Orion Pulse Arc Welding Workbook
12
MELTING TEMPERATURES OF SELECTED METALS:
e table shows a variety of metals and their corresponding melting
temperatures. Note that tungsten has a significantly higher melting
temperature than the other metals. is is an important attribute of
tungsten that aids the welding process. While welding, electrons from
the weld plasma impact the workpiece and form a weld spot. At the
same time, positively charged gas atoms impact the electrode. Both
of these processes create heat. However, more heat is generated by
the electrons impacting the workpiece than the atoms striking the
electrode.
ELECTRODE SHAPE
e electrode shape is a very important aspect to consider and has a significant impact when welding various metals.
e shape of the electrode will greatly affect the welding plasma created during the arc. Poor electrode shape will lead to
plasma arcs that are not repeatable while good electrode shape will help the plasma arc to discharge smoothly from the
welding tip.
e grinding direction to sharpen the electrode is very important. Top Image:
When grinding, make sure that grind marks run parallel to the electrode shaft.
Parallel grind marks will allow the plasma to discharge uniformly and smoothly
from the electrode. Bottom image: Grinding the electrode such that circular
rings or marks show up will lead to a poor plasma arc, affecting weld quality. e
plasma will discharge inconsistently from the electrode ridges and may become
unstable, oscillating in time. e weld spot will not be repeatable.
As a rule of thumb the electrode should be ground so that the taper is approximately
2.5x the diameter. e resulting electrode shape is a good general shape for easy arc
ignition and excellent weld spots.
Always grind the welding electrode so that grind
marks run parallel to the electrode shaft. Placing
the electrode incorrectly on the diamond wheel
will produce circular grind marks and poor weld
results.
HANDS ON: Grind your electrode so that grind marks run parallel to the electrode shaft. Verify by looking under the
microscope. Try to produce a taper that is approximately 2.5x the electrode diameter.
ELECTRODE SHAPING EFFECTS
ere are two main electrode shape configurations that you should consider when preparing for a new project. e first is
the sharp electrode, which is the best for most applications and metals. A sharp electrode is also the easiest to ignite and
Material Melting Point (deg C)
Zinc 420
Aluminum 660
Silver 962
Gold 1064
Copper 1083
Stainless 304 1450
Carbon Steel 1500
Titanium 1660
Platinum 1772
Niobium 2468
Tungsten 3410
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