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Up Topic Welding Industry / Technical Discussions / How to Calibrate a Stud Welder?
- - By eekpod (****) Date 01-23-2009 22:59
Question, has any one ever had there Nelson Stud welding machine calibrated? and if so how was it done?
And for you AISC members, do you think its considered a "welder" and should be done like the regular "arc" welding machines?
How about bridge shops, are they required to calibrate theirs?
Open for a general conversation
Thanks Chris
Parent - By MBSims (****) Date 01-23-2009 23:08
Not sure about how to address your question, but why would you need to calibrate a stud welder if you do the pre-production tests in D1.1 at the beginning of each shift?  I think this is much better than an arbritrary "calibration", since it demonstrates the settings are correct and the welds are sound.  You may want to take credit for the pre-production tests in your quality program as satisfying any "calibration" requirements.
Parent - - By mountainman (***) Date 01-23-2009 23:30
good question. i would consider it to fall under a weld machine that needs to produce a "quality that conforms to project specs" it never crossed my mind to have ours calibrated, but have never had the issue arise during past AISC audits, but i would have to say that we are probably non-compliant to the standard regarding our stud weld machine, i'll have to take care of that. however, almost every single issue with rejectable stud welds that i have seen have been due to operator error on the setup of the gun adjustments rather than the power source for what it's worth. whether it was a setting screw that came loose or plunge depth adj. changing magically? that's typically what i have seen. and of course this is all after the pre-production test has occured.

JJ
Parent - - By eekpod (****) Date 01-24-2009 12:44
MB Sims, our company, and others on this site are audited by another organisation, and one thing they ask for it proof that at least yearly our welding machines are "calibrated" once a year for structural shops per D1.1, and quarterly for Bridge shops.
I spoke with my Nelweld rep. and I would have to send the units to Ohio to have them calibrated, and its around $750 not including shipping.  I don't think other companies have done this, I can't see other places shutting down that portion of their facility for this.
We do do the pre-production tests, and I would agree that its usually operator error.  I get nervous around audit time regarding the stud welder, so now I have time to address the issue, but I can't have the shops shut down and send the units out.
The Nelweld rep said to calibrate them to NIST with paperwork is very involved due to the circuitry inside the units.
Chris
Parent - - By MBSims (****) Date 01-24-2009 16:54 Edited 01-24-2009 16:58
I understand.  What part of the machine is actually being calibrated though?  On a stud welder, the settings that control weld quality are lift, plunge, arc time and arc current.  Calibrating the ammeter on the front is no benefit, because you don't even have time to read it during an actual stud weld.  Lift and plunge settings are on the gun, so you can measure those with a ruler or vernier.  So all that can be checked is the arc timer vs. the setting on the dial and the amperage vs. the setting on the dial.  So a chart recorder that displays current vs. time is all you really need.  Of course the recorder itself would need to be calibrated prior to use.

http://www.microdaq.com/monarch/paperless_chart_recorders/datachart1250_recorder.php

I still think actually passing a preproduction bend test or retest when parameters/settings are changed is a better quality control method and would be sufficient in lieu of "calibrating" the machine.
Parent - By Ke1thk (**) Date 02-02-2009 13:07
Every measurable is being compared against a "certified" unit of measure.  I was like you in that I couldn't understand what could possibly change.  I had my GTAW calibrated years ago and never again.  Not many auditors have ever checked (I doubt that they know how), until recently.

I had a big audit with a new customer and decided to call my welding supplier, who is ISO approved.  My old GTAW welders were up to 70% out of range.  The big surprise was the price, $85 each. 

I would call the manufacture or my local welding supplier or search the Internet.  I'd search "load bank test, or weld calibration."  Some codes require quarterly calibrations.

Keith
Parent - - By CHGuilford (****) Date 02-02-2009 17:51
I'm not so sure that you have to "calibrate" stud welding equipment. 
First, I have never had an auditor ask for calibration records on stud welding equipment.

2nd, you will note that there is nothing listed in D1.5 Table 5.3 for stud welding essential variables.  Nothing in Section 7 says that you need a WPS for stud welding (at least not that I have found).  In fact D1.5 - 7.5.2 says you use the settings determined by past practice to work the best and/or the manufacturer's recommendations.

You have to perform a pre-production test at the beginning of every shift with that particular set-up.  Change the set-up and you have to do more tests.  In essence, you are calibrating the machine every day you use it - you are validating that the variables you are set for will produce acceptable results.
So given that, there seems no need to calibrate the stud welding equipment. 

And that is simply my opinion.
Parent - - By jwright650 (*****) Date 02-02-2009 19:11
Chris, I agree with Chet...apply the KISS method, no need to make it more complicated than it needs to be. I have my machines calibrated by our welding/repair supply shop and they have never issued a report for the two stud machines that we have here, nor has an auditor ever asked to review those records. The other machines all have records, but not the stud machines. The stud welding procedure that I have here is based upon our stud mfg's recommendations, and they seem to work for us. Hope this helps.
Parent - By eekpod (****) Date 02-05-2009 00:34
I'll go with that then, leave em off the list of calibrations and keep doing the pre-production test of the first two studa and were all set.  Thanks for the input guys.  Chris
Parent - - By ziggy (**) Date 02-27-2009 15:48
I agree with Chet's statements on all points.

I might add this: Where in D1.1 is the requirement for ANNUAL calibration of any welding equipment? D1.5 is specific - 4.26 "at least every 3 months", but can someone show me where the ANNUAL calibration of welding equipment is required by D1.1? Thanks,

ziggy
Parent - - By hogan (****) Date 02-27-2009 16:13
As you know AWS is not in the business of designing structures. AWS is typically not the only code/specification required to conform to.
Parent - - By ziggy (**) Date 02-27-2009 16:37
Fair enough hogan.

Besides AISC's requirement for annual calibration of the volt/amp meter, is there another code / specification that requires the annual calibration of welding equipment? I have not come across any that stipulate a time frame other than D1.5 (every three months) or AISC annual calibration of the volt / amp meter used to calibrate the machines. That doesn't mean there may not be one but just have not come across it.

Thanks hogan for your comment. Sometimes I get too focused on something and begin to miss the bigger picture.

ziggy
Parent - By hogan (****) Date 02-27-2009 17:35
Nothing in AWS that I know of
Up Topic Welding Industry / Technical Discussions / How to Calibrate a Stud Welder?

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