This AIR project will bring to commercial prototype stage a new machining-based process, Modulation-Assisted Machining (MAM), for large-volume production of metal fibers. By super imposing low-frequency modulation onto a sharp tool, individual fibers having highly uniform size and shape are created by cutting in a single-stage deformation process. The key research objectives that will be addressed in the proposed work are: 1) scalability of the production rate for creating fibers, 2) repeatability of fiber size and shape under commercial production rates; and 3) and life-cycle analysis related to the modulation device at rates typical of production. The MAM platform offers a unique ability to produce metal fibers with controlled size at high production rates compared to traditional multi-step drawing processes.
A prototype method for large-scale production of fiber materials will be demonstrated, while transforming machining technology across business sectors and opening a new applications domain for machining production of advanced materials. MAM offers a low cost production route and a process breakthrough for producing fibers that are difficult to create using current technology. The unique particle geometries and structure created by MAM will enable new commercial opportunities for production of fiber-based products, and composite material systems. Complementing the research is an education and training program involving company internships for graduate and undergraduate students. The collaborative research will expose the students to advanced materials processing and related commercialization, and the dynamic environment of a recent manufacturing start-up company
This project advanced the commercialization of a new process for producing metal fibers, which are used in filtration systems, textiles and a wide range of composite material. By superimposing a modulation (oscillation) onto a cutting tool, a process called Modulation-Assisted Machining (MAM), individual fibers having highly uniform size and shape are created in a single stage of deformation at frequencies greater than 1000 per second. The MAM process has high potential for cost savings in metal fiber production compared to wire drawing, which requires many reduction steps with intermediate annealing treatments in order to reach the small size of fibers. Lower cost would benefit a range of current fiber applications, as well as enable new materials and applications in which fibrous forms are currently cost prohibitive or impossible to produce by drawing. A prototype MAM fiber making system was developed and used to characterize the process parameters under pre-commercial conditions. The prototype system uses a patented MAM tool (TriboMAM™) manufactured by M4 Sciences, a Purdue-based start-up company and industry partner on the project. The prototype, which is based on an earlier experimental system, is installed on a standard CNC lathe and incorporates design changes for improved frequency response, rigidity and durability. Fibers of 10-100 µm in diameters were created with length-to-diameter ratios up to 150 in metal systems such as aluminum, copper and titanium alloys. Enhancements in fiber production rate from ~1000/s to ~2000/s were realized with the improved frequency response of the new system. A system dynamics phenomenon discovered in the project suggests that MAM fiber production frequencies as high as 10,000 fibers per second can be realized with further modifications. Direct measurement of fiber dimensional uniformity showed standard deviation of the mean (equivalent) fiber diameter of less than 7%. This remarkable uniformity suggests near perfect (size) yields, in contrast to most stochastic particulate production processes. A cost model based on geometrical analysis of the fiber production rate for a single cutting edge indicates up to ~10 times advantage of MAM over drawing. The MAM fiber production rate scales linearly with the modulation frequency and number of cutting edges, providing clear paths for further enhancements. The MAM system proved durable under production conditions, operating continuously over extended periods without failure problems in fiber making. Force measurements during MAM fiber making showed dramatic reductions in the specific cutting energy (i.e., per unit mass removed) compared to continuous chip formation. This fundamental discovery has far-reaching consequences in utilizing MAM for major energy savings across the industrial machining sector. Two graduate students, an undergraduate and a post-doctoral associate gained research experience in advanced materials and manufacturing processes and their commercialization under this project. Besides the human resource development and basic science discoveries described briefly above, the core results provided strong motivation and supporting data for continued commercialization of the MAM fiber making process.