Between the worlds of CNC machining and additive manufacturing (AM), there lies a bridge technology referred to as hybrid manufacturing. Hybrid systems combine both production techniques to join the benefits of subtractive and additive processes—the precision of the former with the freedom of the latter.
One of the first companies to get hybrid manufacturing into the market is Hybrid Manufacturing Technologies, which develops specialty tool heads that make it possible to transform any CNC machine into a hybrid AM system. Now, over half of the hybrid machine tool models available feature tool heads from Hybrid Manufacturing Technologies.
The Birth of Hybrid 3D Printing
Jones explained that, about a decade ago, when he was a senior research fellow at De Montfort University, his lab purchased a 3D printer, which absorbed the lab’s budget across multiple years.
“When it was delivered we were very pleased with new and critical deposition technology, but what we realized is that roughly 75% of the price we had paid was for a 3-axis motion platform,” Jones said.“We looked around our lab and thought that although this motion platform was very nice, we already have eight or 10 motion platforms. Wouldn’t it be nice if we could buy only the deposition head and put it inside a CNC machine?”
It was then that Jones and his lab pursued a competitive grant that resulted in the launch of the four-year research project named RECLAIM (REmanufacture of high value products using a Combined LAser cladding, Inspection and Machining system). Along with eight other companies—including Airfoil Technologies International, Cummins, Delcam, Electrox, the Manufacturing Technology Centre, The Welding Institute, Precision Engineering Technologies and Renishaw, De Montfort University and Jones’ lab were able to pursue this new technology.
“What we really wanted to do was to create a fully automated solution for additive and remanufacturing,” Jones said. “We went around and picked software from Delcam and metrology from Renishaw, The Welding Institute and other local partners in the United Kingdom.”
What Is AMBIT?
AMBIT is a multi-task system that makes it possible for any CNC machine or other robotic platform to perform directed energy deposition (DED) metal 3D printing. While Hybrid Manufacturing Technologies manufactures heads that can be swapped into a CNC machine manually, the automated tool changer is the firm’s specialty.
The AMBIT system can switch between the spindle and the DED head automatically and in seconds. In the case of Hybrid Manufacturing Technologies, the DED process uses a laser as the heat source to melt metal powder. The company has developed a number of different tool heads dedicated to different geometries, laser profiles, powder delivery options and de-focused energy beams.
“In most cases, our technology is used in a machine tool, so it feels familiar to people who use it, making it easier to adopt the use of the technology,” Jones said.
Manufacturing and Remanufacturing
The power of hybrid manufacturing is the fact that it combines the benefits of both subtractive and additive processes. In the case of a component made with AM, significant postprocessing is required to achieve the final part. Oftentimes, particularly in DED, this postprocessing involves milling a near net shape object to its final dimensions. For subtractive manufacturing, a metal block is milled to achieve the desired shape, but the spindle may not be able to access certain areas of a part. Complex geometries may also be difficult to obtain.
By combining both processes into a single platform, either an additive part can be built from scratch and finished in a single operation or a subtractive part can be milled and additional features can be added to the component when necessary to achieve otherwise impossible shapes. Additionally, existing parts can be repaired or new details can be added.
Jones sees these applications as lying on a spectrum related to how much material is being deposited relative to the base part, with repairing on the one end and building parts from scratch on the other.
“DED is really ideal for repair and remanufacturing, and it’s really mature for those type of applications,” Jones said. “In our experience, the halfway point between those is remanufacturing, just adding a little bit of material. In cases where a user can’t turn a part [with a CNC lath] due to part features such as a spigot or a flange, you could turn the base part first and then add the spigot or other types of features afterwards. It becomes a more efficient route to achieve a geometry that would otherwise be time consuming or have a much bigger billet size.”
As for part repair, Jones said that he often sees mold and die repair, where edges are being restored or enhanced, as well as blade repair. When it comes to an increased use of the additive side of the machine, DED is used for what it’s best at, thin-walled and complex objects.
Hybrid manufacturing, then, is a practical technology with practical applications. Though we might envision it as a means of producing impossible parts and finishing them autonomously—revolutionizing the manufacturing industry, for now, Jones believes that the best early business cases for hybrid manufacturing are for repair work and adding features.
The Future of Hybrid 3D Printing
That isn’t to say that a revolution within manufacturing is not in the cards for the future. Hybrid Manufacturing Technologies is working on new developments that may lay the foundation for an autonomous factory of tomorrow.
At RAPID + TCT 2017, the company unveiled what it calls the AMBIT Series 7 range, a set of seven new tools that includes, in addition to more laser printing and drilling heads, an eddy current inspection head. While the AMBIT platform has featured surface inspection for some time, this tool head can verify quality postdeposition, detecting cracks and voids beneath the surface of the part.
Because AM is new to some CNC users adopting this technology, such a tool is necessary for better characterizing the quality of 3D-printed features on parts. It also points to the possibility of all-in-one manufacturing, in which a part can be fabricated, finished and inspected all in one operation.
The goods that make up our world are not all made from metal, however, so all-in-one manufacturing must take that into account. For that reason, Hybrid Manufacturing Technologies is also working on a high-volume polymer extrusion head and a syringe-based material extrusion head.
According to Jones, the polymer head, developed in partnership with Oak Ridge National Laboratory (ORNL), is about 25 times faster than a typical desktop system. Rather than use a typical filament heating setup, the printhead works more like an industrial plastic extrusion machine, melting raw pellets into beads of plastic. This project is just one of many similar endeavors that ORNL is pursuing with industry partners, the most well-known of which is probably the Big Area Additive Manufacturing system developed with Cincinnati Inc. and Local Motors.
Whereas the polymer extrusion head will make it possible to switch from CNC work to printing plastic automatically, the syringe extrusion will enable the deposition of unique materials, like conductive inks. As evidenced by other electronics 3D printing companies, like Optomec and Voxel8, this will make it possible to incorporate electronic circuits directly into a part as it’s being made.
“Depolying technologies in a tool changeable format our unique approach and passion,” Jones said.“This development brings infinite flexibility to the production sequence because hybrid machines can switch on the fly between different types of processing selected from: adding, subtracting or inspecting. In this way the hybrid approach is reducing manual transfer to downstream operations and overcoming the challenge of conventional line balancing. In short, it is redefining the rules.”
Whether or not these new tool heads will actually drive a future of all-in-one manufacturing remains to be seen, but the progress along the way is exciting nonetheless. To learn more about Hybrid Manufacturing Technologies, visit the company website.