The tier one automotive parts company I work
for, has been told by some big three welding engineers that they have to use "self
shielding flux cored wires" when welding their galvaneald parts. These flux
cored welding wires appear to cause us many welding issues. What is the logical,
mechanical justification for using these wires?
Ed's Answer:
The bottom line,
there is no justification for the use of these products on cars or truck parts.
I believe the selection of these welding wires is based simply on " welding
ignorance" that is fed by " weld consumable salesmanship"
Note: One of the biggest problems with arc welding in the auto/truck industry,
is the selection of weld wire consumables poorly suited to the application. In
most instances the weld wires selected are "too large" requiring weld
current levels which are typically too high for thin gage parts, (this is derived
from the big the consumable the faster the weld mentality that dominates welding
in the auto/truck industry) . The self shielding wires typically are available
only in large diameters.
Its unfortunate that as you read this today
that big three corporate engineers are likely informing a part supplier in North
America or Mexico that they must use these poorly suited, self shielded flux cored
consumables.
From a weld mechanical, weld chemistry, weld quality and weld productivity perspective,
in contrast to MIG wires the self shielded flux cored wires will do more harm
than good.
[a] In contrast to MIG, On thin gage applications the self
shielded wires which do not offer short circuit weld characteristics, this mode
of weld transfer can dramatically increase the weld burn-through potential.
[b] In contrast to MIG the weld fumes produced from the self shielded wires
are much more hazardous and actualy contain carcegenic components. When using
these wires weld shops will have to invest in costly ventilation equipment that
would not be required with MIG. Of special concern will be the health of manual
welders that have to use these wire to do the weld repairs which will be necessary
on gage parts.
[c] With MIG, weld spatter is controllable. With these
self shielded products that produce globular transfer additional man power is
typically required for extensive weld clean up. Also the weld cell equipment and
weld part fixtures will typically be contaminated with unnecessary excessive weld
spatter.
[d]
With MIG welds, effective weld repairs should be simple to carry out. The reason,
MIG produces a miniscule amount of thin slag. In contrast with the self shielded
flux cored wires, the resulting weld slag can be both excessive and difficult
to remove. When repairing the self shielded welds with the slag in place, both
the weld fusion and quality potential will suffer greatly. Although its a common
practice in automotive/truck plants, placing a self shielded wire repair weld
on top of a weld with slag is an invitation to a future product liability implicaions.
[e] The fact that the part is galvanealed or galvanized is irrelevant. I
have had mechanical weld tests performed on these wires and also on MIG wires,
the test results indicate that MIG provides the best weld quality meeting the
total mechanical needs.
TO
FIND OUT HOW THE POOR SELECTION OF THESE SELF SHIELDED FLUX CORED WIRES HAS ALREADY
COST A BIG THREE PLANT OVER 12 MILLION DOLLARS, GO TO THE MANAGEMENT OR ROBOT
SECTION UNDER MIG AND FLUX CORED
15Welding
Resolutions for wise weld decision makers
[1]
Avoid purchasing pulsed weld equipment for carbon steel applications.
[2] Avoid any
gas sales rep who wants to discuss the justification of three part gas mixes for
steel or stainless applications.
[3]
Avoid the use of any gas mix for carbon steels that contains oxygen.
[4] Avoid sales-reps
who want to discuss unique new gas mixes for "ozone reduction".
[5] Avoid
sales reps who tell you their gas mix will allow you to weld faster.
[6] Never use
self shielded wires. unless you weld outdoors.
[7]
Avoid metal cored wires, or gas shielded flux cored where MIG wires can be utilized.
[8] If you
have three phase, avoid the purchase of an inverter power source for a traditional
manufacturing environment.
[9]
Avoid unnecessary electronic bells and whistles on welding equipment for both
the weld shop and robot cell.
[10]
Grind or sand blast welded areas "before you weld" rather than after
you weld.
[11]
Provide MIG process training at your facility. The training should ensure your
weld personnel will no longer "play around" with weld equipment parameters
and controls.
[12]
Put in some time to educate managers, engineers and designers on the requirements
of MIG welding and process controls".
[13]
Create discussions with both workers and management about "real weld
costs" (attaining maximum deposition rates). Examine ways to reduce costs.
[14] Ensure
all weld related job descriptions define the responsibilities of an individual
on the influence of your welds.
[15]
Establish effective weld process controls with narrow parameter adjustment windows
to produce consistent weld quality at the highest possible weld deposition rates.
The justification
for these resolutions are found throughout this site and in my books.
Top Six Issues With Robot MIG Welding Applications
[1]
The purchase of useless welding bells and whistles
Weld shop focus is
better directed at:
[a] Establishing and maintaining effective weld
process controls.
[b] Understanding how to optimize both manual and
robot weld productivity.
[c] Showing daily concern for attaining consistent
acceptable weld fusion.
[d] Understanding that their is more to controlling
weld costs than lowering the costs of the welding wires or gas.
[2] Extensive lack of robot MIG process weld expertise.
An extensive
lack of "automated MIG weld process expertise" prevails. The lack of
this expertise leads to:
[a] Extensive weld quality rework issues.
[b] Excessive unnecessary robot down time.
[c] Daily robot weld
productivity issues.
[d] Potential corporate weld liability concerns.
[3] Inappropriate
consumable selection.
Selecting welding electrode wire diameters which
are too large for the applications is a primary issue for the majority of automotive
weld part manufacturers.
[4]
Welding Equipment Manufacturers and Salesmanship.
Believing the sales
influenced advice of the major welding equipment manufacturers creates tremendous
welding issues. Few sales companies employ reps who have extensive, "real
world, weld application expertise", of course there is always a few exceptions.
In weld realty too much welding advice comes from the mouths of sales personnel
who lack effective weld process training, and who may be zealously biased to their
companies welding products.
[5]
Ineffective Responsibility for Robot Weld Quality and Productivity.
Too
frequently inexperienced management will give the robot weld responsibility to
inexperienced, hands off engineers or maintenance personnel who lack weld process
expertise.
[6]
Inexperienced managers and engineers.
If a manufacturing company employs
a manager who simply does not understand, or has no interest in what it takes
for automated weld process controls, that company typically will end up with a
weld department with numerous welding issues. This is a huge issue in the auto
industry.
Six
Power Sources I Would Not Recommend
If you have a robot purchase in mind the following power sources are what I
personally would not recommend.
[1]
The Lincoln Power Wave
This welding unit "will often take you where
you don't need to go, restrict you where you should not be restricted, and make
you pay a price you don't need to pay. With this power source in your robot cell
it would be wise to make sure you have a spare. For optimum manual or robot carbon/stainless
MIG welds stick with the Lincoln CV 400 amp power source.
[2] The Panasonic HM Units.
Pre-year 2000 units. If Panasonic thinks
this is a solution to North American welding problems they should fire their so
called Japanese welding experts.
[3]
The ABB/ESAB Arcitec
Sold with ABB robots. This erratic, poor performance
power source introduced approximately four years must have put Swedish manufacturing
technology back two decades. For more information on this "unique" welding
equipment you know where to find me, and it won't be in Stockholm.
[4]
Miller Maxtron.
Its hard to understand how a company with Miller's reputation
had the nerve to put this machine into any welding shop.
[5]
Miller Invision
Made before 1999, a modified improved Maxtron yet still
in development. Its a pity it took Miller so long to get it half right.
[6]
Thermal Arc
Invertors. Erratic electronics and arc characteristics which
offer less than the traditional lower cost CV units
At this time the best MIG power source for welding "alum or alloys"
is available from OTC. Yes there will be minor weld issues when inter-phasing
to the robots and you may not like the customer support, but this unit has unique
features that actually benefit a weld.
Best pulsed power source for carbon steel welds "even though pulsed is
not required for 99% of all carbon steel applications" is the 2001 Miller
Invision.
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