Weld spatter is an
all-too-common and persistent issue ? one of those things that you hate, but
you figure you just have to deal with. But that’s not necessarily true, because
there are actually many ways to control it. Weld spatter consists of small balls
of molten metal that are created near the welding arc that stick to the gas
shroud of the weld gun and block gas flow. Resulting problems include the
spatter sticking to work pieces and/or tooling, injuries to workers, clean-up,
porosity and loss of material.
Even when using
spatter-preventative methods, it eventually builds up inside and on the weld
nozzle and nozzle tip anyway, restricting the inert gas flow and causing
porous, brittle weld joints. Fortunately, there are many options for reducing,
or even eliminating, this dangerous and costly nuisance.
What causes spatter?
Well, according to Matt Brooks of a
manufacturer of welding equipment, cutting equipment, torches, robots,
positioning equipment, and standard and custom arc welding cells, there could
be several causes. According to Brooks, the main factor is a disturbance in the
molten weld pool during the transfer of wire into the weld, typically caused by
voltage being too low or amperage being too high, which in turn means the arc
is too cold to keep the wire and pool molten and causes a stubbing effect of
the wire. Spatter may also occur because of the gas selected for use ? for
example, CO2 creates more spatter than MAG welding.
Additionally, coatings
are one way to go when looking to reduce weld spatter. For instance, developer of fastening and assembly
technologies, came up with a creative solution to help reduce their weld
spatter problems. Their need for a spatter solution arose because they felt
that cleaning spatter off a welding nozzle took too much time, and that most
anti-spatter sprays or dips do not prevent spatter adhesion, must be frequently
reapplied in order to be effective, and can be messy and even dangerous. In
addition, the company wished to provide an alternative to procedures such as
reaming, which they viewed as costly and inefficient, so they came up with
Spatter-Nix, which is a new coating application. According to the company, this
coating process helps prevent weld spatter accumulation, improves MIG gas flow
and weld quality, reduces the frequency of nozzle cleaning, makes nozzle
cleaning faster and easier, increases the lifespan of MIG weld nozzles and
reduces the need for anti-spatter dips and sprays.
Ideal for thin metal
automotive applications (0.7−1.0 mm) that employ a longer electrode,
Spatter-Nix is a slick coating process that allows the spatter to be vibrated
out. It coats the weld nozzle inside and out, providing maximum protection
against spatter. (Internal coating length is dependent on the presence or
absence of an insulator.) Even if the coating chips or flakes off outside of
nozzle, the coating performance inside the nozzle and on the weld tip remains
unaffected.
According to ND, the
process has been garnering great response from welding companies. FIC
America Corporation, a manufacturer of “stitched” welded muffler parts for
Toyota, experienced improved productivity. Weld nozzle cleaning was reduced
from every 15 minutes to every six hours, and weld nozzle cleaning was reduced
from once every five cycles to once every 500 cycles. At one major automotive
plant, Spatter-Nix was applied to two weld nozzles of robotic welders. Each
robot performed six welds on each piece welded, averaging of 25 to 35 pieces
welded per hour. The robots were employed continuously for two eight-to nine-hour
shifts per day. Normally, operators found it necessary to clean the weld
nozzles an average of three times during every eight– to nine-hour shift, but
with this coating application, the robotic welders ran for six consecutive
shifts without the need for cleaning.
In addition, a Tier 1
automotive supplier used Spatter-Nix on a robotic welder that performed
seven-inch welds. The weld nozzle typically required reaming every four weld
cycles. With the use of Spatter-Nix the robotic welder was able to complete 184
welding cycles without the need to ream the weld nozzle. What little spatter
that did build up inside the nozzle was able to be removed with a gentle tap to
the nozzle. Weld nozzle cleaning reduced from every six minutes to once every
100 hours. Also, a tool and die welding company implemented Spatter-Nix coated
nozzles used in a heavy die repair application. In one application multiple
welds were performed on steel pieces about five feet long and 3/4 in thick. The
welding of one piece took, on average, 45 minutes to one hour. The hand welder
found it necessary to clean his weld nozzle at least 10 times during the
welding of one piece. Using a coated nozzle, the welder was able to weld 10
pieces without cleaning the nozzle.
As stated earlier, the
type of gas used in welding may also contribute to spatter. According to (Cleveland, OH), Argon can be very
useful in this area. According to the company, for most mild steel
applications, CO2 will provide adequate shielding, but when you must have a
flatter bead profile, less spatter or better wetting action, you may want to
consider adding 75– to 90-percent argon to your CO2 shielding gas mix. Argon is
inert to the molten weld metal and therefore will not react with the molten
weld metal. When CO2 is mixed with Argon, the reactivity of the gas is reduced
and the arc becomes more stable. However, Argon is more expensive. In
production welding, selecting the perfect shielding gas can be a science of its
own. Attributes such as material thickness, welding position, electrode
diameter, surface condition, welding procedures and others can affect results.
But fortunately, whether you decide to use a coating, try different gases,
adjust your voltage, or try another solution, combating weld spatter is getting
easier.
FIVE WAYS TO PREVENT
WELD SPATTER
1. Up the Voltage. Cut down on spatter by adjusting your voltage. Voltage
is closely tied to the welding arc’s length and the heat input of the weld.
Find the right balance, so the weld is being created with the right intensity.
2. Up the Voltage. Make Sure the Welding Surface is Clean. One simple
way to avoid spatter is to keep your welding surface free from contamination.
Substances like oil may trigger the welding power supply to alter parameter
settings — creating spatter before and after the right adjustments are made.
Anything that oxidizes the weld pool (such as rust) may cause bubbles — which
burst, creating more spatter. It’s best to clean the surface and avoid the
mess. Remove buildup with an abrasive tool or chemical.
3. Up the Voltage. Secure the Welding Environment. In the fight against
spatter, wind is an enemy. Make sure your shielding gas isn’t being affected by
air circulation. Another environmental problem that causes spatter, cable
grounding, can be easily fixed. Make sure cabling is secure and on clean
surfaces.
4. Up the Voltage. Find the Right Torch Angle. Angling your torch with
the wire in front may make a nice, smooth weld, but it shoots spatter outward.
A drag angle with the wire behind keeps spatter in the weld pool.
5. Up the Voltage. Pay Attention to the Shielding Gas and Wire. Make
sure your shielding gas and wire are preventing spatter, not contributing to
it. Argon gas can minimize spatter, but it can change other aspects of the
weldment. Many wires have deoxidizing substances in them, which will decrease the
amount of spatter. Flux cored wires are a good safeguard against spatter.
