Welding process monitoring is not automatically weld inspection
Current, voltage, imaging and acoustic signals can describe process stability accurately. They demonstrate weld conformity only when the monitoring system is validated for that specific task.
More sensors do not automatically create more certainty
Modern welding stations may record current, voltage, wire-feed speed, weld-pool images, acoustic signals and torch motion at the same time. Combining several data sources can improve anomaly recognition, but the value of the result depends on what the system is expected to decide.
A recent survey divides multi-modal fusion into three levels: raw-data fusion, feature-level fusion and decision-level fusion. Each has different requirements for time alignment, calibration and interpretation.
Four statements that should not be treated as equivalent
- process parameters remained inside a configured envelope,
- the system detected a known process anomaly,
- a model estimated penetration or another property,
- the weld satisfies the product-standard and inspection-plan requirements.
These statements may be related, but they are not interchangeable. A model can achieve high average accuracy and still fail on a new joint geometry, material, coating or camera setup. Representative production validation and a defined uncertainty are essential.
Practical rule
Monitoring provides strong evidence of process control. If it is intended to replace or reduce another inspection, that substitution must be permitted by the applicable specification and the relationship between measured signals and the required weld property must be demonstrated.
Source
- Li, C. et al.: Multi-modal fusion for welding process monitoring: a survey, *Welding in the World*, 10 September 2026.
This article is independent technical commentary based on the public abstract and general validation principles. It reproduces no figures or text from the publication.