and Correcting Weld Problems.
simple rule to remember is that quality usually equals consistency:
welds that are always made within the specified weld lobe will consistently
be of high quality. The question is, how can you determine if welds
are being made consistently within the lobe?
If a weld
control is programmed to deliver a certain amount of current at a certain
amount of force, how can you ensure that the right amount of current
and force was delivered at the tips? The amount of current coming out
of the transformer may be correct, but is the current density at the
workpiece where it should be? How do you know if the weld is good?
common method of answering these questions is through destructive testing.
It's hard to dispute the quality of a weld after it has been pulled
apart and inspected. However, destructive testing produces a lot of
scrap metal, and while it will reveal whether the weld is good or bad,
it cannot explain the specific details of why or how a weld turned out
the way it did.
weld monitoring provides a way to see what is happening while each weld
is being made. Critical parameters, such as resistance and current density,
can be observed and measured at the workpiece during the weld process.
The next chapter will discuss how this process works. These links provide
an abbreviated guide of commonly encountered welding problems and their
possible causes, adapted from documents published by the Resistance
Welder Manufacturers' Association and reprinted with permission.
for Producing Quality Welds
high quality welds consistently, follow these tips:
sure that the electrodes you are using are suitable for the job.
standard electrodes whenever possible.
an electrode tip diameter suited to the thickness of the stock being
use of flow indicators for viewing and assuring proper cooling water
flow through the electrodes (typically, 1.5 gallons per minute).
that the internal water cooling tube of the holder projects into the
tip water hole to within ¼ inch of the bottom of the tip hole.
the internal water-cooling tube of the holder to the appropriate height
when switching to a different length tip.
that the top of the adjustable water-cooling tube in the holders is
the proper height when changing to a different tip length.
the tip with a thin film of cup grease before placing it in the holder
to simplify removal.
ejector type holders for easy tip removal that won't damage the tip
the tip taper and holder taper on a regular basis, removing any foreign
dressing of electrodes on a regular basis to maintain the correct
a rubber mallet to align holder and tips, rather than a metallic tool.
These Potential Sources of Weld Problems
weld using unidentified electrodes or electrode materials.
using special-purpose or offset tips if the job can be handled with
a standard straight tip.
not use a small tip for welding heavy gauge materials or a large tip
on small piece.
not overlook turning on the cooling water to the appropriate force when
beginning to weld.
use a water hose that does not firmly fit the water connection nipples.
leaky, clogged or broken water connections.
not use holders that have leaking or deformed tapers.
not use electrode holders without an adjustable internal water cooling
leaving the electrodes unused in tapered holder seats for long periods.
not use pipe wrenches or similar tools when removing electrodes.
dress an electrode using a coarse file. These recommendations can help
improve the quality and consistency of your welds.