There’s heat, and then there’s “superheat”

Reaching temperatures as high as 1,750 degrees Celsius (3,182 Fahrenheit), CLU converters are essential to turning carbon-rich molten iron into steel. A team at Kanthal’s production unit in Sweden decided to optimize this “superheat” process, which requires skill and precision.

“We are working with an increasing number of different products and some of these alloys have such high-quality demands that we need to put them through the CLU process,” says Lars-Åke Stridh, R&D Principal Engineer.

“One has to monitor and keep a close eye on the process parameters and equipment. Running the processes incorrectly can result in a high degree of wear,” says Lars-Åke, who explains that these converters require regular maintenance, which can take up to one week.

At Kanthal Heating Materials in Hallstahammar, Sweden, there are two of these vessels, which, thanks to their robust and conical shape, are somewhat reminiscent of old-fashioned moon landers. When one of them is taken out of production for maintenance, the second vessel keeps manufacturing going.


As the demand for Kanthal’s products keeps on increasing, Lars-Åke and his colleagues decided to find ways to increase the number of melts that the vessels could process in between regular maintenance. The key would be to minimize wear and tear on the converters and to do so, they had to find the “right weekly mix” of processes – crucially, in which order the various metal products should be put through the superheat process with minimal impact on the interior of the vessel.

Could the team double the number of melts in between maintenance? They decided to try.

With the help of specialists at the companies Magnesita and Uvån Hagfors Teknologi AB (UHT), who came together for a collaborative project, the team set to work. Already ten months into the two-year project, the results were encouraging. “It’s going well,” said Lars-Åke at the time when the CLU project had yielded a 40-percent increase in the number of melts.

“It may look like one small step, but it’s one ‘giant leap’ for the Hallstahammar production unit,” says Lars-Åke, taking inspiration from astronaut Neil Armstrongs’s famous quote after he stepped out of his moon lander.

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