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Forum: Reliability & Maintainability Questions and Answers

Topic: Reliability & Maintainability Questions and Answers

Topic Posted by: Reliability & Maintainability Forum ( )
Organization: System Reliability Center
Date Posted: Mon Aug 31 12:47:36 US/Eastern 1998

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Original Message:

Posted by: Uma
Date posted: Wed Aug 21 9:23:43 US/Eastern 2002
Subject: Year of manufacture
The year of manufacture (used in piG calculation)is supposed to be the year the part was manufactured. Everything is normalised to 1993. But what about a part that was first manufactured in say 2001? If I buy it in 2002, it is only a year old. Shouldn't the piG for this part be much higher? If I use 2002 as the year of manufacture, PRISM gives me a much lower piG value (since it uses the 1993 normalised data). I would have assumed "delta t", the time since it was first manufactured (maturity level) would be used to calculate the growth rate.


Subject: Year of Manufacture
Reply Posted by: David Dylis ( )
Organization: Reliability Analysis Center (RAC)
Date Posted: Wed Aug 21 11:37:10 US/Eastern 2002
Yes, if the design of a part is truly a new design and only in production for only 1 year then it would be incorrect to use the year of manufacture as I previously identified. However, if a component part is a revolutionary new design, then it is unlikely that a PRISM prediction model currently exists for that specific design. A new design may also be a variation of a current product. If this is the case, then it may be correct to use year of manufacture as previously identified, since the component manufacturer would be using previously gained knowledge and techniques that were used in the design and manufacture of this earlier product. PRISM also accounts for some factors concerning the early design stages of parts in the process grading section. You may want to consider using PRISM process grades in your analysis to address these situations. I would further recommend that you obtain test and/or field data for these components to assure that they are a reliable product.

If you have any additional questions, feel free to contact me.

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