Stitch welding, also called intermittent welding, is everywhere in structural steel: stiffeners, secondary members and long fillet seams that do not need full-length welds. A vision welding robot can lay stitch welds automatically from the scan, but only if the stitch settings are consistent. This article explains how robot stitch welding is set up and how to check it before the arc starts.
How does robot stitch welding work?
In robot stitch welding the seam is split into short weld segments with unwelded gaps between them. Two lengths matter: D1 is the length of the first and last segments and D2 is the length of each middle segment. The robot finds the seam from the 3D scan and lays the segments along it. Check the path preview before the first weld.
1Why use stitch welding on structural steel?
Where the drawing calls for intermittent fillet welds, welding the full length wastes wire, time and heat, and the extra heat adds distortion. Typical uses are stiffeners on beams and panels, secondary members, and long lap or fillet seams on platforms. Done by hand, stitch welds vary in length and spacing; done by a robot, every segment is the same.
2What do D1 and D2 mean?
D1 is the length of the first and last weld segments, so the ends of a stiffener can be welded longer for strength. D2 is the length of each middle segment. The software spreads the segments along the seam length it measured in the scan, so the same settings work on stiffeners of different lengths.
3Why must stitch settings stay consistent?
Stitch settings live in the seam’s weld procedure package in the PC software. If a second set of stitch values is entered elsewhere for the same seam, for example on the robot side, the two can disagree. The result is a stop at the first segment, or a robot that runs back and forth on the same seam. Keep one source of truth:
- Set stitch values in one place only
Use the seam’s procedure package and leave any duplicate robot-side stitch field empty unless support asks for it.
- Back up before changing
Save a copy of the template or photograph the values first, so you can return to a known-good state.
- Regenerate after changing
Save, regenerate the template and upload the program again; a change only reaches the robot after upload. The full sequence is in the parameter tuning guide.
4How do you check stitch welding before welding?
Use the path preview instead of repeated test welds. It separates a settings problem from an execution problem in one look:
5Which robot suits stitch welding on large parts?
Stitch welds on beams and panels are usually spread over long distances and on both sides of each stiffener. A rail-mounted cell reaches them without moving the part. A 9-axis cantilever workstation covers long stiffened panels and large assemblies, while a 7-axis cantilever workstation suits H-beams, columns and brackets in a narrower range. The differences are explained in cantilever welding robot: 7 vs 8 vs 9 axis.
Frequently asked questions
What is the difference between D1 and D2 in robot stitch welding?
D1 is the length of the first and last weld segments; D2 is the length of each middle segment.
Why does a welding robot stop at the first stitch segment?
A common cause is two stitch settings for the same seam that do not match. Keep stitch values in the seam's procedure package only, then regenerate and upload.
Can a vision welding robot do intermittent welding?
Yes. The robot measures the seam from the 3D scan and lays the stitch segments along it, so the same settings work on parts of different lengths.
Automate stitch welding on stiffeners and beams
Send us a drawing with your stitch weld symbols. We will check reach and cycle time on a cantilever workstation.
- JTCLASER field commissioning and after-sales records, 2026
- JTCLASER cantilever welding robot workstations, published product pages