Robotic Welding Suitability Checklist for Structural Steel
Check part geometry, torch access and the information needed for evaluation.
Fit-Up and Joint Requirements
Fit-Up, Gaps and Joint Types: Preparing Steel Parts for Robotic Welding
Check assembly accuracy, gaps, groove tolerances and 12 joint types before welding. Use these figures when you plan fixtures, gaps and tack welds for the parts you want to weld on the station.
Assembly and Positioning Accuracy
- Combined assembly and positioning error: <30 mm.
- Angular deviation: <8°.
- Seam length variation: <30 mm.
- Best laser detection width: 100 mm.
- Shortest edge: ≥30 mm.
- Weld access hole: ≥15 mm.
Assembly Gaps and Groove Preparation
| Weld leg | Maximum assembly gap |
|---|---|
| ≥8 mm | 3 mm |
| 5 mm ≤ leg <8 mm | 2 mm |
Groove dimensions have a ±1 mm tolerance, with 0–5° angular deviation and a maximum depth of 25 mm. Place tack welds at least 20 mm from the arc start point.
Torch Space and Collision Checks
The software checks collisions to assess access for camera scanning and the welding torch. Clearance depends on the height of nearby stiffeners and flanges. With a 100 mm, 135° water-cooled torch, allow about 150 mm between stiffeners for flat welding, or about 450 mm for vertical welding with the torch at 0° to the web.
The angle between part plates should be ≥70°. When stiffeners and flanges are 200 mm high, leave at least 200 mm between stiffeners.
12 Joint Types Located by Camera Scanning
| Joint | Location method | Minimum dimensions | Notes |
|---|---|---|---|
| Three-plane intersecting fillet | Static camera scan of the three-plane intersection | Each plane width ≥30 mm | — |
| Two-plane intersecting fillet | Static camera scan of endpoints | Each plane width ≥30 mm | — |
| Lap joint | Static camera scan of endpoints | Overlapping plate thickness ≥8 mm; base width ≥30 mm | — |
| Annular fillet on concentric cylinder walls | Robot-guided camera scan of the whole circle | Radius ≥100 mm; Wall height ≥18 mm; Base width ≥15 mm | Multi-pass welding |
| Solid-cylinder fillet | Robot-guided camera scan of the whole circle | Radius ≥100 mm; Height ≥18 mm; Base width ≥15 mm | Multi-pass welding |
| Annular lap joint | Robot-guided camera scan of the whole circle | Radius ≥100 mm; Wall height ≥12 mm; Thickness ≥15 mm; Base width ≥12 mm | — |
| Solid-cylinder lap joint | Robot-guided camera scan of the whole circle | Radius ≥100 mm; Height ≥12 mm; Base width ≥15 mm | — |
| Closed fillet with straight and arc segments | Robot-guided camera scan of the closed path | Radius ≥100 mm; Wall height ≥18 mm; Base width ≥15 mm | Multi-pass welding |
| Free-curve fillet | Robot-guided camera scan of the whole curve | Radius ≥50 mm; Wall height ≥18 mm; Base width ≥15 mm | Multi-pass welding |
| Free-curve lap joint | Robot-guided camera scan of the whole curve | Radius ≥50 mm; Wall height ≥12 mm; Thickness ≥15 mm; Base width ≥15 mm | — |
| Two slanted plates, fillet | Static camera scan of endpoints | Plate angle 45°–135°; each plane width ≥30 mm | — |
| Three slanted plates, fillet | Static camera scan of endpoints | Plate angle 45°–135°; each plane width ≥30 mm | — |
Use intermittent welding on straight seams and continuous welding on circular and curved seams.
Quick Teach for Seams Beyond the Scan Range
The station also supports full teach programming with a screen-equipped pendant. With quick teach, the operator marks only the seam start, end and transition points; the robot takes the welding parameters from the process library, so no parameters need to be set by hand.
Fit-Up and Joint Questions
How accurate must assembly be?
Keep combined assembly and positioning error below 30 mm, angular deviation below 8° and seam length variation below 30 mm.
What assembly gap is allowed?
For a weld leg ≥8 mm, the maximum gap is 3 mm. For a leg from 5 mm to less than 8 mm, the maximum is 2 mm.
What are the groove and tack-weld requirements?
Groove dimensions have a ±1 mm tolerance, with 0–5° angular deviation and a maximum depth of 25 mm. Place tack welds at least 20 mm from the arc start point.
Can circular and curved joints be scanned?
Yes. The robot guides the camera along the circle, closed path or free curve. Check the minimum dimensions in the 12-joint table and use continuous welding on these seams.
How do I prepare a seam outside the scan range?
The station also supports full teach programming with a screen-equipped pendant. With quick teach, the operator marks only the seam start, end and transition points; the robot takes the welding parameters from the process library, so no parameters need to be set by hand.
Related Pages
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