welding brackets

[ches2443]

I was welding a bracket on a piece of machinery when the factory rep came up to me very upset and made me stop welding. He said that welding on this machine could cause stray current and fry the bearings. (Has anyone had this happen to them?)

 

[iwire]

I was welding a bracket on a piece of machinery when the factory rep came up to me very upset and made me stop welding. He said that welding on this machine could cause stray current and fry the bearings. (Has anyone had this happen to them?)

You can definitely destroy bearings and wiring if you do not use care when deciding where to land the work clamp in relation to the electrode.

Is it likely? In my experience no, but it is possible and I understand why the factory rep would not want to chance it.

 

[celtic]

:-?

Was this some type of ultra sensitive equipment?

 

[iwire]

:-?

Was this some type of ultra sensitive equipment?

I have seen die cast connectors melted off of EMT by welders not thinking where they put the work clamp.

I have seen THHN in EMT melted into one nasty mess by welders placing the work clamp wrong.

 

[celtic]

I have seen die cast connectors melted off of EMT by welders not thinking where they put the work clamp.

I have seen THHN in EMT melted into one nasty mess by welders placing the work clamp wrong.

Thanks for the info ....I just completed a welding class and none of that sort of calamity was ever addressed.

TY.

 

[iwire]

Thanks for the info ....I just completed a welding class and none of that sort of calamity was ever addressed.

TY.

I enjoy fabricating, used to do a lot of it, I recently learned how to TIG.

The couplings where melted when a welder walked in the door from outside and placed the work clamp on a 1/2" EMT from a switch box heading up to the trusses. He then went to work welding on the trusses till the 1/2" couplings melted out.

The THHN was melted when a welder put the work clamp on the edge of a powered truck dock ramp, then went to welding the weather seals onto the overhead door frame.

The current path was through the dock ramps 12 AWG EGC back to building steel then through the EGC to the electric door operator. It also melted the control wires and some of the control buttons for three side by side docks.

When we use to weld on the rides at the amusement park we would try to place the work clamp very close to the spot we were welding. In no case would we place the work clamp on a stationary section then weld on a moving section as that could cause arcs at the bearings.

 

[S'mise]

I've seen senitive electronics get fried but I would not be too worried about motor bearing unless you have a ton of welding to do. You could bond the motor shaft to the frame if you are worried about bearings. Yes I agree that having your anode clamp nearby is a good idea so it don't take a rogue path.

 

[iwire]

I would not be too worried about motor bearing unless you have a ton of welding to do.

I have personally been involved with replacing the bearings on four 500 HP motors that had been ruined by less then 17 amps of current due to the VFDs.

This is far less then any welding current used on machinery.

Remember there is very little contact area in roller bearings.

Do what you want, myself I would be careful. :smile:

 

[cadpoint]

Thanks for the info ....I just completed a welding class and none of that sort of calamity was ever addressed.

TY.

Santa's coming to town, you dropping hints or are U using the class for continuing credits ?

 

[big john]

I've heard of equipment being destroyed by welding current, but only ever seen the side-effects once: A welder building a new frame for an existing conveyor system; the ground clamp went on one end of the conveyer and the welder started working his way along the side. He never moved his ground clamp and had done a couple dozen welds by the time he got to the other end of the belt. Needless to say, with the bearings carrying at least some of the return current, that conveyor belt didn't convey no more.

-John

 

[celtic]

I enjoy fabricating, used to do a lot of it, I recently learned how to TIG.

My training was stick only ...we'll see if I like it in practice [aka, real world application and not the classroom incubator]...and see if I continue on up.

Santa's coming to town, you dropping hints or are U using the class for continuing credits ?

Neither.
Opportunity knocked and I kicked the door open

 

[S'mise]

I've never seen bearing failure because of welding but It never hurts to be cautious. I would think Tig welding might be more dangerous because of higher frequencies. Same with a VFD roasting bearings, they do produce some funny waveforms.

 

[masterinbama]

I had a welder in a pet food plant place his ground on the leg of a large drying table. All was good until he moved up to the carrier that moved from one end to the other.The carrier rolled on neoprene wheels and the only thing carrying his ground current was a #14 in a 2" flex with 126 #16 control wires. Damage was limited to the control wiring the SLC 5 PLC and most of the ice cube relays. The fun part was there were no drawings on the machine so me and the engineer had to"reverse engineer " the whole thing from the PLC program.

 

[zbang]

My favorite was the welder working on the roof of a 12 story building- he dropped the electrode cable over the side and down to the truck in the 2nd floor garage, but ran the work cable from the truck up to the sprinkler pipe 10 feet away. Since he was building an A/C platform for my employer, I know he wasn't working on the sprinkler.