Material selection for laser and EB welding – do’s and don’ts

One of the most important factors in a successful laser or electron beam (EB) welding project is choosing the right materials up front.  The right material can make the difference between a project that runs smoothly and gets delivered on time, and a project that takes longer, costs more, and causes a lot of aggravation. While we could probably write a book on this topic, here are a few do’s and don’ts to get started. 

DO check with us first to make sure the material you’re choosing can be easily welded.  This may seem obvious, but some customers ignore this at their peril.  As an example, many years ago I worked on a project involving parts going on the space station. The customer was so adamant about using a particular material that he ordered $80,000 worth of it… and then realized after purchasing and final machining that the material couldn’t be welded.  We eventually figured out how to make it work, but it took 10 times the effort and 10 times the cost.  The bottom line – make sure the designer and the welding engineer collaborate before making your final material choices.

DO pick good weldable alloys: 

  • Stainless steel is one of the most popular materials for laser and electron beam (EB) welding. But avoid stainless steels containing sulphur and phosphor. Their low melting points make them key culprits for cracking and porosity problems. Customers like 303 stainless because of its ease of machining, but the outcome with welding is not always ideal. Talk to your welding engineer BEFORE deciding on 303.

Stainless steels ending in F for free machining, such as 316 F and 430 F, should definitely be avoided.  Again, the sulphur and phosphor that are added to make them free machining are terrible for welding.  (We like to say the “F” stands for failure!) 

  • Low carbon stainless steels such as 304 L are also a good choice for laser welding and EB welding.

  • Aluminum alloys can also be laser and EB welded. Cleanliness is very important with aluminum, since oxidation can lead to weld failure. If you need a high strength alloy, certain aluminums are precipitation hardenable, which means they can be brought up to full strength after welding with heat treating. Some aluminums will require filler material.

  • Titanium is a popular material for many aerospace applications. Like aluminum, cleanliness is key for welding titanium. Titanium ranges from commercially pure grades to a number of titanium alloys containing things like tin with a low melting point. These titanium alloys are not unweldable, but you may need to incorporate certain joint designs in order to make them weldable.  Again… check with your welding engineer first.

DO preheat high carbon materials. The more carbon in steel, the harder it becomes to weld and the more prone it is to cracking. And I don’t mean little cracks – I mean big cracks with complete weld failure. To minimize the possibility of cracking, high carbon steels should be preheated prior to welding.

DON’T weld in the hardened condition (usually).  The success rate of welding hardened material is generally lower when compared with annealed material.  If possible, do your welding in the annealed condition and harden after welding.

Many factors go into choosing a material including cost, strength, design criteria, post-weld testing, etc.  But to repeat – make sure the material you’re considering is actually weldable BEFORE you make your final choice. 

Contact us at 860.653-0111 to discuss your next project.

Heat treating, before or after welding (or both)

 

I’ve blathered about heat, post-weld heat treatment, heat sinking, and blown a lot of hot air in general. Mostly, the discussion has focused on weld characteristics and weldability. This blog will take a slightly different angle.

Heat treating can be used for a variety of reasons: strengthening, annealing, stress relieving, and wear resistance to name a few. But, when is the best time to heat treat your welded part?

Generally, the answer is after all other operations are complete. But there are always exceptions.

If your material (say 17-4PH stainless) welds well in a hardened condition and the final assembly is quite large, it may make more sense to harden your subcomponents prior to welding and finish machining. That large assembly may require a larger oven, commanding a higher price.

Some of the 400 series stainless steels will tolerate being welding in the hardened condition with excellent strength characteristics retained.

Many grades of (weldable) aluminum do quite well when welded in the hardened condition. That large aluminum case fabrication may not fit into a chamber for heat treatment at all, and may not require any additional strengthening of the weld anyhow.

If you’re working with a material that is not readily weldable in the hardened condition, H13 steel for example, you will want to seriously consider machining and welding it in the annealed state, with the heat treat and temper as one of the last steps in the process. That will ensure that the characteristics of your part are homogeneous and free from defects.

You know I like to toss in a caveat or two into each of these posts, so here’s something to consider.

Just because heat treating beforehand yields a defect-free weld, that does not mean that the weld will always have the same characteristics as the parent material. Contact us at 860.653-0111 to consult with an expert who can tell you what to expect in your welded assembly so you can make the best decision possible about heat treatment.

Laser welding aluminum – stay light by welding with light

Warning: This is a blog, not a how-to guide.  I won’t be giving away any secrets today.  If you want those, it’ll cost you $$$!

This is a hot topic.  Aluminum is a popular material due to its light weight, ease of machining, relatively low cost, and good wear and corrosion characteristics.  It is commonly GTAW and MIG welded – think bicycle frames, hand rails, and truck tool boxes.

Aluminum is rapidly replacing other materials (stainless steel, steel) in much smaller applications – battery cases, tiny enclosures, and handheld devices to name a few.  This requires welding techniques that are both cost effective and capable of precision heat input.

Aluminum can be challenging to weld due to high thermal conductivity and a low melting point.  In thin parts, heat can rapidly build up and turn a precision component into a puddle of goo.  A delicate touch is required.  Enter laser technology.

This blog wouldn’t be very interesting if there weren’t a plot twist.  Here it is – aluminum is highly reflective to laser energy.  It requires a particularly bright laser to get energy into the part without doing more harm than good (or reflecting back into your peepers).  How fortunate that new laser technology has evolved to fit the bill.  As little as a decade ago, laser welding aluminum was considered to be limited to very specific applications.

Ok, so if you’ve read any of my other blogs, you know I like to use examples.  So, here’s one from a battery case application:

A prototyping house, specializing in making stainless steel prismatic cans for the battery industry, was looking to make a new line of prototypes from aluminum to save weight and impress their customers.  Their old style stainless cans could be welded in a variety of ways, but these new aluminum cans required very precise heat input to keep distortion to a minimum and prevent overheating during the weld process. 

A high power NIR laser was chosen for the application, and in conjunction with form tools and proper heat sinking (see our blog on heat sinking), excellent welds were achieved and thousands of pre-production cases were fabricated in very short order.  Not only were the welds structurally sound, they were cosmetically excellent, and the process time was shorter than that for the stainless cans.

Not all aluminum alloys are weldable, so be sure to speak with an expert when you approach your next small-scale aluminum project. 

Got a question or comment? Feel free to leave it in the space below.

In Memory of Paul Lombardini

Folks, today I would like to shift gears from technical discussion and dedicate this blog to an exceptional individual.

Paul Lombardini, our Quality Control Manager, passed away on Tuesday, September 12, very unexpectedly.  This man touched the lives of everyone he came in contact with.  Writing this is surprisingly hard from an emotional standpoint, and exceptionally easy from a content standpoint.

Paul had a way of making everyone around him laugh.  Always smiling and constantly moving.  Never too busy for a lively discussion.  My favorite memory is kind of silly, but here it is.  Every day at lunch (weather permitting), I like to sit out in my car and enjoy the sunshine.  Paul would be outside “making the rounds” talking to folks in their cars.  I don’t know why I enjoyed it so much, but yesterday, not seeing Paul out hamming it up was tough.  He will be missed.

Here are the words of some of his other colleagues and friends at Joining Technologies. There is a consistent theme, and that tells a lot about the man.  Not everyone was able to contribute – some because they were not present, others because it was too painful to discuss.

Robert Kobak, Engineering Manager – “I worked with Paul for about 8 years.  Paul always brought his A-game, intense and passionate about his work.  If you were looking for someone to pattern yourself after, Paul was the guy.  I knew him to be a good friend, family man, father, and husband.  He always took care of the people that were important to him.”

Amy Nelson, Administrative Assistant – “Paul gave me lots of laughs. Loved coming in to work and laughing together.”

Laura D’Angelo, Contract Review – “I looked forward to talking to Paul every single day. His smile and positivity projected onto everyone around him. He will be missed so very much.”

Taylor Beaudry, Contract Review – “In my short time with Joining Technologies, Paul became a great friend and colleague. When you were having a bad day, you could always count on him to brighten your day. Paul was the definition of living life, and always knew how to have a great time. I looked forward to hearing of the new restaurants he discovered while traveling with his beloved wife, which he always seemed to share when you were already hungry. My heart goes out to his family as Paul will be dearly missed.“

Bruce Williams, Shipping Coordinator – “Paul always announced himself when he would come up behind you so that he wouldn’t catch you by surprise – ‘Right behind you’.  I always felt like he had my back.  He changed this department for the better.”

Don Brozowski, Quality Control Inspector – “Paul, you’re a great guy, a great friend, and I’m going to miss all the stories about all the oysters you used to eat with your wife, AND all the pictures of food we used to eat!”

Krystal Bressette, Quality Control Inspector – “I’m going to miss all the jokes.  It was always fun to come into work.  He changed the pace of your day with just one comment.  He could make you laugh.”

Samantha Pasha, Quality Control Inspector – “I’m going to miss him coming into QC all frazzled, and picking on him for running around like a chicken with its head cut off.  Also, giving me 5 different jobs needing to be done at the same time and leaving me to decide which to do first.”

Jessica Livingston, Laser Operator – “I will miss his sense of humor that kept me laughing during the day.”

Jameson Liro, Receiving – “He always knew the best restaurants for me to take my girlfriend to.  I’ll be participating in the Spartan Ultra-Beast event in Vermont in Paul’s memory.  It’s a 26+ mile obstacle course.”

Sean Mullen, Laser Operator – “Paul was always full of life, always upbeat, and kept you smiling.”

James Laclair, EB and Laser Operator – “Paul will be missed, but never forgotten.  He was a kind and very helpful person in everything he did.”

Roman Radionov, Laser Operator – “One time while setting up a job with very small parts, I was having a hard time seeing.  Paul let me borrow his glasses for the day.  He was always helping people.”

Cindia Rivera Hernandez, Laser Operator – “Paul was a great person and a very funny guy.  He had a great sense of humor and always walked into work with a smile.  I miss chatting with him and talking about our weekends over lunch.  I will miss him very much.  RIP Paul.”

Terry Dillon, Laser Operator – “Paul was always ready to help with a smile on his face.  His positive attitude is sorely missed.  My heart goes out to his family.  It was such a shock.”

Doug Tong, Manufacturing Engineer – ‘I’ve been lucky enough to grow a mentorship and friendship with Paul for the past 4 years. I’ll always be grateful for the countless instances of putting his neck out for me and his lessons, I admire his selflessness and ability to bring his 110% with a smile regardless of circumstance, and how he never failed to catch me off-guard with his brilliant sense of humor. It’s been an absolute honor and pleasure working and spending time with such a great man.’

Jay Drew, National Sales Manager – “Paul was the kind of guy you could talk to about anything.  He was a great co-worker and a good friend.  He will be more than missed by his friends at JT.”

Jim Broman, Maintenance – “To me, Paul epitomized our core values.  He was a consummate professional.  It was a real pleasure working with him.  He will be sadly missed, by everyone.”

Greg Miller, General Manager – “He always told me that this was the best place he ever worked, and I knew he meant it because he went out of his way to bring people he had worked with in the past and respected into the company.  When I interviewed him, he said that he had maybe 3-5 years of work left in him.  Over time as he became more involved with the organization and his passion for the success of the company grew, that grew to 5-7 years, and in my last discussion, he said maybe 10 years.  That showed his passion for the success of the company.  He was a technical expert, he was an accomplished leader, he knew when to be serious, when to roll up his sleeves and get the work through, but he also didn’t take himself too seriously.  There was always time for a good laugh, sometimes even at his own expense.”

Paul Bridge, Tool Room Manager – “Paul was a good friend and I always enjoyed his passion for life. He will truly be missed but he would want us to move on. He will keep an eye on us.”

John Britt, Lead QC Technician – “I had the privilege of working under Paul when he first came to JT, and helping him get acclimated to our company. He was a great fit immediately, in part because of his wealth of technical experience but even more so because of his personal character – hard-working, humble, dedicated to live life to the fullest. He helped everyone around him be their best selves.”

Dmitriy Stepanchuk, Machinist – “I think we would all agree that Paul was a great guy, but what I loved most about him was how happy he always was and how he always put a smile on everyone’s face.  I’m going to miss our little conversations.  I just want to say thank you for that and also thank you for bringing me into this company.  You will be greatly missed.”

Patty Pasha, Document Control Coordinator – “Paul was sunshine.  He was warm and welcoming to all. I don’t think there was anyone here that he didn’t leave an impression on. He cared about his Quality team and thought of them as an extended part of his family. He brought fun, laughter and his experience of Quality Control to Joining Technologies. He will be greatly missed.”

Caitlin Scott, IP, Legal and Contracts manager – “Extending sincere condolences to Paul’s family, friends and our staff, as we remember someone who was a hard worker, an exceptional manager and trustworthy team member.”

Trish Billick, Production Control Coordinator – “He was my roomie, a friend, my investment guru, and yes, a jokester.  We had a motto in our office ‘just get the [insert expletive] job done’, and we would laugh.  I will miss him dearly—RIP, Paul.”

Giovanna Carrington, Marketing Manager – “Paul was a very serious person at first, and then all you needed was a quick conversation to meet the real Paul. He was funny, kind and a true professional.  He was such an example for all of us, and he often mentioned how much he loved his wife and kids. He loved life. He will be terribly missed.”

Brian Crafts, Engineering Technician – “Paul was an exceptional man who always had a positive and uplifting attitude. The first day I met him it had seemed as if I knew him for years prior, due to his easy-going and extremely friendly nature. “

Carole Cipkas, Human Resources Manager – “There wasn’t a day that went by he wasn’t pranking myself, Amy or others and in our busy atmosphere, he always made us laugh until it hurt. He truly enjoyed his life to the fullest and talked often about his wife, his boys and the wonderful weekend adventures with his wife and family. His morals and ethics on work and family were refreshing and in line with our group. He became a friend, a mentor to many; never skipping a beat to offer fatherly advice, as well as a sounding board and a great reference for the newest flavors of vodka!  In the short time most of us worked with Paul, there was no doubt in any of our minds, he was such a special guy and we are all very grateful he was a part of our lives.”

Dave Hudson, President and CEO of Joining Technologies – “I met Paul in 1979 and we became very good friends. We both worked at Simon Container, Inc., a packaging equipment manufacturer in Agawam, MA. I was 18 years old and Paul was 21. Even at a very young age Paul was considered an excellent machinist and craftsman. He had a flair for pulling off good-natured practical jokes, and a love for live music. I looked up to him then as I do now. I recall feeling very lucky, blessed really, for having the opportunity to work with him again some 37 years later. I feel an odd distinction in that I both began and ended his career with him.  It’s hard to believe, but Paul joined us just under a year ago. He accomplished so much in so little time. He managed to touch every one of us, leaving behind a legacy of integrity, solid work ethic and good-natured humor.

I will miss my old friend. May he rest in peace, and may Gayle, Ryan and the rest of his family find comfort and serenity.” 

Filler wire selection for welding

Choices, choices.  The designer literally has all of them at some point.  As the design progresses, they dwindle along with flexibility.

When designing a part for welding, there are times where it becomes necessary to incorporate filler material into the assembly.  This can be to accommodate manufacturing tolerances, to reduce stress, or to join materials that may not readily weld without an intermediary.

These have to be considered when selecting an appropriate filler.

If filling a gap related to part tolerances is the requirement, and the material is readily weldable, the filler selection probably is not a complex issue.  Select a filler with similar or the same chemistry as the mating parts and proceed (do not “just weld it”, though).  A common example here is 410 stainless steel.

When a high stress weld joint on crack-sensitive material is the order of the day, there are options.  For a corner or fillet weld where stress is the prime contributing factor to weld cracking, using similar filler can create a smooth, lower stress transition.  316 stainless is a candidate for this treatment.

When the material is of a challenging alloy to weld, this configuration may not be appropriate for similar filler material.  An example for this is 440C, and there are a variety of fillers to choose from depending on the application.  Often times for specialty surgical tools, 308L or 410 filler wire work very well.  Where added strength is necessary, 420 filler may be used and may require a post-weld stress relieve.

The final challenge is one that is usually the result of exhausting all other design options.  A material has been chosen which is simply not weldable without filler, no matter the weld joint configuration.  Low stress, high stress, no stress, it doesn’t matter.  It’s going to crack.  This is where creative problem solving comes into play. 

Hardened high strength steels typically fall into this category, as do some superalloys.  For chromoly (4130, 4340, etc.) steel, an ER70 or ER80 steel filler may be the order of the day, and a pre-heat might also be required, and a post-weld stress relieve or controlled cool down.   As for that superalloy – the choice of filler for that will be driven by too many variables to list here.

With that in mind – before committing to a final welded assembly design, call 860.653.0111 today.  It will save time and money, and reduce your aggravation.