Many different types of cutting tools are used in the milling process. Milling cutters such as endmills may have cutting surfaces across their entire end surface so that they can be drilled into the workpiece (plunging). Milling cutters may also have extended cutting surfaces on their sides to allow for peripheral milling. Tools optimized for face milling tend to have only small cutters at their end corners.

The cutting surfaces of a milling cutter are generally made of a hard and temperature-resistant material so that they wear slowly. A low-cost cutter may have surfaces made of high-speed steel. More expensive but slower-wearing materials include cemented carbide. Thin film coatings may be applied to decrease friction or further increase hardness.

They are cutting tools typically used in milling machines or machining centers to perform milling operations (and occasionally in other machine tools). They remove material by their movement within the machine (e.g., a ball nose mill) or directly from the cutter's shape (e.g., a form tool such as a hobbing cutter).

There are two distinct ways to cut materials when milling, conventional (up) milling and climb (down) milling. The difference between these two techniques is the relationship of the rotation of the cutter to the direction of the feed. In conventional milling, the cutter rotates against the direction of the feed while during climb milling, the cutter rotates with the feed. Conventional milling is the traditional approach when cutting because the backlash, the play between the lead screw and the nut in the machine table, is eliminated. Recently, climb milling has been recognized as the preferred way to approach a workpiece due to the fact that more and more machines compensate for backlash or have a backlash eliminator. Below are some key properties for both conventional and climb milling.

Conventional Milling  (Top Left Image)

• Chip width starts from zero and increases which causes more heat to diffuse into the workpiece and produces work-hardening
• Tool rubs more at the beginning of the cut causing faster tool wear and decreasing tool life
• Chips are carried upward by the tooth and fall in front of the cutter creating a marred finish and re-cutting of chips
• Upwards forces created in horizontal milling tend to lift the workpiece, more intricate and expansive work holdings are needed to lessen the lift created

Climb Milling (Top Right Image)

• Chip width starts from maximum and decreases so the heat generated will more likely transfer to the chip
• Creates cleaner shear plane which causes the tool to rub less and increases tool life
• Chips are removed behind the cutter which reduces the chance of re-cutting
• Downwards forces in horizontal milling are created that help hold the workpiece down, less complex work holdings are needed when coupled with these forces