Tip life

HAKKO Soldering tips are comprised of a copper core for good thermal conductivity, and plated with iron which brings less corrosion.The soldering part of the tips is plated with solder, and the other area is plated with chrome in order to prevent them from being wet with solder.
(Applies to all soldering tips on the irons except for RED, U, PORTABLE, MATCHLESS, JUNIOR)

When you see the phenomena below, replace the tip with a new one.

Iron plating has corroded by solder and got a hole as a result.
The solder plated area has blackened and does not get wet with solder.

An oxidized soldering tip may recover wettability by tip cleaning.

Corrosion or oxidation proceeds fast with lead-free soldering or high heat soldering, resulting in shorter tip life.
You can find some helpful information below about tip maintenance and lead-free soldering.

Lead-free soldering What is lead-free soldering?

Tip maintenance What if solder does not wet on the tip?