Grommets are small plastic bushings that are inserted into holes in a badminton racquet that allow the string to pass through the racquet without contacting the frame. Grommets protect the string from premature breakage and they also protect the racquet frame from damage due to pressure from the strings.
Over time, grommets wear or fracture and therefore they must be regularly maintained. If grommets are not replaced regularly, strings will break more often and the racquet will eventually become damaged.
Most stringers will replace grommets 1 or 2 at a time as needed, however eventually all the grommets in a racquet will require replacing. Replacing all the grommets takes about an hour and is a cost-effective way to ensure your racquet lasts a long time and also ensures that you will break strings less often, ultimately saving you money in the long run.
Check your grommets regularly for damage and any signs where the string may be contacting the frame of the racquet. You should expect to have all your grommets replaced once or twice a year.