SBIR-STTR Award

This Small Business Innovation Research Phase I project will provide the first technical advancement in the specialty metals industry (manufacturers of titanium and nickel) in more than 4 decades. Specialty metals are ubiquitous in our lives, with applications from aircraft parts to medical implants, yet the vacuum arc remelting (VAR) process, the work horse for this industry, has remained relatively unchanged since its development in the 1940?s. By coupling the ability to measure the location of electric arcs used for melting these high value alloys in the VAR, with the ability to steer the arcs, substantial electrical savings can be achieved, decreasing costs to the consumer and increasing reliability of the final products. For example, it is well known that the lack of understanding of the dynamics of the process leads to an estimated 8% yield loss, costing the US industry $1.024B per year in lost revenue through yield loss and electrical inefficiency, contributing to the high price of these products. This project proposes to decrease this loss by 50% by developing an applied feedback control technology capable of optimizing the energy distribution within these systems, providing better quality metals at a cheaper production price.The intellectual merit of this project is to prove that real-time control can improve plasma-based industrial processing systems. The innovation uses externally applied magnetic fields to manipulate arc position modes during melting operations. By coupling arc position sensing, which measures magnetic field vectors exterior to the process to determine arc positions interior to it, with active manipulation of externally derived fields, arcs can be precisely controlled. Relying upon years of development and validation of arc position sensing, coupled with Finite Element Analysis simulations and experimental validation, this technology will become the first active control of arc melting systems. The significant realization is that spatial and temporal control of the diffuse current paths can be controlled precisely if the validated measurement system of current location is coupled with external field generators. This effort will focus on the application to VAR furnaces but may have significant application to other processes with diffuse current pathways such as Joule heated systems, fuel cells, additive manufacturing or industrial microwave processing. The expected impact of arc control during melting is a reduction in manufacturing defects, an enablement of the production of ingots with increasing diameter, a reduction in energy required in alloy production, and improved safety of operations.

This Small Business Innovation Research (SBIR) Phase II project will provide commercial validation at scale of feedback-based control of arc behavior within the vacuum arc remelting (VAR) process. This will improve VAR performance in the production of specialty metals, resulting in improvements to ingot quality while reducing electricity consumption. Specialty metals, such as titanium and nickel alloys, are used in critical high-performance parts in industries such as aerospace, energy, and medicine, where the failure of these parts may lead to catastrophic systems failures and potentially life-threatening situations. In a VAR furnace, extreme temperature gradients from constricted and/or diffuse arcs sustained between the melting electrode and ingot can cause non-homogeneous material and inclusion defects, resulting in up to 8% yield loss per ingot, representing $1.024 billion in losses across the domestic industry. Improved control over the arc distributions during the melting of these metals is expected to decrease the frequency of defects in the final product and increase overall yield from the process. The proposed project is expected to reduce these loses by up to 50% through the application of active, feedback control of the arc dynamics. This type of control is expected to increase yield, decrease energy requirements, and increase safety of the manufacturing process industry-wide.This project will result in a system capable of detecting and manipulating the distribution of the arcs utilized during VAR processing. The Phase I effort showed that it is possible to simultaneously detect arc locations on the electrode and influence their movements, using electromagnetic coils, in real time. In Phase II, the arc measurements will be coupled through feedback to control the arc distribution in an industrial-scale research VAR, providing proof of concept at industrial scale. In so doing, the optimal electromagnetic coil geometry, hardware, and materials for driving the arc motion at scale will be identified and constructed. A series of industrial experiments are planned to validate the control system. The chemical composition of the ingots produced during controlled and uncontrolled conditions will be characterized to correlate defects with observed arc behaviors and to identify optimal control parameters. Similarly, the measured arc distributions will be used to validate the computational solidification modeling, which will be used to identify probable defect regions. The combination of experimental data and validated simulation results will be used to inform the VAR feedback control system regarding optimal arc distribution, yielding an improved control strategy for tailoring the melt process and improving ingot quality.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.