The research objective of this award is to understand the relationships and interactions when combining additive and then subtractive direct manufacturing techniques so that the sequential combination yields the advantages of both production techniques without incurring significant disadvantages. Two specific objectives are: 1) To identify the part geometry inaccuracy and shrinkage in order to establish material allowance during additive processing, and 2) To identify and create mathematical and physical models for setup to account for location error due to the nature of direct metal fabrication surfaces.
If successful, this work will provide a rapid capability to make parts with complex freeform geometries as provided by function free-form additive systems, while providing exacting tolerance control and material properties, as provided by computer numerically controlled machining by using these processes sequentially and automatically. This research will lead to a new technology that would create service parts and prototypes for next-generation complex mechanical part systems with the specified material properties, to the exacting tolerances and advanced geometries as desired, and do so in an automated manner with little or no human intervention required.
The research objective of this award was to develop a better understanding of the relationships and interactions when combining additive and then subtractive manufacturing techniques so that we can better realize some of the promises of 3D printing technologies. Two specific objectives of the project were to: 1) Indetify the part geometry inaccuracy and shrinkage in order to establish material allowance during additive processing, and 2) Identify and create mathematical and physical models for set-up to account for location error due to the nature of Direct Metal Fabrication using hybrid 3D printing and then automatically finish the part using subtractive processing. Both of these objectives have been realized, and an operational system to produce 3D printed metal parts that can then be directly finished on a 4-axis CNC machining center has been demonstrated. This work has provided a pioneering rapid direct manufacturing capability to make parts semi-automatically from a CAD model with complex freeform geometries as provided by a powder-bed metal functional free-form additve system (a EBM 3D printer), while providing exacting tolerance control as provided by a CNC machining center by linking additive and subtractive processes sequentially, and then automatically generating the NC programming instructions. This research has lead to a new technology that will be capable of creating service parts and prototypes for the next generation of complex mechanical part systems with exacting tolerances. The NSF funding has provided us the ability to take basic research in the understanding of hybrid direct digital manufacturing to a level where we have received additional funding from America Makes to further develop the software tools created as part of this research project (TRL levels 4-7). One PhD student, Guha Prasanna Manogharan, completed his graduatied from NC State University and has moved to a faculty position at Youngstown State University where he is continuing the work from this project. A second PhD student, Harshad Shrinivasan, has been supported and is currently completing his dissertation research on "The automatic scanning for offset location of 3D printed metal parts". The NSF funding has provided us the ability to take basic research in the understanding of hybrid direct digital manufacturing to a level where we have received additional funding from America Makes to further develop the software tools created as part of this research project (TRL levels 4-7).
