What happens at a molecular/atomic level when cutting something? Is it different when something breaks?

Question

What happens at a molecular/atomic level when cutting something? Is it different when something breaks?

In: 2

Answer 1

You are breaking the bonds between adjacent molecules (for compounds) or atoms (for elements or mixtures like alloys).

This is the same, physically, as breaking but the cause is different.

With cutting you’re using very high local pressure from an external wedge to force the bonds apart until they break.

With breaking you’re pushing or pulling the bulk material until the bonds break.

With fracturing (like glass) it’s a self-sustaining reaction where the energy released from the bonds breaking is enough to continue breaking more bonds…that’s why cracks can extend on their own.