Spartan's seventh axis is the seventh joint inside the Kassow robot arm. It is not a linear rail. The arm itself has seven controlled joints, giving it additional flexibility in how it positions the welding torch around a workpiece and its surrounding fixtures.
In this Article
- The extra joint is part of the arm
- Why elbow position matters to weld access
- Keep the welding requirement fixed
- Flexibility is different from reach and weld quality
- Apply the advantage to your own assembly
The extra joint is part of the arm
The useful distinction is between the torch's pose and the arrangement of the arm holding it. Pose includes both position and orientation. A welding application needs the torch at the joint with an appropriate orientation, while the rest of the arm also needs room to move.
A seven-joint arm has an additional degree of freedom for arranging its links for a given tool pose. Kassow describes this in terms of elbow-position flexibility. Joint limits and the physical surroundings still constrain the available configurations; the extra joint does not remove those constraints.
Why elbow position matters to weld access
The torch is only one part of the equipment approaching a seam. An arm link can interfere with a frame member or fixture even when the torch has space to reach the joint. Changing the arm's configuration can therefore matter independently of changing the torch's required position.
This is where the internal seventh joint can be useful. It provides additional arm-configuration choices to investigate around the obstruction. The benefit is flexibility within the arm, rather than movement of the robot base along the workpiece.
Keep the welding requirement fixed
A useful access comparison holds the required torch pose constant while examining how the arm can accommodate it. Moving the torch to an unsuitable angle merely to clear an obstacle changes the welding task instead of demonstrating the desired access.
Check the approach, the full weld path, departure, and movement between seams. Reaching the beginning and end of a weld is not the same as establishing a workable path between them. The actual torch package and fixture arrangement belong in that review.
Flexibility is different from reach and weld quality
The seventh joint does not automatically increase a robot model's specified reach. Robot selection still depends on the required working range, the equipment carried by the arm, and the planned mounting and part locations.
It also does not independently determine weld quality. The welding process, joint preparation, and workpiece conditions must suit the application. A six-axis arm can produce acceptable welds; the reason to evaluate Kassow's additional joint is the configuration flexibility it brings to the required motion.
Apply the advantage to your own assembly
Start with the recurring assembly and identify where arm clearance complicates the required torch approach. A drawing, fixture layout, and marked seams give the application discussion a specific geometric problem to address.
Spartan's seven-axis welding approach combines that Kassow arm flexibility with Fronius welding technology. The buying question is whether the internal seventh joint helps achieve the required weld coverage on your assembly. Any handling or production benefit should follow from the verified application, not from axis count alone.
Related Reading
- 7-Axis vs 6-Axis Cobot Welding: Which Is Better for Fabrication Shops?
- Tight Fixtures in Cobot Welding: Why Weld Access Matters
Discuss Your Welding Application
Works Cited
Kassow Robots. "Frequently Asked Questions." Kassow Robots, https://www.kassowrobots.com/faq. Accessed 14 Sept. 2026.
Elias, Alexander J., and John T. Wen. "Redundancy Parameterization and Inverse Kinematics of 7-DOF Revolute Manipulators." NASA Technical Reports Server, https://ntrs.nasa.gov/citations/20240008776. Accessed 14 Sept. 2026.
TWI. "Robotic Arc Welding." TWI, https://www.twi-global.com/technical-knowledge/job-knowledge/robotic-arc-welding-135. Accessed 14 Sept. 2026.