What Makes Variable Flute End Mills So Special?

By Author: Geoffrey Less
Total Articles: 73
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To the layman, and even most professional machinists, a variable flute end mill looks just like any other milling cutter. Unlike most cutting tools, these unique end mills feature a unique asymmetrical design that helps to increase operating speed and efficiency. If you are tired of running your milling machine at low speeds and feeds, a variable helix tool is the perfect way to speed things up.

So what exactly is a variable flute? Now we all know that end mills and drill bits use flutes to cut and evacuate material. Typically these flutes are arranged in a symmetrical helix pattern which helps evenly distribute force across the length of the cutting edge. This seems like the most efficient way to design high performance tools and achieve maximum tool life, but the truth might surprise you.
Let’s imagine a four flute end mill. If you took a cross section along the diameter, you would find that the edges of ...
... the flutes were all spaced 90 degrees apart. This perpendicular orientation means that there is an equal distance and timing between every cutting edge. It also distributes the force of those cuts evenly across the circumference of the cutter. At high speeds, the even timing between cuts can cause the tool to oscillate and shake, which causes a loud screeching known as tool chatter.
If the spacing were 120 degrees, 60 degrees, 120 degrees, and 60 degrees between those four cutting edges instead of having a perpendicular arrangement, there would be two pairs of cutting edges that were twice as close to each other as they were to the other pair(imagine a X that has been stretched to look like “><”). A tool like this would suffer a huge amount of strain as each side made two quick cuts before taking a break. Eventually, the strain on a tool like this would cause a failure.
So obviously having a large difference between spacing will hurt the tool and having perfectly even spacing will produce oscillations in the tool, so how do we make the perfect end mill? Variable flute end mills find the sweet spot between these two extremes. These specially designed end mills have a nearly symmetrical design, with the distance between each flute being just a little different.
This spacing ensures that the forces from the cuts will be distributed almost evenly. More importantly, the timing between every cut will be just a little different. This means that the cutter will naturally avoid oscillating. When you use variable end mills in your shop, you will be amazed at how quietly these tools can operate even at high speeds.
Because the flutes are so close to being symmetrical, there is no significant strain on the body of the variable flute end mill. Instead, the tool should handle operating just like any other end mill. The lack of chatter might even lengthen the lifespan of your end mill.
If you want to try some variable flute end mills in your machining shop, you can find a selection of high quality mills when you check out Online Carbide. Their variable end mills are manufactured in the USA and are treated with TiAlN for extra durability. You can find all of their high quality solid carbide end mills and drill bits when you visit their website at www.onlinecarbide.com. If you have any questions about their products, feel free to reach out to a member of their team by calling 630-238-1424 or sending an email to sales@onlinecarbide.com.
For more information about Stub Drills and Tapered End Mills Please visit : Online Carbide.