A Step-by-Step Guide for Choosing the Right End Mill

by Bernard Martin

Here are some basic rules of thumb on end mill selection

Navigating the vast array of end mills available in the market can be a daunting task, especially when precision is paramount. To aid in this process, we've outlined a step-by-step guide that addresses crucial considerations for selecting the optimal end mill for your machining needs.

Step 1 – Material Identification: Identify the exact material, its condition (billet, forging, etc.), and hardness (HRC). This information directs you to the Non-Ferrous or Ferrous section of our catalog.

Step 2 – Operation Type: Determine whether you'll be roughing, finishing, or both. This guides the choice of the number of flutes and the need for chip breakers.

Step 3 – Programming Style: Choose between traditional programming, high efficiency programming (HEM), or a combination. This decision influences the number of flutes (Step 8).

Step 4 – ADOC (Axial Depth of Cut): Determine the maximum axial depth of cut the tool will experience in the part. This information helps decide the length of cut (LOC) to deploy.

Step 5 – Reach Consideration: Evaluate obstacles to clear and depths to reach. If necessary, consider a reduced necked tool to maintain length of cut while reaching deeper positions.

Step 6 – Tool Diameter Selection: Consider the machine taper, cut depth, reach, and part geometry. Keeping the tool diameter under 3/4" for 40-taper machines and adapting the diameter to programming style, cut depth, and reach requirements.  Keep in mind  what programming style (Step 3) you’re using as HEM can employ smaller diameters than you may be used to. Decide on your cut depth (Step 4). For traditional programming keep it <2xDia., for HEM keep it below 4xDia.  Decide on your total reach depth (Step 5). If needing to machine 4xDia. look at a necked tool to maintain strength and minimize deflection.

​Step 7 – Corner Radius: Determine if your part requires a corner radius. Running a corner radius on an end mill can extend its life and is especially beneficial for pre-finishing.

Step 8 – Flute Count: Consider the material and programming type to determine the ideal flute count. Non-Ferrous machining typically requires 2-3 flutes for traditional programming and 3-5 for HEM, while Ferrous machining may need 4-5 for traditional programming and 5-7 for HEM.

Step 9 – Tool Holder Selection: Always opt for the most rigid and accurate tool holder with minimal runout. Keep the Total Indicator Runout (TIR) below 0.0005 at the tip of the tool for optimum tool life and success. Consider the use of a side lock holder for specific applications.

Remember, our team at Next Gen Tooling is always available to assist you in selecting the correct product. By following these guidelines, you'll navigate the selection process with confidence, ensuring precision and efficiency in your machining operations.