The loud scream of an end mill cutting into steel is a familiar sound to machinists. It’s this chatter that contributes to tool wear and leads to dull mills. This is because that sound is the result of rhythmic oscillations of the edges of the cutting head contacting the material. One way to avoid this chatter and greatly increase your tool life is by using Variable End Mills.
The variable helix end mills’ design helps to reduce chatter. When a standard end mill spins, it contacts the surface at regular intervals. This means that that cutting head experiences regular jostling when it contacts the workpiece, leading to mechanical oscillation and increasing the chatter. Variable end mills contact the materials at irregular times, and this strange pattern of contacting the workpiece actually helps to prevent oscillation.
Lower resonance is achieved due to variations in flute spacing. By grinding the flutes in these mills with variation, the arc spacing between every cutting surface is different. If a standard 4 flute mill has 90° arcs between every cutting edge, there is a 0° different between each cut. An end mill with a variable flute spacing might feature 89.3°, 91°, 90.5°, and 89.2° arcs between cutting edges, causing a +1.7°, -0.5°, -1.3°, and +0.1° differences between every cut respectively.
These differences in the helix are the secret to how these end mills outperform standard helixes. The variations In timing between cuts prevent the cutting tool from resonating consistently. With different timing between every cut, the vibrations are constantly interrupted from forming a regular oscillation. This not only makes these mills extremely silent, but the lower oscillation allows are faster removal rates.
The amazing thing about these variable end mills is that they can function at much higher speeds and feeds. This makes variable mills well suited for high material removal roughing applications in place of a typical hog mill. This is because, unlike a typical mill, high speeds do not cause a significant increase in tool movement, meaning it has far more control at higher speeds.
When you’re choosing a variable end mill, you need to find a manufacturer that can produce these end mills to exact specifications. At Online Carbide, we use a robot fed 5 axis CNC grinder to achieve incredible precision on our variable helix spacing. We make our variable flue end mills, and all of our other cutting tools, using the highest quality solid carbide stock.
In order to help our variable mills last even longer, we treat every one of these mills with a titanium aluminum nitride coating. This TiAlN coating greatly extends the life of these mills, especially when working on harder materials like steel. When a TiAlN coated tool reaches high temperatures, the coating forms a hard protective layer of aluminum oxide, which helps insulate the end mill. This coating helps to deflect heat to the ships instead of having the mill continue to heat. The result is an end mill that can handle faster running parameters without dulling as quickly as your average uncoated tools.
If you are looking for an end mill that can both rough your workpiece quickly, and provide the precision you need to finish without a tool change, check out our variable end mills at Online Carbide. We make all of our mills in the US and keep our prices low by cutting out middlemen from the equation. Don’t overpay for the end mills your business needs. If you need new end mills, get a great deal on the highest quality tools today with Online Carbide.