Making the Right Choice When it Comes to Flute Count on End Mills

There is a vast array of small yet important decisions that must be made when working in CNC machining. For example, it is vital to choose the right number of flutes on end mills to enable your tooling to ensure smooth operation and maximize productivity. Your best option will depend on a number of factors, including the hardness of the materials you are looking to cut as well as the parameters of the tooling at your disposal.

Why Does Flute Count Matter?

The general correlation between flute count, core size and tool strength is straightforward. More flutes equals a larger core equals greater tool strength. Furthermore, end mills with higher flute counts tend to have a smaller cut depth and so can be used to provide a smoother finish on virtually any material.

However, adding more flutes is not without drawbacks, as the larger core takes up space and limits flute valleys that otherwise allow chips to evacuate more easily while machining. As a result, stronger end mills with higher flute counts are better used when cutting harder, more ferrous material that require a faster rate of metal removal.

Optimal flute count also depends upon the specific machining application in question. End mills with high flute counts work well in finishing applications since smaller amounts of material will be removed and chip evacuation will not be a primary concern. On the other hand, roughing operations will benefit from a lower flute count, where it is necessary to have larger flute valley to evacuate chips with increased frequency.

Traditional Flute Count by Machining Application

Most end mill flutes traditionally come in 2 or 4 flute variations. 2-flute end mills have generally been preferred when machining aluminum materials, since the extra space is necessary for the relatively larger chips to evacuate when the tool is operating at a faster feed. 

Meanwhile, 4-flute end mills have been preferred when machining steel and similarly hard alloys since they have more cutting surfaces to contact the part per rotation. Since such harder metals require a slower feed, using end mills with 4 or more flutes serves to increase the rate of metal removal.

Other Flute Count Variations

Today, it is also possible to order end mills with 3, 5, 6 or even 7 flutes. 3-flute carbide end mills have gained popularity when cutting aluminum or non-ferrous materials, offering superior productivity and finish as compared to traditional 2-flute end mills without obstructing chip evacuation.

End mills with higher counts of 5, 6, and 7 flutes are increasingly being used to cut harder materials, as a higher flute count allows for a tool with more strength and less wear, resulting in a longer tool life. High flute counts can also be beneficial in specialty applications when dealing with certain kinds of ferrous materials.

How Many Flutes Is Right For You?

To recap, more flutes on end mills means more strength and a smoother finish. However, lighter metals may require a lower flute count to be sure that any chips have space to clear during operation.

If you have any questions or would like advice regarding the appropriate number of flutes for your end mills, please feel free to get in touch with us at Star Tool Inc today. We currently provide carbide end mills of anywhere between 2 to 7 flutes and are prepared to help you find the perfect carbide end mill solution for your metalworking needs.