Feed Per Tooth

What is Feed per Tooth?

Feed per tooth is a term used in milling that describes the distance the tool's single cutting edge travels in one revolution. This distance determines how much material is removed with each pass of a tool's cutting edge. Feed per tooth is a key parameter in milling, as it directly affects machining efficiency, surface finish, and tool wear. Determining the optimal feed per tooth requires detailed knowledge of the material being machined, as well as the type and material of the tool and the width of cut during the process.

Factors Influencing Feed per Tooth and Its Optimization

To achieve optimal feed per tooth, the machinist must consider several factors that affect the cutting process:

• Machined material: Different materials require different feed rates for the best results. Harder materials, like titanium, call for slower feed rates compared to softer materials such as aluminum.
• Tool type and material: Various milling tools and their materials play a significant role in determining the optimal feed. For example, carbide end mills can handle higher feeds and cutting speeds than HSS mills.
• Width of cut: This refers to how much of the tool’s diameter is engaged in the cut at one time laterally. The width of cut influences chip formation and tool load.

Feed per Tooth and Average Chip Thickness

It’s important to note that feed per tooth doesn’t precisely reflect the actual chip thickness when the tool is taking a lateral cut of less than 50% of its diameter. In these cases, you should consider the average chip thickness, which provides a more accurate representation of the actual chip thickness and cutting conditions.

Adjusting Feed Rate

When the tool is cutting less than 50% of its diameter, feed per tooth should be increased enough to ensure optimal average chip thickness. This ensures that the tool operates properly, is loaded sufficiently, and that the machining process remains efficient. Too small an average chip thickness can lead to excessive tool wear, overheating, and poor chip formation, while too large an average chip thickness can overload the tool and cause breakage.

Summary

Feed per tooth is a critical parameter in milling that impacts tool life, surface finish, and process efficiency. Determining the optimal feed per tooth requires a comprehensive understanding of the materials being processed, tool characteristics, and cutting conditions. Machinists should also account for average chip thickness, especially when the tool’s lateral engagement is less than 50% of its diameter, to ensure an efficient and high-quality machining process.