Calibration

<...procedure for calibration of arc welding machine...>

What does the manufacturer's Operation and Maintenance Manual accompanying the equipment have to say on the topic?

I once had a mechanical engineering boss that wanted some lab type power supplies calibrated. I asked him what he meant, but he really couldn't tell me. He just wanted to be able to put a sticker on the units that indicated that they had been calibrated.

I tried to explain that a 0-30 VDC power supply does not need calibration because it is set by the user who uses a calibrated meter to set it. Only the wall listened to what I said. All the other engineers were too busy laughing out loud.

Since each use was potentially different, just as each weld is different, what is it that is supposed to be calibrated? Perhaps you have some meters or feedback devices that indicate the energy used. Certainly you would have to be able to repeat the exact conditions for each weld such as pressure applied or feed rate of the weld rod (or other media). If this welder is not being used on a robot that is doing the same operation over and over, what exactly is being calibrated?

Perhaps all you need is an operational test on a annual basis. I don't think that warrants a calibration sticker any more than a fire extinguisher needs calibration (I mean verification of pressurized contents in the "green" range of the little uncalibrated gage).

Are you working for my former boss?

If what I understand is correct you might be trying to satisfy ISO team who are asking for a calibration certificate for everything which come across their eye. There are firms in Bombay and other cities in India who are approved for issuing calibration certificates basing on certification issued by the government testing labs, which is approved by ISO team . They have calibrated instruments with which they calibrate your equipments and provide test certificate and a sticker for validity for a specified period. For a welding machine what they normally calibrate is the power controller of the welding transformer which provides the rated voltage as per the specification of the manufacturer so that when a welder set a specific chart the output voltage should be correct as specified so that operator do not have to make any trial and error method to do a good job. Normally an experienced welder knows their requirement for the specified job. But ISO team want a confirmation that the machine used is proper to do a standard job before issuing an approval for ISO certification.

If that's the case then the original poster's operation needs to look at the welds instead, on the basis of showing that the finished weld is always 100% suitable for the task in hand.

The PO has not responded to any of our replies. So we do not know what he wants actually. I presumed that he may be needing the calibration to be carried out for ISO inspection team who normally call for the documents as I have experienced. They normally check the process and documentation . Their view is if system and documentation is correct then the product will be good.They do not check the final product but only the method of inspection and its documentation.

There is another sticker available for the ISO program. It reads "Not Calibrated, For Reference Only"

b) This is easily obtained by carrying out an internet search. Invitation declined.