Real-time quality control for welding processes

Context

In mechanised applications, welding is performed using pre-set welding parameters in order to obtain a repeatable weld quality. Manufacturing tolerances of upstream operations, such as profile cutting and edge preparation, variation in the chemistry and accuracy of assembly, can significantly affect the quality of the welding operation, which can be challenging and expensive to control.

Measurement systems

In the past decades, a lot of research has been conducted to measure the shape of the weld pool. Various types of optical sensors have been applied to provide real-time monitoring of welding parameters, such as arc length, weld pool oscillation and weld pool size measurement.

The weld pool characteristics provide important information about the weld quality. For example, there is a strong correlation between weld pool width and the degree of penetration in TIG-welding. The weld pool width, volume and position relative to the joint are also important to determine the surface profile of the weld and the likelihood of the presence of imperfections, such as lack of fusion and penetration. High-quality images of the weld pool are essential to detect weld pool deviations and to implement the necessary changes of the welding parameters, in order to maintain the weld quality.

Advantages

• real-time process visualisation, monitoring and quality assurance,
• the process parameters can be adjusted in real-time,
• fast error detection reduces destructive testing and scrap,
• data, images or videos can be stored for quality documentation.