One project’s worth of rough lumber is enough to nick and dull the straight, steel knives on your jointer and planer. That's not the case for segmented cutterheads, spelling the end of tedious blade changes. The perfectly indexed, long-lasting carbide teeth on these new cutterheads leave fewer ridges and less
tearout in all types of woods. The typical insert cutter has four sharp edges vs. one or two on high-speed-steel knives, and is made of carbide, making each edge much more durable. When you do finally need a fresh edge, the teeth are simple to loosen and turn, and they go right back into perfect position. Say goodbye to tedious knife changes.

From Fine Woodworking #223