Eli5: What purpose do hard materials serve? What purpose do tough materials serve?

Question

When researching these, I found examples like hard materials are good for cutting tools and machines. Could you explain what machines in specific and why those are the best choice?

In: 0

Answer 1

Tungsten carbide cuts everything, but you don’t need tungsten carbide to cut wood, you just need something harder than wood that doesn’t weaken with heat. Tool steel will cut steel, but you need carbide to cut tool steel. Other options are abrading away material with a disk, but you lose the disk in the process. Same principle applies, you need something harder than what you are cutting.