>I am trying to decide which word is better for the title of a feature. The purpose of this feature is to record that a certain quantity of a part was removed from stock (used to maintain an equipment). And I need to come up with the caption for the menu item for this feature. My choices are: "Post Parts Used" or "Post Parts Usage"
>Which one is better?

For me there's a difference in the focus of each word.

"Post Parts Used" is more concerned with which parts were used.
"Post Parts Usage" is more concerned with how many parts were used.