American Welding Society Forum
I am in the process of completing a welding quality standard to bring our company into ISO Compliance. Under equipment control, I am specifying that our machines be calibrated on a regular basis.
I am looking for sample calibration plans and criteria, or directions to where I may be able to find such information. Any help is appreciated!
What I've done is written my own procedure. I removed Current from all WPS's and only refer to Wire Feed Speed. Then I purchased a volt meter that I send out once a year for tracable calibration. I attach the meter to the output studs of the power source and calibrate to OCV, adjusting the annolog meter of the machine to match the reading of my calibrated volt meter +or- 0.5v. Follow that up with paper work stating that you did so.
For WFS I did the same thing with a WFS meter I send out once a year.
Write me if you want to talk more
One of the difficulties about welding machines and the word "calibration" is that you are really not calibrating the welding equipment. You are doing parameter verification. A true calibration would require that the equipment be measured through the full range of the welding machine. In our shops we perform parameter verification, we measure the output of the welding machine against the posted welding procedure.
I personnally do not believe "calibration" of welding machines is worth much. What you are concerned about is the completed weld, most experienced welders and welding operators can tell you if the machine is performing correctly. What difference does it make when the meter said it should be 250 amps and you measure it and it was only 225 amps. If the completed weld is acceptable, I would not spend alot of time chasing "calibrations". IMHO.
Take Mr. R. Johnson's words to heart. We made the mistake of stating we would "Calibrate" 2 times a year. That is a lot of over kill. half our machines do not have any gauges digital our other wise and if they did they would be real hard to see when you have your hood down. Put more time and effort in to "Filler material controle" My under standing is that all WPS's should state a range of volts and amps so calibration is moote point.
I think it's very important that you calibrate (verify) the volt meter on the machine. If the meter is not accurate how could the operator follow the procedure?
The operator can pre-set his voltage using OCV (see Ed Craig training material, www.weldreality.com).
I would forget about calibrating amps.
I am of the same mind as previous responses the need for a calibration or verification is seldom worth the effort and cost 9 times out of 10.
It becomes more signifigant to have a readily verified process / parameter control for Q&T steels and Duplex alloys.
Review your applications and see if it is adding any value to the product
In the UK, we have a British Standard (BS 7570) for the calibration of welding equipment.
Our facility is currently in the process of attaining ISO 9002 registration. ISO does not state that you have to "calibrate" your welding machines and in my opinion you are opening your company up to alot of problems when you "over" do the quality system. To many consultants will do this to you. Our company is using a consultant with tie ins to Quasar which is a division of the Canadian Welding Bureau (sp) and they never even once mentioned calibrating our welding machines. ISO can be as simple as saying what you do and doing what you say. Do not make the mistake of making it harder to attain and keep your registration than it already is.
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