the question of weld machine's property

Date 02-15-2014 13:15

10 years is a long time to have done nothing. Our machines are used for the GMAW and FCAW processes. We remove the sides and blow out each machine once a month. It's amazing how much dust can accumulate in a few weeks. We assign a distinctive number to each welding machine, and using calibrated volt/amp meters, each machine is calibrated annually. Our maintenance team performs the calibrations and QC witnesses them. All our welding machines have analog and/or digital gauge indicators. If needed, amperage and voltage gauges or indicators are adjusted to read within 10% of actual amperage readings and ± 7% of actual voltage readings obtained from calibrated volt/amp meters. After an acceptable verification, we attach a calibration sticker to each machine indicating the verification date, the next due date, and the initials of the persons who performed the calibration. In the event a machine can't be properly calibrated, we remove it from service until necessary repairs can be made. We make a notation on our welding machine calibration report, which is kept on file in the maintenance department. Any machine not bearing a valid calibration sticker is not used. If your machines are without the indicators I've mentioned and they have position switches only, they should at least be checked for output and obvious operational deficiencies.

By Blaster (***)

Date 02-15-2014 20:56

In my experience with machinery, outside of an inconsistent current path due to loose connections and oxidization, the most common output problem is the output and wire feed speed knobs don't work consistently over time as they oxidize and pickup contamination. I like to exercise the range of the knob each time I use a machine rather than just leave it in one spot or close to one spot. On some at least this may be helpful in wiping crud off the contacting surfaces.

In my experience, dirty machines usually work pretty well until a short is made and there is a catastrophic arc flash and melting, or small explosion, of which I have seen plenty. I have our machines blown out at least every 6 months and the ones in the dirtiest environment get blown out every 3 months.

By 46.00

Date 02-16-2014 02:36

It is fairly common, if not mandatory, to calibrate welding machines on a yearly basis. Ten years sounds like a bit of a third world back street fab shop outfit to be honest! You cannot expect any welding machine to output or perform the same after 10 years in an fabrication environment as the day it was bought. You need to set up a quality document that lays out a regular and traceable calibration schedule for your machines!

By 357max

Date 02-18-2014 16:23

After the machines have been blown clean have a service technician "Load Bank" test the rated output of each machine and if they have meters for amperage and voltage have them calibrated.

By Tommyjoking (****)

Date 02-20-2014 02:37

Hey 46

Jeez they put the clamps on my old beasty about every time I test. How the heck can you follow a WPS without qualified equipment?

By welderbrent (*****)

Date 02-20-2014 02:56

It depends upon the type of work and thus the applicable codes involved. Or, occasionally, the Job Specifications. But either way a good many shops and portable outfits will totally waffle on the issue of machine calibration. And scream bloody murder when it is required.

Generally speaking, in the structural world of D1.1 all we need do is use our own calibrated volt/amp meter to check volts as close to the electrode as possible. Then, amps if running SMAW, WFS if running wire. I don't use the digital or old style meters on any machine as verification of following the WPS even when in a shop that I know has calibrated machines. It isn't that big of a deal to check it myself.

As to your question Tommy, I'm sure you can pretty well tell within the first few inches of weld if you are set correctly and not even look at what any gauge says. Especially with SMAW, is machine calibration really that important? To a QC person on some jobs maybe. But it is more important that the welder knows where to set the machine regardless of what a gauge may read.

Then, you will come upon some materials and jobs where repeatability is crucial. And if it is a job where you are restricted to tight parameters then it will become important. Even then, as a welder in a previous life, a volt/amp meter is more accurate day in and day out and easier to send to the shop for calibration than the gauges on my machine.

All that said, it's great when you go to a shop that regularly calibrates and after you verify that their numbers are reasonably close to yours you can glance at their digital gauge to see if anyone is changing things around.

Have a Great Day, Brent

By Tommyjoking (****)

Date 02-20-2014 03:59

"But it is more important that the welder knows where to set the machine regardless of what a gauge may read. "

Oh heck Brent, we cannot do that if it falls outside the parameters of the wps EVER. Even if all these welds pass the test parameters, shots, ut or destructive tests, I know exactly what your saying, and I agree but...in the hard core field world we MUST hit those parameters on test day....if not we drive home no matter how clean we may shoot or how ridiculous are bends are. 75% of the time that is it on the road testing for a job. INMHO I have little faith in the parameters assigned for rod dia, material, joint design etc. I guess what I am getting at is there are plenty of guys running really wet machines, High ocv, that can pass this or that test with that machine......it shoots clean and is acceptable deposit....however it will not meet the test parameters for quals. The voltage/current relationship on my particular favorite machine is very low in comparison to certain other types of engine drive machines....however I will shoot the same freaking test with them back to back. I think it all revoles back to the same old thing....it is in the hand, not the equipment. Therefore some of these engineering concepts on weld parameters are suspect, we are human beings, not all of us do it the same way yet we can achieve the same result. I guess the best example I can give is manual tig, the deposition rates are very user defined as well as heat input....wow how the hell do you set parameters for that>>>> simple ...those that can and those that cannot and leave it wide open. There are quals out there from the AWS in particular that have extremely stringent criteria however it is an open ballfield how you get to that test sample. I am sorry Brent, I am just a stupid welder, but I am not so dumb I cannot read between the lines so to speak. A procedure is just what it is: do this under these conditions and you will be tested to this code. I am just a welder as I said...give me your requirements and I will perform accordingly. I voluntarily censor the rest of my commentary.

By welderbrent (*****)

Date 02-20-2014 08:01

Tommy,

I'm pretty sure we are going the same direction here. The question revolves around machine calibration. Most of the equipment out there in the field doing the work on pipelines and many other kinds of work are Lincoln's, SA whatevers. Many don't have gauges to go by. You have two controls for controlling the arc and the volt/amp curve. It's all a matter of knowing how to set the machine in order to achieve the correct results on the inspectors volt/amp meter and comply with the wps in use on the job.

Now, in the shop it can be slightly different with the kinds of equipment in use. Calibration and accurate gauge readings are a real advantage for both the welder and the inspector to do quick inspections with little effort on his own so the inspector can get back in the office and watch his movie, play games, or flirt with some secretary. But it definitely adds to the shop efficiency when it comes to making sure the welders have set all the parameters to the wps. It would not be cost effective to have the shop maint person going from machine to machine setting them. And the inspectors would always be complaining about the work not being correct.

Quick note, now, the comment you quoted from me referred to having the correct amperage regardless of the gauge, not just whatever suited you. Though I understand, many of us have our personal 'sweet spots' and it also combines arc length which will alter volts and amps. Both SMAW and GTAW, even FCAW and GMAW. No two welders, person or machine, truly run 100% the same even when wire feed speed and voltage show the same. But that's one reason why manufacturers spec and wps's have a 'range'. Even if the wps is very tight, there are still applicable tolerances before you are out of compliance and have to have another one.

Anyway, I really do think we are on the same page here, just using different trains of thought trying to say it.

Have a Great Day, Brent