In clean solid timber, years of workshop use. In MDF or chipboard, a small fraction of that — the resin and mineral filler in sheet goods abrades carbide fast enough that a bit used only on MDF can be finished within one kitchen.
Bit life is decided by what you cut, not by how much you cut. The difference between materials is larger than most people expect.
Why sheet goods are so hard on carbide
MDF and chipboard are wood fiber held in cured resin, and both the resin and the fillers are abrasive in a way solid timber is not. The edge does not chip, it wears back and rounds over. Laminate faces are harder again.
The other big factor
Feed rate and depth. A bit moved too slowly rubs instead of cutting, and rubbing generates the heat that softens the braze and dulls the edge. Taking one deep pass instead of three shallow ones does the same. Ironically, being cautious wears bits faster.
The tells that a bit is finished
Burning where there was none before, in the same material at the same feed. A fuzzy rather than crisp edge on the cut. More force needed to move the router along.
What to do about it
Buy solid carbide or a good brazed bit for the profiles you cut constantly, and accept cheaper bits for the ones you cut once. Keep a separate straight bit for sheet goods so you are not blunting the good one on MDF.
Clean bits before they look dirty, and check the bearing every time.
Last reviewed 2026-08-12