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Nancy Golden
User Rank
Platinum
Re: Common Assumption
Nancy Golden   5/5/2012 5:33:18 PM
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That's funny tekochip - I had the opposite problem. When I was a test engineer and parts started failing, everyone always wanted to point to the test set. I always kept calibrated "golden" units around so that I could verify tester operation. I made sure my golden units included passing units at both ends and the middle of the spec as well as rejects. Most of the time that would satisfy all involved that we needed to look at the parts themselves...

Nancy Golden
User Rank
Platinum
Re: Check and Double Check ?
Nancy Golden   5/5/2012 5:34:36 PM
NO RATINGS
The author did a good job isolating the problem. I think perhaps the other folks were not so experienced in troubleshooting. I'll never forget as a young tech making an assumption that wound up delaying a resolution to a problem we were having. I don't remember what the problem was but I sure remember my angry boss pulling me into his office and writing       ASS U ME in large letters on his white board. He then asked me if I knew what happens when I assume - If you look closely, I  am sure you can figure out the rest of the story...

That happened in 1990 but is a lesson I carry with me to this day!

GlennA
User Rank
Gold
Assumptions
GlennA   5/7/2012 8:38:00 AM
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The 'When you assume...' phrase is common, but useless.  Everybody makes assumptions.  Assuming the rejected parts are actually bad, or assuming the rejected parts are really good is a beginning of troubleshooting.  The real trick is to know and realize what your assumptions are, and be prepared to revisit them when troubleshooting doesn't agree.  During a light-hearted conversation I was asked of I knew what happens when you assume.  I replied 'Did you assume that I was listening to you ?.  Of course you can't say that to your manager.

OLD_CURMUDGEON
User Rank
Platinum
Re: Check and Double Check ?
OLD_CURMUDGEON   5/7/2012 10:01:36 AM
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In one of the more famous (TV) episodes of the ODD COUPLE, Felix Unger told the judge a simple fact .......  When you ASSUME something, you make an ASS of U and ME!  Very sage words, indeed!!!!

Nancy Golden
User Rank
Platinum
Re: Check and Double Check ?
Nancy Golden   5/7/2012 10:12:57 AM
NO RATINGS
The Odd Couple - Felix and Oscar - haven't thought about them in years! I probably saw that episode, I can certainly picture Felix doing exactly that, LOL! Thanks for the memories, OLD_CURMUDGEON!

jhankwitz
User Rank
Platinum
Gage R&R
jhankwitz   5/7/2012 10:51:45 AM
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Most any Quality Manager worth their salt will run Gage R&R (gauge repeatability and reproducibility) on their test and verification people and equipment on a regular basis.  When you don't do this, you haven't a clue as to what you're producing.  You need to understand or get get full control of all variables in your inspection processes.

Our people are amazed when we report the source of variables and variation in our most basic inspections (like using a mic or caliper).  It's a real eye-opener for most people outside the Quality field.  Managing Type I and Type II inspection errors is a fundamental problem in most every company.

roddalitz
User Rank
Gold
Precise failure mechanism?
roddalitz   5/7/2012 11:35:28 AM
NO RATINGS
I read that the position which failed held the batteries in a "canted" position, but what was the precise reason for the test failing? Did the canted batteries fail to make contact at all? Was there poor contact resistance, or what? The observation and deduction is smart, but I feel I am left hanging.

3drob
User Rank
Platinum
Re: Check and Double Check ?
3drob   5/8/2012 8:22:07 AM
NO RATINGS
I appreciate that you want to be fair, but step # 1 in ANY endeavor (Engineering or other) is to identify the task or requirement.  In this case, to identify what kind of failure you are investigating (luckily there was a quar. set of failed batteries to test).

If you manually test your failed bin of parts and the failure rate matches the expected (hopefully low) failure rate, then NDF (no defect found).  Of course, you want to cut a few "good" ones apart to make sure there are no latent or intermittent problems before you announce to your boss NDF.  Task identified:  find out why good batteries tested bad.

Which is what the author did, which is what makes this one a good story.  Kudo's.

ScotCan
User Rank
Platinum
Re: Precise failure mechanism?
ScotCan   5/8/2012 9:57:11 AM
NO RATINGS
Apologies for keeping you hanging...the canted condition caused bad or high resistance contact and the test registered as a failure. The observation that the test position was canted jogged my memory about other tests I had done varying the terminal contact which led to a wide variance in test results.

JimT@Future-Product-Innovations
User Rank
Blogger
Fix the Process and not the Part
JimT@Future-Product-Innovations   5/8/2012 1:09:48 PM
NO RATINGS

When part & component designers experience fit problems with their designed parts, they often point a finger at the tooling & mold engineers; "must be out of spec ; making bad parts".

When industrial automation engineers experience testing and analysis problems, they often point a finger at the component engineers; "must be a design flaw; back to the drawing board".

Then tooling & mold engineers experience trouble getting mold cavities to spec, they often point a finger at faulty heavy equipment manufacturers; "the CNC has slop in the indexing plate".

Truth be told to all, problems and anomalies can exist in every aspect, and looking at yourself first can save a lot of time and embarrassment. 

We used to have a mission statement: "Fix the Process and not the Part".  It tought a lot out looking at issues from a system level

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