cost of the widgets.
As defined in the American Heritage dictionary, quality is "An inherent or distinguishing characteristic; a property."
Widget A has the distinguishing characteristic of failing and widget B has the distinguishing characteristic if lasting a lifetime.
So, the word quality on it's own means nothing.....it's the level of quality that either satisfies or irates the customer and the higher the level the better which means basically, you only get what you pay for.  Like the Chevy and Mercedes example.

Haggis  

RE: What is quality

BJC,
  I agree with you to a point.  You are stating what quality means to the manufacturer.  Once defined, all of the product that passes QC is of quality.
  As haggis stated above, quality means nothing if not quantified.  Both Hershey and Godiva sell quality products.  It is up to the end user to decide what level of quality they desire and are willing to pay for.  It is in that sense that I feel that quality is subjective.

RE: What is quality

BJC,

Your example is of infant death.  Given your premise, A and B have identical operational behavior.  Once all the DOA widget A's are dealt with, the remaining product behaviors are identical.

This is what's called "initial" quality in the automotive industry, which works great if you junk your car every 2 years.

However, for those who keep their cars, the supposed additional quality of B does not really exist, since the initial screening only captures infant failures

TTFN

RE: What is quality

IRstuff
I think you explained my Pontiac.
A and B cost the same to make?
If your specing lug nuts for a car, do you buy to a loose spec and sort out the bad ( achieving quality by inspection is never a good or workable solution ) or you can just put them on the and car let the lawyers tell you there bad.
Do peoplse  still read Demming in the auto business?  
Does the Firestone for SUV tire thing sound like a quality problem or an inspection problem?

RE: What is quality

MintJulep, I'm not sure if your example is taken from real life, but I can think of real products that are successful that have each of your quality limits individually.

"If I ask you to provide me a product that fails to perform as intended 76% of the time,"

This is failure to perform during the mission. 76% might be an acceptable failure rate where the product depends on a scattergun or bulk property - eg microballoons as fillers in resins. Filtering systems might only be 24% efficient, per stage. But with enough of them you can build atomic bombs. Another class of example would be where the performance of the vital few is of far greater impact than the majority.

" requires twenty hours of maintenance for each hour of use,"

Modern fighter planes, or torpedoes, would easily exceed this

" and, when it does work, 50% of the product produced must be rejected and you provide me exactly that,"

One example might be a tyre and wheel  balancing machine. I'm not sure if 50% is a reasonable estimate of the number of wheels that need a second go, but it must be of that order.

" have you provided a quality product?"

If those were sensible and compatible customer defined specifications, then I believe, yes, it is a quality product. The last one is the most interesting, since the high reject rate has an enormous effect on the manufacturer's costs, yet with 100% testing, it has no effect on the customer. At the same time this is not regarded as an acceptable solution where I work, since any failure of the inspection process will result in poor product. There's also the question of how exactly the pass mark is set - how sure are we that a 49th percentile part is a failure in the cutomer's eyes, and a 51% is satisfactory?


Cheers

Greg Locock

RE: What is quality

Greg,

I was trying to  do the "reduction to absuridity" thing, but was rather pressed for time.  I was attempting to refute the "quality is compliance to specification" definition.

Put more simply, my point was "If I ask for crap, and you give you crap, have you provided quality?"

I did however attempt to pick individual limits that are accepted for some applications, as you note.  Minor point, you missed the "perform as expected".  A 24% efficient filter is good if it filters out 24% of the stuff (performs as intended), but is not good if it filters out only 12% (does not performe as intended).

RE: What is quality

Haggis,

You cannot inspect in quality.

Perhaps factory B needs to do 100% inspection because their processes are out of control.  What is their scrap rate?  Maybe they only produce 1 perfect widget for every 99 thrown away.

Factory A might have excellently controlled processes, and has determined that a 10% random inspection level is sufficient to identify that their processes have strayed.  They could produce 1000 widgets, inspect 100 and find only one defect.

Factory A has much better quality (or at least quality control) than factory B.

In your example you incorrectly assume that there is a relationship between inspection frequency and both the minimum standard of "it's good" and the ability to ship a good product.  Neither relationship exists.

RE: What is quality

BJC,

I was simply pointing out that given two identical processes with 10% sampling and 100% sampling; post-production testing would only catch infant-failures.  The long-term failure rate would essentially be the same and therefore, even with 10 times the testing, the net quality is the same.

Quality CANNOT be assured by testing.  Testing is expensive and cannot catch life failures.  It must be done by design and process.

TTFN

RE: What is quality

To me, a quality product is one that performs better than its competitors and suffers fewer defects. I think that this is the general view of the public.

RE: What is quality

I think the public would view quality as "it works when I need it to work".

Good Luck
--------------
As a circle of light increases so does the circumference of darkness around it. - Albert Einstein

RE: What is quality

(OP)

It might be of value to those involved in quality control to have a look at the "loss function, orthogonal experiments, parameter and tolerance design" introduced by the japanese as explained in Taguchi Techniques for Quality Engineering" by Phillip J. Ross (McGraw-Hill). ISBN 0-07-053866-2.

RE: What is quality


Everybody including myself seemed to have gone off on a tangent. The answer to the question What is Quality? is as I said, "An inherent or distinguishing characteristic; a property."

This can be poor, fair, good, or excelent. What most of the posts, while making sense, are lacking is, the use of one of these abjectives preceeding the word quality.

Every product as a whole or component thereof has quality.

Haggis

RE: What is quality

From an MSNBC article about the safety failures at NASA:
http://www.msnbc.msn.com/id/6872105/page/3/

Quote:

A good place to start is with the words of Admiral Hyman Rickover, father of the nuclear navy and founder of a safety culture with a remarkable record.

“Quality must be considered as embracing all factors which contribute to reliable and safe operation,” he wrote. “What is needed is an atmosphere, a subtle attitude, an uncompromising insistence on excellence, as well as a healthy pessimism in technical matters, a pessimism which offsets the normal human tendency to expect that everything will come out right and that no accident can be foreseen -- and forestalled -- before it happens.”

TTFN

RE: What is quality

Let me bring us back to the idea that quality is conformance with the requirements.  My son is a recent EE grad now attending graduate school.   Two years ago when I was on an offshore platform in Mexico I asked via email what he wanted for Christmas.  His response was a rugged reliable watch.

I did not buy him a Rolex; I bought him a Casio model that I found on the Internet.  The Casio that I selected was the G-Shock series, water resistant to 200 m, solar powered with internal battery, receives the 60 kHz time signal.  The G-Shock is rugged.  My son is a certified SCUBA diver although he has not dived in  a while.  He also participates in the martial arts.  I doubt that he wears his watch when practicing but he can.  He should not worry about changing the battery for about seven years.  A month later I also bought one for myself as a birthday gift.  I get what I want if I buy it myself.

A Rolex is a QUALITY watch.  I see them on the yacht skippers who participate in serious regatas.  However, besides my unwillingnes to spend that much for my son's present, I do not think that they typically meet his requirement for ruggedness.  The Casio meets my son's requirements.  It is a quality watch.

John

RE: What is quality

Rolex is a high quality watch.

RE: What is quality

A Sponge Bob watch from Burger King is a high quality watch as well.

RE: What is quality

As the last few posts point out, there are subtle, yet really distinct forms of quality.  

One is inherent, e.g., it meets or exceeds its requirements or expectations.

The other is what is called in business "good-will."  From a specification/performance standpoint, Rolex and Casio have equal quality.  But, Rolex, like HP and IBM have additional good-will; a warm-and-fuzzy based on customer support, how much the salesperson pampers or strokes you, etc.  

IBM is/was a good example; I had an IBM CD-drive many years that died relatively early.  Called their tech support and a new one was shipped to me that day; no RMA, no fuss.  That's an intangible that is not reflected in the numerical assessment of quality.

TTFN

RE: What is quality

(OP)
I think haggis has a point. Quality as an attribute, may mean a degree of excellence or worthiness, as most of the posts indicated, or just a trait, feature or characteristic.

It all depends on the preferred definition, which itself depends on who is asked, the manufacturers and suppliers, or the users of products and services.

Thanks for all your contributions.

RE: What is quality

BJC,
  I guess I just have a problem accepting that anything manufactured and released to the public is of high quality, just because it meets the manufacturers specifications.

RE: What is quality

That's yet another form of quality, e.g., how do the specifications relate to the intended or desired use.  Followed by how thoroughly the product performance is verified.  A product may appear to meet its requirements, works in its intended environment/application, be reliable, have great product support.  Yet, it may actually not meet ALL its requirements; it may be that its requirements are grossly in excess of how it's actually used.

Somewhere in that is the degree-of-difficulty of achieving the requirement itself or achieving the level of compliance to that requirement.  That's another intangible that makes one feel that a Burger King Sponge Bob is still low quality because it should be trivial for it to meet all its intended requirements and it's free.

TTFN

RE: What is quality

(OP)

More than once I've heard (free translation) that "advice given for nothing is worth nothing". To all participants, do you think that since the advice given through eng-tips is free, would one have to attach a "low-quality" label to all the advisory inputs because of that trait ?

RE: What is quality

ewh
If the public buys it, it meets there expectations.  The manufacturer made a quality level to meet the publics expectations.  
  The Sponge Bob and the Rolex have equal quality, different standards.
 If your buying a watch that will last the rugrats a week before it goes in the trash, the Sponge Bob watch is the item.  IF your doing the solo round the world yacth race would your choose the Sponge Bob or the Rolex watch?

IRstuff
Rickover is generally credited as being the one who worte 10CFR50 appendix B.   It's short but is the basis for all Nuke QA/QC progarms.

RE: What is quality

Not to kick a dead horse, but the Pinto would be an example where the public DID buy the car and obviously, the car had less than stellar quality, w.r.t., to expected performance in a rear-end crash.

TTFN

RE: What is quality

Rolex watches have a perception of being high quality.  Truth be told, they keep rather lousey time.  The Casio G-shock is much less likely to deviate from a calibrated reference over time.

This is not to say that Rolex does not produce quality watches, for they do.  The workmanship and attention to detail is outstanding.  They are reliable, and sufficiently accurate for most purposes.  They are also very nice looking.

Perception is an important component of quality.  But perhaps imperception is even more important.  Things that simmply work, day-after-day, for years and years, yet go unnoticed by the vast majority of people are the true champions of quality.

25362,

Your last post asks us to compare quality against value.  There is no relationship between the two.

A Rolex is a high quality, high value watch.

A Casio is a high quality, low value watch.

The free sponge Bob watch is a moderate quality, low value watch.

The Steinhauser watch (see Thread1010-109172) is a low quality, low value watch masquerading as a high quality high value watch being represented as as a high quality exceptional bargin.



RE: What is quality

I think quality depends on the prespective you take to look at something.  As engineers, I saw all the right responses that quality has to be tied to something that can be compared to a standard specification.  

Step into the publics shoes and quality seems to relate to the experience.  I see a lot of Pintos still driving around, and I would believe to the owner, the car has quality as it is still running and they are not dead, even though the Pinto was not a quality product.

Step into managements shoes and quality seems to be based on performance.  The Sponge Bob watches are flying off the shelves, making their assumptions about product acceptance quality assumptions.  Can these watched tolerate some variation in conformance with specifications, yes, I would think so.  But the net effect was a quality management job in getting product to market.

Step into the accountants shoes and quality seems to be based on investment and return.  That Pinto design saved moeny on each unit produced, which to an accountant is a quality approach to building a product.  

True quality is obtained when one can understand balance all these prespectives to generate somthing that allows all those involved to succeed.

Pabst Blue Ribbon beer was a quality product.  They had a quality marketing approach (PBR me ASAP).  I wouldn't blame the consumers for the products failure, Pabst was sold off and those people that looked out for the quality of the Pabst experience were gone.  Everyone involved was still delivering quality aspects of the Pabst experience, but somehow quality was no longer linked to success, and sadly, my poor PBR's are gone for ever....

BobPE

RE: What is quality

If I need a tool for a home project, and I'm only going to use it once, I look for an inexpensive tool, even though I perceive it to be a low quality item.  Therefore, for my purpose, it is high quality.  Again, I fell that quality is subjective.

RE: What is quality

(OP)

MintJulep, in the watch example, wouldn't the word price (or cost) be more appropriate than value ? Wouldn't price/cost be one of the various overall quality characteristics, in this case a mitigating factor ? I think there is indeed a relationship between the two.

Value, like quality, would be a translation of our satisfaction, or pleasure, obtained from the acquired product, or service, more as a chelant (borrowing from chemistry) of quality and price. Kindly recall the quality triangle mentioned by TrevorP in his post of Jan. 25.

Do you agree ?

RE: What is quality

I saw this in a Thailand shop of sartorial splendor and I think that it defines quality (I've modified it slightly):

Quality is never an accident.
It is always the result of intelligent effort.
Thre must be a passion to produce superior products.

RE: What is quality

25362,

I will agree that "price" or "cost" would be a better choice of words for the purpose of my previous example.

However, just as there is no relationship between quality and cost, neither is there a relationship between price and value.

You may value the sponge Bob watch given to you as a gift from your daughter more than you value a Rolex you bought for yourself from the proceeds of a fortunate stock pick.

I disagree with TrevorP that there is a correlation between quality and cost.  Take the Fctory A Factory B example from above.  

Factory B sends only perfect widgets to market, but scraps many imperfect ones.  Thus the cost of Factory B's widget reflects the cost of all the raw material that was thrown away and the costs associated with converting that raw material to scrap.

Factory A may let the occasional bad widget out the door, but the vast majority will be good, and much less expensive.

Assuming that Factory A and Factory B have the same standard for good and bad, I prefer the less expensive widget.

RE: What is quality

It may seem logical to assume something made to a higher standard would cost more ( that is, take more dollars, material and manpower to make).
But one defination of a good engineer is to do for $1 what any one else can do for $2. Isn't part of engineer doing more for less.
Value can be intrinsic and not calculated exactly, or if it's something like a machine in a shop I define it's value exactly.

RE: What is quality

Economics is part of Engineering.  Designing or producing a product at the most economical value or "value for money" is one of the keys for success in Engineering.

HVAC68

RE: What is quality

(OP)

Since we already got to the point of cost vs quality, I thought it is the right time to mention Taguchi's (successful) attitude towards this subject.

Taguchi's (Japan's) approach to quality is based in the "total cost to society". When the consumer's cost would rise while the producer's cost is falling, Taguchi adds both and gets what is called the "loss" function. When this function reaches a minimum it quantifies, in fact, the optimum quality.

Loss could be quantified in relation to time lost, wear, ultimate strength, fuel economy, health problems, etc.

Following this phylosophy, if someone steals $10, the net loss to society is apparently zero; someone has a $10 loss while the thief has a $10 gain. If, however, the manufacturer causes an additional loss to society, everyone in society has suffered some loss.

Thus, a producer who saves less money than the customer spends on repairs has done something worse than stealing from the customer...

Take the case of Japan's position in the worldwide economic competition. It is an island with a large group of people but otherwise limited natural resources.

The method they selected to survive and thrive is to import raw materials, add to their value by processing, and export high-value-added products (cars, TV sets, etc.).

Their success is due in part to the efficiency of this process. A low loss to society fits neatly within the niche of competing effectively in a value-added product area.

In Taguchi's mathematical technique the loss function entails two aspects of quality management within a factory: the variance, and the center in the distribution.

It is the engineers' job to establish the variance before the start of production, and to improve it as time goes on by off-line quality control. The second is the responsibility of the manufacturing people on a continuous basis, i.e., on-line quality control.

In short, Taguchi's strategic view of quality differs from the more traditional "conformance to specification", in the sense that it stresses a greater concern for "uniformity of products" i.e., a narrower tolerance.

It considers the relationship of variability to customer desires, and looks for a method of quantifying the value of quality by the use of a loss function and a continuous reduction in variance (factory's tightening of tolerances).

The descriptive statistics being the average and the variance. One probable quagmire in this approach lies in the measurement (repeatability and reproducibility) and interpretation of data.  

The book I mentioned in a previous post brings numerous examples where Taguchi's approach was successfully applied.  

As it has been already said in previous posts, the cost to society is always lower when making the product right at the factory than to find a poor quality product when the customer has it in hand.

Better yet, it is always of a lower cost to society to make it right at the point of production than to have to rework within the factory at a later time.

RE: What is quality

Quote (25362):

Jeff Dewar of QCI International once said:

If we accept 99.9% as our goal, we'd have to accept the following conditions:

• 2 unsafe plane landings per day at O'Hare airport
• 16,000 pieces of mail lost by the USPS every hour
• 22,000 checks deducted from the wrong account  
   every hour
• 20,000 incorrect drug prescriptions each year
• 32,000 missed ehartbeats person per year

That puts quality goal in perspective. Thus perfection should be the aim every way every day...

This completely ignores the notion of risk assessment, of fitting the criterion to the situation.  Two unsafe plane landings a day is not acceptable.  Finding a cracked egg in one out of every ten cartons I pick up is acceptable.  With finite resources, perfection in all things at all times is not attainable, and priorities must be established.

Hg

RE: What is quality

Quote:

Jeff Dewar of QCI International once said:

Let's not forget that Jeff Dewar sells quality management systems....

Quality in it's colloquial sense (A Rolex is a quality watch) is rather different to quality in it's technical sense (Fitness for purpose to predetermined criteria)

Good Luck
johnwm
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RE: What is quality

This has become a great topic!

Hopefully there are other members following this thread who can relate to the following with some item or other:

The story is, my wife goes to the supermarket for the groceries and they have a limited time special. A no name circular saw for $15.95. Wishing to surprise me, bless her heart, she buys one and presents it to me. To describe this saw, it's housing is made of a light white metal casting and it's inner workings, well, only time would tell how good or bad they are. My guess was that they would be good for maybe a dozen 2 x 4's at best.  Oh well, the main thing is the thought was there.

That was 28 years ago and in the mean time has seen service on 3 rec rooms, 4 decks, numerous small projects and I'll be using old faithful on the weekend.  The question is, is it a good quality saw?  I think so, for it's intended use that is. If I was working as a framer day in and day out, this would not have been the saw of choice although there were no disclaimers on the box like "not intended for industrial or commercial use" as some products do have today, but it was obviously not as robust as a $200 DeWalt.

If I had have used the saw in an industrial environment and burned it out just after the one year warranty, would it have been percieved as poor quality? No, I would have been guilty of abusing it.  Much like using a Chevette for the duties of a Humvee.

I think johnwm's  quote  Quality in it's colloquial sense (A Rolex is a quality watch) is rather different to quality in it's technical sense (Fitness for purpose to predetermined criteria) sums it up.

So, did I get a good quality saw?........Yes.  Did I get value for money?.....Darn right I did (wish I could estimate in cents per cut and compare it to a continously used industrial saw)

Lastly, every time I use it, I remember how I came by it. This also makes it priceless.

Haggis

RE: What is quality

I think that Taguchi's emphasis on reducing variance is not the end, but the means to the end.  

A process that is highly variable is difficult to optimize and improve.  Consider how difficult it is to fix intermittent failures.  Every time I've run across that type of problem, I wind up sitting around, waiting and hoping the failure becomes permanent, so that it can be more easily found.

One of the hallmark results of control of variance is that miniscule optima can be and are found.  

The apocryphal, but supposedly true, story of Mazda building engines for Ford resulted in Mazda delivering the engines which turned out to be unusable by Ford.  Turned out Ford's own production lines were highly variable, resulting in mix-and-match process of selecting engines that would "fit" with equally variable transmissions.  Since the Mazda-built engines had extremely low variance, Ford could not get more than a few percent of the transmissions to match.  The moral of the story is that Ford wasted a lot of time and energy downstream to accommodate poor process control.  They could have been more efficient and faster and more profitable.

Additionally, Mazda pointed out that since their own process was so well controlled, they could shift the design point so that the engines would be significantly more reliable.  The variance in the Ford process would have never let them find that result.

TTFN

RE: What is quality

IRStuff,

A star for you because you correctly used "variance" instead of "tolerance".

RE: What is quality

OK, here's a case where we deliberately engineer an error  into one system in order to control another input.

Tyres always generate a once per revolution force, as the bit where the belt overlaps is stiffer than the rest.

So, in some cases, we drill the wheels off centre, and match the low point of the eccentricity of the wheel to the high stiffness part on the tire. That's what some of those blobs of paint on your tire mean.

The same idea is used elsewhere, in many balancing or goodness of fit situations - we measure the uncontrollable system and then stuff around with the mating part to bring the assembly into spec.

Cheers

Greg Locock

RE: What is quality

(OP)

The Mazda-Ford story, as I was given to understand by reading the book on Taguchi's techniques, was based on the fact that Ford (Batavia, Ohio plant) contracted Mazda to make a certain portion of their front-wheel-drive automatic transmissions.

Both companies used the same blueprints. Mazda version,as warranty records showed, had a substantially lower claim rate than the Batavia version.

Ford investigated this phenomenon and found that Mazda's transmissions were made more consistently than their own. Mazda was using only 27% of the allowed tolerance range, while Batavia was using 70%.

Mazda was using a slightly more expensive and more complex grinder to finish valve outer diameters. At first glance, one may think their parts were more expensive, but knowing that the loss function was at work, the parts were actually cheaper, a fact substantiated by the lower warranty bill.

By using this information, the Batavia plant was able to improve its quality substantially and, in the first quarter of 1987, surpassed the Mazda level.

This anecdote is meant to show that a continuous reduction of variation within the allowed tolerance limits is a must i/o to provide a more desirable product to the customer. Which, in turn, results in a more competitive product with a lower associated loss to society.

RE: What is quality

Quote:


This anecdote is meant to show that a continuous reduction of variation within the allowed tolerance limits is a must...

Yes and no.  Here's the rub.  Assigning tolerance limits is a design function.  How much manufacturing variation can be tolerated on an individual part such that the assembly as a whole will still work properly.  However, a truly well designed part takes into consideration the processes that will be made to produce it.  That consideration includes knowledge of the of the variations expected to result from that process, and the distribution of thoese variations.  Thus, for a properly designed part it should be expected that ALL parts produced will be within the allowed tolerances.  Given that, a minor loss of control of process may be detected by a change in the shape of the distribution, even though not a single bad part has been produced.

Therefore, the only way to reduce the variation is to replace the existing process with a process with inherently lower variation.  When this is done, the tolerances should be reevaluated and tightened in accordance with the new process.

The real goal needs to be continuous improvement of the process, not reduction of variation within allowed tolerance.

RE: What is quality

To put in simple words - redefine the tolerances.  If the tolerance levels were so high that the outcome was a bad product, then, can we say that there was a problem in the initial definition of the tolerance level ???

HVAC68

RE: What is quality

Reduction in variance is purity.

To what degree is quality subjective?  It's interesting to consider what Persig has in Zen and the Art of Motorcycle Maintenance (supposedly from Plato's Symposium, but I've not yet found it):

"And what is good, Phaedrus, and what is not good?  Need we ask anyone to tell us these things?"


Jeff Mowry
www.industrialdesignhaus.com
Reality is no respecter of good intentions.

RE: What is quality

IR wrote awhile back:

"The second issue is that some of the details are conflicting.  Is it even possible to make something perfectly safe?  If so, can it even be built or sold at a reasonable price?  Does the customer even care; since he probably is more interested in sharpness and durability in a knife than its safety? "

Geez, IR, if I start seeing safety warning labels on paring knives at the Target store, I'll know who to blame for the idea's origination.  :)

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