Archives For Arc Welding


RealWeld iconIn breaking news, Cleveland-based 
Lincoln Electric Holdings Inc. has acquired the assets and intellectual property of RealWeld, the EWI spinout company that pioneered the first live-arc training system for welders, the RealWeld Trainer.

To learn the full story, click here or read this message from RealWeld Launch CEO Bill Forquer.

 

 

 

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WELDEREWI will again host its five-day Fundamentals of Welding Engineering course at its Columbus, OH, headquarters, November 10-14, 2014.

Taught by top-notch EWI engineers, this class provides engineers and technicians with an overview of the various aspects of welding technology including welding processes, welding metallurgy and weldability, welding design and testing (including mechanical testing and NDT), and qualifications and procedure review.

“This course provides an excellent mix of classroom and laboratory training with the lab portion enhanced by EWI’s world-class welding facility,” says Dr. Doug Fairchild, Sr. Metallurgical and Welding Consultant with ExxonMobil Upstream Research Company. “We have found it particularly useful for engineers who were not originally educated as welding engineers.”

Registration is limited to ensure all attendees will have the opportunity to interact directly with instructors. For more details or to register, please click here.

Fabtech focus groups 2014EWI will be chairing two special focus groups at FABTECH 2014 in Atlanta, GA, November 10-13. The sessions, geared toward manufacturing industry leaders and stakeholders, will be conducted as part of the NIST AMTech initiative to develop the first comprehensive national technology roadmaps for materials joining and forming technology.

Admission to the focus group meetings is by invitation only. If you are interested in participating in either group, please contact the session leader directly:

Materials Joining Focus Group, Monday 11/10 (pre-show)
Group Leader: Tom McGaughy, Director of Technology (tmcgaughy@ewi.org)

Forming Center Technology Focus Group, Thursday 11/13
Group Leader: Hyunok Kim, EWI Forming Center Technical Director (hkim@ewi.org)

Who Let the Frogs Out?

Marc Purslow —  October 13, 2014 — 1 Comment
Suhas Frogman

AMS Frog installed in TTCI’s test track

I recently rode my bicycle across America and saw a whole bunch of craziness: A hurricane in Maine, hail storms in the Arizona desert, a haboob in the California sand dunes, and hundreds of giant frogs…giant steel frogs…more specifically, giant battered austenitic manganese-steel frogs!

No, I didn’t lose my mind cycling for 43 days alone. I’m talking about a type of special trackwork used by railroads which allows track to converge, diverge, or cross. These components take a serious beating on a daily basis, and must be repaired due to wear, fatigue cracks, or when the train’s wheels simply rip a chunk of damaged material out as they make a transition (a.k.a. a “breakout”). It turns out that these battered frogs require the most maintenance of any track component and are unsurprisingly the most expensive to keep in good working order.

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Typical AMS “breakout” defect in need of repair

Here’s the kicker – While austenitic manganese steel (AMS) has some great qualities (high toughness and great work-hardenability), it’s a bit tricky to weld. Unlike typical rail steels,  AMS does not respond well to high preheat and interpass temperatures. When this material gets too hot carbide precipitation occurs and it loses much of the toughness that makes it so attractive for this application. As such, the temperature of the base material must be kept unusually low. This impacts productivity negatively, making it difficult for repairs to be completed properly within the time allotted. In addition, since repairs are currently made with manually applied shielded metal arc welding (SMAW) and flux cored arc welding (FCAW), adherence to strict interpass temperature limitations is up to the individual welder and can’t be easily controlled.

EWI has conducted a project sponsored by the Federal Railroad Administration to develop a better method of repairing these components. Through a partnership with the Transportation Technology Center, Inc., and with guidance from the CSX corporation, EWI successfully used automated FCAW to achieve impressive results. Laboratory testing has revealed that EWI’s automated FCAW frog repair process results in a significant improvement in weld quality, reduced interpass temperatures, and increased productivity. The real proof is in the performance of these welds during in-track testing at Transportation Technology, Inc. (TTCI).

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AMS frog repaired using EWI’s automated FCAW process

The life of rail components is measured in million gross tons, or MGTs. When an AMS frog is new, it will typically last between 55 and 60 MGTs before repair is required. Once a repair is performed this number drops to between 30 and 35 MGTs, provided that proper repair procedures are followed. A frog repaired with EWI’s automated FCAW process is currently being tested by TTCI and has accumulated over 90 MGTs to date. This is nearly triple the typical life of a repaired AMS frog and 50% more MGTs than a new frog, and testing hasn’t ended yet.

If you’re stomach turns at the thought of a battered frog, give Marc Purslow a call at 614.688.5150 or email him at mpurslow@ewi.org.

 

My Dad the Toothpick Ninja

Marc Purslow —  September 24, 2014 — 1 Comment

Toothpic EWIKnowledge is funny. Once you know something, it seems so obvious. I once had a door in my house that would barely scrape against the floor. I asked my father to give me a hand with it, expecting that we’d need to shave some material off of the bottom to give the clearance needed. I owned no such tools, so that when my father showed up empty-handed I was baffled. He said, “Let’s go to the grocery store, we can get what we need there.” My father emerged with only a box of toothpicks. When we arrived home, he removed the door and the hinges, placed a toothpick in each screw hole, and broke off the ends flush. He then reattached the hinges and replaced the door, the toothpicks offsetting the position of the door upward just enough to eliminate the scraping. As he triumphantly opened and closed the now quiet door he smiled. “Son,” he said, “Sometimes you just need a shim.”

I’ve worked at EWI for nearly nine years. This is a special place. Special because of the variety of individuals, the collective breadth of knowledge under one umbrella, and the knowledge that if it can be done, we can do it (and if it “can’t be done” we can probably do it anyway!). Rarely are we faced with a “normal” task, because our customers are often readily capable of solving such problems. More often we are faced with things that have never been done, or have never been done so quickly. We are confident in our ability to meet these challenges because of the knowledge gained from our collective vast and varied experiences. With specialists in every welding technology on the planet, machining, forming, design, modeling, metallurgy, and failure analysis (to name a few), EWI is a truly unique and valuable resource to customers across many industries.

We don’t do a whole lot of door shimming at EWI, but the story about my father demonstrates an important concept: When you need to solve a problem and you ask someone who has experience and is willing to share their knowledge with you, you get smarter and your life becomes a whole lot easier. This is true within EWI and equally true for our customers. We often tell our members that they should think of EWI as an extension of their staff, as a massive resource at their fingertips. Maybe we should tell them to think of us as their carpenter father who knows how to fix a door in five minutes with a $0.99 box of toothpicks. By benefitting from our breadth of experience, our customers can free themselves up to focus on the things that will help grow their businesses and reach new levels of success.

Ninja!

Sheet Metal Welding Conference XVI, sponsored by the American Welding Society – Detroit Section in cooperation with EWI and the Advanced Laser Applications Workshop (ALAW), will be held in Livonia, Michigan, October 22-24. EWI Technology Leader Jerry Gould is co-chair for this year’s technical program, and Technology Leader Ian Harris is chairing a session titled “Arc Welding: Lightweight Materials.”

EWI Associates George Ritter, Warren Peterson, and Jerry Gould will also be making presentations during the 3-day conference.

SMWC XVI is an excellent opportunity to get up-to-date on the most recent technical breakthroughs in nearly every aspect of sheet metal joining. The biennial conference includes information of importance to anyone welding sheet metal plus access to the leading technical and equipment experts.

For program and registration information, click here.

Reciprocating wire feed gas metal arc welding (RWF-GMAW) is a low heat input, precisely controlled variation of the GMAW process.  With the RWF-GMAW process the wire is reciprocated in and out of the weld pool.  The wire motion is synchronized with the current waveform to produce a weld that is characterized as having minimal if any spatter, and very controlled heat input, bead placement, and base metal dilution.  Manufacturers of RWF-GMAW equipment include Jetline Engineering (Controlled Short Circuit (CSC)), Fronius (Cold Metal Transfer (CMT)), SKS Systems (micro-Mig), and Panasonic (Active Wire Process (AWP)).  The purpose of this article is to describe the reciprocating wire feed gas metal arc welding (RWF-GMAW) process and to provide examples of applications where this variation of the GMAW process may be advantageous.

The gas metal arc welding (GMAW) process is a fusion welding process that produces coalescence of metal using the heat from an arc between a continuously fed consumable electrode wire and the base metal.  An illustration of the GMAW process is shown in Figure 1.  Electrical contact is made to the consumable electrode wire at the contact tip.  A stream of shielding gas is fed through the nozzle and displaces the atmosphere in the vicinity of the arc and the weld pool.  In addition to preventing atmospheric contamination of the weld pool and the heated consumable electrode wire, the shielding gas also provides the medium for current flow (i.e. the arc).

Figure 1 Illustration of the GMAW Process

Figure 1.  Illustration of the GMAW process

For conventional GMAW there are four primary modes of metal transfer: short-circuit transfer, globular transfer, spray transfer, and pulse spray transfer.  Short-circuit transfer has historically been the GMAW mode used for applications requiring low heat input, low distortion, and/or small weld size.  With the short-circuit mode the current level is not sufficient to maintain an arc or to enable transfer of droplets across the arc.  The droplet forms on the end of the wire and is transferred to the weld pool when the wire with molten droplet come into contact with the weld pool.  When the wire with molten droplet comes into contact with the weld pool, an electrical short is created and the current spikes.  The combination of surface tension forces and the magnetic pinch force created by the current spike cause the droplet to transfer to the weld pool and the arc is reestablished.  This process repeats itself about 100 times per second.  The short-circuit mode can be used to produce relatively low heat input welds, with lower distortion levels than that achievable with other GMAW modes.  The process uses conventional GMAW equipment and has a limited number of controls, making it very user friendly.  However, because of the violent nature of the short-circuiting event, the process mode is characterized as having high spatter levels.  The short-circuit mode also has a tendency for incomplete fusion discontinuities when welding thicker materials and is not allowed by several codes.

Figure 2 HSV image of a short circuit transfer weld made with conventional GMAW equipment

Figure 2.  High speed video image of a short-circuit transfer weld made with conventional GMAW equipment

Several manufacturers have advanced versions of the short-circuit mode that enable more controlled droplet transfer, more precise bead placement, and reduced spatter levels.  These advanced versions control the current waveform throughout the stages of the short circuit transfer cycle.  Specifically, when the wire with molten droplet is in contact with the weld pool, the current increase that occurs is controlled so that spatter resulting from the clearing of the short circuit is reduced.  These advanced short circuit transfer modes are deployed for many applications including those that have historically used short-circuit transfer GMAW but desire lower spatter levels, and root pass welding in the pipeline industry.  Both the conventional and advanced short circuit modes are most often deployed semi-automatically.  The advanced short circuit modes are insensitive to changes in the contact tip-to-work (CTWD) distance making them ideally suited for semi-automatic operation.

With RWF-GMAW the wire is reciprocated in and out of the weld pool in synchronization with the current waveform.  This process is an even more controlled variation of the GMAW process because of the synchronization between the wire feed and the current waveform.  Plots of wire feed speed, current, and voltage verses time for a weld made with Fronius’s CMT mode are shown in Figure 3, while high speed video images of a CMT weld are shown in Figure 4.  During the arcing phase a droplet is formed on the end of the wire.  The wire is retracted and then moved toward the weld pool.  The shorting phase begins when the wire and molten droplet come into contact with the weld pool.  The current first increases slightly, and then reduces to a minimum value.  The retraction of the wire, in combination with the surface tension forces cause the droplet to detach.  After the droplet detaches an arc is formed and the cycle repeats itself.  Similar wire feed speed, current, and voltage waveforms are expected for RWF-GMAW welds made with other manufacturer’s equipment.  With the RWF-GMAW process there is no current spike when the wire and molten droplet come into contact with the weld pool.  With both the conventional and advanced short circuit modes droplet transfer is achieved through the combination of the pinch force imposed by an increased current level and surface tension forces.  With the RWF-GMAW mode the current isn’t used to transfer the droplet, rather the droplet is transferred through the combination of surface tension forces and the mechanical retraction of the wire.

Figure 3 WFS, current, and voltage verses time for a weld made with the Fronius CMT system

Figure 3.  WFS, current, and voltage verses time for a weld made with a Fronius CMT system (numbers in parenthesis correspond to images shown in Figure 4)

Figure 4

Figure 4.  High speed images of a t-joint fillet weld made with a Fronius CMT system (image numbers correspond to the waveform location in Figure 3)

The RWF-GMAW process has very low spatter levels when setup correctly.  For many applications the RWF-GMAW process will produce no visually observable spatter.  The process is capable of heat input levels ranging from less than 1-kJ/in up to heat input levels approaching that of the GMAW-P mode.  WFS settings commonly range from 35-in/min up to several hundred inches per minute.  In addition to its low heat input and low spatter characteristics, the RWF-GMAW process is capable of producing low dilution levels and precise bead placement.  The RWF-GMAW process is more complex than the conventional and advanced short-circuit modes.  A given wire feed speed setting can have 11 or more parameters associated with it.  Many equipment manufacturer’s offer pre-canned programs that enable synergic control of the welding program.  These pre-canned programs can be used in the as-received condition, or the background parameters can be tailored for the specific application.  Modification of the background parameters is often required for difficult applications.  The RWF-GMAW process is most commonly applied as a mechanized or automated process rather than a semi-automatic process.  RWF-GMAW equipment is also more expensive than the equipment required for the conventional and advanced short-circuit modes.

Due to the added complexity and cost, the RWF-GMAW process is most often utilized for applications that warrant its positive attributes.  For the majority of the applications that EWI has applied this process for, the reasons for evaluating the RWF-GMAW process were due to one or more of the following process characteristics: 1) low heat input, 2) low and controlled base metal dilution, and/or 3) precise bead placement.

The RWF-GMAW process has been applied for automotive applications where it’s low spatter and low heat input characteristics result in less spatter and distortion.  The RWF-GMAW process was evaluated as an alternative to GTAW for titanium sheet metal applications because the RWF-GMAW process has adequate arc stability and spatter characteristics with much lower heat input and distortion levels.  EWI has also applied the RWF-GMAW process as an alternative to shielded metal arc welding (SMAW) for the fabrication of thick section weldments made from crack sensitive steels.  Procedures were developed for the RWF-GMAW process that produced welds that met the ASME Section IX qualification criteria while providing increased travel speed (and production rates) and crack-free heat affected zones.  EWI applied the RWF-GMAW process to the wheel to shaft joint illustrated on the left in Figure 5.  This application utilized a partial penetration, narrow joint configuration.  The weld was required to penetrate to the root of the joint, have complete sidewall fusion, withstand a torque of 1680-N/m, and due to an o-ring on the backside of the wheel, the maximum temperature on the backside of the wheel was limited to 100-deg C at any time.  EWI developed RWF-GMAW procedures that met these requirements.

Figure 5a Illustration of the wheel to shaft jointFigure 5b Macrograph from the wheel to shaft joint

Figure 5.  Illustration of the wheel to shaft weld joint (left) and a macrograph of the welded joint (right)

EWI has applied the RWF-GMAW process for numerous other applications that are proprietary to the project sponsors.  Many of these applications have involved non-ferrous high alloy materials that are sensitive to heat input and dilution and require precise bead placement with no spatter.  The RWF-GMAW process can produce welds with quality comparable to that of the GTAW process, at production rates characteristic of the GMAW process.  The ability to produce welds with low and controlled heat input has enabled this process to be successfully used to weld crack-sensitive materials.  The RWF-GMAW process should be considered for applications that require one or more of the following attributes: low and/or controlled heat input, low and/or controlled base metal dilution, precise bead placement, and spatter free welds.

For more information on the RWF-GMAW process, contact Nick Kapustka at 614-688-5175 or nkapustka@ewi.org

Marc on bike

If you are following EWI Associate Marc Purslow’s cross-country, solo bike trek to raise money for ASAS (After-School All Stars), you’ll know that he’s relentless in achieving his goal. Since he embarked on his journey from Maine on July 3rd, he has left New England, crossed New York State, and made his way through Ohio. For news about his adventures and challenges, be sure to follow his blog. To find out where Marc is at this very moment. click here.

Ride on, Marc — we’re proud of you!

EWI won the latest EWI-MDK Bike to Work Challenge by a score of 60 to 48. The Challenge started  Monday, June 2, 2014 and ended Friday, June 13, 2014.  The scoring was one point per day of commuting to work by bicycle during the work week, regardless of distance (you didn’t need to ride the full distance).  Tracking of rides was done on RideNet | Home.  Our challenger is a locally-based law firm, Home : Manley Deas Kochalski, LLC (employer of Blake McAllister’s sister and Jim Tighe’s sister-in-law).  Several of us from each team met for a Happy Hour last week to celebrate (or lick our wounds, as the case may be).

On a larger scale, Thursday, May 1 was the start of the National Bike Challenge.  This covers all types of riding and will continue until the end of September.  EWI has a team in this event.  Information can be found at Home | National | National Bike Challenge.

A bit of history:  The first Central Ohio Bike to Work Week was held in 2008.  Five EWI Associates participated that year and Team MDK won the 100 to 499 employee division.  I looked at the numbers and realized that we could have won if we doubled our score.  With a bit of a push in 2009, EWI had 17 riders and won our division. Team MDK was second. The photo below shows most of our team that year, including Jim Tighe holding our trophy.

2009 Bike to Work Week Victors

The third year of the local Bike to Work Challenge, Jim’s sister-in-law said in an email “You may also want to spread the word around your office that the bike to work week cheating that costs us our title last year will not be tolerated.  God sees all, and I’m going to give you the benefit of the doubt and believe that you had nothing to do with it.  Prepare to be schooled in the correct way to win.  Let me be your guide.”  With this extra motivation, we had 33 people (nearly 25% of our workforce) ride at least once and won our division a second time.  Team MDK was second. The end results were the same for the top two of our division in 2011, the last year of the local challenge.

EWI and MDK have held our own Bike to Work Challenge the past two years.  EWI has continued to prevail.  The power of innovation…

 

 

Marc Purslow is passionate about helping disadvantaged kids succeed. That’s why the EWI Applications Engineer (arc welding) is taking time this summer to raise money for After School All Stars, a program that provides free afternoon programs that keep at-risk children safe and help them achieve in school and life.

Marc and kids

But if you know Marc, you know he doesn’t do things half-way. He’s made a commitment to ride his bicycle solo across the country to raise $50,000 for the ASAS program! Marc starts his journey in coastal Maine on July 3rd, and plans to end in San Francisco some 4-5 weeks later.

We at EWI are incredibly proud of Marc, and are thrilled to support his ASAS Cycle America Challenge. We’ll be keeping up with his adventures and reporting on his cross-country progress throughout the summer. If you want to “join the ride,” you can check “Latest News” at ewi.org, where we’ll post Marc’s regular reports from the road.

You can learn more about ASAS and support Marc’s goal, by clicking here. All donations from his ride will benefit ASAS Ohio.

Go, Marc!


Challenge map

Marc on bike