BOC Smootharc MMA 170, Руководство по эксплуатации, Страница: 9 / 36

9
Electrodes and Typical Applications
Name AWS Classification Application
BOC Smootharc 13 E6013 A premium quality electrode for general structural and
sheet metal work in all positions including vertical down
using low carbon steels
BOC Smootharc 24 E7024 An iron powder electrode for high speed welding for
H-V fillets and flat butt joints. Medium to heavy structural
applications in low carbon steels
BOC Smootharc 18 E7018-1 A premium quality all positional hydrogen controlled
electrode for carbon steels in pressure vessel applications
and where high integrity welding is required and for
free-machining steels containing sulphur
BOC Smootharc S 308L E308L Rutile basic coated low carbon electrodes for
welding austenitic stainless steel and difficult to weld
material
BOC Smootharc S 316L E316L
BOC Smootharc S 309L E309L Rutile basic coated low carbon electrode for welding
mild steel to stainless steel and difficult to weld material
Electrode Size
The size of the electrode is generally dependent
on the thickness of the section being welded,
and the larger the section the larger the
electrode required. In the case of light sheet
the electrode size used is generally slightly
larger than the work being welded. This means
that if 1.5 mm sheet is being welded, 2.0 mm
diameter electrode is the recommended size.
The following table gives the recommended
maximum size of electrodes that may be used
for various thicknesses of section.
Recommended Electrode Sizes
Average Thickness
of Plate or Section Maximum Recommended
Electrode Diameter
≤
1.5 mm 2.0 mm
1.5–2.0 mm 2.5 mm
2.0–5.0 mm 3.15 mm
5.0–8.0 mm 4.0 mm
≥
8.0 mm 5.0 mm
Welding Current
Correct current selection for a particular
job is an important factor in arc welding.
With the current set too low, difficulty is
experienced in striking and maintaining a stable
arc. The electrode tends to stick to the work,
penetration is poor and beads with a distinct
rounded profile will be deposited.
Excessive current is accompanied by overheating
of the electrode. It will cause undercut, burning
through of the material, and give excessive
spatter. Normal current for a particular job may
be considered as the maximum which can be
used without burning through the work, over-
heating the electrode or producing a rough
spattered surface, i.e. the current in the middle
of the range specified on the electrode package
is considered to be the optimum.
In the case of welding machines with separate
terminals for different size electrodes, ensure
that the welding lead is connected to the
correct terminal for the size electrode being
used. When using machines with adjustable
current, set on the current range specified.