Almost everything that a welding shop does – particularly with thicker materials – requires a profile, or bevel, on the edge of the material. When two pieces of metal need to be joined, the beveled edges come together to create a trough in which to place the weld material. A beveled edge can be made in a few ways, but more often than not, fabricators make a 90-degree cut, which they then need to manually grind or file down into a bevel.
When the choice is made to bevel the edge – instead of making a straight cut – those secondary operations can be eliminated. By removing the need to bevel the edges manually, the welder can quickly and consistently fill the gap with weld material and, therefore, produce a strong, quality bond.
Consistent cuts
“Fortunately, the industry is moving away from the straight 90-degree edge in favor of cutting the bevel profile in the cutting pass,” says Dave Maxham, vice president of sales and marketing at Soitaab USA. “This is thanks to the advancements made in high-definition plasma cutting and the control software. It allows you to really dial in on producing the perfect beveled edge ready for welding.”
What it all comes down to is consistency, according to Maxham. Plasma cutting removes the need for secondary operations, where inconsistencies can emerge. Previously, welders had to do their best to grind the correct edge profile, but the quality varied with each job and the process was labor-intensive. Later, nibblers were employed, which are similar to a router that moves along the edge of the material, but again, it was still a secondary operation that couldn’t offer consistency across the board.
When fabricators first started plasma cutting beveled edges for their welding operations, the task was a manual one, turning and locking the torch at a 45-degree angle. Since then, the task has progressed to automation. The shift was important, considering the need for consistency and also the need for various beveled angles – at 15, 30 or 35 degrees, whatever the welding job calls for.
“Where the automated plasma cutting process really comes into play is when the top and bottom beveled edges are different,” Maxham explains. “You might have a 45-degree angle on the top and a 30-degree angle on the bottom. Or, the degree of the angle might vary over the length of the edge. Like in every industry, the artisan skill level isn’t as high as it used to be, so welders have to be able to rely on cutting automation to achieve less variation to give them an accurate edge profile.”
Welders can also rely on automation to handle difficult or out-of-the-ordinary jobs. With newer automatic bevel plasma heads, welders can bevel around a corner and can even bevel holes.
One example of a difficult application is a bolt with a beveled head that needs to sit in or be welded flush with the finished surface. “Putting a bevel on the hole can help achieve a perfect fit or a tight weld, which is difficult to do without an automated system,” Maxham says.
Another example is producing saddle cuts in tube and pipe material. Without automatic beveling, pipefitters and pipe welders have to spend extra time manually grinding the profile. And in some cases, manual grinding isn’t even an option.
Sometimes the holes are too small for a grinder, Maxham explains. Other times, such as when working with a pressure vessel with a dome, a 45-degree angle is required, which can be difficult to produce. On top of a tight outer diameter, the curve of the dome carries additional complications. Those complications, however, can easily be overcome when an automatic bevel plasma head is put to use.
Equipment expectations
Whether it’s overcoming the challenge of creating consistent fit-ups or eliminating secondary operations, plasma cutting can be an ideal solution. However, various factors come into play to create the precision beveled edges that welders need.
First and foremost, the equipment needs to be robust and repeatable. The mechanical apparatus needs to be able to lock into a specified angle to turn the torch around the material being cut. When it comes to Soitaab’s high-definition plasma systems, a scissors mechanism is paired with a servomotor to handle the rotation of the plasma head.
“Soitaab’s equipment allows users to mechanically control the motion of the torch to achieve a better bevel and an incredibly accurate cut,” Maxham explains. “I can put my torch at 45 degrees, knowing it will maintain its cutting distance from the surface throughout the entire cut.”
To achieve consistent, accurate cuts, Soitaab’s high-definition plasma systems rely on sophisticated software. The software calculates all of the compensations that are needed for bevel cutting versus straight cutting.
“Because the torch is at an angle when you bevel cut, you’ve changed the distance from the cut surface and changed the thickness of the material to cut through,” Maxham says. “If the software can’t compensate for that, your cut isn’t going to be correct because your off-contact distance was lengthened. If you go from a 30-degree to a 45-degree bevel, the compensations that have to happen are mindboggling. Luckily, the software can make those calculations for you. The role of the software is to make the process as simple as possible for a machine operator by putting all of the control into the CNC.”
For further accuracy, a bevel plasma head must be easy to recalibrate. Sooner or later, a part will flip up and run into the plasma head, which means it will have to be recalibrated.
“The older systems used to be painful to recalibrate,” Maxham notes. “I’ve heard stories of it taking more than eight hours. That downtime is why it’s so important for the system to be as mechanically robust as possible. Today’s bevel plasma heads add or subtract compensation values electronically in the CNC rather than needing manual adjustments.”
Additional considerations
In addition to the overall system and the software, the size of the bevel plasma head is also a critical factor. A drawback found in many bevel heads is that they’re too big for some applications. The bigger they are, the heavier and more cumbersome to work with and repair.
“Soitaab has a large bevel head for shipyard operations, but the company also developed a compact bevel head,” Maxham says. “It opens up the whole world of bevel cutting to small, independent fabricating shops. It’s less expensive and because it’s not a massive contraption, it’s easier to maintain and can be put on a much smaller machine.”
In regard to maintenance, it’s key when an OEM places priority on its service organization. Beyond having a large service team, Soitaab also provides customers with a bill of materials for every machine that lists OEM part numbers, making it easy for them to source parts. Soitaab also offers an online diagnostics tool, which can be connected to customers’ machines. After diagnosing a machine’s issue and sourcing the part in question, the actual repair is also simplified due to the modular nature of Soitaab’s equipment.
Founded in Italy in 1938, Soitaab focuses on producing cutting systems that can make a welder’s job easier, including combo machines that merge plasma cutting capabilities with other processes on one gantry. From drilling and tapping to oxyfuel, waterjet and fiber laser cutting, the company’s machines are geared for ease of use and producing products in short order.
