A vapour cavity forms and
allows the laser beam to
penetrate deep into the
material (energy input
deep beyond the workpiece
surface); this effect is
called the “deep penetration
effect”. The cavity
which is moved though the
joining zone and is prevented
to close due to the
vapour pressure is surrounded
by the largest part
of the molten metal. The residual material vaporises and condenses either on the cavity side
walls or flows off in an ionised form. With suitable parameter selection, an almost complete
energy input into the workpiece can be obtained.