Why are cuds smooth?

[JeffH]

A cud is formed when a piece breaks or chips off a die. I would expect the surface where metal has gone missing to usually have, at least, a grainy surface -if not tearing and cracking.
The cud is the metal that flows into the missing section of the die. But, all the cuds I ever find seem to have a smooth surface.

As professor Julius said "Why is it so"?

[nealeffendi]

Maybe most lumps that people call cuds are not cuds.
And why are cuds called cuds? What is the etymology of the word and is it even a word as oftentimes I see it written as CUD like it is an abbreviation, no different than ATM or WTF. Does the C stand for coin/coining and D for die?

[markn]

A cud is formed when a piece breaks or chips off a die. I would expect the surface where metal has gone missing to usually have, at least, a grainy surface -if not tearing and cracking.
The cud is the metal that flows into the missing section of the die. But, all the cuds I ever find seem to have a smooth surface.

As professor Julius said "Why is it so"?

You'd need to know the failure mechanism (spalling fracture, compression fracture or stress cracking) of the die and the microstructure of the steel to be able to answer that question.  After all it's the broken surface of the die that is smooth that forms the smooth cuds.

[JeffH]

Most metal fractures I have seen are textured in some way -I would expect dies (high strength, work hardened steel which will be relatively brittle) to show distinctive fracture patterns.
It would be interesting to see an uncirculated cud coin and a circulated one side by side. The cud being relief (high spot) will wear quickly which will, of course, smooth it.

I too have wondered about the etymology of "cud"