Conversation so far:
what is the role of a drum in a photocopier
The drum in a laser copier/printer is a vital component that receives the image from the laser and transfers it to the paper to produce the final print.
what happens if the drum becomes damaged in a photocopier
Damage to the drum may cause unwanted markings on the printed page or deletions of the image. Laser printer drums have a limited life span.

Question: what is the lifespan of a drum
Self-contained rewrite: what is the lifespan of a drum in a photocopier