BAAM printer from Cincinnati Inc. demonstrates 3D printing with recycled composites
BAAM multi-material extrusion system. All photos: Cincinnati Inc.
Cincinnati Inc. (CI, Harrison, Ohio, US) announced that it has used its Big Area Additive Manufacturing (BAAM) machine to demonstrate that recycled materials can be used for 3D printing by producing what the company is said to be one of the largest multi-monolithic-material objects to date. The demonstration successfully demonstrated that large-scale multi-material printing can be done efficiently and economically with recycled composite materials.
Large-scale multi-material printing was achieved by making modifications to the BAAM and including a new extruder design that accommodates a dual feed system.
Over the past several years, CI has worked with the Oak Ridge National Laboratory (ORNL, Knoxville, Tenn., USA) of the United States Department of Energy (DOE) to continuously improve and develop the BAAM. Initial research focused on large-scale printing of single-material systems, typically short-fiber reinforced polymers.
The large dual material thermoplastic extrusion system would allow the user to print with several different materials in a single construction using a single extruder.
“The objective of this particular study was to demonstrate the impression of a multi-material composite tool comprising transitions, exceeding 10 feet in length, containing recycled materials and printed without manual intervention”, explains Alex Riestenberg, Product Manager of additive manufacturing from CI.
The part selected for this demonstration was a unique facet of a precast concrete tool used in the production of commercial window panels for a high rise development in New York City. The mold weighed about 400 pounds, with a length of 10 feet 10 inches. Printing time was around seven hours.
“Studies have shown that by using multiple materials in a structure, new mechanical and multifunctional responses can be achieved – such as lightweight structures with suitable mechanical properties, flexible and rigid segments in a part, and impact resistant structures. Explains the ORNL materials scientist. Vidya Kishore.
The two materials used in the construction were a blend containing 100% recycled CF / ABS and standard CF / ABS and ABS synthetic foam.
In addition to the environmental benefits of using recycled materials, Cincinnati Inc. claims that the benefits of multi-material extrusion include the incorporation of conductive circuit printing for smart structures, lightweight core structures, reduction of tooling costs, easier removal of the support material, localized reinforcement of specific areas the possibility of using different materials in different functions of the component and even changing the color of the part.
3D printed multi-material composite tool.
The key to achieving the objectives described above was the BAAM multi-material system, developed in collaboration with ORNL. The large dual material thermoplastic extrusion system would allow the user to print with several different materials in a single construction using a single extruder.
“The source of material fed into the extruder is switched on the fly at specific times during printing by sliding two material holes back and forth across the extruder feed,” explains Riestenberg. “The system also includes a material mixer outside the machine frame that can mix specific amounts of different materials and loads on the fly for specific custom material grades.”
Riestenberg explains that the combination of the material feed switching mechanism and the material mixer gives users the ability to print with several different material types and material combinations in one build, instead of two.
“The BAAM with a multi-material system upgrade is the only machine that can currently do this, and that sets us apart from our competition,” says Riestenberg. “Thanks to scientific research support from the DOE and ORNL advanced manufacturing office, we were able to take this manufacturing step forward.”
Materials and processes: tooling for composites
Composite parts are formed in molds, also called tools. Tools can be made from virtually any material. The type, shape and complexity of the material depends on the part and the length of the production. Here is a brief summary of the issues related to the election and the creation of tools.
Welcome to the SourceBook Online, the equivalent of the printed SourceBook composites industry buying guide published annually by CompositesWorld.
Impact testing of composite materials
Dr. Donald F. Adams (Wyoming Test Fixtures (Salt Lake City, Utah) discusses impact testing methods for composites.