Background
The fixture determines the quality of the seam
A significant proportion of weld irregularities are not caused by incorrect welding parameters, but by a component that deviates from its specified condition. No matter how precise the welding procedure is — if the component is positioned differently in every cycle, the result will vary.
For designing and fixture construction, this means that clamping, positioning and accessibility are quality-critical decisions, not a minor matter.
- 01 Root gap and rib spacing vary across the range
- 02 Edge misalignment due to parts not being centred
- 03 Forced position instead of the WPS-qualified position
- 04 Clamping devices cover the seam and the inspection access point
Requirements
Six requirements for welded fixture contruction
Process
Standard components throughout the welding process
For the design
Integrate the function directly into the welded construction
Not every function needs to be constructed. Weld-on standard components provide stop and hinge functions with defined geometry and documented specifications within the assembly — this saves on drawing, production contracts and an additional item in the directory.
- Weld-on D-rings
Compact design, loadable from all sides, no additional threads — for the transport of heavy welded assemblies.
- Weld-on hinges
For hatches, doors and panelling on steel frame and housing structures.
| Task | Product group |
|---|---|
| Maintain the gap and edge offset | Positioning elements (03000), stops, rest pads |
| Enable welded positions | Angle plates, clamping cubes, tooling plates (01000) |
| Quick fixation, keep seam accessible | Toggle clamps (05000) |
| Flat clamping | Clamp straps and claw clamps (04000) |
| Control stress, maintaining tolerance class | Locating pins, positioning elements |
| Reduce set-up times, maintain zero points | Zero-point clamping systems (42000) |
| Set up the control fixtures | 3 axis clamping system for tooling plates (41000) |
| Weld on the fitting | Weld-on hinges (27000) |
| Transport assemblies | Weld-on D-rings (07000) |
Standards
What standards mean for fixture selection
Service
From selection to design
Frequently asked questions
Toggle clamps for rapid clamping, clamp straps and claw clamps for hold-down clamping, positioning elements and stops for precise component positioning, tooling plates, angle plates and clamping cubes as fixture basics.
Using mechanically fixed stops and centring elements in the fixture, rather than manual alignment during clamping. This ensures that the gap dimension remains constant throughout the production run, and the parameters specified in the welding procedure specification always produce the same result.
Place clamp points close to the weld but outside the heat-affected zone, and ensure that the weld is accessible for the torch and visual inspection. Shrinkage should be controlled rather than completely prevented, as restricted shrinkage generates internal stresses.
Tight tolerance classes can only be cost-effectively maintained if the component’s dimensions are specified on a fixture-by-fixture basis. Manual alignment introduces variation into the process, which limits the achievable grade range.
The standard requires controlled and traceable manufacturing conditions. Modular, repeat accuracy constructed fixtures constructed from catalogue parts permit the fixture status to be documented using part numbers.