CNC End Mill Comparison Guide
There are many different factors that go into the objects you can create with a CNC mill, but the biggest contributor is going to be your CNC end mills. At the most basic level, end mills are like drill bits but instead of only drilling vertically, they can also cut horizontally and have several form factors to get the cleanest cut for specific materials. Some are used only for plastics to keep from heating too much, some are designed to keep wood from chipping or tearing out, and some are designed for ultra-fine detail work. ;
Shape
From one end mill to the next, the most obvious difference you will find is that end mills come in many shapes and sizes. Some are thin and pointy, and others are wide and rounded. Some of the most common shapes you will find are fishtail (or flat), ball-nosed, and the bullnose, and each of these can be a straight cut or a tapered cut.
Size
Size is the biggest determination of what you can do with any given end mill. Large ones excel at grinding through a lot of material at once, but you don’t get a lot of detail out of your parts. With CNC milling, the radius of your end mill is the radius of any internal corner, so you will almost never have a perfectly square corner on the inside of a milled object. Smaller and smaller end mills can be used for each pass to clean up an edge and get the part to the final dimension and shape. ;
Straight vs. Tapered
There are generally two forms of end mills: straight and tapered. This is a choice based on the geometry of your finished part because a tapered end mill won’t be able to do all the same things as a straight end mill, and a straight end mill may not be the most efficient choice. By using a tapered end mill, the cross-sectional area is larger than a straight end mill of the same tip diameter, creating a much stronger end mill that is less likely to bend while milling. For perfectly vertical walls you will need to use a straight end mill as the taper just won’t reach. However for angled walls, using a straight end mill is not the most efficient, ideal choice.
Why Use a Single Flute End Mill?
There are a lot of strange beasts out there in the cutting tool world and a lot of physics that are not obvious. For example, many machinists will know that more flutes mean more productivity, but that certain materials, like aluminum, require fewer flutes–usually two or three. If that's the case, when would it ever make sense to use 1 flute end mill? Is there a time when the least number of flutes possible is a good idea?
Now let's take a CNC Router example. ; Say it's got a spindle capable of 24,000 rpm, but it will go no slower than 12,000 rpm. ; When cutting aluminum, the first thing we discover is we need carbide to run at those surface speeds–preferably a good coating is needed to up the limit even more. As we begin working through the feeds and speeds (hopefully using G-Wizard Calculator!), we discover we're going to need some pretty high feed rates at those RPMs too. ; For a 1/4″ endmill, it wants to run at 24000 rpm and a feed rate of about 255 IPM. ; ;Now depending on the machine, we may have discovered a problem. What do we do if our machine can't feed that fast?
The answer is to use a 1 flute endmill because it halves the necessary feed rates without rubbing. So there is one case where it helps when the machine just can't feed fast enough to keep up with what the spindle is putting out and maintain adequate chip loads.
FINISHING END MILLS-2 FLUTE
Finishing End Mills are used in metalworking applications for removing material or burrs from a workpiece and leaving behind a smooth finish. 2 Flute End Mills ;are used for center cutting (plunge cut) operation and when chip removal in slots and grooves is a problem. A wide range of coatings such as Titanium Nitride (TiN), Titanium Carbon Nitride (TiCN), Titanium Aluminum Nitride (TiAlN or AlTiN), and Diamond finishes permit maximum performance and value for a particular application or material. Both standard and metric shank and cutting diameters are available.
Uncoated High Helix Single End Mills from TTC Production. These HP series of single-end mills are exclusively designed to work on aluminum workpieces. TTC's HP series are available in two-flute, spiral designs and come in regular, long, and extra-long lengths. The tool is made from high-speed steel and the center cutting makes it suitable for peripheral, ramping, helical, plunging, and slotting operations. The high helix angle wraps around the tool faster and provides excellent chip evacuation at high speeds. ;
3 Flute End Mills - Carbide, Cobalt & HSS
Three flute end mills ;are used for higher feed rates than two flute end mills and are often used in aluminum machining. ; They are commonly used in grooving operations where the chip is crowded. ; They are also used in non-ferrous milling applications where high feed rates are used. ; Three flute mills tend to reduce vibrations during the cutting operation. ;