RMD and Pulsed MIG Processes with Metal-Cored Wires Improve Pipe Fabrication for Swartfager Welding, Inc.
November 6, 2012
Pennsylvania fabricator builds systems that increase productivity, reduce non-value-added activities such as grinding, and simplify processes for operator training.
Process, Wire Combine to Reduce Cleanup and Rework
Swartfager reports that the combination of metal-cored wires and RMD and Pulsed MIG processes substantially reduces spatter. While this is a quality improvement, it also helps increase productivity by allowing workers to move on to the next part rather than to spend more time cleaning a part.
“Just the reduction in spatter from the root pass when you’re dealing with a water pipe (is important),” says Swartfager. “The savings is substantial because you’re not putting in man hours, at your shop rate, to grind out BBs. If you were to take every joint on the inside of a water pipe and grind it, and it took the guy 15 minutes at a shop rate of $75/hour, compared to maybe five minutes with metal-cored, the savings are substantial. When you look at the cover pass, when you go out of position with solid wire, you better have sanding consumables to clean up the mess. With this, it takes us five seconds to scuff up the joint and send it to paint.”
The reduction in spatter also reduces the need for consumables, such as anti-spatter solution. “We used to go through seven or eight 55-gallon drums (of anti-spatter solution) a year, now we’re down to maybe one,” he says.
Processes Simplify Operator Training, Improve Performance
Like many parts of the country, Swartfager in western Pennsylvania is experiencing a shortage of skilled welders. The advances in technology and the simplification of the processes with RMD, Pulsed MIG and metal-cored wires have substantially helped to get new welders up to speed faster.
“The technology allows you to bridge the gap between education and lifetime work hours in a field,” says Swartfager. “You take somebody that has a basic, good understanding and might not be as proficient as someone that’s done it for 10 years — with the technology that’s available now, you can get an end result almost as good or as good in weeks instead of years. You can give them all the tools necessary to complete a job, do everything the right way in a shorter amount of time. You keep your investment lower to get the same return. Without the new equipment, that just wouldn’t be possible.”
Because processes like RMD maintain a consistent arc length even at varying electrode extension, welding operators who may not be as skilled at maintaining wire stick-out can still have good control of the process.
“RMD is an excellent way to get a root pass from guys that might not be able to do it with TIG,” he adds. “It gives you the ability to take somebody off the street, teach them how to listen for a sound (sizzling bacon), and produce a weld that is acceptable anywhere for any application. Instead of six months of hands-on training in the shop, you get what you need out of them with two weeks and some practice. It’s probably one of the greatest things we’ve seen in welding in the last 15 years.”
The same ease of use translates to the Pulsed MIG processes with metal-cored wires.
“My guys spend as much time out of position and in non-user-friendly welding positions as they do laying a flat bead,” says Swartfager. “Half their day is spent welding out of position. Without this application, they’d just be dripping filler wire all over everything. It keeps it where it needs to be. It allows you to control the arc, it allows you to control the puddle, and it allows you to make sure you have good deposition and tie-in into the weld.”
The equipment and process itself are also designed to simplify training and improve operator performance. In manual applications where Swartfager uses metal-cored wire and PipeWorx on both the root and the hot pass, operators only have to hit a button to switch processes from RMD to Pulsed MIG. In applications where a TIG root is required, switching back to a wire process is as simple as picking up the gun and pulling the trigger.
“You can go from cover pass back to the TIG root pass (on the next pipe) by touching the TIG pedal,” explains Swartfager. “There’s no turning around, there’s no switching, there’s no nothing. You can switch from wire to wire and back to TIG all either by clicking the switch or pushing the foot pedal. There’s no downtime, no anything. It’s dual gas and it’s ready to go.” “Just in operator time and keeping everything in a nice, tight, neat package, it probably saves you half an hour to 40 minutes each day.”
Proof in the Final Product
One recent application that shows the overall benefits of metal-cored wires with RMD and Pulsed MIG welding involved a prototype part built from 6-inch diameter, Schedule 120 pipe. A competitive shop, using solid wires, quoted the fabrication process for each part at 30 minutes. Using the PipeWorx system with metal-cored wires, laying an RMD root pass and a Pulsed MIG hot pass, Swartfager was able to produce the same part in seven to eight minutes. These results won’t be universal or proportional to every application, but it showcases the possibilities when implementing this system approach.
“We want to be on the cutting edge every time, that’s the only way we progress,” concludes Swartfager. “This is the first time we’ve bought something all hyped up and it worked the way they said it would. And I don’t care if metal-cored wire costs $50 more a spool, I’ll still use it. It gives us the quality we want.”
Swartfager Welding, Inc. is a family business that works.
Ken Swartfager began welding at an early age, under the guidance of his grandfather and great-grandfather. Dustin Swartfager, Ken’s son, also took up the trade at an early age and is now actively involved in the family business. Now operated by the sixth generation, Swartfager Welding got its start in the 1800s as a traditional blacksmithing operation. Today it’s a leading fabricator for the rail and marine industries, as well other heavy fabrication applications, such as aggregate plants and infrastructure.
Much of the work done by Swartfager Welding involves pipe fabrication and other high-pressure applications. Working to AWS standards — as well as industry-specific certifications, such as Germanischer Lloyd for the shipping industry — Swartfager has relied heavily upon both Regulated Metal Deposition® and Pulsed-MIG processes with metal-cored wires to exceed code requirements and improve their operation through increased productivity, less post-weld cleanup, and easier operation and training for the workforce. Some applications have even cut up to 70 percent of total production time out of the process. One manual application (described below) cut welding time from 30 minutes down to seven minutes. Robotic applications have also been made substantially faster.
“(Germanischer Lloyd) is one of the most painstaking things in the world to get an accreditation for,” says Dustin Swartfager, “and we have four or five guys qualified for all of their shipping bureaus so we can provide oil and water critical piping systems for marine applications, and metal-cored is our defined process that made it a lot easier to get certified. It took our certification window from normally 18 to 36 months down to about four because every time they sampled our stuff, they couldn’t find anything to balk at.”
“In the type of pipe fabrication we are involved in, you’re always looking for the highest tensile strength weld for whatever you’re working with,” he adds. “When you’re dealing with high pressure piping or just something as simple as low pressure water piping, your weakest link is always your weld joint. That’s always where your material characteristics vary and everything changes. Metal-cored allows us to take about any type of piping or tubing, 1026 through your regular A53 grades of material, and produce a joint that is structurally better, it looks better, it gives us the ability to weld out of position and still keep joint integrity. Spatter is at a minimum when you’re out of position with Pulsed MIG welding (with metal-cored wires). We probably get a 30 to 40 percent increase in production during the day because we don’t have to go back and grind all of the spatter off the pipe. We don’t have to worry so much about fit-up being perfect on the root pass because metal-cored wire and RMD allow you to sidestep and actually make it all look nice. You can get good backbone structure on your cover pass with metal-cored wire by just changing your gun angle. For pipe welding, it’s what everybody should be running.”
Equipment and Wire Combinations Enhance Pipe Fabrication
Swartfager has two primary setups for pipe fabrication: the company owns four PipeWorx multiprocess pipe welding systems for manual applications and also runs an automated cell powered by the Auto-Axcess™ 450 robotic welding power source. While traditional TIG welding is used in some root applications, the company relies heavily on .045- and 1/16-inch Metalloy® 76 metal-cored wires from Hobart Brothers with a mix of 75 percent Argon/25 percent CO2 shielding gas for root (RMD) passes and 90 percent Argon/10 percent CO2 for the fill and cap passes (Pulsed MIG). Both manual and automated systems are capable of running both processes.
Prior to implementing metal-cored wires, Swartfager relied almost exclusively on the TIG process for root passes and solid wire for remaining passes. The introduction of metal-cored wires and RMD — a precisely controlled short-circuit metal transfer process — helped significantly to increase travel speeds (compared to TIG), bridge gaps and eliminate lack of fusion or lack of penetration by providing a thicker root pass, reduce spatter (compared to conventional MIG processes) on root passes, and achieve a better weld compared to a solid wire.
“Some of our applications can’t use a solid filler wire and get the right quality for the application,” says Swartfager. “That’s when we switched to a metal-cored wire on the root pass, which allows us to get a better weld.”
Using the same wire and the same machine, Swartfager can then switch directly over to the Pulsed MIG process for the remaining passes. The Pulsed MIG process helps reduce spatter, improve weld quality and has made it much easier for operators to weld out of position.
“Solid wire cover passes didn’t look good,” says Swartfager. “You had spatter issues and a multitude of problems that were hard to overcome, such as achieving proper fillet shape while out of position and lack of proper fusion from the lower heat setting to keep the solid wire in the appropriate spot while being out of position. Gary (Kahle with Valley National Gas) worked with us to use metal-cored wire, and that ran great when you turned the pipe, but we also had to get out of position with it. That led us to pulser boxes on existing machines and eventually to the PipeWorx and a new mindset that any equipment capable of running a good pulse program with metal-cored wire allowed us to do things, where now we don’t have to un-fixture a pipe. We can go out of position with the same wire we’ve become accustomed to and get the same results.”
Compared to trying to weld the remaining passes with a solid wire and a standard CV process, Pulsed MIG and metal-cored wires help Swartfager increase productivity by offering faster travel speeds and reduced repositioning of the part to get it into position.
“Either horizontal or vertical, out of position, any way you can dream it, you can get it done with Pulsed MIG and have a weld that looks respectable and to print,” he says. “If you try to run a solid wire and CV at the same deposition rate (as Pulsed MIG and metal-cored wires while out of position), you are going to drop slag all over the floor.”
And while metal-cored wires typically run hotter than solid wires, the Pulsed MIG process provides precise control over heat input into the pipe, preventing distortion and costly rework. “With a pulse setup on your cover you can really control the heat and not slow down,” he says. “We’re not really worried about joules of input changing the characteristics of the material we’re working on, because the pulse programming allows us to keep it from getting that hot.”