Why did you go to Sandvik Coromant in Västberga?
I went there to test how the semiconductor structures that I had deposited on tool inserts would withstand the harsh conditions during metal cutting. The structures were un-coated and therefore highly exposed to both mechanical wear and high temperatures. This was the first test using structures fabricated on this type of surface, and the main purpose was, out of curiosity, to get a rough idea of how lithographically patterned structures behave in such an experiment.
Additionally, I visited to see the facilities and meet some of the people at Sandvik involved in the Sentio project, and I was given a tour of their laboratories.
What did you learn?
We tested three patterned inserts under different cutting conditions by varying the process settings. I learned how metal cutting is performed and how the insert surface is affected during the process. For instance, I discovered that stainless-steel chips sliding along the surface become sticky at elevated temperatures, leading to thin deposits of stainless steel on the insert surface. This means that any future structures will need a protective coating, not only to provide mechanical durability but also to prevent electrical short-circuiting.
How did the experiments go?
It went very well. The structures turned out to be remarkably robust. I was initially concerned that they might delaminate, but in general they remained intact after cutting, except in areas where even the surface of the insert itself had been worn away.
What's the next steps?
We are planning an experiment at MAX IV (FlexPES beamline) to investigate possible chemical changes of the semiconductor surface at different distances from the insert’s contact zone. Since the temperature gradient during cutting is extremely steep, it would be interesting to see whether this gradient is reflected in the chemical composition of the surface as well.
Photos: Susanne Norgren
