Thanks
to the many changes that occurred over two decades during the pulsed equipment
evolution, at this site, time frames will often precede my comments.
<
2006. Numerous
global weld shops purchased pulsed MIG equipment before 2006.
When promoting pulsed equipment for welding steels, the marketing and sales personnel
who manufactured and sold the costly pulsed equipment may have told your organizations
that with the pulsed MIG equipment you would not have to
worry about:
[a] poor arc starts,
[b]
weld spatter,
[c] smoke,
[d] weld inconsistency.
It's
one thing for sales or equipment reps to promote real world weld benefits about
a weld process or consumable, it's another thing to promote ignorance or stretch
the truth to an already confused weld industry.
Weld
Reality. "Arc starts". Take any well made, traditional CV power
source manufactured since the nineteen sixties. With this power source you should
have the ability while manually welding to produce "100 arc starts"
without one arc start issue. Those golden oldie power sources will provide consistent
arc starts as long as correct weld data is applied.
MIG arc start issues
in many "robot cells" are not typically caused by that USA or Japanese
manufactured MIG power source. Most of the robot arc start issues are simply a
result of people induced, poor robot weld start and weld end data.
If you want to cut down on robot down time, my robot
MIG Process Control book and training CDs provide the unique data required
for optimum robot arc starts.
Weld Reality. "Weld
spatter". If spray or short circuit weld transfer is set with "correct
weld data", the weld spatter that will occur on most applications will be
minuscule and should not have cost consequences for most weld applications.
Weld Reality. "Weld smoke". The weld smoke
from carbon steel welds and traditional MIG spray transfer welds with optimum
argon mixes that contain 10 to 20% CO2 is minimal, especially if the weld voltage
is set for the shortest arc lengths. In over three decades of testing MIG smoke
that occurs with carbon steel welds and argon mixes, the smoke has never been
proven to be a health issue. Also lets face it, some of the largest complaints
about weld smoke come from union shops in which the majority of robot and manual
cells have an exhaust system installed.
Weld Reality. "Weld
consistency". On the subject of weld consistency and steel welds.
In forty plus years of MIG welding using good CV equipment, I have never made
a weld that was negatively influenced by the so called inconsistency of the CV
MIG power source. In contrast, with with the majority of
pulsed equipment built before 2006, to attain your most consistent weld results,
you simply switched the pulsed mode "off".
WELD MANAGEMENT AND PULSED:
THAT
MANAGER OR ENGINEER WHO LACKS PROCESS CONFIDENCE, WILL BE RELUCTANT TO PUSH THROUGH
PROCESS OR CONSUMABLE CHANGES:
Irrespective
of the weld equipment utilized, the biggest deterrent to weld optimization through
weld change is often apathetic, process manufacturing and engineering management
who may be provided with cost effective, TOUCH IT, FEEL IT, SEE IT solutions to
their weld manufacturing issues, and yet they simply lack the manufacturing balls
and process confidence to change what's happening on the shop floors.
2008.
MIG EQUIPMENT AND WELD COST JUSTIFICATION: After
MIG welding for four plus decades, I believe all you need for optimum welds on
the majority of all carbon steels, low alloy steels and stainless applications
is a traditional, low cost, durable, easy to repair CV MIG power source like this
approx. $3200, Miller, CP302 MIG power source and wire feed package. Similar packages
are available from ESAB and Lincoln.
TECHNOLOGY
VERSUS REAL WORLD WELD BENEFITS. When
you examine the 
pulsed
MIG electronic technology required to create one weld drop per pulse, it's impressive.
When
you examined the weld application benefits derived from the single drop per-pulse
process on carbon or low alloy steels, the practical and measurable weld benefits
are minuscule or often the figment of a weld equipment marketing managers imagination.
2008:
PULSED EQUIPMENT SELECTION AND TRADITIONAL WELD MODES. The
ability to provide a logical, unbiased weld process application comparison of
the pulsed mode benefits and disadvantages, against the benefits and disadvantages
of the traditional MIG short circuit, globular and spray transfer modes, is what
should make the selection of pulsed equipment either a success or failure for
many welding shops.
UNQUALIFIED
WELD EQUIPMENT EVALUATIONS,
ARE AS COMMON AS HANDS OFF MANAGERS.
WELDING
SKILLS ARE ONE THING. WELDERS, ENGINEERS, SUPERVISORS AND TECHNICIANS WHO LACK
WELD PROCESS CONTROL EXPERTISE AND THEN TRY TO EVALUATE A WELD PROCESS OR WELD
CONSUMABLE, ARE SURE TO COME UP WITH SOME INTERESTING CHOICES OR COMMENTS THAT
WILL HAVE COST CONSEQUENCES.
.
There is a common problem that occurs daily
in the welding industry with MIG weld equipment and consumable evaluations. Most
manufacturing companies employ welding individuals that may have extensive "welding
skills" however few companies have employees that have the in-depth "MIG
weld process / consumable expertise" necessary to evaluate MIG equipment,
weld transfer modes and consumables.
Managers: If the employees
in your shop "play around" with the MIG equipment and weld parameters,
how do you expect them
to provide a qualified evaluation of new MIG welding equipment or consumables?
WHY
DO SO MANY COMPANIES STARVE THEMSELVES FROM GOOD PROCESS CONTROL TRAINING RESOURCES?
When you go into the supervisors or managers office, look to the shelves for any
books or training resources on Robot / Manual MIG / FCAW "Weld Process Controls".
You won't find any as, they are here in my
office ready and waiting to be shipped out.
.
<2006:
WELD EQUIPMENT COSTS AND DURABILITY CONCERNS?
It's
an ironic fact, that today in many weld shops that use pulsed equipment, the shop
manager or maintenance supervisor may think the pulsed equipment is doing great,
that is if it only breaks down once a year, or it lasts through it's 36 month
warranty. In contrast a typical, traditional, lower cost CV MIG power source,
should last at least 15 years before Fred the electrician and Joe the millwright
in the the maintenance department to take a look inside it.
.
CONCERN
FOR SO THE CALLED WELD VARIABLES:
As mentioned in section one, with pulsed weld procedures we have more than wire
feed rates and weld voltage to be concerned with. A slight change in the pulsed
peak, background current, pulsed frequency, pulsed width, or wave forms and the
influence on the weld energy (weld fusion) and weld plasma can be considerable.
Pulsed
Welding and Essential Variables. All primary pulsed weld parameters will have
a dramatic impact on the weld quality. Each pulsed power source typically will
have it's own "unique built in weld schedules" and you can almost
guarantee each weld schedule on each pulsed power source will typically provides
a different way to weld that simple 3/16 or 1/4 steel fillet weld.
.
"Essential
weld variables have a place" in
a weld procedure should be adhered to if welding nuclear or any critical welded
components. However when robot welding that sad looking Ford truck frame with
it's 1 to 4 mm weld gaps, who with a logical mind would give a dam about essential
pulsed weld variables.
"Weld
Essential Variables" and weld quality control will have little meaning in
many auto / truck plants where management weld process ownership is lacking and;
[]
best weld practices are none existent,
[] weld process controls have no meaning,
[]
design tolerances are a joke,
[] weld process control training is none existent.
2008.
It's
ironic that most weld equipment manufactures do not appear to be in the least
concerned about developing a "uniform pulsed weld process" so uniform
global pulsed weld process procedures can be implemented.
When
manufacturing companies, and also the North American and European weld code committees
give the ever evolving, electronic pulsed MIG equipment subject some consideration,
(after two decades of ignoring the issues) its important you always remember the
following weld equipment, marketing and sales driven bottom line.
2008:
Each year, pulsed equipment manufacturers will continually strive to make their
top end weld equipment "electronically unique"
with the addition of more and more unnecessary bells and whistles. The weld reality
is, what applies to one pulsed power source will typically not apply to another.
The standard, simple, universal, two parameter CV short circuit and spray transfer
weld procedures which have been practical, logical and effective for more than
five decades, are slowly becoming meaningless as the heavilly marketed pulsed
MIG process takes root.
.
In
a time when "product liability"
are two words that should make every engineer and weld manager
cringe, it's rather strange that few Ford manufacturing managers or engineers
seem concerned with daily maintaining the fundamental, uniform weld process qualifications
and procedures for their welded parts.
The
above was taken from a 1990s report delivered by Ed, to the engineers and management
at one of the largest Ford plants in Detroit. Note: As common with all the big
three plants, this type of report and criticism quickly gets tossed into the garbage
pail.
|
.
.
2008.
All the big auto / truck
manufacturers and their tier suppliers have spent hundreds of millions on ISO
compliance and lean manufacturing methods, yet the weld reality is few of these
companies will employ managers or engineers who will spend a few hours in trying
to understand the manufacturing equipment utilized on the shop floors. Even fewer
will be aware of the requirements to establish MIG and flux cored Weld Best Practices
or how to implement manual / automated Weld Process Controls.
It's
not just the unnecessary pulsed MIG equipment complexity and price that 
should
be an issue at many plants, the less durable pulsed equipment brings it's own
concerns. After
more than two decades of MIG pulsed product development, some weld equipment manufactures
have finally built an electronic pulsed MIG power source which has enabled them
to extend the pulsed weld equipment warranty from 12 to
36 months.
Are you aware that your repair costs on that Lincoln
Power Wave could readily reach $4000 to $5000. For the cost of the pulsed equipment
repair you could buy two new Lincoln CV 400's, and do the same quality carbon
steel welds and not touch the power sources for the next two decades.
.
.
.
MID
1990s: THE JAPANESE, PANASONIC PULSED ~~~RIPPLE~~~ STORY.
If
one true weld tale represents the BS that has surrounded the pulsed process, it's
this Panasonic pulsed equipment story. A few years ago a Panasonic rep approached
Airgas the company I worked for. Airgas is the largest global weld supply company.
Panasonic wanted Airgas to represent their so called, unique pulsed product line
for the USA market.
It
was my job at Airgas to evaluate MIG equipment and select equipment to be sold
by the Airgas distributors. The Panasonic rep sat in my office, and for two hours
described the wonderful feature benefits of his superior electronic pulsed power
source. I listened as the enthusiastic rep showed me his oscilloscope photographs
and informed me how his unique MIG power source had "smoothed out the traditional
power source output ripple effect" The "ripples" I was told, occurred
with a regular MIG CV power source. While the Panasonic rep showed me his ripples,
I thought it was interesting that he did did not show the weld current and voltage
out put.
What
a fool I had been. I
have been around MIG welding since 1961 and did not realize I needed ~~~"Ripple
Proof Welds" ~~~
The
ripple photos were taken from an oscilloscope screen, (please don't confuse ripples
with weld current and amps) . The rep then went over the pulsed power source,
numerous electronic features. He was really impressed with the fact that the pulsed
power source provided "self diagnosis"
of its electronic ailments. In other words his pulsed power source shuts down
if the weld output deviates from the information put in.
I told the
Panasonic rep to send one of the welding units to my companies training department
in Chicago. At this location I could compare the pulsed equipment along side a
regular 450 amp, CV power source from Miller. This Delta Weld 450, was a MIG power
source that unfortunately and unknowingly provided the "inconsistent
~~~ripple output effect~~~ . At the same time I knew the
Delta Weld was the world's best CV MIG power source.
The Panasonic unit sat in the training facilities three
weeks before I could test it. The reason for the delay was the power source with
it's intelligent self diagnosis feature, shut itself down on three separate occasions.
To add to it's misery the poor Japanese power source would not restart after the
third shut down. To restart the Panasonic power source we had to bring in the
MIG equipment specialist from Panasonic.
Finally
after flying in half the Japanese population and many wonderful lunches in local
Japanese restaurant, Panasonic got it's state of the art MIG power source running.
The power source was fixed, and it actually stayed on after switching it on.
I
then invited the Panasonic rep to demonstrate his unique pulsed equipment. As
with all MIG equipment evaluations I provided steel and stainless weld samples
that were 1/16 - 1/8 - 3/16 - 1/4- 1/2 (1.6 - 3.3 - 5 - 6.4 -13 mm). This
steel thickness range represents the majority of North America's bread and butter
steel welding applications.
The Panasonic welding package presented at that time for the test sold for approximately
three times the cost of a regular MIG power source. The Panasonic Japanese weld
team and electronic power source team went head to head with myself and the trusty
blue Miller Delta-Weld. As Paul Harvey likes to state on his radio show, "well
now for the rest of the story".
On every weld I made, the less costly,
the more durable Delta-Weld was easier and quicker to set, and from a weld quality
and productivity perspective the Delta Weld easily out performed the Panasonic.
After all the welds were complete, the Panasonic rep spluttered a few Midwest
words I usually only hear in welding shops, and left looking for another ~~~rippless
North America sucker~~~. Note: They found many.
Mid
1990s. The Panasonic Chicago test was my first introduction
in the USA to a Japanese MIG pulsed power source, and my first introduction to
the appalling lack of Japanese weld process expertise. This solid weld equipment
test was the reason why Panasonic did not at that time get its weld product line
into Airgas, the world's largest weld distributor.
As
the Panasonic power source manufacturer believes their product represents one
of the most sophisticated electronic state of the art pulsed MIG power sources
sold in the USA, I thought I would spend some time seeing what the 1999 pulsed
Panasonic HM 500 power source had to offer. The 99 AWS weld show provided the
opportunity. The following is not word for word but it is does represent the fundamental
content of my conversation with the Panasonic rep.
.
The
Panasonic ~~~
Pulsed ~~~
BS Saga Continues.
When
I asked the Panasonic rep to describe his new HM 500 pulsed power source at the
1999 AWS show, the conversation that followed was quite interesting.
A
Panasonic rep at the weld show who did not know me said:
"Ed
our new, dip pulsed power source is really unique, it provides "artificial
intelligence" and many electronic benefits. The power source is constantly
analyzing the pulsed arc output weld data and making parameter corrections for
the arc. This power source provides superior penetration
to any other pulsed power source. (This guy did not
mention ripples).
The Panasonic sales rep continues.
"Ed
you may not be aware that after the Kobe earth quake in Japan, weld penetration
became a prime issue (I guess in Japan weld penetration was not a concern before
the earth quake) . He continued,
"one of the things that effects pulsed weld penetration is when the pulsed
arc length changes, if the arc length, (the distance between the wire tip and
weld) is shortened, the pulsed weld drop is not allowed to form without interruption,
This weld drop interruption and weld transfer inconsistency would effect the consistency
of the weld fusion attained.
At
this stage of the one way weld conversation from the Panasonic rep, by the way
this kid looked like he had just graduated from high school. His comments left
me speechless, which for me on the subject of welding is really unusual. For the
last three decades, in ten different countries I have set thousands of different
MIG weld applications always with a focus on attaining optimum weld fusion with
maximum weld deposition. The welds I produced could pass any code weld spec and
were all carried out with traditional, durable low cost CV MIG equipment. The
readers may want to note, that in the last forty plus years, I have never had
a MIG weld quality or weld fusion issue.
It's
a pity it took an earthquake in Japan before some Japanese weld equipment manufacturer
became concerned about weld fusion.
An ironic weld
point. If the Panasonic equipment and the MIG and flux cored process had been
used for structural steel applications used in seismic locations, in contrast
to traditional CV equipment and argon mixes, there is no doubt in my mind that
the Panasonic equipment would produce inferior weld quality with extensive lack
of weld fusion issues.
.
.
When
welding salesmen start to talk in a
language unfamiliar to you,
take three
steps back, say good buy and get on with your life.
This
was an oscilloscope Volt / Amp
reading of a Panasonic Power
source taken shortly after the Big Ripple and
"Constant Weld Fusion" discussion.
Volts
Red. Weld Current Black.
.
The
following is an oscilloscope of weld voltage and current from a traditional CV
power source that cost 200% less than the Panasonic power source
with it's
magic ripples.
Volts
Red Current Black.
.
PERHAPS
PANASONIC PERSONNEL SHOULD HAVE BEEN EDUCATED AS TO WHY THE REGULAR MIG PROCESS
WITH
SPRAY AND SHORT CIRCUIT TRANSFER, HAS
BEEN SO EFFECTIVE FOR 50 YEARS.
.
The
regular, low cost MIG power source, provides that unique constant voltage (CV)
attribute, in which the MIG power source instantly make its own weld current correction
for a wire stick-out variation.
With CV equipment, weld voltage and current
variations should be minuscule, during a robot weld in which the wire stick out
variations should be minimal. With MIG welding, even a novice will understand
the importance of stable weld current and voltage.
.
It's
interesting to note that the Panasonic rep placed concern on the negative attributes
of a short
arc length with the pulsed process and the negative impact on the weld fusion
potential. In contrast, the regular spray mode plasma and weld stream has much
less sensitivity to arc length variations and provides more consistent weld fusion.
I did not get into this discussion with the Panasonic rep, it would have been
time wasted. To try and rectify brain washing or process ignorance takes extensive
time, and I only had one hour with this guy. In my mind, I instead gave him a
pat on his head and sent him back to his Japanese MIG master.
[]
Japan is a country that for decades used straight CO2 for most
of it's globular, spatter covered MIG welds.
[]
Japan is a country that lacked gas plants that could make argon mixes to enable
controlled spray transfer.
[]
Japan is a country that for decades lacked knowledge about MIG Spray Transfer
mode that comes with using argon mixed gases.
At
the same show, I asked another Panasonic rep a simple question about the "pulsed
wire feed range potential". I said, "can your intelligent power
source provide a practical measurable benefit like extending the traditional MIG
spray wire feed range so that robots can weld faster? The Panasonic rep instantly
developed my wife's weld glazed blank look. He replied finally
with an answer that made sense. He stated "he was not
qualified to answer", and he handed me over to his technician.
The
technician was ready to demonstrate his latest Panasonic Power source with an
0.052 (1.4 mm) carbon steel wire. I asked that the weld wire be set at a common,
"high spray transfer" setting of 420 in./min. This setting would be
used to weld a 6 - 8 mm fillet welds on > 9 mm plate. As I expected, at the
wire feed rate of 420 in./min, the pulsed plasma was highly agitated and digging.
The pulsed plasma was simply unsuited for a controlled weld. I
of course wondered how it was possible that the Panasonic reps and technicians
were "qualified to discuss the influence
of highly complex, artificial intelligence" on the MIG arcs weld characteristics,
yet they did not know a simple limitation on the MIG pulsed wire feed range capability.
For
five decades, Japan with no argon mixes had MIG welded with straight CO2 and the
resulting erratic, globular weld transfer, daily created a welding mess. In
the nineteen nineties, Japanese companies like Panasonic went from boom boxes
and TV manufacturing to try to make sophisticated welding equipment. The Japanese
made poor, erratic, pulsed MIG equipment which they attached it to their robots
and brought this package to the USA, a country that for
more than five decades had provided most of the world's best MIG equipment.
When
it came to MIG welds, Asian auto giants like Toyota and Honda employed engineers
that experienced welding the Japanese way which was first you MIG weld then you
grind, with typically more grinding than welding. Panasonic a prime supplier to
these companies came to America with electronic MIG equipment that could barely
function, equipment that provided zero weld benefits and created numerous weld
and robot issues. How did America respond to the Japanese weld equipment? The
apathetic North American manufacturing management, led by auto / truck industry
weld decision makers, (an industry also notorious for it's bad welds) opened the
door, and said if it's Japanese it must be good, so come
on in.
©
Nov. 2007: THE PULSED ACHILLES HEEL:
Even with the world's best pulsed equipment, when
welding many common applications, the Pulsed MIG process will always have it's
Achilles Heel. This
web site is the only place in the industrial world where you will read the following
negative point on pulsed MIG welding. Please note the copy right symbols are
in place for a reason.
With
the formation of each pulsed MIG weld drop, the fluctuating pulsed MIG arc plasma,
goes from a "narrow to wide plasma profile".
The pulsed MIG plasma changes are of course influenced by the back ground to peak
current changes. With the low back ground current, for a micro second you have
much less ionization taking place in the plasma zone.
In contrast. The
traditional spray transfer, will provide a more constant, cone shaped, plasma
profile. Improving the ionization stability and maintaining the surface area of
a MIG arc plasma enables the following;
[] More consistent electron transfer
from the negative weld surface to the positive wire tip. Useful in improving arc
stability especially in automated high weld speed applications and also in maintaining
consistent weld fusion.
[] Improving the
density and coverage of an arc plasma improves oxide surface removal. Also adds
to arc stability. Beneficial on mill scale / coated applications and on those
single pass welds larger that 7 mm.
[]
A consistent, denser wide plasma also provides wider distribution of weld heat.
Improves weld fusion profiles, especially over the length of the side wall
weld fusion on fillet welds.
Of
course pulsed works well on many applications yet anyone who has used the process
on a wide range of applications is aware that it's a process that can cause issues
on many welds. When you add the pulsed arc instability that is common from many
pulsed power sources, with the fluctuating pulsed plasma, you can understand why
in two decades I went into hundreds of companies around the globe and switched
the pulsed mode off and changed the arc back to spray. Changing wave forms does
not change the Achilles Heel.
"The
welds produced should always be
mightier than the weld sales reps word"
.
.
<2005:
Pulsed MIG equipment in America's farmlands. What was
the engineer who made
that equipment decision smoking?
.
.
.
<2004.
I was really surprised at a visit to a large manufacturing plant in the middle
of the corn fields of the mid west, to find that the plant had purchased a large
number of Panasonic, pulsed welding machines to weld carbon steel, farm and related
equipment.
I mention the mid west, because in this part of the US, you
will typically find a few hard working, workers like welders and supervisors who
weld during the grave yard shift, then take care of their small farms during the
day.
You might ask, how is it that practical, rational Mid West people can get sucked
into purchasing costly, Japanese Panasonic bells and whistles for welding thin
gage to 1/2 (12mm) carbon steel farm equipment applications? These applications
have been successfully MIG welded by Deere, Massey Ferguson, Caterpillar and Harvester
for the last 50 years using less costly, easy to operate, more durable North American
MIG welding equipment.
More
cost effective, greater productivity, practical, logical, easier to use, greater
durability and no bull. These are the words that people in the mid west used to
like to hear.
These were not the words used
when a John Deere weld engineer made what I think was an illogical and costly
weld process decision. In the nineteen nineties this man converted his organization
over to over priced, poor performing, low durability pulsed MIG equipment. (Can
you remember in the nineties how unstable computers were? well pulsed equipment
was much worse). To add insult to mid west logic, the weld engineer made the MIG
equipment conversion based on "weld smoke reduction".
I hope we are all aware that when MIG welding carbon steel applications,
the weld smoke from traditional MIG with argon 10 - 20 % CO2 mixes has never been
an industrial safety or work issue. I believe it would have been more logical
and beneficial to his company's bottom line, if this weld decision maker had instead
focused on his products weld fusion potential, arc stability and weld deposition
rate potential.
.
A
FLAW WITH MANY TECHNICAL PEOPLE, IS THEY DON'T WANT TO SPEND MORE THAN FIVE MINUTES
ON A SUBJECT, AND WHEN THEY WANT TECHNICAL ADVICE THEY WON'T THINK TWICE ABOUT
ASKING A SALESMAN.
.
2008:
Is it possible that this computer driven, we have to have it now generation of
weld shop decision makers is enamored by electronics or just completely screwed
up.
In many of the weld shops
I deal with, I will often meet robot weld technicians, many of them just out of
high school. Many, (not all) of these young guys will have spent five minutes
reading a Lincoln or Miller glossy sales brochure on a new artificial MIG power
source, and bingo they become welding experts. You have met these guys, these
are the new weld experts that would much rather give you their highly qualified
opinion on the welds, rather then spend five minutes listening to some one who
was MIG welding a decade before they were born.
The
Miller & Airco Pulsed MIG Fiasco.
.
To
be fair, it's not just the Japanese pulsed equipment manufacturers that stretched
the MIG welding truth, for god's sake, you would never want to place a bible in
front of Lincoln or Miller corporate personnel and ask them to tell the truth
and nothing but the whole truth on their pulsed MIG equipment issues. It's also
fair to state that in the mid eighties if you had purchased a US made Airco pulsed
power source, (a company that once had pride in its MIG equipment performance)
you would have got more from your money if you had placed the money in a paper
bag and burnt it.
1980s early 1990s. A common problem that occurred with the Airco pulsed equipment,
was 
apart
from the fact that the pulsed mode was simply useless,
also the printed circuit board that controlled the pulsed parameters would frequently
malfunction.
In
many cases the Airco pulsed circuit board failures would occur not long after
the power source was delivered or even during the delivery. Many weld shops who
had purchased the Airco pulsed power source, would use the pulsed equipment for
years without being aware that the pulsed control boards were shot. The actual
pulsed weld transfer mode that resulted from the faulty boards produced an erratic
globular / spray transfer. A condition that many of the weld shops believed was
normal pulsed. Of course Airco never informed
the customers about the board problem.
Its
another sad reflection of an industry who uses MIG equipment, to find that there
are few welding personnel who can look at a weld transfer and know the difference
between globular, spray, short circuit and pulsed transfer.
If you were
one of those unfortunate companies that purchased either the Miller, Airco or
Lincoln pulsed power sources, the best thing you could have done was either sent
the equipment back or sued the power source manufacturer for selling you weld
equipment that negatively impacted your companies ability to produce consistent
weld quality.
.
.
.
MILLER ELECTRIC:
PROCESS IGNORANCE, EQUIPMENT ISSUES
DENIAL AND EXAGGERATED
PULSED WELD CLAIMS WERE GENERATED FOR APPROX. TWO DECADES.
THE
1980s. THE CANADIAN TECHNICAL COLLEGE AND THE MILLER PULSED WELDING FIASCO:In
the nineteen eighties, the largest community college in Vancouver, BC, was one
of the first locations in western Canada to purchase Miller's first pulsed power
source, the very costly Miller Pulstar.
The Miller Pulstar power source
cost the equivalent of four regular CV. MIG units. The college was exited about
it's so called high tech, weld equipment acquisition and it's trip into a new
weld technology.
A month after the pulsed weld equipment purchase, the
college realized it could not get the power source to do anything out of the ordinary.
At the time the college was finding a little pulsed reality, I was the Western
Canada weld training manager for Linde, (Union Carbide, Praxair, ESAB, what ever).
As Miller had not been able to provide for the college weld instructors, any weld
benefits from their pulsed power source, the community college asked if I could
come to Vancouver and show the weld instructors how to set the pulsed equipment
for all position welds.
In this time period, an exaggerated claim made by the global pulsed weld
equipment manufacturers for the justification of the costly pulsed equipment,
was in contrast to traditional CV MIG equipment,
the pulsed equipment was supposed to be able to produce acceptable "vertical
up" pulsed MIG welds on carbon / stainless steels.
With
the Miller Pulstar, I decided to set the process for a vertical up pulsed MIG
fillet weld. To attain the pulsed vert up fillet, I set the Miller power source
at every possible pulsed frequency, wire feed, and weld voltage combination. The
bottom line, it was impossible to produce an acceptable, simple vertical up ,1/4
(6 mm) pulsed MIG fillet weld, with the costly Miller Pulstar.
2008: Note:
Talk about premature product introduction. It took Miller another 20 plus years
before Miller made pulsed equipment suited to weld that vertical up fillet weld
and the ironic point is, pulsed MIG in 2008, when used for all position welds,
is inferior to the gas shielded flux cored wires used with low cost CV equipment...
With
this Miller pulsed equipment
Miller could have made this claim.
USE
THE MILLER PULSED EQUIPMENT AND
INCREASE YOUR WELD LABOR AND WELD EQUIPMENT
COSTS.
When
using the Miller Pulstar and welding with the pulsed mode in the flat and horizontal
weld positions, numerous companies that purchased this costly equipment were not
aware of the cost consequences of the erratic pulsed transfer or of the "low
recommended pulsed wire feed rates" they had to use.
<2006.
IF WELD SHOPS HAD MORE AWARENESS OF THEIR WIRE FEED AND WELD DEPOSITION RELATIONSHIPS
FOR THE COMMON WELD APPLICATIONS, THEY WOULD THINK TWICE BEFORE PURCHASING THAT
PULSED EQUIPMENT.
<
2006: Many companies using recommended pulsed parameters
found when
welding in the flat or horizontal weld positions, that the optimum, pulsed parameters
resulted in wire feed rates that were twenty to forty percent
lower than the wire feed rates they could have attained from the traditional
lower cost MIG equipment and using the traditional spray transfer mode.
THIS
MILLER BEAUTY MADE ME A LOT OF MONEY:
For many years after the introduction of the useless Miller
Pulstar, I traveled across North America visiting weld shops and switching
the useless pulsed mode off. With a little process
training I brought the unfortunate pulsed customers back to spray transfer
that enabled the weld shops to best utilize that costly Miller MIG equipment.
Come to think about it, I don't believe I ever recieved a thank you card from
Miller for this service.
Out of the frying pan into the fire.
.
After
the Miller Pulstar Fiasco, along
came the Miller "Maxtron"
For
the first time in its history Miller was embarrassed by its MIG
weld equipment and the Miller Pulstar had to be put down. The next pulsed package
from Miller was the infamous, electronic "Maxtron". I liked to call
it Mad Max.
I believe that the Maxtron's
claim to fame, was apart from the utilization of more electronics, this
power source made
a
lot of money for weld equipment repair shops, especially
those repair shops who liked the novelty of CHARGING A PREMIUM for working on
new, clean, weld equipment failures.
The Miller Maxtron power source and all other pulsed equipment
in this time frame, made weld equipment repair shops wake up to the fact that
they had better get their weld equipment repair employees better trained on dealing
with circuit board failures. These companies also realized that fixing the new
electronic MIG equipment was going to be a very lucrative business.
Remember before the introduction of faulty pulsed equipment, Miller had
a reputation as one of the world's most reliable MIG weld equipment manufactures.
If you had purchased a Miller Maxtron and it was not in the repair shop, you would
have learnt with use, that the poor quality of the preprogrammed pulsed weld data
in the weld schedules, was in reality an indication of the lack of weld process
knowledge of the responsible Miller personnel who designed and developed the Maxtron.
Constant voltage power sources have traditionally lasted ten to twenty
years. In contrast, the Maxtron as mentioned often had electronic issues ten to
twenty weeks after it was delivered. Like it's predecessor, Miller decided that
Mad Max should be put to sleep and painfully withdrawn from the market.
The
Maxtron was replaced with a third pulsed attempt from Miller, a power source called
the "Invision". From my perspective, it was a vision without a future.
The
Inconsistent Invision was another Miller power source that came to welding shops
before it was ready. This was a power source many weld shops paid a steep price
for the automated, inconsistent pulsed weld performance.
1980s
to 2005. It was obvious that the global pulsed equipment manufacturers were having
a difficult time trying to identify practical, cost effective weld benefits for
none pipe, carbon steel pulsed applications.
2005:
It's still evident that many of the engineers who design pulsed welding equipment
understand little about arc physics, weld requirements, weld process comparisons
and weld process application considerations. However
as mentioned in the equipment section after two decades one or two companies are
showing some progress with their pulsed MIG equipment.
Feb
2004. Location. A message from The Miller Electric web site. The Miller product
manager describes the new Miller Acupulse and makes the following statements.
" Miller pulsed equipment developed during the last decade was limited to
the electronics that were available and cost effective at the time". As part
of their process control feedback loop, the pulsed MIG equipment would sample
the voltage value once per period, (a period being one cycle of peak and background
current, one weld drop). If a short circuit occurs of the drop, the detection
may not happen for nearly a full period. During that time, the wire electrode
becomes buried in the puddle and takes a fair amount of current to clear. To clear
the short circuit and restart the arc, an increased current level is used. This
current tends to "punch" the puddle and cause excessive weld puddle
agitation, adding to both arc instability and weld spatter.
.
Note
from Ed: It's nice in 2004 for Miller to finally admit about "one" their
many pulsed electronic problems, especially after almost two decades of selling
"arc instability." If the Miller pulsed equipment was known to not work
correctly, (I seemed to be the only one complaining about it for those decades)
why was it sold to welding shops? Why was the faulty pulsed equipment not recalled?
Why was it that the companies who purchased this faulty equipment and had extensive
weld issues, did not sue Miller for their quality issues or lost weld production?
BIG
TROUBLE FROM BIG
RED.
If
you want to make your weld life more expensive, more complex and less meaningful
than it needs to be you could listen to the Lincoln reps, then purchase the pulsed
MIG, Lincoln PowerWave:
.
ED.
WE JUST NEED TO PULSED MIG WELD A MILLION AXLES EACH YEAR:
<1999:
My weld task appeared simple. A a tier one, axle manufacture located in Michigan
ordered two robot systems to weld truck axles. The company I worked for supplied
the robots, we were also responsible for setting up the robot cells that would
provide one million axles annually. When the robot cells were complete, we were
required to provide approx. 5000 welded axles as part of the robot cell run off.
The axle manufacture had previously utilized the traditional Lincoln CV.
400 to 600 amp MIG units. This equipment using the spray transfer mode had never
created any serious weld quality or productivity issues. A weld engineer at the
axle manufacturer who listened to Lincoln's advice was responsible for the selection
of the Lincoln pulsed Power Wave weld equipment. The carbon steel, MIG wire selected
by the axle manufacturer was 0.052 (1.4mm).
Two factors were critical
for the axle pulsed weld project:
[1] The axle fillet weld sizes must
never be smaller than a 1/4 (6mm).
[2]
As the annual axle production was a million plus units, every second used on the
robot weld cycle time was considered critical.
TRADITIONAL
WELDING METHOD: The axle manufacture had produced
axles for decades. With the regular MIG CV equipment. The axles were welded with
an 0.052 (1.4mm) MIG wire and an argon CO2 mix. The CV equipment used spray transfer
to weld the 1/4 (6mm) fillet welds at typical robot weld travel speeds of 20 to
22 in./min. My first objective with the Lincoln PowerWave and pulsed mode and
the 0.052 wire, was to try to attain the same travel (production) rates as that
previously attained.
PULSED
AND DEPOSITION RATES: When setting the Lincoln pulsed PowerWave weld data,
to attain the desired weld speeds, I had to set the 0.052 (1.4mm) pulsed wire
feed rate at approx. 420 in./min. This wire feed
rate is considered the high end of traditional spray transfer for an 0.052 wire.
Using
regular MIG spray transfer and traditional CV MIG equipment, a MIG wire feed rate
of 420 inch/min was used with the 0.052 (1.4 mm)
carbon steel MIG wires. This procedure had been used by the axle manufacture successfully
for many years.
This traditional CV weld equipment, sells in the USA
for $3000 to $4000. This equipment was very durable and successful and had hardly
changed in more than four decades.
.
The Lincoln PowerWave
Dilemma
It
was evident when I was setting the Lincoln Power Wave, that the pulsed equipment
did not respond well to the 0.052 wire and the 420 in./min wire feed settings.
The resulting high energy, pulsed arc plasma was both "narrow and intense"
resulting in a weld arc plasma that caused a "deep
penetrating (digging) effect" on the axle welds.
The
first big news that came from the high Powe Wave pulsed settings, was with the
robot weld travel rates attained. At a weld speeds of 20-22 inch/min, I ended
up with an external fillet weld profile that measured only 3/16 (4.8mm). When
the 3/16 fillet weld was cut and a macro evaluation of the internal weld profile
provided, it revealed that the intense, narrow pulsed plasma had caused the weld
to penetrate almost threes times greater than traditional MIG spray penetration,
so you end up with a smaller, visible weld profile.
To get the deep penetrating,
undersize fillet weld to an acceptable 1/4 fillet weld size, the robot, pulsed
weld travel rate would have to be reduced to a travel rate of 15
- 17 in./min. This 25% reduction in weld travel rate would have a huge
impact on the axle weld cycle time, remember every second lost was multiplied
by a million axles. I went through all the possible external Power Wave pulsed
parameter adjustments, however I could not change the intensity or the profile
of the pulsed MIG weld plasma at the 420 inch/min wire feed rates we had to use.
I reluctantly contacted Lincoln. The reason I was reluctant to contact Lincoln
was simple, a life time of dealing with Lincoln had provided me with thick skin,
an allergy to BS and an attitude of little expectations. I was not disappointed.
Lincoln
with its reputation on the line,
flew in one of their brighter weld engineers. The engineer arrived with his laptop
in tow. Its a sad state of affairs when to fix a weld someone believes they need
a computer.
I
demonstrated to the Lincoln engineer how at the required 420 inch/min wire feed
rate, the resulting pulsed plasma from the PowerWave was "too narrow and
too intense" for the thick wall steel axle application. The Lincoln young
engineer, who by the way looked like he was just out of high school, smiled and
assured this old fart that one of the prime features of the PowerWave was that
with the assistance of his unique lap top software, he could change the power
source wave forms to suit the application. I smiled back at him, and said "good
luck son".
To perform the test welds for the
Lincoln rep, I provided the engineer with a long piece of 3/8 (9 mm) carbon steel
plate. I had the plate surface ground. I let the engineer know that when his power
source could place a robot butt weld on the surface of this 3/8 plate using the
0.052 wire without providing an unacceptable digging crater and undercut effect,
then his work was done.
Two
days later, his over worked lap top had provided every possible combination of
pulsed weld parameters and wave forms. With the 0.052 wire feed rate set at 420
ipm, the high energy, digging pulsed arc plasma still remained narrow and too
intense for the axle application.
The red faced
Lincoln rep was frustrated with his red power
source. No longer smiling, he packed his computer
and left. He did promise make a Hollywood promise that "his people"
would look into the situation and get back to us. Over the years, when dealing
with Lincoln welding issues I had heard this "will get back to you, canned
response promise" many times. Of course his people never got back to us.
Lets face it, a duck is always a duck and a bull is always a bull.
I had
hoped while trying to set those pulsed welds, that the young
Lincoln
engineer had absorbed a weld fact that I had known while he was still in his mothers
womb. Pulsed
welding equipment may offer millions of wave forms, however as with all weld transfer
modes the pulsed mode provides a limited optimum weld parameter range for a specific
wire diameter.
The pulsed weld parameter range has both wire feed and
peak frequency / peak current limitations. For a given wire diameter the resulting
average weld current attained from the peak and back ground current cannot typically
exceed the maximum current utilized for traditional spray transfer.
Fundamental arc physics: Irrespective of the potential wave form configurations
from a power source, there are only so many electrons that can be squeezed into
a MIG wire and across an arc. Also to attain optimum weld fusion on a specific
steel thickness, the weld wire size and wire feed rate must provide a specific
voltage, current and weld travel rate.This is of course a fundamental weld fact,
however the wave form ~~~ crowd ~~~ often will place more faith in wave forms
than they do with weld logic.
.
No
Wave Forms, just a Perfect Weld
from Low Cost, CV, MIG Equipment.
With
the MIG CV spray process, a stable, optimum, cone shaped weld plasma is produced.
The cone shaped plasma provides wide, consistent coverage of the weld area.
When
using pulsed MIG and large diameter MIG wires
like 0.052, (1.4mm) and the requirement is high wire feed rates > 400 inch/min,
you will be achieving deposition rates > 14 lb/hr. When using this data its
likely you will be welding on steels > 8 mm. For this application a typical
spray weld current range of 380- 450 amps would be required. With the pulsed mode,
a very high peak current and pulsed frequency is required to provide sufficient
energy for the high deposition weld. The resulting high peak pulsed parameters
will result in a narrow, concentrated energy, agitated pulsed plasma. This plasma
may have more in common with a plasma cutting arc than it does with a controlled
MIG welding arc.
 THE
LINCOLN ENGINEER LEFT US WITH A PULSED MIG WAVE FORM THAT CREATED AN ARC AND PLASMA
THAT HAD MORE IN COMMON WITH THE PLASMA CUTTING PROCESS, THAN THAT WITH A CONTROLLED
MIG WELDING
ARC.
|
As
the down cast Lincoln engineer walked towards the plant exit with his lap top
looking less important, I who have little patience for the universal, sales induced,
bovine fecal weld matter that daily saturates this industry, and being a pragmatic,
thick skinned Manchurian, (means born in Manchester. UK) decided to pour a little
salt on his wounds.
I
asked the Lincoln rep, "don't you think it's a little ridiculous that at
the end of the day, your costly Power Wave provides inferior weld results than
your traditional DC 400 amp MIG power source that cost a third of the price? The
Lincoln rep did not reply to my question, he just shrugged his sagging shoulders
as he left the building.
SOME REAL WORLD WELD BENEFITS FOR THE 1 MILLION
A YEAR AXLE APPLICATION: The
lower cost, traditional Lincoln CV. DC. 400 amp power source, or a Miller Delta
Weld power source used on this axle application would produce spray transfer welds
with superior weld fusion profiles, less weld quality issues and 20% faster weld
speeds.
.
THE
LINCOLN POWER WAVE SAGA CONTINUED WHEN WELD CRACKS OCCURRED
IN THE AXLE WELDS.
After
the Lincoln rep left we went back to using a lower pulsed setting for the 1/4
(6 mm) fillet welds. A few axles were then pulsed welded with the Power Wave at
the low robot weld travel rates of 17 ipm.
Attention was now focussed
on the Ford weld specification for the truck axles. The weld spec required a "macro
examination" of a specific amount of axle fillet welds. A measurement of
the internal fillet weld cross section was required to ensure the minimum weld
throat dimensions were being attained.
In
evaluating the Lincoln Power Wave weld cross sections from the axle pulsed welds.
I noticed even at the lower pulsed settings the penetration was still deep and
narrow and "center weld hot cracks" had
occurred in more than 20 % of the axle weld samples
we tested.
.
Due
to the narrow, pulsed deep weld penetration profiles and restrained high
tensile
steel weld joints, we were getting classic "hot cracks" in the axle
welds.
.
As
we had minimal weld test equipment at the robot company, I had the University
of Colorado metallurgy department verify that the axle weld cracks did result
from the poor pulsed weld profile. They provided written
confirmation.
The center weld cracks
were not a surprise from the Lincoln Power Wave pulsed welds as I had previously
complained to the axle company management about the poor pulsed weld depth to
width ratios and predicted the weld cracking issue.
Before we produced
any more axles I notified my management, who then notified the axle manufacture
management of the pulsed production and weld crack issues. We informed American
Axle that the use of the Lincoln Power Wave pulsed mode would result in deep,
narrow weld fusion, and this poor weld profile combined with the high strength
steels and restrained weld joints was a classic set up for potential hot center
cracks. At this time I requested to call a hold on the project.
The
robot project manager and I flew to Michigan where we had a meeting with the American
Axle corporate management and the responsible engineers. I explained to these
personnel that their choice of the Lincoln Pulsed PowerWave, and the pulsed weld
parameters utilized were creating weld cracks and reducing the axle cycle times
by approx. 25% . I explained that if they complained about the Power Wave weld
equipment to Lincoln, I believed Lincoln would have no choice but to exchange
the four Power Wave power sources for their conventional CV. MIG equipment. If
the axle company would make the power source change we could get the desired weld
cycle times and eliminate future potential weld crack issues and reduce future
liability concerns for axle failures. The axle company management thanked us for
the data and said they would consider the matter.
WITH
MOST ROBOT MIG AND RESISTANCE WELD PROBLEMS, IT'S THE HUMAN ELEMENT THAT'S TYPICALLY
THE CAUSE OF MOST WELD ISSUES.
The
bottom line: This axle company employed a weld engineer who lacked weld process
expertise. He was no different from many of Detroit's engineers who when requiring
weld answers, seek out a Lincoln or Miller sales rep. This engineer was now in
a difficult position as he did not want to loose face in front of his management.
The Axle company management decided to let the decision stay with their
incompetent weld engineer. The engineer would not back down from his Lincoln,
Power Wave equipment selection and after we left, he convinced his managers that
irrespective of the technical facts and weld crack samples presented, that he
had made the right weld equipment choice. The weld equipment decision was made.
American Axle stuck with the PowerWaves.
Meanwhile as the axle company could not take immediate delivery of the robots.
The robot company I worked for was asked to weld a great number of axles. During
this manufacturing period I noted the center weld cracks continued. I left the
robot company a short time later.
In 2007 I believe the axles welds to this day are still made with this equipment.
American Axle switched the PowerWave pulsed mode off. Maybe
the Detroit best selling trucks will die of rust before the axle weld cracks can
propagate to failure. Maybe
the PowerWave was eventually used with lower pulsed settings that don't cause
cracks.
No one I discussed this with seemed
to want to take this issue to a higher level, however I happen to be a catholic
with a conscience. I sent a registered letter to one of Ford's lawyers in Detroit.
In the letter I spelt out my concerns with the axle weld cracks on their trucks.
The lawyer or Ford never replied.
Could
it be that Ford did not get to hear, or did not want to hear about it's axle weld
issues. Is it possible that Ford would rather wait to see how many axles fail
on it's trucks and how many life's are lost before it decides what action has
to be taken.
There
is this weld reality. Many of America's best selling > 1998 trucks will have
axle cracks that were caused by management that would not take responsibility
for its manufacturing weld problems.
WITH ALL
ENGINEERING DECISIONS IT PAYS TO BE OPEN MINDED,
IT ALSO PAYS TO KNOW THE
PROCESSES YOU CONTROL.
ONE DAY SOON I WILL WRITE MY LAST BOOK TITLED,
"IMAGINE
A WELD SHOP THAT RUNS
WITHOUT THE INFLUENCE OF SALESMEN"
I
always try to keep an open mind when evaluating new MIG welding equipment even
when its made by Lincoln. When I examine a new MIG power source I look for the
following three factors. 
WITH
THE DAILY, COMMON, POOR WELD PROCESS DECISIONS SOMEONE HAS TO PAY THE PRICE:
Both
the 
Spray
can weld in the flat, horizontal and vertical down weld position on steels <
3/16, (< 4.8 mm). Over 3/16 spray can be used on flat, horizontal and specific
overhead applications. 
power
source that Fred the local welding salesmen is promoting. The following is what
I have to consider.
