Archives For Steve Massey

Last week EWI had the first EWI ShipIt! Days. Employees were given 24-hours to do anything they wanted that wasn’t related to their regular job. The catch? You have to deliver something at the end of the 24-hours. This commercial about EWI is what my team delivered. Enjoy!!

 

 

If you are not familiar with the original Dollar Shave Club video, check it out.

We receive  many questions about the difference between soldering and brazing.  They are very similar joining techniques, both involving the melting of a filler metal to join two or more components without melting the base material of the components.  The American Welding Society (AWS) defines brazing as such a process which involves a filler metal which has a liquidus above 450°C (842°F).  Soldering, on the other hand, involves filler metals with a liquidus of  450°C or below.

The issue is further confused by the use of such terms as “silver solder.”  This is a misnomer, because silver-based alloys all melt well above 450°C and are therefore clearly brazing filler metals. The proper term for all alloys used for brazing, including silver-based alloys, is “brazing filler metals.”AWS has developed a designation system for brazing filler metals which uses the primary element(s) and a number for unique compositions of brazing filler metals.  All designations begin with a “B” for “brazing”.  The silver-based alloys are thus designated BAg-x, where x is a number corresponding to a certain alloy composition.  BAg-1 has a nominal composition of 45%Ag, 15%Cu, 16%Zn, 24%Cd.  BAg-34 contains nominally 38%Ag, 32%Cu, 28%Zn, 2%Sn.   Other brazing filler metal families include aluminum-silicon filler metals (BAlSi-x), magnesium filler metals (BMg-x), copper, copper-zinc and copper-phosphorus filler metals (BCu-x, RBCuZn-x, and BCuP-x, respectively), nickel and cobalt-based filler metals (BNi-x and BCo-x, respectively) and gold-based filler metals (BAu-x).  Titanium, palladium, platinum and other metals can also be used as brazing filler metals.  Brazing is used in numerous automotive applications, jet engines, cookware and utensils, and HVAC systems, to name a few.

Soldering, in addition to having a lower processing temperature, typically results in a lower-strength joint than a brazed joint.  For many applications, this is suitable and even desirable.  The shear strength of brazed joints typically exceeds that of soldered joints by a factor of five.  High heat input can damage sensitive electronics or small components.

laser brazing SiC

Figure: Laser brazing of silicon carbide (SiC)

Heat for either soldering or brazing can be applied in a number of ways; through flames, by resistive heating, by inductive heating, by use of a laser, by combustion and subsequent radiant heating, etc. Both soldering and brazing  can be done in open air (usually with a flux to reduce surface oxides and enable wetting and flow of the solder or braze filler metal) or in protective atmospheres (e.g. inert, vacuum, or active atmosphere).  Both techniques can be used to join many metals and metallic alloys, ceramics, and composite materials, to like and dissimilar materials.

So should you solder it or braze it?

The answer to that depends on many factors including the service loading and temperature, to name two.  Many substrates are damaged by the high temperatures required by brazing.  Wettability of the substrate by either the solder or brazing filler metal is another key consideration in selecting the appropriate process.  The ability to remove flux residue can be an important factor such as in certain HVAC and other fluid transport systems; closed loop systems which cannot be readily cleaned after joining must often be brazed or soldered in vacuum or under a protective atmosphere, or a self-fluxing filler metal such as the copper-phosphorus alloys (BCuP-x) in copper-based assemblies must be used.   Certain ‘no-clean fluxes’ leave minimal residue after joining, but hardened residues can create abrasive wear situations in tight clearance moving components, or can hydrolyze and create corrosive conditions.

If you would like assistance in selecting a suitable brazing or soldering process for your application please contact Kirk Cooper at kcooper@ewi.org .

Well folks, Movember is in the books for 2013 and we had a great month raising awareness and cold hard cash for men’s health issues. In our third year of participating in Movember, we set the fundraising goal pretty high at $5000. I say pretty high, because in the prior two years combined we had raised about $5100.

The team really stepped up to the challenge in the fund raising department. We had some of our usual strong fund raisers along with some new creative ways to raise money. The Project Management Office put on a multi-day bake sale in which your sweet tooth could be satisfied in exchange for a donation to the Movember cause. This bake sale raised a total of $293! Another event was the “Epic Stare” contest. Contestants submitted a photo of themselves sporting a Mo and an epic stare. Here was mine:

epic stare movember

Voters cast their votes in the form of cash donations for their photo of choice. This impromptu contest brought in about $65.

All told, we raised about $6600 this year, absolutely crushing our goal! I want to thank all of the Mo-bros and Mo-sistas that participated this year. I especially want to thank all of the folks that made donations.

Thank you very much!

Here is a shot with many of the EWI Movember participants. We have some dudes that can grow some pretty strong ‘staches in 30 days. We also have some that fall in to the “not so much” category, bit their heart is in the right place.

EWI movember 2013

 Bonus Content: Click this link to see my various Faces of Mo in random order.

This is a Technical Brief written by Dr. George Ritter, Principal Engineer in our Materials group. George can be contacted at 614.688.5199 or gritter@ewi.org. You can view George’s bio here. If you would like more information about EWI, please feel free to contact me, Steve Massey at 614.688.5000 or smassey@ewi.org. If you are interested in this article, you may also be interested in another article on lightweighting.

Composites as Structural Materials

Composites provide directed, purposeful stress management using strategic placement of reinforcing fibers, often combined with core materials to provide stiffness. Fiberglass reinforced composites have been used in marine and other extreme environments for decades. Carbon fiber reinforced composites offer the ultimate in strength-to-weight ratio and are now universal in aerospace and marine applications. Modern materials have tensile modulus equal to that for aluminum, half that for titanium, and one-third that for steels. Structural composites offer many advantages in weight savings, corrosion resistance, and design versatility.

Why Bond Composites to Metals?

Joining composites to metals often invokes mechanical fasteners, such as rivets or bolts. This requires hole drilling, which is expensive. The composite and metal thicknesses must be increased overall to accommodate the stress concentrations at the hole and fastener point loads, sacrificing weight advantage. The holes and fasteners invite corrosion problems along with the potential contact of the carbon reinforcements with the metal, inviting galvanic corrosion.

Bonded structures overcome many of these issues. First, the entire bonded contact surface participates in load management. The adhesive and primer combination isolates one surface from another which sharply reduces issues from galvanic interaction. Because the joining system provides more efficient load management, the thickness and weight of both materials can be reduced. And there are no holes to drill, align, or seal. The strength of a bonded composite system is typically limited by the ability of the composite itself.

approach

Engineered Bonded Systems

How Do I Design a Bonded System?

EWI offers comprehensive contract engineering services to develop bonded system solutions. We have worked with fiberglass-based, carbon-based, and cored-wall reinforced systems, including bonded applications to carbon steel, stainless steel, aluminum, and titanium. The EWI Adhesives team has experience with primers and corrosion control materials to develop the best combination of corrosion protection, bonding strength, and adhesive for the materials being combined. Drawing upon internal resources, EWI forms an engineering team to provide design, FEA, analysis, adhesives and primer selection, testing, and structural verification along with the program management to integrate our work with yours. This enables us to provide Engineered Bonded System solutions.

Teamed with your structural engineers, EWI develops a modeled joint design based on the demonstrated effectiveness of preferred shear joint and socket joint configurations.  This requires a 3D CAD drawing which is often supplied by the client design team. A custom experimental plan is developed with the client. Critical material properties are collected or measured at EWI and entered into the resulting FEA design.

 

cored wall in socket

Cored Wall in Socket or Clevis Shear Joint Configuration

Joint design and analysis begins based on nominal material and load values. The final design requires actual values for the proper combination of selected adhesive, primer, and surface preparation. Test specimens are built to measure effects of variables such as temperature, humidity exposure, corrosive environment exposure, bondline thickness or variability, and cure conditions. The model is first calibrated against control test specimens. Then the manufacturing and operating extreme conditions are introduced and their effects are predicted. Finally, calculated factors of safety (FOS) are developed to quantify structural redundancy in the design.

 verification of model

Modeled System at Ambient and Elevated Temperature, Verified Against Actual Specimens

 

 joint model 1 joint model 2

 Modeled Lap Shear and Cored Composite Structures Showing the Bond is Stronger than the Composite Itself – A Successful Design

Once the model is calibrated, performance predictions can be generated. After developing a test plan with the client, a full-scale demonstration article is produced for verification tests of the bonded system. EWI can produce the test articles or work with the client to produce them at their facility. EWI develops a construction crawler sequence document to begin the manufacturing transition. We can also provide training and onsite assistance.

Other Client Needs

Bonded structure offers an attractive package of load management and design efficiency. It also offers the opportunity to use the most efficient and intelligent combination of materials. How does the client know the system is functionally trustworthy?

 

nde scan

NDE Scan of Composite-Metal Interface Showing Implanted Defects

The design and modeling methodology is aimed at providing a design with the necessary factor of safety under all design load conditions. Normally, that range is FOS = 1.2 to 2, depending on the requirements. EWI also offers development of NDE techniques that address the complications of using multiple materials with an adhesive interlayer.

You can download a copy of this information here.

 About EWI

EWI is the largest North American organization dedicated to the advancement of materials joining technologies for manufacturing industry. With some 220 industrial members from all manufacturing sectors, EWI also provides joining technology development for the Department of Defense and Department of Energy. Our nearly 100 technical staff, many with advanced degrees, represent disciplines in welding engineering, materials science, mechanical engineering, modeling, NDE, and testing services. Onsite joining technologies include all welding methods, adhesives bonding, brazing, and soldering for metals, plastics, composites, and ceramics.

An area where EWI is expanding its knowledge is in characterizing and cataloging mechanical properties of additively manufactured metals (metals AM). The work described here was performed to obtain baseline mechanical property data for Ti 6-4 ELI weld metal buildups that were produced using hot-wire gas tungsten arc welding (GTAW-HW).

The equipment used to weld the buildup was a conventional GTAW-HW system. This work was not performed in a chamber, it was performed in open air with a trail shield added to the torch. The torch and trail shield gases used were both Argon.

jetlinetrail shield

The buildup deposited was 1.25″x7.0″x2.5″ high. The parameters used to produce the buildup were 340-amps with 260-inch/min wire feed speed. The wire used was 0.045″ diameter Ti6-4 ELI (Grade 23) wire. The buildup and the test sample locations are shown below.

buildupsample locations

The macro showed that there were no incomplete fusion or porosity type discontinuities in the sample deposit.

macro

Two tensile samples were tested from both the horizontal and vertical build direction. The test results were:

  • horizontal UTS – 137 and 133.4 ksi (125 ksi minimum required)
  • horizontal Yield strength – 124.5 and 116.1 ksi (115 ksi minimum required)
  • vertical UTS – 136.3 and 134.6 ksi
  • vertical Yield strength – 119.2 and 117.4 ksi

A chemical analysis was performed to determine if the sample could meet the following ELI requirements:

  • H – less than 0.0125%
  • N – less than 0.0301%
  • O – less than 0.13%

The sample easily met the ELI requirements with 0.0013%-H, 0.0078%-N, and 0.077%-O. (as measured using the LECO Furnace method)

Further work is required to evaluate this material in the stress relieved and beta annealed conditions.

If you are interested in learning more about additive manufacturing or the properties of materials being used in your additively manufactured parts, please feel free to contact me, Steve Massey, at 614.688.5000, or smassey@ewi.org.

You can also contact Ed Herderick at 614.688.5000, or by email at eherderi@ewi.org.

EWI hosted a welding merit badge clinic on Saturday 13 April for Boy Scouts in Columbus and the surrounding areas.  The welding merit badge is one of the newest in scouting. It is the 128th current merit badge and was released on Feb. 24, 2012.  The event was held at the EWI facility in Columbus and utilized the high bay lab in the OSU Welding Engineering side of the building. Twenty four scouts participated in the all-day event and all but one scout, who had to leave early, went home at the end of the day meeting all of the requirements to receive the merit badge.

welding_instructionwelding_instruction_2

After receiving initial safety instructions, the scouts were divided into four groups. Half of the scouts, assisted by Tim Moore, Steve Massey, Randy Dull, Doug Clark, and Aaron Shira, were given hands-on instruction on gas metal arc welding (GMAW).  Doug Clark also instructed the scouts on using the RealWeld trainer.  The other groups of scouts were instructed in welding processes (Warren Peterson), first aid and accident prevention (Rich Minshall), cutting processes (Seth Shira), and careers in welding (Dave Phillips of OSU WE dept.). These activities represent all of the skill areas required to qualify for the merit badge.   Following lunch, the groups switched so that everyone could have the opportunity to meet the requirements for the welding merit badge.

Everyone attending had a good time and came away with a better appreciation of welding – toward the end of the day, one scout even asked how expensive weld power supplies were and where he could go to buy his own welder!

RealWeld trainerdata acquisition

Besides letting the scouts try their hand at GMAW (making welds in both butt, lap, and  t-joint configurations), they also got a chance to try out the RealWeld trainer, see demonstrations of Drop Tower Testing, Oxyfuel Cutting, Plasma Cutting, Robotic Welding, Resistance Welding, Data Acquisition, and Metallurgical Examination.

flame cuttingmechanical testing

Thanks for all who helped with this successful event!!! We look forward to hosting it again!

We would like to thank the following volunteers for graciously taking the time to support this event:

  • Rich Minshall
  • Tim Moore
  • Paul Zelenak
  • Steve Massey
  • Angi Cox
  • Seth Shira
  • Aaron Shira
  • Steve Levesque
  • Randy Dull
  • Warren Peterson
  • Doug Clark (RealWeld)
  • Leah Kohr
  • Lynn Price
  • Rebecca Gurk
  • Dave Phillips (OSU-WE)
  • Mark Matson

We just finished celebrating National Engineer’s Week 2013 here at EWI. After all, our engineers are our products, and their knowledge and abilities are great reasons to celebrate. Our Staff Association did a great job of putting together a fun week of activities to celebrate our engineers. On Monday we had Chris Cakes come to serve breakfast to the staff. Basically, they provide a pancake and sausage breakfast with a little twist. The pancakes are placed on your plate by being thrown by the griddle meister.

chris cakes engineers week 2013

I’m not sure what’s going on here, but I’m pretty sure that this is the guy behind the griddle’s first time doing this.

chris cakes engineers week 2013-2

On Tuesday we had a paper airplane competition. The paper supplied to the competitors was a “modified” 8.5″ x 11″ piece of paper. One corner of the paper was cut off to challenge the competitors a little more. The competitors had 20 minutes to construct and test their plane and then fly them for the maximum distance. A very conventional looking plane took the top prize with a very impressive flight.

paper airplane competition 1

paper airplane contest 2

Wednesday was a geeky t-shirt contest. There were some really great entries for this. You really can’t get the full impact of the equalizer shirt from a still photo. This thing had a microphone pickup and would respond to sounds and indicate levels. It was pretty cool, even for an HR guy.

heavy metal shirt

geeky t-shirt contest 1

geeky t-shirt 2

geeky t-shirt contest 3

The finale for Engineer’s Week was a pinewood happy hour on Thursday. There were a lot of original entries in to the race. Some of my favorites were the snack wagon (sponsored by hutchbags), the better mouse trap, and the Crew car. We were fortunate to get a track on loan from an associate’s former Cub Scout pack.

pinewood derby snack wagon

pinewood derby cars

Can you guess which car in the picture below belongs to the CFO?

pinewood derby cars 2

pinewood derby track

The best in show vote was a tie between the Crew car and the better mouse trap:

 

pinewood derby best of show

These were the top four racers (note the cars of three arc welding types and one HR person):

pinewood derby top four

 

The three most common metal to metal joints in a lithium-ion battery pack are foil to tab, tab to tab, and tab to bus. All three joints pose joining challenges, but of the three, welding multiple layers of foil to a tab is the most challenging. The joint is often made up of dissimilar metals, the metal thickness is mismatched, and one side (the tab) is relatively thick (e.g. 0.2 mm) while the other is made up of multiple, extremely thin, layers. The image below shows a schematic of a large format lithium-ion battery pack cell.  The foil to tab weld is needed to gather all the current collector plates (foils) inside the cell and join them to a tab which exits the cell casing and allows the cell’s energy to be transferred to an external source. There are two foil to tab welds in each cell, and hundreds of cells in a typical lithium-ion battery pack. Because of the series and parallel connections, one failure in a foil to tab joint will compromise the output of the entire pack, therefore, a robust joining process is required.

 

lithium-ion cell

Ultrasonic metal welding (UMW) was evaluated for this particular application. A schematic of the process is shown below. Ultrasonic metal welding is very capable of welding similar and dissimilar combinations of battery related materials such as copper, aluminum, and nickel. Ultrasonic vibrations, typically 20 to 40 thousand Hertz, are used to rub two parts together under pressure. The scrubbing action breaks off oxide and contamination on the surface and breaks down surface asperities creating two ‘smooth’, clean metal surfaces. Once these contact under moderate heat and pressure, a weld is formed.

UMW process schematic

The process has several advantages. Since it is a solid state process, it can be adapted to dissimilar materials combinations and avoids most concerns about formation of intermetallic compounds. It is ideally suited to welding the highly conductive materials used in batteries including plated copper. It does not require high power and weld cycles are very short, fractions of a second. It also joins multiple layers of thin materials in one operation.

Both resistance spot welding (RSW) and laser beam welding (LBW) were also considered, but lack certain attributes that make UMW a more desirable joining process for the lithium-ion battery application. RSW relies on the resistance of a material to generate heat for joining. However, the aluminum and copper foils typically used in the battery industry have extremely low resistance, in addition, aluminum alloys form a tough surface oxide layer which inhibits RSW and is further compounded by the fact that the oxide layer is present on both sides of each foil layer. UMW does not rely on bulk resistance and inherently scrubs away oxide layers as part of the process. LBW is very sensitive to gaps between material layers in the weld joint. As a general rule of thumb, the gap should be less than 10% of the material thickness. Joining a 12 µm foil would require a 1.2 µm, or less, gap which is very difficult to achieve and requires excessive fixturing. Because UMW is self-clamping, gaps are not an issue.

UWM test sample

 

A typical large format lithium-ion cell uses copper foil as the anode current collector and aluminum as the cathode current collector; therefore, both copper and aluminum have been evaluated with the UMW process. The experimental joints, as shown in the image above, were limited to similar material stacks only, meaning aluminum foils were joined to aluminum tabs and copper foils to copper tabs. The tab thicknesses were held constant at 0.005-inch. Two foil thicknesses, 12 and 25 µm, and two foil stack heights, 20 and 60 layers, were evaluated to prove feasibility and to study the effects on joint properties as the foil thickness and number of foil layers varies.

Cross Section – 20 layers of thin copper

Cross Section – 60 layers of thick aluminum

Analysis of the above cross sections provided a closer look at foil compression, foil damage and the final state of the weld joint. The samples with thinner and fewer layers of foil show an increase in foil movement directly adjacent to the weld zone.  In contrast the samples with thicker and more foil layers  showed a consolidation of the foils adjacent to the weld zone often resulting in a larger bond region. The consolidation and increase in bond region occurred because the thicker foil stacks bottomed out on the weld tool causing compression in the area adjacent to the weld zone.

Conclusions:

Joining multiple layers of thin foils to a tab in a single ultrasonic metal weld operation is feasible. The welds are achievable without fracturing the delicate foil layers. Bonding occurs at the foil to tab interface as well as at each foil to foil interface which results in a strong, highly conductive electro-mechanical joint.

IR videography shows that all joints, with the exception of the copper sample made from 60 layers of 25 µm foil, stayed under 60 ºC during the weld cycle indicating the process will not harm nearby heat sensitive components.

If you would like further information on this topic, feel free to contact Mitch Matheny at 614.688.5000, or by email at mmatheny@ewi.org.

You can also contact me, Steve Massey, at 614.688.5000, or smassey@ewi.org.

 

More and more, robotic welding is becoming a viable option for use in heavy fabrication. The sophistication and capacity of modern robot systems is suitable for large structures which require multi-pass welds. Processes used for heavy fabrication such as preheating, gas metal arc welding (GMAW), flux cored arc welding (FCAW), tandem gas metal arc welding (T-GMAW), submerged arc welding (SAW) or flame cutting can all be deployed robotically. An example of a mult-pass weld that was made with a robot is shown below.

multi-pass robot weld

One of the challenges with automating heavy fabrications is the high mix low volume nature or this type of work. To maximize the production time of the robot, an off-line programming tool should be utilized. Off-line programming, or OLP, has matured to a point where it can be used without an operator touching up program points. An example of a virtual system used in an OLP software is shown below. To succeed with OLP in high mix low volume applications OLP should be used in conjunction with robotic options that search for the weld start location and track the joint while welding. Some systems are even capable of adaptively filling a weld joint that varies in volume along the length. EWI has significant experience in creating multi-bead multi-layer adaptive welding solutions for third party equipment platforms.

off line programming cell

When considering moving to automation from a manual or semi-automatic process it is important to consider many factors. The quality of the parts that will be feeding the robotic welding system are very important and will directly influence the level of productivity possible from the system. Consistent dimensions, part fit-up, and surface condition are important factors to control on the parts that feed the robot system.  When parts are more consistent, higher production rates can be achieved. Deciding whether you want to pre-tack parts, or use hard tooling is another consideration. Using a tack fixture and presenting a tacked part in a holding fixture to the robot can be more cost effective and allow more access for the robot to perform welding.

Probably one of the most important things to consider is the selection of the personnel that will be responsible for the robotic welding in your facility. The welding is by far the most difficult portion of applying automation to heavy fabrication, the robot and system portion are easy to deal with in comparison. I would much rather have someone that knows about welding learn how to teach and operate a robot than try to teach a CNC programmer about welding. The best welding robot programmers that I know are experienced welders or have a welding background.

If you would like to discuss the possibilities of using automation in your facility, please feel free to contact me at 614.688.5000 or smassey@ewi.org.

Thanks for your interest in EWI. If you liked this post, you may also like this article on high-speed welding of aluminum.

Gas metal arc welding (GMAW) and gas tungsten arc welding (GTAW) are both regularly used for welding aluminum. GTAW is a slow process when compared to GMAW and GMAW is typically used when extremely high weld quality (with respect to porosity) is not required. GMAW works well for welding aluminum in structural, automotive, or thick section multi-pass welding, but can reach a limit at over 40-inch/min travel speed.For welding thicker aluminum structures (0.25-inch or above) a higher productivity welding process may be desired.

Tandem-GMAW, which is traditionally applied to steel for higher productivity, can also successfully be applied to aluminum. Work has been performed at EWI to demonstrate fillet welds on 0.25-inch thick 6061 aluminum plates in t-joint and lap configurations. The electrodes used for these demonstrations were 3/64-inch diameter ER-5356 and the shielding gas was 100% Argon. Welding speeds of 60-inch/minute were achieved in both joint configurations. In both cases, the process was stable and minimal spatter was ejected from the weld pool. The stability of the process at 60-inch/min suggests that higher travel speeds could be possible.

Figure 1 shows the fillet weld in the t-joint configuration. Note the consistency of the weld toes. Figure 2 shows a macro of the same weld; which indicates ample fusion at the weld root.

tandem-gmaw aluminum t-joint

Figure 1.  0.25-inch fillet weld in t-joint at 60-inch/min travel speed

tandem-gmaw aluminum t-joint macro

Figure 2.  Macro of fillet weld in t-joint showing good fusion profile at the weld root

Figure 3 shows the fillet weld in the lap joint configuration, which also exhibits consistency at the weld toes. The fusion at the weld root for this weld, shown in Figure 4, is also ample.

tandem-gmaw aluminum lap joint

Figure 3.  Fillet weld in lap joint configuration

tandem-gmaw aluminum lap macro

Figure 4. Macro of fillet weld in lap joint showing good fusion profile at the weld root

If you are currently welding aluminum or other metals with GMAW and desire a productivity increase, tandem-GMAW may be an option for you. EWI has acquired expertise on many ways to apply tandem-GMAW and has an in-depth understanding of the interaction of the variables involved. To find out if tandem-GMAW is for you, or if you would like to speak to one of our experts on tandem-GMAW, please contact Adam Uziel at 614.688.5000 or auziel@ewi.org. You can also contact me, Steve Massey, at smassey@ewi.org.

Thanks for your interest in EWI.