Ed, I would agree with you and with the other people who have responded to your letter - I don't see any issues with not calibrating supplies and generators as long as you are using a calibrated meter/scope/measuring device/whatever to monitor the uncalibrated instrument. I currently work for a small design and manufacturing company in Portland, Oregon and prior to that I worked for a third-party regulatory agency, and in both cases it was considered acceptable to use uncalibrated sources as long as they were monitored in testing by a calibrated meter of some type and the meters used were recorded in the datasheet package along with calibration dates, etc. At the regulatory agency there were sometimes calibrations of things that didn't really seem to need calibration, like yearly calibrations of 20-lb weights for pull tests, but I was told by one of the lab staff that once they got a scale and had that calibrated yearly, they weren't required to submit the weights themselves for calibration. This is almost exactly the scenario you are describing . . . . use a calibrated measuring device during a particular test to measure a stimulus and the stimulus itself shouldn't have to be separately calibrated. I don't have any experience with ISO 9000 procedures, so I guess it might be possible that a particular company's procedure insists on the calibration of every piece of equipment (though it seems pretty unlikely). I know I've never heard of that being a general ISO requirement that everyone has to follow. Has the Metrology Department declared this requirement off the cuff, or have they been able to point to a specific clause or clauses in the company policy manual or ISO 9000 handbook or standard procedures that says you MUST calibrate all sources? -Camille Portland, Oregon
"Price, Ed" <[email protected]> wrote: In some ways, I have the luxury of having a Metrology Department that maintains the periodic calibration on all of my test equipment. OTOH, as a "customer" of this Metrology Department's "product", I would like to have some control over my overhead costs. And my latest bright idea has me getting stomped by the gurus of the status quo. I need to get smarter about how a calibration system works, and how flexible it can be. My lab has about 500 pieces of capital equipment, and the way I see it, all my equipment falls into one of two categories. The first category consists of those instruments which are used to measure the parameters of our company's products, and determine if the performance of those products falls within a range of acceptable tolerance. Data from these measurements is often contractually reported to our customers. Every equipment within this category needs to be maintained on a program of periodic, traceable calibration. But then there's the second category; which consists of support and stimulus equipment. Items here are old analog signal generators, function generators, amplifiers, pulse generators, sweepers and power supplies. To me, none of this equipment needs ANY periodic calibration. I base this on practical usage. Who can accurately read a power supply mechanical 80-amp ammeter that has a 1.5" long scale? Who can set a function generator frequency control that covers 2 decades, logarithmically, in 270 degrees of rotation? If I need to apply a 100 kHz signal in bursts of 2 milliseconds at a 1 Hz rate, I'll use a calibrated, traceable oscilloscope to set the uncalibrated generator to exactly what I need. The same for that power supply; if I need to know the current to 2% or better, I'll use a calibrated resistor and a calibrated DMM. And I couldn't care less about the gain of an RF power amplifier, as long as it pumps out enough power to! create the field I need. Now, I'm not trying to justify the use of distorted, unstable or junky equipment. I'm just trying to spend my calibration dollars the most efficient way. And the way I see it, about 1/4 of my equipment fits my definition of not needing periodic calibration because I can monitor the results with calibrated equipment. So I proposed that these items be tagged with some kind of "uncalibrated" or "user verified" or "no calibration required" label. The gurus of Metrology say this can't be done, our ISO9000 Quality System will not allow this. I can't understand how a customer-oriented quality system can't be crafted to meet the needs of all of the customers of that system. And I suppose I'm felling a bit squeezed, what with my customers expecting me to use COTS equipment to function in military environments. I have to get more out of what I have, and the old military concept of everything in sight is on periodic calibration has to yield to current reality. So, am I getting shoveled upon regarding the impossibility of having a category of officially non-calibrated equipment alongside my calibrated equipment? How have you dealt with calibration program costs? Regards, Ed Ed Price [email protected] WB6WSN NARTE Certified EMC Engineer & Technician Electromagnetic Compatibility Lab Cubic Defense Applications San Diego, CA USA 858-505-2780 (Voice) 858-505-1583 (Fax) Military & Avionics EMC Is Our Specialty _____ Do you Yahoo!? Protect your identity with Yahoo! Mail AddressGuard <http://antispam.yahoo.com/whatsnewfree>
