I'm not Jerry
, but I will add a few thoughts for you!
We are doing calibrations for soldering stations (Accuracy is defined as ±5°C, do not know how it is defined, but the process is not critical for our application and it works till now. during verification we will give go ahead for production if the deviation is within ±5°) in house and other instruments like vernier caliper, micrometer goes to outside calibration agencies (NABL accredited).
Sowmya
You did not list the process requirement, so I am not sure how to address that. You state accuracy is defined at +/-5 degrees C. Are the stations meeting that criteria when you verify them? If so, you should be fine. If not, then you need to address what the problem is. Either the stations cannot meet that accuracy, there are significant errors in your measurement system, or a combination of both. I assume you have the appropriate standard to measure these.
For vernier caliper model 500-196, the accuracy given is ± 0.001in. Is that means, for a nominal value of 20mm it if measures 19.97mm we need to reject the instrument or give correction factor?. confused.....
I'm confused also!
You have a nominal value of 20mm listed, but then the accuracy listed as +/-.001 inch. I would keep to one criteria (mm or inch). The caliper information should listed a tolerance for mm and inch. If this is a four place caliper, .001 inch should be obtainable. If it is a 3 place unit, that will be difficult. Too, there is some error accumulated through measurement styles and such that should be accounted for.
The calibration agency has given a statement on the top of the results.........instrumental allowable error of measuring length ± 0.03mm. which error it talks about?
Sowmya
Without seeing it, it's hard to determine. It can either be what they are stating the acceptable tolerance is on the instrument they are verifying, or the uncertainty of their standard measurement system. At .03mm, I would think that would be the error of the instrument they are verifying for you.
Just something for you to think about....I sense that you are getting frustrated dealing with tolerances on the certificates, in/out assessments, etc. A good calibration house is well-worth what you pay them; and they are there for you. However, there is no magical book or lists of perfect tolerances for equipment/instrumentation. There are simply too many variables. You need to establish good communication with them.
I encourage you to determine what your requirements are, and that the measurement system is working for those requirements. You should make sure that all your instruments are providing the proper confidence you need in measurements. Talk with your calibration source about the tolerances they have on there. They should be more than happy to assist you with that. In the end, you should have established knowledge that you are providing the proper system for your customers, and your calibration vendor is providing information that you understand and can use.
I hope something here helps.