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Laser welding is an effective method for joining small parts with tight
tolerances. In the future, it will compete with
traditional methods of welding or replace assembly/joining technologies
benefiting industries that have never used laser welding before.
The Laser Welding Process
Using light in the form of laser radiation as the energy source is a
process used to achieve a balance between the process of thermal fusion
and metallurgical effects. Functionally, the laser generates infrared
or visible light (usually with the use of Nd-YAG lasers or frequency-doubled “green” lasers
for reflective metals) which is delivered through an optical fiber and
focusing lens onto the workpiece. Welding is the process that occurs
when laser radiation is absorbed by the workpiece and turned into heat
raising the temperature in the localized area above the melting point.
Movement of the worktable is controlled by CNC in order to produce 2
or 3 dimensional welds. The Focal Point is the “melt pool”.
It follows the transition of stages on the surface of the workpiece.
The newest techniques to synchronize laser pulsing with certain value
of motion (fire on position of the encoder) creates an unprecedented
quality of welds on complicated 3-dimensional objects. The quality of
a weld is defined by the depth, width, mechanical strength, and hermetisity
of the welds. It is ultimately controlled by speed and acceleration
of the workpiece.
Applications Present Possibilities
Laser welding can be a powerful tool when used in conjunction with other
machining methods for manufacturing scientific instrumentation, building
medical devices, electronics applications, and consumer driven products.
There are various ways parts can be joined and/or machined to achieve
desired functionality.
A micro gear made from 400 series stainless steel (in
hardened condition) needed to be joined to a driver made of powder-metallurgical
methods. A very high torque application was required for a mechanical
strength test. The issue was resolved by running multiple passes of welding
at relatively low energy penetrating deep into the material. Helium purge
gas with special heat treatment was used to relieve the process stress
without compromising the hardness of the parts. The method was successful. Currently
these gears are flying in space.
Gateway Laser Services has developed a special process
for welding a very thin-walled hypotube produced from
303 stainless steel. Although in the past it was
considered unpopular to weld 303 stainless steel, now
we apply this same method for that configuration to medical
devices. |
