Instructions / Assembly

38
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GMAW
AWS Specifications for Manufacturing GMAW Wires
Keywords:
C
ast
Helix
Heat or Lot
T
he American Welding Society has manufacturing specifications
and acceptance standards for GMAW electrodes. In addition to
chemical composition and mechanical property requirements,
AWS also has specifications for:
• Method of manufacture
• Wire electrode diameter
• Electrode surface finish
• Packaging
• Winding requirements
Carbon steel wire electrode diameter tolerances are:
.045” (1.1 mm) and smaller diameters ±.001”
.052” (1.4 mm) diameter ±.002”
.062” (1.6 mm) diameter ±.002”
AWS specifies the surface finish of GMAW wire electrodes to be
smooth, uniform, free of scratches, scales, and any depressions
that could adversely affect the welding characteristics of the wire
electrode and/or the properties of the deposited weld metal.
Also, the wire on the spool (or other packaging) must be from
one "heat" or "lot" of raw material. This helps to minimize
changes in chemical composition within a spool.
There is also a specification on standard welding electrode pack-
aging and the identification used on packaging. AWS identifies
standard packaging for GMAW wire electrodes as coils with
supports, coils without supports, spools and drums. Sizes and
dimensions of these packages are specified to help manufacturers
design equipment with wire holding devices that are appropriately
sized. The next page shows various packages. Each package
of wire electrode must have the appropriate product information
easily identified along with the required warnings and
precautionary information. Each spool, coil, reel or drum must
be individually identified along with the outer packaging.
Finally, AWS specifies winding requirements for GMAW solid
wire electrodes. Cast and helix are two key requirements.
Figure 31 shows a graphic depiction of cast and helix in a
GMAW wire electrode. To measure cast and helix, a sample of
wire electrode should be taken from the spool large enough to
form a loop when it is cut from the package, and then left unre-
strained on the floor. Cast is essentially the diameter of the loop
(if the shape is an oval, it is the largest diameter circle that will fit
within the oval). AWS requires the cast to be not less than 15”
for 0.035” (0.9 mm) and larger diameter electrodes and not less
than 12” for 0.030” (0.8 mm) and smaller diameters on all spool
packaging larger than a 4” spool, [1 lb. and 2 lb. (0.5 and 0.9 kg)
spools]. Helix is the rise of the wire electrode off of a flat sur-
face. AWS specifies that the helix be less than 1” (25 mm) at
any location.
Specific bulk packages, such as Accu-Trak
®
and Accu-Pak
®
utilize a unique winding technique that elastically twists the wire
to provide consistent twist-free "straight" wire. Wire from these
packages will not form a loop when cut and therefore, standard
cast and helix measurements can not take place. Individual
manufacturers shall inspect this product to meet customer
requirements.
GMAW Wire Package Selection Guidelines
When choosing a GMAW wire electrode for a welding applica-
tion, there are many factors to consider, such as mechanical
properties of the base material, chemistry of the base material,
surface condition of the base material, and packaging
requirements.
Once the mechanical properties and chemical makeup of the
base material are known, it is fairly easy to choose a GMAW
solid wire electrode. The tensile strength of the wire should, at
minimum, match the tensile strength of the base material in
order to get the full strength of the weld joint.
Alloyed base materials are generally higher strength steels and
therefore not only are mechanical properties a consideration but
also the chemistry of the electrode. Many of these requirements
have already been discussed when defining each individual AWS
classification of GMAW wire electrodes.
Package selection, however, can be based upon user preference,
welding application, volume consumption, floor space and cost.
The photo on page 39 shows a variety of GMAW solid wire
packages from 2 lb. (0.9 kg) spools through 1000 lb. (450 kg)
drums and reels. Lincoln Electric’s SuperArc
®
and SuperGlide
®
GMAW wire can be found in a full range of these packages to
suit a wide variety of requirements.
A 2 lb. (0.9 kg) spool of solid GMAW wire electrode is a four inch
diameter package that is generally used for self-contained small
wire feed welders, such as Lincoln Electric’s SP-135T or in
spool guns. They are generally used for occasional use for
hobbyists, tack welding, or for applications where weld joints are
restricted and the spool gun is the preferred option.
FIGURE 31: Cast and Helix in a GMAW Wire Electrode
Wire Loop
Cast
Helix
Floor
Coil Style Packaging Winding Check