Testing ground to workpiece

[iloveturbolag]

Hello all,I'm new to this forum but have heard great things from people in the industry. I'm currently working in a manufacturing plant with a few robotic welding cells and a dozen or so manual welding cells. Is there any good way to test the ground to work pieces in high volume/high mix welding other than individual testing of conductivity with an ohm meter??? Thanks for the help!

[Cgotto6]

Are you having troubles and suspect a poor ground connection? What machines? Serial numbers help too.

[iloveturbolag]

We are having various consistency issues and i am working on mapping out all the possible failure modes and the process to troubleshoot each one. The way our fixtures mount to our tables is by sitting on 4 small rest pins and secured by 2 bolts that keep the fixture in place with a tight tolerance bushing. I suspect the conductivity between the fixtures and the tables is very poor because of this. Our power sources are all OTC.

[cruizer]

Problem is that all it takes is one machine to screw up the whole line, so its likely not a ground (work lead) error. I am thinking that one of your tables isn't isolated from a power supply. I've investigated this problem way too many times, and now is the first thing I look for.

Other than the usual metal spool on the feeders touching a chassis, however, this is an erratic error as problems occur as the arc is turned on and off.

If your running tubs of wire. the wire feeding is a steel liner encased in a rubber tube. The tube cuts easy and shorts to a chassis. The chassis could be anything, though being a potential ground, all machines are using the same ground, and presto, alota problems everywhere.

[Sberry]

I am kind of curious,, what do you mean isolated from a power supply?

[cruizer]

I am kind of curious,, what do you mean isolated from a power supply?

The bots like to sense feed back DC voltage, from the welders. They don't like to sense transient AC voltage from a non isolated receptacle or other device.

[iloveturbolag]

Thanks Cruizer, I will investigate this further.

[iloveturbolag]

If your running tubs of wire. the wire feeding is a steel liner encased in a rubber tube. The tube cuts easy and shorts to a chassis. The chassis could be anything, though being a potential ground, all machines are using the same ground, and presto, alota problems everywhere.

Found this exact problem on 2 robots yesterday. Thanks for the tip cruizer! I will be regularly inspecting our liner conduit for wear spots now.