Drawn-arc stud welding is an extremely
efficient method of attaching fasteners primarily to mild steel and
stainless steel by utilizing a constant-current DC power supply,
typically a 3-phase transformer-rectifier, equipped with integral
controls to operate a special drawn-arc stud welding gun. When a weld is
initiated, current begins to flow through the stud while the weld gun
simultaneously lifts the stud to "draw an arc", which melts
the base of the stud and adjoining surface on the workpiece. Upon
completion of the weld time, the gun plunges the stud back to the
workpiece, resulting in a permanent bond as the molten material
solidifies…….all in less than one second.
In general, the drawn-arc process is
capable of welding a broad range of stud diameters (up thru 1-¼"
or 32 mm) and to almost any material thickness above 0.040" (1 mm).
To accommodate such a broad range, the process is actually split into
two categories: Standard Drawn-Arc and Short-Cycle.
Standard drawn-arc is used with studs
¼" (6 mm) diameter and larger, and base material thicknesses at
least 1/3 the stud diameter. This process requires the use of
flux-loaded studs and ceramic ferrules, included with the studs, to
contain the molten material during the weld and form a fillet around the
stud base.
Short-cycle is an abbreviated version
of drawn-arc for studs 3/8" (10 mm) and smaller, especially when
welding to base materials as thin as 1/5 the stud diameter. With this
method, the weld current is usually much higher and weld time much
shorter (short-cycle), resulting in lighter penetration and less molten
material, thereby eliminating the need for ceramic ferrules and
flux-loaded studs, though shielding gas is often recommended.
Several standard handgun models are
available from stock to accommodate routine applications, while
automated production systems are available on a custom-designed basis
for high-volume applications.
Additionally, a complete range of standard US and
Metric studs is readily available from stock in mild steel and stainless
steel, while non-standard stud designs and alloys are available upon
request.