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Category: World History
Date Submitted: 04/04/2014 12:56 AM
■ 31.8 ARC CUTTING
Virtually all metals can be cut by some form of electric arc. In these processes the material is
melted by the intense heat of the arc and then permitted, or forced, to flow away from
the region of the slit or notch (kerf). Most of the techniques are simply adaptations of
the arc-welding procedures.
Each has its inherent characteristics and capabilities, including tolerance, thickness capability, kerf width, edge squareness, size of the heat-affected zone, and cost.
Selection depends upon factors such as tolerance requirements, the subsequent processes that will be performed on the cut part, and the end use of the product.
CARBON ARC AND SHIELDED METAL ARC CUTTING
The carbon arc cutting (CAC) and shielded metal arc cutting (SMAC) methods use the
arc from a carbon or shielded metal arc electrode to melt the metal,which is then removed
from the cut by gravity or the force of the arc itself.These processes are generally limited
to small shops, garages, and homes, where there is limited investment in equipment.
AIR CARBON ARC CUTTING
In air carbon arc cutting, the arc is again maintained between a carbon electrode and the
workpiece, but high-velocity jets of air are directed at the molten metal from holes in the
electrode holder.While there is some oxidation, the primary function of the air is to
blow the molten material from the cut.Air carbon arc cutting is particularly effective for
cutting cast iron and preparing steel plates for welding. Speeds up to 0.6 m/min are possible,
but the process is quite noisy, and hot metal particles tend to be blown over a substantial
area.
OXYGEN ARC CUTTING
In oxygen arc cutting (AOC), an electric arc and a stream of oxygen are combined to
make the cut.The electrode is a coated ferrous-metal tube.The coated metal serves to
establish a stable arc, while oxygen flows through the bore and is directed on the area of
incandescence.With easily oxidized metals, such as steel, the arc...