Automatic welding

A natural response to the usual problems of human limitations (aptitude, strength, fatigue, vulnerability), task enhancement, production organization and cost reduction, automation has a vast field of applications and developments in welding. The main aspects are :

• handling heavy or cumbersome tools or parts;

• the use of powerful tools ;

• observation of severe and critical welding conditions (time, space, position);

• development of operating cycles that can include effort, etc.

These points are all objectives that are taken into account by various means already known and exploited elsewhere.

Welding techniques do, however, have a number of special features compared with other production techniques, such as machining, to which we often rightly refer. These arise essentially from the fact that every welding operation is affected by random disturbances which ultimately determine the quality of the assemblies. This quality cannot be determined with complete certainty. It is of a probabilistic or statistical nature, because it is difficult to measure other than by costly and cumbersome indirect means, such as the destruction of sample parts, radiography and ultrasound, which pose problems of extrapolation and interpretation.

This is why the automation of welding processes also aims to guarantee, in particular, better quality by reducing the number of defects or defective parts, and significantly lightening inspection operations and their costs. Various means are used to this end, such as :

• precise welding systems and conditions that are insensitive to hazards and adapt automatically without manual intervention, systems based on the regulation of electrical or thermal parameter values (currents, voltages, temperatures) and capable of taking account of random variations in welding conditions, or deviations in the geometry of the parts to be joined resulting from their manufacture;

• automatic monitoring of welding operations in progress, with event recording, message transmission and report generation.

The more efficient the automation at this level, the better the quality of the assemblies will be assured, and the easier and cheaper it will be to control.