Friday, October 4, 2013

A Welding "Ground" doesn't ground anything!

What makes a good ground (Work Lead) connection and why is it important?

In a welding circuit, current needs to pass through as few connections as possible and the circuit it self needs to be as short as is practical.
On the positive (+) side current passes through the (+) stud connection, the feeder connection, the Gun connection and the contact tip (to the wire) connection. With the exception of the wire, all of those connections are typically, copper or brass.
On the negative (-) side current should passes through the (-) stud connection, the cable to the Work Lead (ground) clamp, possibly across a rotating surface and then to the work piece.
When any of these connections are anything less than clean copper or brass to clean copper or brass the possibility of a poor connection and a current and/or voltage loss exists. These losses can be great enough to run outside the parameters of the weld procedure causing spatter or a lack of fusion. That can get a welder into trouble.
Some good examples of poor connections would be:
  • A Work Lead (ground) connected to a building column. 
    • Using a steel building column and a steel bolt, this connection will oxidize (rust) and create resistance.
  • A Work Lead (ground) connected to a steel plate run across the floor. 
    • Of course the initial connection is the same as the building column. 
    • When that steel plate isn't of a sufficient size (area) and that plate is joined by one or several welds (extra reduction in area) the condition are ripe for a drop in current and/or voltage.
The 2 conditions mentioned above also create a safety issue. Once a Work Lead (ground) contacts a building it gives current alternate routes. One of the most popular is through a jib or bridge crane.
Aside from creating havoc with the cranes electrical system, current passes through the lifting devices (cables, hooks and chains), heating them over and over and thus weakening them and making them susceptible to failure.
One last good example of a poor connection would be an unlubricated rotary clamp, or a rotary clamp lubricated with a lubricant that is not made for electrical connections.
A key to quality welding starts with a good quality circuit and a key component of that circuit is the condition of the Work Lead (ground).

Side Note: Notice I’ve replaced the word “ground” with “Work Lead”.  You should too.  Keep in mind, a welding “ground’ doesn’t ground anything.