Mazak Corporation, headquartered in Florence, Kentucky, USA, and Oak Ridge National Laboratory (ORNL)’s Manufacturing Demonstration Center in Oak Ridge, Tennessee, USA, have entered into a Cooperative Research and Development Agreement (CRADA). Under the agreement, they will work on behalf of the US Department of Energy (DoE) to further develop the use of Hot Wire Deposition (HWD) in the Additive Manufacturing of parts.
The project addresses Mazak’s Hybrid Multi-Tasking HWD technologies as a commercially viable solution which, upon completion, will result in a closed-loop control system featuring the ability to make on-the-fly adjustments according to sensor feedback during the HWD builds. Such in-process adjustability is expected to further ensure the consistency, quality and reliability of HWD AM technology, especially for manufacturers in the aerospace, automotive and die/mould industries, among others.
Specific applications for the technology include the repair of turbine blades and other high-wear parts such as engine blocks, cylinder heads and moulds and dies. With the ability to build up worn or damaged parts and refinish them on the same machine, manufacturers can increase the working lives of those parts and avoid the cost of producing new ones.
In operation, the closed-loop system will monitor and control the HWD meltpool temperature. As new layers are formed/built, the initial layers cool as more layers are built above them. Conversely, as the HWD build continues, overall process heat levels also gradually increase as compared with those at the start of the build. For both scenarios, the control system will vary the laser intensity – higher or lower – to maintain consistent temperatures.
Through their collaborative research, Mazak and ORNL plan to generate an HWD process guide that will provide parameters for not only the process itself, but also for different metals. Mazak will then incorporate these parameters as a database into the control of the machine tool to automate the HWD process.
Mazak’s Hybrid Multi-Tasking machines combine AM technologies such as Laser Powder Bed Fusion (L-PBF) and multi-laser HWD with subtractive manufacturing operations. Mazak developed its initial Hybrid HWD technology in partnership with Lincoln Electric; the two companies collaborated to combine Lincoln’s HWD process with that of Mazak’s Multi-Tasking subtractive (conventional machining) manufacturing technology. Mazak’s VC 500A/5X HWD machine uses a laser head to grow part features, then exchanges that head for a milling head to finish machine the feature and generate a smooth surface finish to complete the part.