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Cutting in 3-D

Robotic plasma cutting in a 3-D world

Automating plasma cutting in 3-D space requires everyone involved to be at the top of their game. Programming a robot to maneuver the plasma torch at different angles and speeds to create steady curves and smooth bevels in three dimensions simultaneously is a tall order.

The FlexFab robotic plasma cutting cell is proficient at creating 3-D parts and complex shapes, but it can also cut 2-D parts, which is a must for custom shops or those who deal with high-mix, low-volume work.

Arc Specialties Inc. thrives on solving problems just like this. Leveraging nearly 40 years of metal joining and cutting experience, the Houston-based automation integrator has built machines for the consumer, oil and gas, defense and research industries in more than 30 countries. Rather than take a one-size-fits-all approach, the company creates innovative solutions that meet unique operational needs and support sustainable growth. Arc Specialties always matches the solution to the problem.

As more industries began to demand metal cutting processes beyond traditional 2-D plate cutting, advanced cutting solutions manufacturer Hypertherm Inc. approached Arc Specialties with the idea to design and build an automated solution for 3-D robotic plasma cutting. The result was a collaborative effort.

Essential programming

This particular puzzle had three parts: the cutting system, the robot and the software. Hypertherm’s advanced plasma cutting systems and Kuka Robotics’ powerful robot controller use EtherCAT communications, making them a good fit out of the gate. Both companies already had a relationship with Arc Specialties and were well aware of the integrator’s motion control expertise. Kuka’s recommendation for Arc Specialties to tackle the software side and integrate all of the plasma cutting cell components only reinforced the alliance.

The idea was to create a turnkey fabrication system that could quickly and easily convert CAD drawings into 3-D plasma cut steel parts without labor-intensive programming. That’s where Hypertherm’s Robotmaster offline programming software became an integral piece of the puzzle.

“Robotmaster is essential,” says Dan Allford, Arc Specialties’ founder and president. “A 3-D CAD drawing simply shows what the final part should look like. There is a huge amount of information needed to generate the robot path and parameters to create the part. The plasma torch must be offset to the outside of each cut line and angled in the right direction. Complex curves must be broken down into small spline segments to create a smooth final cut.

“It could be thousands of lines of code,” he says. “No human could possibly do this. That’s all Robotmaster.”

Robotmaster software eliminates the need for point-by-point robot programming, saving time and labor. Offline programming also increases uptime, as there’s no need to shut down production while programming the robot for a new job.

With all collaborators on board, Arc Specialties designed and built the FlexFab 3-D robotic plasma cutting cell. The system made its debut at Fabtech 2019. Show-goers were able to see CAD-to-path in real time and witness first-hand how easy it was with Robotmaster software. While onlookers watched, a user would change the design of a part, push a button and the robot would cut it immediately.

“Anybody can hang a plasma torch on a robot,” Allford says. “But then you still have to teach the robot the path. For us, we can take a CAD drawing and import it into Robotmaster software. From there, we convert that into robot code and make 3-D parts with no programming in between. FlexFab turns 3-D drawings into 3-D parts without any intermediate steps.”

Integrated flexibility

The FlexFab plasma cutting software converts CAD models for 3-D plasma cutting, saving users substantial time and labor.

The 3-D world demands flexibility. What puts the “flex” in FlexFab? The 6-axis robot for one. The software is another.

Compared to a standard CNC plasma table or a purpose-built machine, the flexible robotic plasma cutting cell is not only proficient at creating 3-D parts and complex shapes, it can still cut 2-D parts. This is particularly advantageous for low-volume, high-mix applications where fabricators need the flexibility of frequent changeovers and easy programming.

Arc Specialties’ customers have included fabricators of pipelines for gas and oil and general industrial use and manufacturers of pressure vessels and filters. But any fabricator cutting plate, pipe, Ibeam, channel or angle can benefit from the FlexFab system.

No matter the application, Robotmaster software’s flexibility and ease of use also make the integration process easier.

“Robotmaster allows us to take on more challenging problems,” says Kevin Sevcik, control systems programmer at Arc Specialties. “It’s faster than other approaches we’ve taken with cells like this in the past. Some geometries are more complicated shapes that wouldn’t be practical to do from a type-in-a-bunch-of-dimensions standpoint. You really need offline programming software, and Robotmaster is the easiest to work with.”

Sevcik was responsible for bringing precision control to the FlexFab system. The cell’s ability to – on the fly – optimize cutting parameters every few millimeters demonstrates Arc Specialties’ motion control prowess. Robotmaster’s simulation and path optimization tools help even highly skilled, experienced programmers like Sevcik visualize and optimize error-free robot trajectories for simple and complex applications.

“Sometimes, there are motions you need to do with the robot where you’ll run into a singularity or you’ll run into a limit on one of the axes,” Sevcik says. “Robotmaster’s path optimization makes seeing those limits and working your way around them a lot easier.”

Robotmaster’s pre-processing tools are designed from the robot programmer’s viewpoint. On the screen before them, users see potential errors before they occur. Angle the plasma torch in this direction, the zone turns red. Try it the other way, it turns green. The path optimization is visualized and good to go.

Future partnership

Watch the video to see a demonstration of Hypertherm’s and Arc Specialties’ FlexFab 3-D robotic plasma cutting cell.

Looking forward, Arc Specialties will work closely with the Robotmaster team to fine tune the robot path generation process for 3-D plasma cutting. The flexibility of the Robotmaster platform makes it malleable to integrators’ unique needs.

Arc Specialties has recently integrated Fanuc robots into the FlexFab concept and plans to integrate the system with ABB robots, as well. This is easy with Robotmaster, as the single software solution works with any of the major robot brands.

“When we have a problem, we need to know that we can call on somebody that is knowledgeable about the process,” says John Martin, Arc Specialties’ vice president of operations. “That’s why these types of relationships with Robotmaster and Hypertherm are so important.”

With the right partners by their side, manufacturers and fabricators can face any challenge.

Arc Specialties Inc.

Hypertherm Inc.

Kuka Robotics