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# Precision Dornicks

## Question

As the Design Engineer at Precision Dornicks, Ltd., you have designed, and PDL has built, numerous dornicks over the years, with good quality, though slightly high price.

This next dornick, however, requires a design that hinges on the availability of a high-precision bazfaz. Good news is: Amalgamated Bazfaz Corp sells them in bulk. Bad news is, NOBODY can manufacture a bazfaz with the needed precision--you need 0.001% tolerance on a 10-whozatz bazfaz. ABC offers a dozen precision grades of bazfaz: 30%, 10%, 3%, 1%, 0.3%, 0.1%, 0.03%, and 0.01%. The whozatz values include 1-wZ, 3-wZ, 6-wZ, 10-wZ, 30-wZ, 60-wZ, 100-wZ, etc.

You have spot-checked hundreds of examples of ABC bazfaz, and they are always within the advertised tolerance: for example, every single 1% 60wZ bazfaz that you've ever tested fell within +/- 1%, that is, between 59.4 and 60.6 wZ, as measured on your industry-standard whozatometer.

The funny thing is, we all know that technology does not permit manufacturing control of the whozatz parameter of a bazfaz more closely than 30%.

Two questions:
( 1 ) How can ABC reliably sell product at a higher precision than manufacturing process technology can achieve?
( 2 ) How will your design allow PDL to manufacture the next dornick to achieve .001% tolerance using the ABC .01% 10-whozatz bazfaz?

("higher precision" means "lower tolerance"--a 10% bazfaz is said to have a higher precision than a 30% bazfaz, because the actual measured value is closer to the nominal value)

## Recommended Posts

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This is actually a common problem with some electrical components.

The solution is that you build a large quantity of Bazfaz and then test them

The 30% defines the limits of the curve, but some of the units will be very close [ less than 1%].

You sell the ones that happen to be more precise for a higher price. Less precise units are sorted by precision and sold at lower prices.

Edited by dgreening
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Thank you, dgreening. That's the answer (as you know). When that was explained to me, I was tickled by the apparent bizareness--for example, a 30% bazfaz would actually be rather precise around one or the other tail of the distribution, because, as you point out, the ones in the center of the distribution were moved to a higher-priced product. As a result, a 30% 100 wZ item will turn out to be an 8% 125 wZ item OR a 12% 85 WZ item. What a scream! All the purchaser has to do is the same thing the supplier did--test each item, and put them into other bins. Buy the cheap ones, and discover their actual characteristics.

Edited by CaptainEd
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Aha!

I just didn't follow the same process through to get the supper precision devices!

Thanks

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