1
general::
1. Strike repeatedly, as in Mary is always banging away on the piano, or The doorbell must be broken; see who is banging away at the door. [First half of 1800s] Also see BANG OUT. 2. Go ahead; begin or continue. This slangy imperative usually calls merely for energetic action, as in You can start without me? bang away. Also see GO TO (IT), def. 3.
American Heritage Idioms