type of equipment, without any heat-affected zones and with
optimal, consistent high quality.
Special cases concerning processes using
high density energy sources
High density energy source processes concern laser and electron
beam welding. Both processes use a beam (a laser or electron
bombardment) accurately focused to make the energy that is
aimed at the part to be welded melt the metal. Using these
techniques, welding can be performed over depths of several
hundred millimetres in a single pass and with a bead that is rarely
more than 5 mm wide.
Assemblies welded in this way do not require bevels but
extremely accurate facing on part ends. For example, preparation
for laser welding will be acceptable if the alignment fault is less
than 1/10
th
of a millimetre. Moreover, parts must be totally free
of any contamination for using these technologies successfully,
especially electron beam welding. As electron beam welding
operations are carried out under vacuum conditions, no water
or hydrocarbon residues must be allowed to enter the chamber
as their presence is liable to make creating a vacuum a more
delicate task.
Using these ultra hi-tech methods requires the presence of
suitable machining equipment capable of perfectly preparing the
ends to be welded.
Welding is always a delicate operation. A large number of
parameters have to be known and mastered for obtaining the
best possible results. Otherwise, they are all as many defect
causing factors liable to occur during or after completing the
welding bead and which may deteriorate the quality of the total
assembly.
Despite upgrading techniques and increased knowledge on
the subject, industrialists are regularly confronted by problems
involving non-conform welded joints. The consequences of a
poor weld can be disastrous for the success of a project, in terms
of both schedules and budgets. Eliminating a welding bead and
re-building it may take several hours or even several days in the
case of major assemblies.
Correctly preparing the edges to be welded will never
prevent 100% of all the reasons for defects from occurring, but
it will increase the final quality of the welded assembly in every
single case.
Figure 6.
Protem splitframe TTNG.
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