Wednesday, January 23, 2008

Types of End Mills

Flutes - Spiral cutting edge on the end mill. 2 and 4 flute end mills are the most commonly used.

  • 2-Flute - Allows maximum space for chip ejection. Used for general milling operations.
  • 3-Flute - Excellent for slotting. Used for general milling operations.
  • 4, 5, 6, and 8 Flute - A greater number of flutes reduces chip load and can improve surface finish, if feed rate remains the same.

Ball End - Used to mill die cavities and fillets, round bottom holes and slots.

Carbide End Mills - This tool material combines increased stiffness with the ability to operate at higher SFPM. Carbide tools are best suited for shops operating newer milling machines or machines with minimal spindle wear. Rigidity is critical when using carbide tools. Carbide End Mills may require a premium price over the cobalt end mills, but they can also be run at speeds 2 1/2 faster than HSS end mills. For best results mount in a hydraulic type holder.

Coatings - The use of Titanium coated tools will increase the surface hardness of the tool to near 85 Rc. This will allow for greater tool life at increased cutting speeds & feeds (15 - 25%). Melin offers Titanium Nitride (TiN), Aluminum Titanium Nitride (AlTiN), and Titanium Carbonitride (TiCN).

Cobalt - Type of high speed steel tool which has a 8% cobalt content (M42). This material has excellent abrasion resistance for improved tool life over standard high speed steel (M7).

Corner Radius - Conventional end mill with radius ground on the tips of the flutes to help reduce chipping on the tip. For mold applications, radius tools can remove more material faster than ball ends.

Corner Rounders - Cutters having form ground radius with relieved clearance.

Double End - An end mill that has teeth on both ends of the cutter. End mill holders must have sufficient clearance to allow for the use of a double end cutter.

Drill Point - Multipurpose tool which can be used for drilling, milling, or chamfering.

High Helix - Usually a 40 to 60 degree spiral on the tool's flutes. Effective for rapid chip ejection in milling of aluminum and other materials.

HSS - A baseline tool steel. In the past, a majority of end mills were made from standard High Speed Steel (M7). Usually inexpensive, but do not offer the tool life or speed and feed advantages of Cobalt and Carbide end mills.

Left-Hand Spiral - Used for milling multiple layers of thin sheets where chip flow is directed away from work.

Rougher (Hoggers) - End mill with interrupted shape on outside diameter to remove large amounts of material quickly. Typically can remove material up to three times the rate of conventional end mills with different types available to achieve the desired finish on the material. Melin offers roughers in Coarse Pitch, Fine Pitch, Rougher/Finisher, and 3-Flute for Aluminum styles.

Single End - Teeth on one end of the cutter only. This style is the most common available.

Stub Length - Used for milling of shallow slots in all types of materials where heavy feeds are required and tool deflection is minimized.


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