The MRI of vacuum arc furnace systems

An installation showing two VAR furnaces with 15 ton/900mm diameter ingot capacity
An installation showing two VAR furnaces with 15 ton/900mm diameter ingot capacity

Consarc’s vice-president of technology Andrew Elliott, and Ampere Scientific’s founder and CEO Paul King, reveal how the introduction of VARmetric is bringing data science to vacuum arc remelting.

Imagine the gruelling environment in which an aircraft engine must function. Intense stress. Extreme temperatures. High stakes. And that engine is only as safe and reliable as its parts. So, every day, millions of lives depend on safe, durable engine components working properly to transport passengers, crew and cargo from point A to point B. Additionally, the market’s expectations keep increasing. Those safe, reliable engines must also be lightweight, efficient, and eco-friendly. Quality has never been more important, and the definition of ‘quality’ is growing more complex and challenging.

But manufacturers can only push engine parts as far as their processes - and technologies - allow. Today’s manufacturing processes won’t produce the aircraft engine components of tomorrow. Meeting those exacting standards calls for a revolution in metal producing, where impeccable processes and precision equipment deliver supreme confidence in the material’s ability to achieve maximum performance.

Material safe limits

As OEMs develop new alloys and processes to improve part safety and performance, metal producers must ensure their processes are keeping pace. But even they cannot fully determine the exact limits of a material. An ingot’s metallurgical quality cannot be fully known until it exits the production line, and then only after extensive testing.

Some quality measurements can be captured during the melt stage, but the process of melting and forming ingots is long, complicated and often occurs where human senses cannot go: for example, inside the intensely hot, controlled environment of a vacuum arc remelting (VAR) furnace. VAR furnaces are the workhorses the specialty metals industry uses to remelt and refine high-value metals and alloys (for example nickel, titanium, zirconium and niobium), including those used in critical engine components for commercial and military aircraft. 

Advancements in VAR technology have given operators the advantage of basic metrics to monitor and manage the melting process, enabling them to produce high-quality, durable metals to withstand the most demanding conditions and meet the most precise specifications. And yet, the work-in-progress is largely invisible. Until now.

Magnetic field signatures along an ingot profile during the manufacturing of the ingot

Curiosity and a drive to truly master the intricate science of melting led Consarc to explore how combining data science with VAR remelting technology could advance vacuum arc remelting and yield higher-quality aircraft engine parts. Since patenting Automatic Melt Control for remelting furnaces in the late 1970s, a technology that’s become a trusted, ever-improving force in metal manufacturing, Consarc aspired to build on its innovation to take the next great leap forward. Ampere Scientific’s VARmetric is the game-changing technology Consarc sought.

Together, Consarc and Ampere Scientific can provide never before captured data, gathered and processed in real-time during the melt, to improve melt consistency and ingot quality. This partnership gives manufacturers more confidence in their components, helping the next generation of aircraft fly lighter, faster, stronger and safer.

Changing the course of VAR

By integrating traditional process data with new, never-before analysed information that VARmetric captures comes the potential to reveal previously unseen realities of the physics of the manufacturing process, to know with greater certainty the quality of the ingot produced much sooner - even as it’s being formed.

Much as an MRI gives doctors a non-invasive look inside the body, VARmetric provides a non-destructive view into the inner workings of a VAR furnace, using sensors strategically placed around the furnace to monitor fluctuations in the magnetic field during remelting. The captured data is translated into a detailed map that plots every step of the melting process to quickly identify abnormalities that could compromise the quality of an ingot or even trigger alarms to off-normal events in real-time.

While VARmetric can be retrofitted to existing VAR furnaces, Consarc is equipping new models with this ground-breaking technology in a fully integrated package. Together, Consarc and Ampere-Scientific are discovering what is really happening inside a VAR furnace at each moment of every melt and capturing the data to revolutionise vacuum arc remelting. 

Driving quality and confidence

Making an ingot in a VAR furnace is one step of many in a metal’s transformational journey. Depending on the product the ingot will become, it will be heat treated, forged and may undergo various additional finishing processes. The processes, including destructive testing and evaluation at various times throughout, can take months of costly work before the ingot can be graded to determine its final use. Imagine confidently grading an ingot when it comes out of the furnace before continuing with additional processing. 

For manufacturers, VARmetric provides a deeper look into the melting process - one that is more detailed than the standard charts and measurements available today - to help identify variations in the melt that lead to inhomogeneity in (chemical) composition or changes in crystalline structure. Armed with additional data, manufacturers could selectively cut the ingot to allocate portions to different grades or assign ingots to appropriate uses (and corresponding finishing treatments) before investing time and money in additional steps. The result? Higher-quality materials engine OEMs can be confident will perform.

Whether retrofitted to an existing furnace or engineered into a new one, VARmetric transforms the manufacturing process with never-before-seen insights. Not only does VARmetric help identify quality, but it also brings visibility to undesirable events during the manufacturing process for potential real-time intervention and correction.

As the aviation and aerospace industries continue to evolve, manufacturers and OEMs are seeing the real value data can provide to improve production processes, elevate product quality and make better informed decisions. Today, VARmetric captures data throughout the melt process and creates a detailed map to assess ingot quality long before any microscopic or macroscopic quality testing is conducted on finished parts.

Arc distributions over a user-prescribed period during the processing of an ingot

Tomorrow, as the technology matures and stores of data grow, VARmetric will become an early warning system, enabling operators to respond proactively during the melt to avoid exceeding process limits during production. VARmetric builds assurance into the melting process, guiding operators to optimal results on every melt.

That’s just the beginning. Consarc and Ampere Scientific’s long-term vision for VARmetric includes digital twinning - creating a virtual model of the ingot in real-time as it forms in the furnace as required for Industry 4.0. The digital twin will predict the physical ingot’s quality based on actual melting conditions. Predictive technology provides the opportunity to signal more than warnings; rather, based on data from the digital twin, the furnace of the future will automatically adjust to avoid ‘off-normal’ events during the melt, preventing a defect before it occurs.

With detailed data and informed guidance, ingot quality will rise to new levels. As OEMs push the limits of the materials used in their engines, confidence that the materials can withstand the rigors they’ll face is paramount. Robust, reliable data from the melt process can ensure variations are minimised, so part quality is known with certainty. These technological advances are leading the way to a better future - where better quality ingots yield higher quality materials that can then be used to build superior aircraft engines, making better, safer planes.

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