Metallic Laser Additive Manufacturing Using 2D Arrays of Scanning Laser Power Sources for Advanced Structural Material Processing
Abstract
The major objective of the proposed effort is to significantly advance metallic laser additive manufacturing (LAM) technology via introducing a novel powder bed selective laser melting (SLM) technique based on utilization of densely packed two-dimensional (2D) array of scanning laser energy sources (2D-LAM laser energy source) capable for parallel processing of the entire powder material layer.It is expected that utilization of the proposed innovative 2D-LAM technology will provide up to two orders of magnitude acceleration of LAM build rate. Besides high material processing speed, the proposed technique will significantly reduce thermal gradients thus leading to better quality as-build parts.The multi-kW 2D-LAM laser power source ~ the key element of the proposed effort ~ provides simultaneous melting of significantly larger volume of powder material leading in dramatic build rate increase (~ 1000 cubic centimeters / hour vs. 100 cubic centimeters / hour in the current LAM systems). One the other hand utilization of the 2D-LAM laser source will result in generation of enormous amount of heat within constrained volume of powder bed SLM processing chamber.Analysis of complicated spatio-temporal dynamics of heat transfer during the 2D-LAM process is one of the key basic research topics of the proposed effort. Being under control, the generated multi-kW heat flux may play a positive role. The generated heat could be used for pre-heating of powder material and slowing down molten pools solidification process. This results in smoothing thermal gradients during material melting and solidification leading to more uniform (predominantly equiaxed) material grain microstructure, reduction of porosity and cracks, and improved material surface finish. The heat transfer analysis for the 2D-LAM process will be performed using the recently developed by our team reduced complexity mathematical and computational models.Vast amount of heat that is generated by the 2D-LAM laser source, may also cause unacceptable temperature rise of both powder and solidarities material leading to powder particles sintering and even material re-melting. We also expect that strong heat flows above the processing layer may cause aberration of laser beams and overheating of the powder bed chamber and parts inside it. Thus, for the 2D-LAM technique to work, the powder bed chamber should have integrated capabilities for active heat removal. For controllable removal of unwonted heat, the powder bed chamber should be designed as a high intensity thermal heat exchanger. In the proposed effort the heat management problem will be analyzed. The preliminary concept is based on consideration of the powder bed chamber being composed of 3D-manufactured heat transfer cells (heat exchange surfaces) with densely packed micro-fins having optimal shapes and material properties for optimal thermal exchange. The concept of heat exchanger for powder-bed chamber will be analyzed using computational fluid dynamics (CFD). The analysis includes optimization of heat exchanger cell geometry, micro-fins shape, aspect ratio and density.The bulk of the research will utilize the GPU-based software tools developed by the team. This research will take also advantage of the UD high-performance computing system received through an AFOSR DURIP grant, and the metallic powder bed SLM machine developed under the ONR SALAAM SBIR and WALAM STTR contracts.
Document Details
- Document Type
- DoD Grant Award
- Publication Date
- Apr 24, 2019
- Source ID
- N000141912122
Entities
People
- Mikhail Vorontsov
Organizations
- Office of Naval Research
- United States Navy
- University of Dayton