How to Stud Weld Through Paint
Normally, no one would think of being able to stud weld through paint. The usual procedure is to grind a bare metal spot on which to weld. Everyone knows a good electrical connection is necessary for a welding arc to form.
Are we using some form of magic? Not really, but the stud welding process is pretty cool. Part one of the magic starts in the point of the weld stud. We manufacture a sharp point on the tip of the weld stud. This tip is sharp enough to pierce paint. In fact, it acts like a small, one use, center punch tool.
Part two of the magic is contained in the stud welding machine (power source). Image has a special mode called the hammer mode. Normally, a stud weld system lifts the stud off the work, holds the stud in the lifted position for the prescribed arcing time and then drops (plunges) the stud back to the weld zone. The Image stud weld machine is more sophisticated. When the trigger is pressed on an Image stud welder, the welder checks for continuity, in other words a good electrical connection. If no good welding circuit is detected and hammer mode is turned on, the system lifts the special, pointed stud off the work piece and drops it back into position. This lift/drop motion allows the sharp point of the stud to penetrate the paint.
The process starts over again with the power source checking for continuity. This sequence happens very quickly bap, bap, bap, bap. When continuity is detected, because the sharp point has penetrated the paint, the unit begins a normal stud weld sequence.
The arc in a stud weld is 6,000-7,000°C (10,800-12,600°F) so the small amount of paint around the point of penetration is immediately vaporized and the weld stud can plunge into the molten pool of metal created by the arc to form a good quality stud weld.
That’s how it is possible to stud weld through paint.