Sensitive equipment welding.
Sensitive equipment welding.
(OP)
I have a question regarding safe chassis welding on sensitive production equipment. Some of our new equipment (joining the 80's here) actually has plc's, touch screens, and prox sensors, etc. What if any additonal saftey precautions should I take when having this equipment welded? Removing source AC and saftey grnd has been suggested to prevent possible looping. Any thoughts on this would be appreciated. Schdled project would be involving 300+ amps DC. Thanks very much...





RE: Sensitive equipment welding.
That sounds like a very risky proposition. With the few details given, there's no way to assure an undamaged system. It would be a good idea to keep the arc-current return path as small as possible, but I think this is potentially a real can of worms. The weldor has only limited control of the current path, and no control-equipment manufacturer is going to stand behind components subjected to such large electromagnetic and/or electrostatic stresses. I will be interested to hear other opinions.
RE: Sensitive equipment welding.
take the part off, or the panel off, at all cost try not to weld on the machine. same concept with an over head crane never weld something that is hooked to a sling from an overhead crane.
RE: Sensitive equipment welding.
Good point, jlh. Doing that on some conveyors will give you a barrelful of hopelessly wasted bearings. Most don’t ever do it twice.
RE: Sensitive equipment welding.
RE: Sensitive equipment welding.
i do work on sensitive production equipment too...a long production line with 4 kinds of touch screen, 3 types of PLC's, a check weigher, induction sealer and communication cables. We do all of our welding OFF the production line...i am not sure if this is possible in your case...mounting of any kind are done by nuts and bolts using a properly designed plates.....
dydt
RE: Sensitive equipment welding.
RE: Sensitive equipment welding.
Maybe the "drawing head" manufacturer could be consulted on the matter.
RE: Sensitive equipment welding.
I have been involved in several welding projects involving delicate insturmentation. The best way that we have found is to ground directly to what ever is to be welded if possible using a bolted ground vs a ground clamp. As busbar stated in the begining, this shortens the currents travel path. If it is not possible to ground directly to the item being welded, other mounting methods should be considered. We just had a similar scenario here where an unsupervised contractor "took out" $ 50,000 worth of load cells on one of our vessels.
Good luck,
Micjk
RE: Sensitive equipment welding.
Boy Howdy, micjk. The hard-found cashflow perspective can vividly accentuate a 'lessons learned' episode.
RE: Sensitive equipment welding.
1 - ensure that the part being welded is directly connected to the ground grid
2 - connect the ground calbe from the welder directly to the part being welded and to no other part of the machine.
RE: Sensitive equipment welding.
...one thing you can do is make sure that the ground is bolted not clamped....free from paint, grease or any non-conduting material...make sure that the welding rod is as close as possible to the ground termination point.....
good luck
dydt
RE: Sensitive equipment welding.
mike
RE: Sensitive equipment welding.
In the IEEE document, notice that it was the welding machine ground lead that was not supposed to be connected anywhere other than the part being welded. Normal equipment grounds to ground grid are ok to be connected at other locations and I'm pretty sure they should stay in place.
RE: Sensitive equipment welding.