Radiant Energy:

This category is recommended to cover the new procedure such as laser and electron- beam welding and others, which might yet to be developed. The necessary feature of a radiant-energy procedure is that energy is focused on the workpiece and heat is produced only where the focused beam is intercepted.

This is not possible to define all welding procedure completely by the source of thermal energy. This applies specifically to the various variations of arc welding and it is customary to complete the definition by reference to the way the procedure satisfies the condition of atmosphere control. All welding procedures might be examined in the same way by placing the names of the procedure in a grid formed by listing the sources of heat along one axis and methods of ignoring atmospheric contamination along the other axis, as is done in Figure 2. Now the diagram might be divided up into areas enclosing procedures with a basic similarity. Seven such areas are readily identified equivalent to processes as follows :

1. solid-phase,

2. thermochemical,

3. electric resistance,

4. unshielded arc,

5. flux-shielded arc,

6. gas-shielded arc, and

7. radiant energy.

in the diagram ,certain areas might be marked out as regions where welding procedures could not exist, for instance flames cannot be utilized in vacuum.

This way of classifying welding procedure is less rigid than the family-tree method and makes it possible to account for certain anomalies. The resistance butt-welding procedure, for instance, while truly a solid-phase welding procedure, is normally included in the resistance-welding category. In Figure 2 the position of this procedure is clarified by drawing the boundary of the group (1) solid-phase procedures to include resistance and to exclude the remaining resistance procedure. Likewise, electro-slag welding and its derivatives might be placed correctly in the resistance heat source grid, but might be linked with the flux-shielded arc procedure with which they have a great deal in common.

There is no consistent method of naming welding processes. Various processes are named according to the heat source or shielding method, however certain specialized procedure are named after the type of joint produced. For example stud, spot and butt-welding. A total classification cannot take account of this because the similar type of joint might be produced by a variety of procedure. Arc or projection welding and spot welding might do stud welding by electric resistance, arc, or electron-beam procedure. Resistance, flash or any of a number of other methods might do butt-welding.