Extending tool lifetimes

Manufacturers always seek ways to extend the lifetimes of their cutting tools while boosting productivity. A team of researchers at Linköping University (LiU) in Sweden is helping to do just that.

The team has focused on how tools degrade, specifically examining the materials used to coat metalcutting tools to make them harder. In particular, the team has researched TiAlN, a ceramic material widely deposited as a coating.

On one hand, the material is effective for coating because it becomes harder while in use. This age-hardening process works well up to about 700° C. However, degradation starts to occur when the temperature reaches 900° C, which can happen after a few minutes of cutting into an especially hard material.

The TiAlN alloy. Image courtesy of Georgios Almyras, Davide Sangiovanni and K. Sarakinos

“It’s one thing to know that the material degrades at those higher temperatures,” said Kostas Sarakinos, head of LiU’s Nanoscale Engineering Division. “It’s another thing to know why and the way by which it degrades during cutting. To fully understand that, we need to get down to the alloy’s atomic level.”

He and his colleagues have spent four years developing a theoretical model to explain the degradation, examining over three dozen structures and configurations of TiAlN to determine how the atoms interact in different conditions, including the high temperatures and pressures that prevail during machining.