1) Powder dispensed 2) Features created 3) Build platform lowered
& powder dispensed
4) Features created
Build plate Melted &
IMPROVEMENTS IN PROCESS COST AND SPEED
ARE NEEDED TO ACHIEVE GOOD PART QUALITY
Laser additive manufacturing (LAM) is rapidly becoming an important method for the fabrication of both prototype and production metal parts. However, the technology is really just in its infancy, and significant work still needs to be done in the development of new materials and in
understanding how various process parameters affect results.
In particular, LAM methods typically have a relatively small process window for laser performance, where minor changes in
beam and scanning parameters can significantly affect results
quality. This article examines the need for laser beam characterization to deliver optimum results, and then shows how a new
beam monitoring technology enables rapid measurements in
laser-based 3D manufacturing systems. Ultimately, this technology will allow beam issues to be identified and corrected before
they seriously impact the quality of parts produced using LAM.
Most traditional machining techniques are subtractive. That
is, they selectively remove material from a substrate to create
the desired shape. Additive manufacturing methods work the
opposite way, building up a part layer by layer from nothing.
Powder bed fusion (PBF), the primary LAM technique for producing finished parts (see “LAM techniques,” p. 11), is essentially a form of 3D printing that uses metallic powders and a
laser source to melt them.
In PBF, a layer of metal powder about 20–60µm thick is first
spread evenly with a recoater blade over a build plate, which
is a platform that can be moved vertically. Then, the laser is
scanned over the powder to selectively melt and resolidify it
in the desired pattern for that layer. After a layer is finished,
the powder bed is lowered an amount equivalent to the thick-
ness of the layer, and a new layer of powder is spread over
it. The laser writes that layer, and the process is iterated until