Miles Cao
Global Product Manager for High-temperature tubes and Tubothal®, Kanthal

Over its nearly 40-year history, the Kanthal® APM alloy has become renowned for making electric heating more efficient, but now it’s increasingly important from a sustainability perspective, too.

Kanthal® APM

Kanthal® APM

A powder-based alloy that enables electrification of heating processes in steel making.

Kanthal® APM was first introduced by Kanthal, an Alleima company, as far back as 1986, but in today’s industrial heating processes the alloy, along with its ‘cousin’ Kanthal® APMT, has become more important than ever.

Originally developed to support the growing production of semiconductor wafers, Kanthal® APM has emerged as a crucial enabler of the transformation in various industries (steel, glass, and automotive part-makers among them) from fossil fuel-based furnaces to electric-based industrial heating. In doing so it’s also addressing the twin priorities of productivity and sustainability.

Miles Cao Global Product Manager for High temperature tubes and Tubothal®

“The focus on sustainability and reducing greenhouse emissions is becoming a key driver for our business today. But Kanthal® APM also has productivity and cost efficiency benefits because it helps make the heating process more efficient, withstands higher temperatures for longer without deforming, is easier to control, and is easier to maintain,” says Miles Cao, Global Product Manager for High-temperature tubes and Tubothal®, which make extensive use of Kanthal alloys.

How Kanthal® APM meets the challenges of industrial electric heating

The industrial furnaces used for the likes of steelmaking, aluminum production, and auto industry components have traditionally been heated by a large number of gas burners with large CO2 footprints.

“Taking steelmaking as an example. There are huge continuous annealing furnaces and galvanizing furnaces that can be over 100 meters long,” Cao explains. “That can involve hundreds of gas burners: imagine how much CO2 is emitted from those furnaces! That’s why heavy industry such as steel producers are converting to electric heating, which drastically cuts down emission footprint. Zero if using carbon-free electricity.”

So far, so good then, but electric furnaces also have their challenges if they are to perform as effectively as possible. One example is heating elements made of electric wire, which in certain applications require support to hold them in place, and stop them from ‘creeping’ (deforming) in temperatures that can reach 900 to 1,000 degrees Celsius, or even higher.

Miles Cao takes up the story

“Let’s take the example of electric furnaces being used in the production of semiconductor wafers, the original inspiration for the development of Kanthal® APM. The chip manufacturers needed to use furnaces with larger diameters so they could produce larger wafers which yields more chips. This requires more power input and the use of larger-diameter wire coils."

“But the conventional heating wires were too weak and would deform under the higher load and element temperature. In the meantime, supports were needed to hold longer elements in place, which in turn absorbs some of the heat you want for the wafers.”

Therefore, Cao says, the industry had to find a way to manage the trade-off between preventing the electric wires from deforming and wearing out, versus reducing the supports to increase the efficiency. The answer lay in increasing the material strength of the element to hold its form stable under the extra load. The material that allows that to happen and which solved this problem is Kanthal® APM.

The unique properties of Kanthal® APM

Kanthal® APM (The A is the series number, and the PM stands for powder metallurgy) combines the traditional high-temperature corrosion resistance of Kanthal alloys with increased high-temperature strength and form stability. It’s produced by Kanthal at its production sites in Surahammar and Hallstahammar, Sweden, using powder metallurgical processes.

Since Kanthal® APM is part of the FeCrAl (iron-chromium-aluminum) family, the material inherits great oxidation and corrosion resistance compared with conventional FeNiCr (iron-nickel-chromium) and NiCr (nickel-chromium materials) and has high electric resistance properties.

Its form stability and corrosion resistance at higher temperatures allow producers to get more power in the furnace at a longer lifespan for the electric wires. This means less factory downtime, in turn increasing productivity, cost efficiency – and sustainability.

The Kanthal alloy has since become a standard for the semiconductor industry. However, its form stability has made it well suited to other high-temperature industrial applications too. Since 2004 Kanthal® APMT, an even stronger alloy, together with Kanthal® APM, have become mainstay materials in high-temperature radiant tubes that are used for industrial heating processes. “Today, most of our customers prefer to use the combination of heating elements made of Kanthal® APM and radiant tubes made of Kanthal® APM or APMT for the best results of their heating processes,” says Cao.

“These materials are much stronger and that’s where they stand out compared with the competition. None of the other materials on the market match them in performance and production capacity.”

Miles Cao, Global Product Manager for High temperature tubes and Tubothal®

Kanthal’s leading position

Faced with the growing trend towards electrification, the industries that have industrial heating as a core part of their processes need to tick the sustainability box but not sacrifice productivity.

Thanks to its ability to make electric heating furnaces more productive and longer lasting, Kanthal® APM is an answer to their prayers, as well as another important improvement to industrial processes that contributes to a cleaner, lower-emission industry, and, by extension a better world. It’s another example of the ‘butterfly effect’ in action.

“Now, when electrification is such a strong trend throughout the world, we think that Kanthal is so well positioned in this type of market,” says Cao. “It’s a great opportunity for Kanthal and from my standpoint, it’s very exciting to work with it too.”