I have loved reading this thread. I especially love the (interpolated)statement that we can't jump to experienced engineering conclusions until we have the SPC data to support our position.
I am going to throw in a "hypothetical bit of personal anecdotal trivia" to put the importance of data points and statistics into perspective.
It is a known fact that several million airbag propellant devices on cars built in the US and Europe since 1996 are defective, and after approximately 10 years in service, they will not function at all in a collision. The reason they are defective is that they were knowingly produced from materials, out of product specification, with an obvious (under significant magnification) visible defect and shipped to the end user.
The DOHS was contacted, and eventually a committee chairman was talked to directly by telephone. (Additionally John McCain was written a personal land letter, fully explaining the situation, sent priority mail, with no reply to date). The DOHS representative stated that even though, to it was factual knowledge that the airbag devices were not produced to specification, nothing could be done until a statistically significant number of deaths occurred due to non-deploying airbags.
Facts mean nothing without the accompanying average, +2 sigma deviation variation to support it. I'm sure all traffic accidents in this country are thoroughly and technically researched and there is a uniform data base compiling this information so that when we reach this alarm threshold, we can take the appropriate corrective actions.
Regarding ASTM, I have served on two committees in my career. Unfortunately for the most part, the committees are composed of producers, few end users or general public types generally even aware of the ASTM or their meetings or the ability to sit in on particular meetings. The specification creations are usually done by the raw material suppliers in a majority of the instances, so I can understand how the BOSCH group had their specification basterdized as it was.
I sat in on a roof mining bolt (the contraptions that hold the roof up in a coal or other underground mine) committee meeting in DC one afternoon. We were discussing the minimum strength requirements for a roof support mining bolt. There was no problem with the discussion of the strength of the bolt, but the problem arose when it was suggested that the strength of any coupling needed to be of the same minimum strength tolerance if two or more bolts were required to be threaded together to reach an adequate stable base material. No one on the committee (no engineers in the room other than myself) could understand why the coupling should be required to meet any strength standards.
I understand that this post has nothing directly to do with the USLD subject, but with regard to specifications and the people who create them, it has everyrthing to do with it.
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