Summary
A novel computer numerical control (CNC) machine and tool base significantly reduces costs and speeds production while enabling manufacturers to produce parts larger than the machine’s physical workspace. This innovation lowers economic barriers for small- to medium-sized US manufacturers, as well as offer strategic advantages for forward-deployed military units.
Problem
Traditional machine tool bases, typically made from cast iron, are expensive and time consuming to produce, prompting much of this critical manufacturing capability to shift overseas, beginning in the 1980s. Despite being among the world’s top five machine tool consumers, the US has since lost its position as the leading global producer.
Producing large components requires substantial capital investment in equipment—often more than $10 million—for large-scale CNC machines, which can be prohibitive for smaller enterprises.
Scientific Challenge
The project faced two main challenges: identifying a suitable alternative material for machine tool bases and designing a CNC machine tool capable of creating parts larger than its work volume. The alternative material had to match iron in stiffness and vibration damping, be domestically available, and economically viable. Additionally, creating large parts with small, affordable equipment required addressing precision and accuracy challenges, especially given that small milling errors amplify significantly at larger scales.
Innovation
Researchers at the US Department of Energy’s Manufacturing Demonstration Facility at Oak Ridge National Laboratory used Big Area Additive Manufacturing (BAAM) to 3D print a thermoplastic shell filled with fiberglass-reinforced concrete from a local supplier. The process took only two days, which is dramatically shorter than the months required for traditional cast-iron bases.
Recognizing concrete’s superior performance under compression rather than tension, the researchers designed an innovative H-shaped base rather than the traditional C shape. This design facilitated incremental feeding of material through the machine, allowing production of parts substantially larger than the tool’s actual workspace, employing a “pass-through” machining strategy.
Results
The concrete base exhibited stiffness and damping characteristics comparable to traditional cast iron, but at significantly reduced cost and production time. The innovative design also facilitated embedding sensors within the base for enhanced operational monitoring.
Concrete curing achieved over 95 percent strength within four weeks, ensuring stable machine accuracy. Additional measurements of the structure can be completed over time to diagnose changes in the dynamic performance and accuracy of the machine.
Using the pass-through machining method, a machine with a 20-inch reach successfully created a solid 9.5-foot part. Moreover, the concrete base machine maintained precision comparable to traditional CNC machines.
Impact
By significantly reducing costs and lead times, this innovation enables smaller manufacturing enterprises to competitively produce large-scale parts. Greater accessibility to affordable, reliable machinery strengthens US manufacturing competitiveness and bolsters economic security.
The ease of sourcing and transporting materials for the machine base opens potential military applications. Mobile CNC machine packages can be rapidly assembled on-site, allowing forward-deployed units to construct vital equipment in remote areas with limited resources. Ongoing research aims to further automate and simplify the machine’s operations, enhancing its accessibility and practical application.
Support
This project was funded by the US Department of Defense Industrial Base Analysis and Sustainment program. — Logan Korn
Contact
Emma Betters, R&D associate staff, bettersed@ornl.gov
Justin West, R&D associate staff, westjl@ornl.gov
Bob Slattery, industrial collaborations manager, slatteryrs@ornl.gov
