Robotics Industry Insights
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Cloning Master Welders with Robotics
by Tanya M. Anandan, Contributing Editor
Robotic Industries Association Posted 06/28/2017
With all the talk about robots replacing humans, we're here to show that they need us as much as we need them. The robots can't do it alone.
Precision, consistency, control … qualities we've come to expect from welding robots. We've come to appreciate even more from our Master welders.
But the skills gap keeps widening. There are less welders to go around. They are retiring or leaving industry for other pursuits. They are taking that welding expertise with them.
In 2010, the American Welding Society (AWS) reported a shortage of 200,000 welders. As the crevasse widens, AWS estimates a projected shortage of 372,000 welders by 2026.
What's not clear is whether this is a true shortage. Will we really miss all those welders, especially as more welding is automated? Will other technologies replace welding? The jury is still out.
What is clear? It's the mastery of the process that will be missed. The experts will tell you that the best welders make the best robot programmers. Without our Master welders, how will the next generation of welders fare? How will our robots improve?
Zane Michael, CWI/CWE, is Director of Thermal Business Development for robot manufacturer Yaskawa Motoman in Miamisburg, Ohio. Michael has nearly 40 years of experience in welding. He is an AWS Certified Welding Inspector (CWI) and Certified Welding Educator (CWE). He has degrees in mechanical and electrical engineering, and master's degrees in manufacturing and operations management from Kettering University. This Master welder began his career in 1979 teaching at the Hobart Institute, now known as the Hobart Institute of Welding Technology.
A quick historical aside: In 1989, Yaskawa and the Hobart Brothers Company formed a joint venture – Motoman Robotics – to market welding automation in North America. In the '90s, Hobart sold back its half of the robotics division to Yaskawa. The Motoman Robotics Division is now solely owned by Yaskawa Electric Corporation. For more about this Japanese powerhouse, check out The Robotmakers – Yesterday, Today and Tomorrow.
Michael is on the road most of the time, traveling to his customers' facilities. Customers like Bobcat, Manitowoc, and John Deere, giants in construction, agriculture, and mining equipment. He sees firsthand the challenges manufacturers contend with on a daily basis.
"When I visit customers, I ask them why they're interested in robots. What problem were you trying to solve? Nine times out of 10 they tell me, I can't get qualified welders, or I can't keep welders."
This is the battle cry across the nation. The response is often coming from automation. This is where cloning comes into play.
Your Best Welders Make the Best Robot Programmers
Flexible welding automation with robots essentially clones your best welders. Those in the know will tell you. It's much easier to teach someone to program a robot than it is to teach someone to weld.
"To be a top-notch welder, if you want to come to the best welding school, which is the Hobart Institute of Welding Technology in Troy, Ohio, you will spend nine months there," says Michael. "Nine months to come out as a certified, qualified welder in multiple processes, multiple positions."
That's nine months, full time. By contrast, he says it's much easier to teach an experienced welder how to program a robot than it is to teach a programmer the nuances of welding.
"In less than two weeks, I can have you programming a robot. But when I give you a weldment and say program this robot to put the welds on like the print shows, if you don't understand the welding process, if you can't do it by hand correctly, then you don't have a good chance of being successful with the robot.
"Anybody's robot is capable of holding a welding torch in a joint, turning the arc on, and making a weld. That's easy," says Michael. "But understanding all the critical welding variables to produce a quality weld – is not. The burden on the programmer is to have a very good understanding of that welding process."
Michael teaches a class in welding processes at the University of Dayton.
"I tell these students that welding is like making an apple pie. You have a recipe you have to follow. You have so many apples, so much sugar, you bake it at a certain temperature, and you're guaranteed that apple pie is going to taste the same every time. Welding is no different, except there are many more variables involved, like travel angles, amperage, and stick-out. All these critical variables have to line up to produce the expected quality outcome, which is called the Welding Procedure Specification (WPS)."
For gas metal arc welding (GMAW), or what's commonly called MIG welding, those five critical variables are:
- ~ Electrode size
- ~ Current
- ~ Arc length or voltage
- ~ Travel speed
- ~ Electrode angle
"As they're welding, manual welders will read that puddle," says Michael. "They can change their stick-out, as an example, to increase or decrease the welding current to help control the puddle and produce a quality weld." (Stick-out is the proper tip to work distance for the MIG welding process.)
"These are all factors that a robot programmer has to know. I tell my customers it's a recipe for disaster if you send me one of your mechanical or electrical engineers and expect them to be the programmer of your welding robot when this individual has never welded."
It's All About the Process
Welding, whether manual or automated, is process-specific. You have to understand the process to clone it.
"Robots, I don't care whose brand it is, are easy to program. It's the process," says Michael. "Even when we automate non-welding jobs, like an operator sanding a casting or forging, where they are running that across the belt sander, we will study the operator's motions and angles because we basically have to duplicate that process with the robot."
How the process is done is critical. Expertise that can only come from hands-on experience.
"Anytime that we start a new process, or approach a new part, a lot of the time it is something that we're taking over from a manual process," says Brendan Brown, Virtual Solutions Engineer at Genesis Systems Group, LLC, in Davenport, Iowa. "Those are some of our best advocates. The guys who have been hand-welding these parts over the course of years. How they approach the sequencing of the welding, what they weld first, and the appropriate angle, and all the push and the travel speeds. That's information we always want to gather. Who would know that part better than the guy who's been welding it?"
Genesis is one of the largest automated solutions providers in North America and an RIA Certified Robot Integrator. Brown is an offline programmer with almost 20 years of robotic welding experience at Genesis.
"You have to look at the whole process," stresses Brown, echoing Michael's sentiment. "One thing we see a lot with first-time robot users is they have automated this process, but you have to look down the line to see how you're making the part, how you're tacking the part together. We often get customers that build their own tooling or outsource the fixture. They are not necessarily controlling the appropriate datums or securing the part properly. Even the best welder has to look at the entire process to get a good weld."
Genesis' headquarters in Davenport has a training lab and two private classrooms where customers' programmers and machine operators can gain hands-on experience and instruction. Brown helps teach the basic and advanced training classes.
"When you buy a system from Genesis, most customers get training credits with the purchase, so they will typically send two or three operators and maybe one engineer," he says. "The majority of our students have some kind of welding background, whether it's manually welding the parts they are getting ready to automate, or just the company's weld engineer that will be overseeing the machine and will need to understand how to touch things up. When they come into the class, we say here's the robot, your new tool. We don't need to teach proper push and work angle."
The best welders understand the subtle nuances of the process.
"That's why it is much easier and more successful to take an experienced welder and teach them the robot," says Michael. (Yaskawa Academy offers training courses in basic and advanced programming at several locations throughout the Americas.)
"When my customers ask, 'Who do we send for training?' I say, I want your best welder."
Efficiency Doesn't Always Mean Faster
A common myth about robotic welding is that people think you're going to weld much faster. That's not true.
"A robot will give you more parts in the bucket at the end of the day, but it is not physically going to be welding faster," explains Michael. "When a manual welder puts his helmet down and strikes the arc, let's say his forward speed as the weld is being made is 20 inches a minute. The robot will basically weld at the same speed. That's the recipe. Just like mom's apple pie recipe. Bake for 450 degrees for 30 minutes.
"You wouldn't bake your apple pie at 900 degrees for 15 minutes. To produce a quality weld, one of the essential variables is travel speed. You put too much heat into a part, you can create issues."
Welding robots are not necessarily faster. They're more efficient.
"A manual welder is about 20 percent efficient," says Michael. "What that means is that out of the 8 hours you pay a manual welder, the arc is only on for about 20 percent of those 8 hours. The welder lifts his helmet up, repositions his chair, or she cleans the weld off. There's a lot of in-between, getting-comfortable time before I make the next weldment."
In contrast, a robot is about 85 percent efficient.
"The robot will get from one arc to the next weld and the next weld much faster. If it takes the welder 15 minutes to produce that part, the robot will do it in approximately less than 4 minutes.
"When I walk through a plant and I see three to four welders, I think that could be one robot," says Michael. "Not in the sense that one robot is going to take their jobs, but I can use those welders on more critical jobs that a robot can't do."
Take the case study of Onken's Inc., an Illinois-based maker of bulk grease-collection systems and oil storage tanks. For decades the company had relied on a team of experienced welders to manufacture its leak-proof tanks. But with the rising welder shortage, quality welders became harder to find. Enter the robots.
With a two-zone workcell, an extended-reach Motoman MH50 II-20 robot, and some training for its welders, Onken's was able to eliminate up to 20 hours of production time and complete the same amount of work with three welders instead of five. The two freed-up welders could then work on other projects, reducing the need for contract welders and further increasing cost savings. Check out the full story.
The MIG welding cell (pictured) created for Onken's tank production was a custom-engineered workcell with two zones. This allows the operator to load and unload tanks in one zone, while the robot is welding tanks in the other zone. Yaskawa's welding robots have built-in adaptive control, so they're able to adjust travel speed, stick-out distance, and torch and travel angles as needed. Advanced weld seam finding and tracking tools were used to accurately locate and track the various types of weld joints on these 120-gallon to 500-gallon tanks.
"Robots are very repeatable," explains Michael. "You program a path from point A to point B and a robot will follow that path all day long, plus or minus five thousandths of an inch depending on the robot spec. To make a quality weld, the weld joint has to be positioned within roughly plus or minus one-half the diameter of the weld wire. If I'm using .045 diameter MIG wire, that's a little over plus or minus 20 thousandths of an inch for the weld joint repeatability requirements."
With welding often comes distortion.
"We're heating up the metal, so it wants to move on us. In larger weldments (like Onken's tanks), distortion is more predominant. If the weld joint repeatability is not satisfactory, we have to use sensors for the robot, so it can alter its program path to match the location of the welds for that part during welding."
Touch sensing is used to locate a large circular flange and several smaller threaded couplings on the top of the tank. Once each component is located, the programmed paths are automatically shifted to match the location of the weld joint for that one tank. Yaskawa's ComArc thru-arc seam tracking enables the robot to alter its path and keep the weld puddle in the seam of the weld joint during welding.
In this video of Onken's tank welding cell, you can see the touch-sensing operation in action. At 0.55 seconds into the footage, the laser seam finding and tracking technology is also shown.
As the robot welds the joints, which include contoured rolled corners, a SERVO-ROBOT POWER-TRAC™ laser sensor provides real-time seam finding and tracking just ahead of the weld torch. In the video, you can see the laser strike out in front of the torch nozzle just before it begins welding. This enables the robot to alter its path to compensate for any variations in part fit-up. Accurately locating and tracking the weld joint also eliminates the need for costly complex tooling.
"We recently invited a customer to visit our factory," says Operations Manager J.R. Onken. "He said he had 10 minutes to spare for a tour. Once he saw our robotic welding cell in operation, he studied it for 30 minutes. He grew up as a welder and couldn't believe the quality we were getting from automation.
"Automating our welding process has ensured we'll be around as a company for another two or three decades," adds Onken. "It's secured our future."
3D Welding Simulation
For Genesis, the future is digital. Simulation allows Genesis to visualize and demonstrate complex or large-scale robotic processes before anything is built. In their Virtual Solutions Center, the simulation environment goes big and in 3D.
Genesis' 3DG Environment harnesses the power of virtual reality and immersive 3D visualization to allow Genesis, their customers, and prospective clients to visualize a robotic process in the concept and design phases. With the 3DG technology, Genesis can ergonomically evaluate parameters such as welding torch access and robot reach.
The system consists of a 16-panel audiovisual wall that displays 2D and 3D images. It's also portable, so Genesis can easily dismantle it and set it up at tradeshows like this appearance at FABTECH in 2015.
"It's a great tool for us," says Brown. "With the 3DG Environment, we're able to draw clients into the experience and give them a real-life feel for what they will get with one of our systems. They get to see what we do upfront and all the pre-order work we do to give them the right solution."
Genesis also uses the 3DG system to conduct reviews with their in-house design and tooling groups for a truly collaborative process.
"You wear a set of regular 3D glasses like you would get at a movie theatre," explains Brown. "Then with the joystick, you can drive around the model, to go around the machine, get underneath it, come inside, and look at it from all angles."
In the model (pictured), a Panasonic welding robot on a three-axis gantry is in position to MIG weld the frame of a large dump truck used in the mining industry. The part is represented by the multicolored sections.
"Some of these parts are 40 feet long," says Brown. "This part requires multi-pass, heavy thick-plate welding. It's a 48-hour cycle time to weld one piece. This part actually grew 2 to 3 inches during the welding process just because of the heat and draw on it (distortion)."
Brown says the simulation environment allows them to demonstrate advanced processes to their clients that they made not have imagined were feasible. The automotive and appliance industries are taking a closer look at laser welding.
"We won a handful of customer orders because we were able to laser weld, which has a lot less heat and distortion. We've done simulations to show them. One gentlemen in my department does strictly weld distortion and heat analysis. He can show a customer how with traditional MIG welding on a certain part you might have 5 mm of draw or deflection in it, but with laser welding it's down to 1 mm."
Across the hall from their Virtual Solutions Center is Genesis' Automated Solutions Center, where they test technologies such as remote laser welding and a laser seam stepper. Check out the video.
Genesis is using the robotic laser seam stepper (pictured) to test customers' parts that have been traditionally spot welded. They also have a few robotic systems already in the field.
The laser seam stepper is a servo-driven self-contained laser head. One of the advantages is that you don't need the large laser safety cabinets common with most laser welding processes. Brown explains.
"The robot will move above the part, then drive the laser head down, basically applying force with the head, which helps push the two materials together. Then it runs a bead up to 40 mm in length. You don't need the giant light-tight enclosure, and a lot less fixturing is involved. It's a much better finish than a traditional spot weld and certainly more consistent."
Now check out this video showing a different configuration of the laser seam stepper. Imagine the implications for the automotive assembly line.
Brown says advanced welding technologies like remote laser welding and the laser seam stepper still require the same concerns for part fit-up and other critical variables as conventional welding processes. You still have to understand the process in its entirety to successfully automate it.
Harness that Knowledge
They say artificial intelligence will someday allow us to download our experiences, to digitize them for future generations, to essentially clone our memories. Or at least our limitless brain power, in spite of our finite bodies. But that's still a long way off.
For now, we need to capture and disseminate that knowledge or forever lose it. This is not theory or textbook smarts. This is hands-on experience accumulated over decades. Know-how that is difficult to demonstrate with words and diagrams. It varies from process to process.
Until AI reaches the pinnacle, it's just us and the robots, Master and tool. Let's not waste this opportunity to put both to good use.
Originally published by RIA via www.robotics.org on 06/28/2017