Optimizing feasibility of using Additive Manufacturing to print 3D metal parts
This project will simplify and improve the Bureau of Reclamation's (Reclamation) efforts to leverage metals additive manufacturing (AM), or 3D printing, for hydropower applications by dramatically simplifying post-processing. To achieve this goal, this project will study and validate the mechanical and corrosion performance of metal AM components processed using a support dissolution technique developed by Professor Owen Hildreth from the Colorado School of Mines.
Reclamation is currently pursuing a goal to be able to use AM to replace parts of structures or features that are broken or in need of repair. Since many of Reclamation's structures were built nearly a century ago, replacing certain metal features is difficult and expensive as most original manufacturers are no longer in operation and the parts essentially must be custom-made. AM could be used to print the actual part or the mold that can be used to cast a replacement part, however, current AM technologies require support structures to print fluid pathways, overhangs, and many of the complex geometries found in Reclamation-relevant replacement parts. At best, removing these support structures adds considerable costs (support removal accounts for approximately 46 percent of the total cost of metals AM) and at worst, removing the supports is impossible (e.g. an internal fluid pathway) and an entire class of parts cannot be manufactured using AM.
Although it may be possible for Reclamation to print the needed parts, post-processing of the complex geometries could be too costly and time consuming for AM to be a feasible solution. In addition, some parts, like impeller blades and hydraulic passageways within generator air coolers, require certain design tolerances to function appropriately (e.g. smooth surfaces to enable proper hydraulics). Currently, as demonstrated by researchers at Oak Ridge National Laboratory, AM of impeller and other blades inherently produces a step-like profile on the blade's sur
Need and Benefit
Although AM is a growing technology with the potential to revolutionize the manufacturing of metal parts, it is currently severely limited in the design and complexity of parts that can be printed due to the necessity of structural supports that must be removed during post-processing. The post-processing procedure accounts for nearly half of the total cost of printing a part. In addition, some structures that Reclamation could benefit from printing would be impossible to print due to the inability to manually remove internal support structures. Optimizing the post-processing procedure by implementing dissolvable supports will enable printing of any part independent of component geometry, complexity, and build orientation. In addition, the same technique may be used to improve the general surface finish of a printed part.
Manual removal of the structural supports needed to print an AM part can cost upwards of $100/hour, requires skilled labor and dedicated equipment, and can take weeks to complete. Implementation of dissolvable supports negates the need for skilled labor, only requires a few dollars' worth of chemicals, and can be completed in less than two days. For large or numerous parts, cost savings of dissolvable supports have been estimated to be 1/14,000th that of manual removal while requiring only 1/450th of the processing time (estimates assume 40 hours of machining time per part at $100/hr = $320,000 per 80 parts traditionally post-processed, compared to 0 hours of machining and 10 minutes of low-skilled labor at ~$75/hr, plus ~$10 in chemicals = ~$23 total per 80 parts). (Cost/time source: machinists at the Colorado School of Mines)
Contact the Principal Investigator for information about partners.
Bureau of Reclamation Review
The following documents were reviewed by experts in fields relating to this project's study and findings. The results were determined to be achieved using valid means.
Investigating the Effect of Post Processing Procedures on Corrosion Resistance of Additively Manufactured 316L Stainless Steel (final, PDF, 2.9MB)
By Stephanie Prochaska
Report completed on September 30, 2020