Has anyone heard of calibrating a o-scope in 10 minutes?
How about a 8340A/B in one hour manually?
Or a microwave counter in 5 minutes?
Well, it's being done or at least claimed to be done by "Fake" calibration companies.
This is one thing that really gets my blood boiling. I talked to a friend of mine who had taken a job with a Calibration Company that wanted him to do these things mentioned. My friend is a true Metrologist, like many of us, and refused to let go of his integrity. He quit the job after one week of working there. The real sad thing is that there are several people working for this company that are fine with Hot Stamping equipment. I personally would not hire anyone that ever worked for that company for more than a month, because if they did I would know that they have no integrity. I have heard of more and more companies hot stamping equipment to make more money. Not only is this dangerous to the customer, but it is dangerous to our profession as well. The only way we will stop these Fake Calibration Companies is to refuse to work for them, just like my friend did. They cannot operate without techs. How will the "Lick it and Stick it" companies effect the rest of us? Well, they will stop hiring real techs for one. They will be able to undercut every real calibration labs' quotes. Which will effect all of us that work in a real cal lab. This is becoming an ever increasing problem and something needs to be done about it.
What are your thoughts about these Fake Calibration Companies?
Let's have examples, company names- a lot of our buddies will send us an email after they get a job offer from one of these money labs, and they'll ask us what we think.
There should be two lists permanently posted on this site- the good companies to work for, and the bad. Of course, determining "good" vs "bad" is subjective, and there is a lot of personal preference involved. Coup would never work for a certain company in Georgia, while one of my best friends is there and doing fine. Incidentally, my buddy has a very high level of integrity, so I have to assume there's no "lick it and stick it" going on there...
Think about it this way- a Chevy mechanic makes a lot less money than a Mercedes mechanic. So in kind a "Chevy" lab doesn't have the same technical, quality, or ethical standards as a "Mercedes" lab. "Chevy" labs have their place in the world, I suppose, but I'll never send anyone to work there, and I'd sure never send any gear there to be worked on.
What state and city is this lab located? :? We should be able to figure it out from there! :-D
Be careful of the legal ramifications of listing good vs bad cal labs.
I'm pretty sure I know what company he is talking about. I almost went there a couple of years ago.
Quote from: step30044 on 12-11-2006 -- 19:09:42
Be careful of the legal ramifications of listing good vs bad cal labs.
How 'bout "Companies I'd like to work for" vs "Companies that don't have enough money to hire me"
Theres a company like that in Minneapolis. I went to do a job that this other company did the previous year. The technician for the other company did the job manually in 6 days. The costomer had over 250 pieces of electronic test equipment with probably 75 to 100 being RF work. The customer told me the guy would show up late hungover and leave early everyday. We've been taking customers from them every month.
Doc,
Great idea!!
Any of you guys heard of a company called QualityCal out of Tennessee :?
Nope. Are they hot stamping? They don't even have a website.
Its funny that someone would say that there are indeed fake or just
hot stamping comapanies out there. I've seen it over the past
15 years or so. There out there trying to make a buck.
I've personally seen bigger Calibration companies (I won't give names), also do a less than a job well done. I'm not sure
how a major lab can hire less than qualified Techs. Or
have the right equipment also.
When a customer shows me there old
certification and see the standards listed. I just know there
not following any 4:1 ratios or procedures.
Example: someone
who uses a Fluke 8050A to calibrate a DC calibrator that
has an accuracy of 0.005% or better is not doing a true calibration.
I'm fortunate to have worked for a company since 1992 that frowns on this type of calibration practice. Its the quality that counts, not the fastest way to make money. The companies that do this
soon get complaints about the quality of work and look for a real calibration lab like the place I work. The bad cal labs out here are making us a breath of fresh air to them with audits and 17025.
When you have your test standard calibrated with measurment uncert. provided then you use those uncerts in your budget. rather than the specified accuracy of the equipment. The company that calibrated the DC standard with the 8050 could have used the uncert. of the 8050's cal. Example: you can have a class 2 mass standard, but the uncert. is provided with mass correction then you could calibrated a class 1 mass standard with that class 2. We don't practice this because we have a class 0 set. However, our uncert. on our class 1 set is good enough to use the class 1 standard to cal another class 1 set with a T.U.R. of 8:1. Another example would be a resistor that is 100 ohm +/- 1%. You can provide actual value with the uncert of about 0.2ppm. Now the resistor is accuracy is +/- 0.2ppm instead of 1%. Using Measurement Uncertainty is a more accurate way to cal than using a 4:1 ratio. :-) This is how A2LA does there accreditation.
However I agree that there is many cal companies out there that hot stamp for a buck and that is why I started this post.
That practice is valid as long as your standard is extremely stable and very well characterized. I agree that a good Class 2 mass standard will warrant using the uncertainty of calibration and the actual mass value. I'm not so convinced about the resistor example you present. If the temperature coefficient is known and compensated for, and the drift rate is known (we won't even delve into humidity or barometric pressure issues) then you can at least get close to using the stated uncertainty. Trying to push electronic instruments is significantly more risky because of their probability for drift.
Remember, a calibration and the stated uncertainty of a calibration, is only a single point in time, performed under optimum conditions and usually doesn't and can't take into account drift over time or temperature compensation errors.
Just my 2 cents worth.....
Quote from: flew-da-coup on 01-25-2007 -- 05:08:37
When you have your test standard calibrated with measurment uncert. provided then you use those uncerts in your budget. rather than the specified accuracy of the equipment. The company that calibrated the DC standard with the 8050 could have used the uncert. of the 8050's cal. Example: you can have a class 2 mass standard, but the uncert. is provided with mass correction then you could calibrated a class 1 mass standard with that class 2. We don't practice this because we have a class 0 set. However, our uncert. on our class 1 set is good enough to use the class 1 standard to cal another class 1 set with a T.U.R. of 8:1. Another example would be a resistor that is 100 ohm +/- 1%. You can provide actual value with the uncert of about 0.2ppm. Now the resistor is accuracy is +/- 0.2ppm instead of 1%. Using Measurement Uncertainty is a more accurate way to cal than using a 4:1 ratio. :-) This is how A2LA does there accreditation.
However I agree that there is many cal companies out there that hot stamp for a buck and that is why I started this post.
You can't see 50ppm on the 8050A. Even with the uncertainties
included, the poor customer is getting a limited cal unknowing
that they used a less accurate standard.
I would be utterly impressed if I saw the uncertainties listed
on there old cert including how they attempted to acomplish a
full cal on it without a limited cal documented.
We don't have a standard thermistor probe. However, the company accepted our uncert. of +/- 14mK with a 1:1 T.U.R. . In accordance with A2LA and ISO all I have to supply them is the cal data and a standard cal sticker. It would not have to be a limited calibration. All I am saying is if the customer with the DC Standard agreed to the measurement uncert. then it does not require a limited sticker just data and the standard cal sticker. I do agree that they should have never had the DC Standard calibrated with that wide of uncert. I also thought that you wrote DC Calibrator and not Standard. Maybe I should read a little closer next time.
Quote from: OlDave on 01-25-2007 -- 14:45:19
That practice is valid as long as your standard is extremely stable and very well characterized. I agree that a good Class 2 mass standard will warrant using the uncertainty of calibration and the actual mass value. I'm not so convinced about the resistor example you present. If the temperature coefficient is known and compensated for, and the drift rate is known (we won't even delve into humidity or barometric pressure issues) then you can at least get close to using the stated uncertainty. Trying to push electronic instruments is significantly more risky because of their probability for drift.
Remember, a calibration and the stated uncertainty of a calibration, is only a single point in time, performed under optimum conditions and usually doesn't and can't take into account drift over time or temperature compensation errors.
Just my 2 cents worth.....
We do it here with resistors. We have a MIL bridge and send our standard resistor directly to NIST. We have them submerged in an oil bath @ 25C with the temp being monitored with a PRT. We do it just like NIST. Trust me it can be done and it is done. NIST uses a MIL bridge too. The MIL bridge is automated and takes up to 30 samples to find the actual value. he again I went back to look at my scope ( becuase I no longer work in the area ) and we can do 1ohm @ +/-0.4ppm with a T.U.R. of 1:1. We can do 100ohm @+/-0.7ppm and not 0.2ppm. But yes you can do this. It is on our A2LA scope.
About the uncert. of time of measurement. You don't use the calibrations uncert. directly. You have to do RSS to come up with your uncert. .
Don't misunderstand me. I didn't say it can't be done. Just that it's not as simple as just reading the uncertainty off the cal certificate and running with that number. I've seen too many people think like that. The point I was trying to make was that the uncertainty of measurement is not an absolute value and only reflects the measurement at the time of calibration under conditions at the time of calibration. If other factors that can and do affect the accuracy and stability of the instrument over time aren't considered then people are fooling themselves.
It sounds like you have taken the necessary steps to maintain that level of uncertainty so it is usable and transferable. I never meant to imply otherwise, just pointing out that there is more to it than just getting an accredited calibration on an instrument and reading the numbers.
I just wanted to make sure that you knew that we calculate our expanded uncert. correctly. We do RSS (2 sigma). Some people who have worked only in government labs have no understanding of expaned uncertinty and they get confused about how things are done this way.
Quote from: flew-da-coup on 01-26-2007 -- 10:28:47
I just wanted to make sure that you knew that we calculate our expanded uncert. correctly. We do RSS (2 sigma). Some people who have worked only in government labs have no understanding of expaned uncertinty and they get confused about how things are done this way.
Now could you and Old Dave please come and explain this to a fellow technician here that believe our S-1 weights can be used as Ultra class, E1, 0 regardless of where he is just due to the uncert. given by Troemner.
For the love of god, I have tried enough times already.
MIRCS, Lets run with this example and see how many people want to take a shot at it....
Actually I will challenge anyone to tell by any method other than weighing, whether a Troemner weight is an UltraClass, Class 1, Class 2, Class 3 or even a Class 4 weight. I can't, and I'll bet you can't either. They all are made of the same material, are two-piece construction, and even have the same surface finish. The only difference is their closeness to the nominal value.
Lets say you are calibrating a Mettler XP205 balance. That's a 220 gram 0.01mg resolution balance. You would typically check span at 200 grams. If I remember the Mettler spec correctly the span tolerance is ±0.40 mg. Now lets say you have set of UltraClass weights with you that range from 1 gram to 500 gram. In it there are 2 200 gram weights. You put one of the weights on and the balance reads 199.99989 grams. Outstanding! We're good to go. But out of curiosity you decide to drop the other 200 gram weight on the pan and oops....it now reads 199.99951 grams. Hmmm....we gotta problem. Is the balance good? Is the balance bad? Are one of the weights bad? We don't know.
Lets think about this, the tolerance for a 200 gram UltraClass weight is ±0.30 mg. Lets say the first weight is heavy by 0.21mg (200.00021 g), still within tolerance, not a problem. And the second weight is light by 0.17 mg (199.99983 g), again within tolerance. But since we don't have our weights charted we don't know this.
This balance is actually reading 0.32 mg light isn't it. So the balance is within its tolerance of ±0.40 mg, but we can't prove that with the standards we have.
But suppose I had a set of Class 3 weights that have the actual mass value and uncertainty of measurement reported. Troemner's typical uncertainty at 200 grams is around 0.027 mg. However the Class tolerance for a 200 gram Class 3 weight is a whopping 2.0 mg. I place this 200 gram weight on the balance and it reads 199.99867 grams. Ouch! But before I panic, I look at the report of measurement and see that the actual mass value of that weight is 199.998986 grams with an uncertainty of 0.027 mg (well within the class tolerance of ±2.0 mg). Since I'm out in the field I'll most likely just blow off the uncertainty of 0.027 mg since the balance has an accuracy of ±0.40 mg and just subtract the balance indication from the mass value of the standard (199.99867 – 199.998986) and see that the balance has an error of –0.000316 grams. Within my calibration limit of ±0.40 mg.
Now which weight set allowed you to perform the better calibration? The UltraClass without a report of measurement or the Class 3 set that did?
Well said Ol' Dave. However, remember that you need to do your expanded uncertinty of the calibration uncert. of 0.027mg. Even still your explaination was perfect. We use Rice Lake standards, but it's all the same. We calibrate mass up to 25kg class 1 weights and we can do 1:1 cal's with class 0 weights. Doing mass with the lowest uncert. is obtained using 3 in1 weighing design. However, useing double substitution weighing design is good to do up to class 1 and class S weights.
I know, you need to use the 0.027 mg as the uncertainty of the mass standard but my example was getting long enough to put most people to sleep as it was. And since we weren't really trying to discuss a full blown uncertainty analysis I took a couple of short cuts.
I only use a 3 in 1 weighing design for all of our check weights in the Institute. Since we don't perform outside calibrations I have a good deal of control over how stuff gets done here....
I gottcha Ol'Dave. :-D
Just interviewed with a company in Atlanta area, the manager stated in the interview that a person with my experience should have no trouble calibrating a scope in 15 minutes :-o A signal generator should take no more than 30 minutes. :-o I guess he was interviewing for a lick it stick it position...funny it was posted as a calibration tech. Thats why Im going to try to get into nuclear work. :roll:
Holy crap... :-o Cal a scope in 15 minutes? I can't cal a scope that fast using MET/CAL... I'll bet they have a pay rate that keeps their turnstile spinning, too.