Application Stories

Tube.tec - Robotics Reduce Spatter and Improve Productivity

Robotic WeldingHigh quality and lower cost. If a supplier can provide these two items, its business will grow and prosper. And, this is exactly what is happening at tube.tec® (Advanced Tubing Technology, Inc.) in Statesville, North Carolina. This three-year-old company that manufacturers structural tubing assemblies to the booming All Terrain Vehicle (ATV) market has seen business take off due to high quality, aesthetically pleasing parts and the ability to provide these components at a lower cost. But just what is the secret to success at tube.tec? A high-tech shop stocked with the latest equipment including robotic welding systems featuring Lincoln Electric’s Surface Tension Transfer® (STT®) power sources. Not only do the robots provide repeatable, consistent welds that require little, if any, repair work, they also manufacturer seven of tube.tec’s popular carrier products in the time it would take to produce one using a manual welding process.

“When we opened our manufacturing facility, we decided right from the beginning that we would outfit our shop with the latest technology products available,” says Doug Smyth, President of tube.tec®. “The very first item we purchased was the robotic welding system. We decided on automation because of the consistency it provided and the add-on capabilities it offered as we grew.”

From its initial purchase of one robot when the plant opened in 1997, tube.tec has added six more robots that produce 8,500 parts per week. During the company’s busiest season, these robots work 24-hours a day for up to 142 days straight. Tube.tec’s product offerings include cargo carriers, bumpers, footrests, handrails and other structural tubing components.

An Informed Buyer

According to Smyth, tube.tec researched a number of robotic suppliers before deciding on Lincoln. “After reviewing all of our options, by far Lincoln rose to the top because of its technical expertise. When we met with other suppliers, they would have to bring in automation specialists from their headquarters. With Lincoln, our local representative had been through robotic training and was very familiar with the product. In addition, Lincoln promised 24-hour support should we experience any downtime. Both of these factors made them the logical choice.” 

But it wasn’t only the service factor that led tube.tec to Lincoln. First and foremost, the company needed a first-rate welding machine that could do the job with the best possible quality. “We were impressed immediately with the STT. Compared to what we had seen previously, spatter was virtually eliminated with this power source. Reducing spatter is critical because a carrier is one of the most visible parts on the ATV and creates showroom appeal. In addition, little spatter means little rework so that we could keep costs down.”

The Tube.tec Process

Tube.tec is a full service company that takes pre-cut lengths of steel tubing and precision stampings and manufacturers them to finished products made to customer specifications. In the first stage of the process, tube.tec operators use forming tools such as CNC tube bending equipment and PLC automated endforming machines to cut, bend, crimp, press and punch the steel tubing to form product frames.

In the robotic welding process, these formed tubes and pre-fabricated stampings are automatically welded to form an assembly. After welding is complete, the assemblies then move to the powder coating area where they are washed, treated with a rust inhibitor and electrostatically coated. Lastly, parts are inspected and shipped.

Robots In Action

Robotic welding at tube.tec is accomplished with FANUC ArcMate 100i six-axis robots. This high-speed, GMAW welding unit welds one component while the operator simultaneously loads the pieces for the next component onto the other side of the fixture. The turnstock then rotates so the next part can be welded while the operator unloads, inspects and reloads the other side – this continuous process provides for high production rates. In addition, the cells also utilize the STT power source, Lincoln’s system-matched STT® 10 wirefeeder and RJ robotic controllers.

Robotic Welding SystemThe material welded at tube.tec is carbon steel that ranges from 14 to 18 gauge with a wall thickness of 16 gauge on average. Because of this thin material, warpage is an issue. The robots are strategically programmed to “jump” from one side of the part to the other so that no area receives too much heat that could lead to warpage.

What makes this application unique is that the part has to adhere to very tight tolerance of ± ½ mm to be able to mount to the ATV in an exact location. Depending on the type of part – front or back carrier, foot rest, bumper – the robots may be required to make from between 21 to 35 separate welds on the part. Welds include butt and fillet welds and may require the robots to move from uphill to flat to downhill – positions that couldn’t be attempted in one continuous bead by manual welding methods. The robots uses .035” Lincoln SuperArc® MIG wire with an AWS classification of ER70S-4 and a mixture of 75 percent argon and 25 percent CO2 shielding gas.

The heart of the robotic welding systems, the STT power source, uses high frequency inverter technology with Lincoln’s Waveform Control Technology™ to produce a weld with reduced spatter and smoke. It does this by sensing and adjusting the weld current during the welding process to optimize the finished bead. This is especially critical on tube.tec’s carbon tubing application.

As far as tooling and fixturing, Smyth notes that tube.tec has grown to take on more and more of the process internally. “With the first robot we basically had it delivered to us as a turnkey package ready to weld. But as we become more familiar with robotic capabilities, we have designed and built more of the weld tooling, fabrication dies and gauging in-house.”

“Using robots has also helped us to keep up with demand by allowing us to easily add extra capacity,” notes Smyth. “If we had to rely on hiring skilled welders each time our production increased, I don’t know if we could have kept up, especially with our location where skilled labor is hard to find.” 

The company currently has 80 employees, 21 of those man the robotic welding stations while nine run the manual welding stations. These 21 robot operators fall within three skill levels: the first is an operator who only loads and unloads parts. The second is an operator that can perform simple adjustments to the robot and the third, and highest level, is an operator that has full programming privileges of the robot. All programming is handled through the robot’s teach pendant that provides easy programming capabilities. With it, tube.tec operators can adjust the size of the weld, change heat settings and parameters to obtain a consistent bead. Smyth says that most of these operators “truly enjoy” running the robot.

“The STT robotic units are outstanding in terms of accuracy, productivity, penetration and overall quality,” notes Smyth. “These robots have helped us to be competitive. Manufacturers come to us for our quality, they also appreciate the fact that we can keep costs down because we don’t have to spend time trying to either weld the whole item by hand or even spend a lot of time removing spatter. You can even hear the difference in the arc – the STT has a different sound than standard MIG equipment.”

But visual inspection of the parts is not the only test of quality. Random parts are pulled from the robot and microetched with solution to test for penetration. In addition, random units are also mounted on a check gauge to ensure that all the mounting points are correct and if not, the tooling is adjusted.

For safety, the robot is contained in an electronically locked safety enclosure. An electronic curtain makes certain that the area is clear before the robotic welder will operate.

Manual Welding

For repair welding operations, tube.tec turned to Lincoln’s new Power MIG™: The Professional Choice, 255. This unit is a DC combination wire feeder/welder, featuring Lincoln’s innovative new Diamond Core Technology™ to provide an extremely smooth and stable arc across a wide range of procedures. Its attributes include dramatic low-end performance, a soft stable arc, superior starting and low spatter.

“We made a commitment to Lincoln technology and have even carried it through to our hand welding station,” reports Smyth. “Other manufacturers may be able to come in and offer us lower pricing on manual systems, but our relationship with Lincoln is so important that we support them because they support us.”

Service Capabilities

Tube.tec is extremely pleased with the service provided by Lincoln. “Our first robotic installation occurred over a weekend. We talked to the Lincoln automation expert in Cleveland at 10 am on a Sunday regarding a problem we had with the installation. Not only was he available at that time, the next day he was in our plant and ready to help.”

Since that time, tube.tec has received excellent service from its local Lincoln representative who is on-site to check the robots and offer technical advice when necessary. The local distributor, Machine & Welding Supply, has also been ready to help and is a constant supplier of wire and other needed essentials to tube.tec.

Smyth reports that the robots has been virtually maintenance free, which is excellent considering the company calculated that it would cost $369 for every hour of downtime.

Future

In the future, tube.tec hopes to penetrate other markets such as automotive, transportation, motorcycle, marine and recreational vehicles with its structural tubing products. The company has grown so much that it is currently doubling the size of its plant with an expansion and plans to add more robots in the near future.

Originally Written 6/12/00

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