LASER PROCESSING OF ORTHOPEDIC BIOMATERIALS - Advanced Biomaterials: Fundamentals, Processing, and Applications - page 277

fl owing through a multi-nozzle assembly. The nozzle is designed such that the
powder streams converge at the same point on the focused laser beam. Subse-
quently, the substrate is moved relative to the laser beam on a computer-
controlled stage to deposit thin layers of controlled width and thickness [24].
There are four primary components of the LENS™ assembly: the laser
system, the powder delivery system, the controlled environment glove box, and
the motion control system. A 750 W Nd : YAG laser, which produced near-infrared
laser radiation at a wavelength of 1.064

m, is typically used for the depositions.
The energy density is in the range of 30,000 to 100,000W/cm 2 . The oxygen content
in the glove box is maintained below 10 ppm during the depositions. The powder
fl ow rates are typically 2.5 g/min while the argon volumetric fl ow rate is main-
tained at three litres/min. The LENS™ offers a unique combination of near-net
shape manufacturing and rapid solidifi cation processing that can be particularly
useful for manufacturing orthopedic implants. A schematic representation of the
LENS™ process is shown on the top of Figure 9.2.

μ

750W Nd:Y AG LASER

Glovebo:

Figure 9.2. Schematic representation and image of the LENS™ laser deposition system.
[Rajarshi Banerjee et al. Laser Deposited Ti-Nb-Zr-Ta Orthopedic Alloys (J. Bio. Mater. Res., 78A
(2), 2006), 298.]