Nominal reach is not a guarantee that a robot can weld every joint inside that distance. A usable welding workspace also depends on torch orientation, robot configuration, obstructions, and the selected tool. Treat reach as an initial sizing constraint, then test the required poses and paths.
In this Article
- The farthest point is not the whole working area
- Why articulation belongs in the specification
- A two-part comparison that exposes the difference
- A useful workspace worksheet
The farthest point is not the whole working area
Start with the full assembly, including its location on the table. Then consider the torch orientation needed along every seam. A nominal reach figure does not describe all usable tool angles at every location.
Long parts can create a separate challenge from crowded parts. A large open frame may need a different reach solution than a small weldment containing several obstructed internal joints. Neither problem should be reduced to selecting the largest available arm.
Why articulation belongs in the specification
The Kassow KR Series combines seven-axis articulation with model-specific reach and payload ratings. Those are separate selection criteria, not interchangeable benefits.
For purchasing, make two lists: the locations the tool must reach and the obstacles the arm must clear. This keeps an attractive reach number from concealing a difficult approach. It also prevents paying for a larger footprint when articulation is the more relevant issue.
A two-part comparison that exposes the difference
Consider two hypothetical assemblies. Part A is a long, open frame with its required seams facing the robot. Part B is a smaller enclosure with joints behind internal ribs. The larger part can be the simpler access problem even though its farthest seam is farther from the robot base.
For Part A, the first concern is whether the intended poses fit within the selected system's usable range. For Part B, the first concern may be whether the torch and arm can approach without interference. Buying a longer arm addresses a different question from gaining another way to arrange the elbow.
| Requirement | Information needed | What the information does not prove |
|---|---|---|
| Reach the far seam | Base location, part position, and complete tool geometry | Clearance for every torch angle |
| Weld behind a rib | Tool approach and arm-link clearance | That every joint on the assembly is accessible |
| Cover a family of sizes | Required poses for the limiting family members | That the same setup suits every intermediate variant |
A useful workspace worksheet
Mark the nearest seam, farthest seam, lowest approach, and most obstructed joint on a drawing. For each, record the required torch direction and the part orientation. This turns a general size request into several checkable conditions.
Include the actual tool package because the tool center point is not located at the robot flange. Also distinguish the weight of equipment carried by the arm from the weight of an assembly supported on a table. A robot welding a supported frame is not lifting that frame.
The output of this review should be a defined set of achievable paths, not a circle drawn around the robot base. That is the difference between buying nominal reach and buying usable welding access. Spartan can review that worksheet alongside the intended seven-axis configuration.
Related Reading
- 7-Axis Cobot Welding for Hard-to-Reach Welds: What to Check First
- Welding Automation System Requirements: What to Gather Before an Application Review
Discuss Your Welding Application
Works Cited
Kassow Robots. "7 Axis Collaborative Robot Arm: KR Series." Kassow Robots, https://www.kassowrobots.com/products/7-axis-collaborative-robot-arm-kr-series. Accessed 14 Sept. 2026.