In the MRO (Maintenance, Repair, and Operations) world, replacement parts are key for production lines and machines. They oversee keeping things running with little down time and in the most efficient manner. One such piece of the machine puzzle are end mills. This small part is crucial in many machines for creating or modifying custom parts. It is the piece that cuts your workpiece to your specifications and using the correct one is key. It is the contact piece at the end of your machine with the workpiece.
End Mills are a cutting tool used in many machines including, milling and turning machines. They are used for drilling, reaming, slotting, contouring, and profiling as well. Their physical appearance is commonly confused with a drill bit but they are different in many ways. While drill bits cut in one direction, axially only, end mills can cut in multiple directions. This comes in handy with precision cutting and the variety of cutting methods mention previously. Keyway shapes are produced using end mills as well as many other custom shapes. Drill bits simply cut cylindrical holes.
The shape and cut of the end mill are what allows for the ability to cut both axially and laterally. Roughing end mills are designed with serrated cutting edges. This produces fine chips and reduces vibration while machining. They provide a rough surface finish to the work piece. Carbide end mills are designed to be rigid and withstand high heat. High-speed steel is as the name suggests for high-speed cutting applications and provides good wear resistance.
The grove between teeth that is shaped helically along the mill is called the flute. The number of flutes will determine how smooth the finish will be as well as chip clearing. It is important that chips clear to not create build up on the mill and overheat the tool. Overheating will cause the mill to wear prematurely. 2 and 4 flutes are most common and produce full chip lengths to prevent this aforementioned build up. The basic concept here is more flutes make a smoother finish while fewer flutes make rougher cuts.
Helix angles also play an important role in the shape of your end mill. Ranging from 15 degrees to 60 degrees the helix angle will determine the amount of shearing action in the cut. The higher the angle the cooler it stays, the higher angles can be used for softer materials where rigidity is not an issue. Helix angles also reduce chatter during cutting.
MISUMI carries carbide end mills with different end shapes. One is called radius end, this shape is used for tool strength while cutting. Radius end also reduces wear if the mill cut were a sharp corner. Another is ball end mills or ball nose mills which produce rounded details to the workpiece such as a bearing groove. Square end mills for square and sharp edges. Tapered end mills for machining deep grooves, engraving. These shapes are also available in HSS (High-Speed Steel) material. As per our configurability model, the length can also be chosen up to 1mm increments. MISUMI also carries customizable end mills. Available in ball end, radius, V-groove and carbide blanks.
Every workpiece does not come in the same material, size, or shape nor are they going to be cut in the same manner in regards to feed rate. This is why end mills must have coating options. Some coating is applicable to the speed in which the piece is cut others are for the non-conductive features. TiAIN: Titanium Aluminum Nitride is best for high-temperature cuts. TiN: Titanium Nitride is also great for heat resistance and provides the end mill with hardness for durability to run at higher speeds. TiCN: Titanium Carbonitride is one step up from TiN giving the end mill more hardness and can run at twice as much speed as TiN. AlCrN: Aluminum Chromium Nitride for non-conductive materials.
Overall, when choosing your end mill there are many factors to consider. Shorter length end mills provide more rigidity. For higher speeds and life, add a coating. More flutes generate a cleaner and finished work-piece. Once you find your perfect end mill, it will be the end of all other mills! 🙂