Method of Layer Height Control in Direct Laser Fabrication
of 304L Stainless Steel
International Congress on Applications of Lasers & Electro-Optics
(ICALEO 2003), Jacksonville, Florida, October 13-16, 2003,
Paper No.904, Laser Institute of America, Publication No.595,
Vol.95, ISBN 0-912035-75-7, 2003
Watkins, The Laser Group, The University of Liverpool,
Liverpool, United Kingdom, L69 3GH, UK
Eamonn Fearon, The Laser Group, The University of Liverpool,
Liverpool, United Kingdom L69 3GH, UK.
Direct Laser Fabrication is a blown
powder laser deposition process capable of producing fully
dense metallic parts by a layered manufacturing method.
The process has applications in the fields of rapid manufacture
and the repair or modification of existing metallic parts.
However, a common problem encountered with this technique
is the unwanted variation of layer height during the deposition
process. This variation can lead to non-uniformity of the
build and a deviation from required tolerances. Investigation
of methods of delivery of powder to the laser-generated
melt pool has resulted in a means of ensuring the deposition
of consistent and controllable layer heights under a variety
of process conditions. This paper describes how this is
achieved while using an in house four port powder delivery
nozzle. The process is demonstrated for the manufacture
of 304L stainless steel samples and shows control of cumulative
height errors in multilayer builds. In addition, the ability
of the powder delivery system to deliver a near-constant
layer height for different layer deposition parameters and
to allow the generation of a variety of consistent layer
heights for a single set of process parameters is illustrated.
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