system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5: Why are metal shavings flammable?

im just curious how Metal shavings of something like Steel can be flammable even though the metal itself ( and most others) do not combust like that.
gpt
Metals can oxidize- this is what happens when they rust or otherwise react with oxygen. Usually this happens slowly, since only the surface is exposed to air and rust/oxides on the surface actually block the air from touching fresh metal underneath. 

Rusting/oxidizing produces heat. A rusty nail is rusting very slowly so the heat is easily dissipated and not noticed.

If you shave the metal super-thin, thee is more surface area that can react with oxygen, and if it's thin enough it will react *very quickly*, and the small amount of heat will help feed the reaction even more.

Rusting is just burning *really slowly*.