Depth of cut

What is depth of cut?

Depth of cut refers to the penetration depth of the cutting tool into the workpiece material in a single machining pass. In milling, depth of cut is denoted by the symbol aₚ, and it represents the axial engagement of the tool into the part. The depth of cut determines how much of the cutting edge length participates in chip formation.

Depth of cut is a key machining parameter in cutting operations, and it directly affects the amount of material removed, cutting forces, load, and tool life during machining.

Depth of cut in milling

In milling, depth of cut determines the axial contact length between the tool and the material being machined. As aₚ increases, more of the cutting edge engages in chip removal at the same time. This increases the material removal rate but also raises the tool load and machine power requirement.

A small depth of cut reduces tool load and improves process stability but also decreases the amount of material removed in a single pass. Therefore, the depth of cut should be selected in relation to the chosen milling strategy, tool diameter, overhang, and the material being machined.

Managing depth of cut is especially important when machining with carbide tools or hard materials, to avoid excessive cutting forces, vibration, and premature tool wear.

Depth of cut and material removal

Depth of cut directly affects material removal rate along with the width of cut aₑ and feed rate. Finding the right balance between these parameters determines machining efficiency.

A higher depth of cut can increase material removal rates, provided the machine has enough power, the fixturing is secure, and the tool is sufficiently rigid. If the set-up is not stable enough, too great a depth of cut can cause vibration, surface roughness issues, and tool breakage.

The effect of depth of cut on machining

In machine shops, optimizing the depth of cut is an essential part of setting machining parameters. A correctly chosen aₚ boosts productivity and enables controlled chip formation.

Depth of cut should always be selected in conjunction with width of cut, cutting speed, and feed per tooth. In CNC machining, CAM programming allows you to manage depth of cut at different stages of the process, combining high material removal rates and process stability.

Summary of depth of cut

Depth of cut, or aₚ, describes the axial penetration of the tool into the material. It influences material removal rate, cutting forces, tool load, and the stability of the machining process. Proper selection of depth of cut is a key factor for efficient and controlled machining.