VIDEO: Fluted End Mills

When to use two, three, or four flute end mills. The big question when picking an end mill is how many flutes are right for the application? Two flute end mills are the weakest of the end mills, but are best suited for deep slotting due to a large chip carrying area, but they tend to not give consistent straight wall because of deflection. Three flute end mills are more limited in variety but are an excellent choice over the two flute end mills. They provide good chip space and are not only stronger but also provide a straighter wall and should be the first consideration over a two flute end mill. Four flute end mills are the backbone of any end mill offering and have universal application. Although they're not the choice for slotting beyond one diameter deep, they are the tool of choice for any surface, pocketing, or peripheral milling applications. All of these end mills are available from Greenfield Industries in high speed steel, cobalt, powdered metal, and carbide as well as various material-specific designs.