Schulterfräser

Schulterfräser, also known as shoulder cutters or offset end mills, are rotary cutting tools used primarily in metalworking and precision machining to produce shoulders, slots, and stepped profiles on workpieces. The tool features a cylindrical shank, a cutting diameter equal to the intended shoulder width, and a protruding cutting edge that extends perpendicular to the axis of rotation. By advancing the cutter radially, the operator can create a defined step or shoulder with high dimensional accuracy.

Typical shoulder cutters are made from high‑speed steel (HSS), cobalt alloys, or carbide. Carbide versions, often coated with TiN or Al₂O₃, provide greater wear resistance and allow higher cutting speeds, especially on hardened steels and exotic alloys. The basic geometry includes a cutting edge, a relief angle to prevent rubbing, and a front clearance angle that facilitates smooth entry into the material. Variants exist with different flute counts, helix angles, and tool lengths to suit specific machine tools and workpiece geometries.

In practice, shoulder cutters are employed on CNC milling machines, universal milling machines, and manual lathes equipped with milling heads. Common applications include machining keyways, forming internal and external steps, and drafting precise clearance zones for assembly. Correct selection of cutter diameter, material, and cutting parameters is essential to minimize tool deflection and achieve the desired surface finish. Proper coolant application reduces thermal deformation and extends tool life.

Safety considerations involve securing the workpiece, using appropriate personal protective equipment, and ensuring the spindle speed matches the cutter material and cutting conditions. Regular inspection for wear, chipping, or coating loss helps maintain machining accuracy and prevents unexpected tool failure.