America Makes
Additive manufacturing (AM) technologies are known to provide benefits for low-volume, high-mix casting production. They offer advantages for tooling design and opportunities to improve productivity rates in upstream or downstream operations from the casting process. As such, the U.S. government, and the Department of Defense (DoD) recognize the need to prioritize AM integration in casting applications.
Although AM promises to augment the casting industry, its current limited utility, especially in defense and sustainment, prohibits full integration. Additionally, a decline in U.S. foundries exacerbates an existing workforce shortage, further hindering progress.
Nonetheless, AM's potential to improve the casting sector is enough to draw on the broader industry for innovative solutions with America Makes, the national additive manufacturing innovation institute, at the helm. Tasked by the DoD, the Institute, in partnership with Deloitte Consulting, developed a multi-year technology roadmap to create and deploy AM capabilities in the casting and forging (CF) industry. This roadmap assessed issues affecting the CF industry, identified AM opportunities to mitigate these issues and determined the investments needed to support AM integration into manufacturing operations. Based on these findings, a portfolio of projects and their corresponding execution plans were defined and are now being deployed to drive AM usage in the casting and forging industry.
The need to scale sand printing capabilities was a high priority, high impact project that emerged from the roadmap activities. To address the immediate need, America Makes released a project call to meet market demand.
Aerospace industry leader, Honeywell was awarded the project, and in October 2023 began working on the two-year endeavor to improve the casting quality of parts produced with AM sand molds and cores.
Areas of focus included:
- Evaluating and implementing measures to improve surface roughness.
- Identifying methods to minimize dimensional variations.
- Determining cause and identifying methods to reduce porosity caused by sand mold outgassing.
- Developing methods to disseminate findings and best practices to industry.
Navigating part quality pain points in AM sand casting components
Binder jetting is among the AM techniques used for creating sand molds and cores. However, like other AM technologies, its limitations currently restrict usage due to its influence in critical part applications.
These include:
- Surface roughness (caused by stepping where finished metal parts retain the layered texture of the 3D sand mould).
- Dimensional inaccuracies
- Porosity due to mould outgassing during the casting process.
The project explores the application of AM sand molds and cores to produce Honeywell's gearbox housings, covers, and inlet housings for the Chinook Helicopter T55-714C engine. Working in tandem with project partners ExOne, Hoosier Pattern, Ohio Aluminum, and Chicago Magnesium, Honeywell is evaluating the current processing parameters for AM sand molds and cores. Cast part assessments based on design requirements will ultimately identify quality gaps and gauge technological improvements.
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The success of this project will provide a new baseline of recommendations for improving AM sand molds/cores for the broader sand casting industry.
Transitioning best practices and technology improvements
AM technologies provide an opportunity for greater profitability, new markets, and new business models, but without an expansive understanding of how to address workforce gaps and limited capacities of small-to-medium-sized foundries, the industry will remain at a crossroads.
A second layer of this project is to support small and medium-sized foundries lacking the necessary data and models for their casting operations, which is crucial to mitigate business risks while competing in the bidding process for low-volume or high- mix products.
These efforts, led by the American Foundry Society (AFS), include developing training materials and courses for domestic sand casting industries. The objective is to promote best practices and methods to improve the quality of cast parts produced with sand-printed molds and cores. Additionally, industry events will feature presentations that highlight technology improvements and best practices for additively producing sand castings.
AM sand casting and broader industry impact
America Makes recognizes that transitioning from AM usage to wide adoption requires a joint effort to assure the needs of the larger market are met. The ongoing project demonstrates the Institute's commitment to staying ahead of innovative solutions, providing practical steps that create a significant impact.
This project lays the groundwork to enhance the quality of sand-cast parts, accelerating AM adoption across tooling for sand casting applications. From a broader perspective, leveraging the America Makes road-mapping efforts to identify and address CF industry gaps presents a significant leap in AM maturation, ultimately enhancing national security.
Litsa Rubino manages the National Additive Manufacturing Innovation Institute’s technology projects and is also responsible for leading internal strategy development and formation of new project efforts that focus on integrating additive manufacturing into casting and forging technology.
This article originally appeared in TCT Magazine North American Edition - Volume 10 Issue 3. Read the digital edition and get your free print subscription.
