One of the most commonly used of all milling cutters is the end mill. Solid carbide, indexable, and modular versions are available, as are ones with square, ball, and radiused cutting ends. They are used to machine slots and shoulders, mill pockets, and cut the inner and outer perimeters of various part features. As suggested earlier, some end mills have center-cutting capabilities, allowing them to plunge like a drill or ramp into a workpiece surface.

Its Duo-Lock series of modular end mills, for example, provides a best of both worlds solution to anyone needing solid carbide performance at an indexable price range. There are also high-feed “Beyond” style milling tools, the Mill 4 and KSSM series of shoulder mills, Fix-Perfect face mills, and much more. Most are available in material-specific or general-purpose carbide grades, and all are available either online or in-person through an authorized distributor. Long story short, Kennametal has milling cutters covered.

One of the first lessons in many machine shop programs is learning how to set up a fly mill or fly cutter. Used primarily on manual knee mills, this most basic of cutting tools is equipped with a hand-sharpened bit that's secured to the tool body with a series of set-screws. As the tool rotates, the machine operator engages a mechanism that moves the workpiece beneath it, removing a small amount of material from its top surface with each pass.

Due to its material cost, solid carbide tools are generally smaller than an inch or so in diameter. Above this size, almost all milling cutters use indexable carbide inserts attached to a steel cutter body via small screws or clamps. They provide an effective yet affordable solution for the vast majority of all machining operations, although solid carbide tools are still used for small part features and for finishing work.

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HSS drill bits (High Speed Steel drill bits) are the most common type of drill bits on the market today. They come in a huge variety of types, shapes and materials, and each is designed to do one or more jobs particularly well.

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In the end, you can use cobalt drill bits in faster drills than standard HSS bits as well. There are many situations where you could use a cobalt bit dry when you would need to use cutting fluid to cool another type of HSS bit, for example.

HSS drill bits were invented to cut into steel and other metals, but they are also very effective at cutting other materials, such as wood or plastic. There are 5 kinds of HSS drill bits, one of which we’ll look at in more detail below.

That's where Kennametal comes in. Granted, they're not the only cutting tool supplier out there, but they are one of the oldest, filled with experienced applications and support people. The tooling manufacturer also carries an extensive lineup of most every cutting tool mentioned here (sorry, no fly mills).

Straddling the fence between these two are so-called modular end mills, which employ a solid carbide head that threads onto a steel body. As with modular carbide drills, these cutting tools provide the performance and accuracy of solid carbide but at a far lower cost. And because a worn head can be swapped out in a few seconds, modular tooling also increases productivity.

Cobalt drill bits Are the best of the best for cutting into hardened metals like steel. Most have between 5% and 8% cobalt. Because pure cobalt has such a high melting point (1495OC), it conveys a higher melting point to the steel. That means you can push it farther and harder when cutting metals, and it won’t soften or deform.

Each of these is an application-specific cutter, limited to relatively small amounts of material removal and the creation of distinct part features. In a moment, we'll talk about the more general-purpose tools—the end mills, shell mills, and other workhorses of the machining industry. For now, though, it’s important to recognize that all milling tools (with one or two exceptions) are just as described previously—multi-toothed rotary cutters that utilize a shearing action to remove material along the periphery of the tool and, in some instances, can act like a drill as well.

In the world of industrial milling, two broad classes of cutting tools exist. These are solid milling cutters and indexable milling cutters. As the name implies, the first of these is made from a solid piece of cutting tool material—usually tungsten carbide, although high-speed steel (HSS) and cobalt milling cutters are also available for hobbyists and low-volume or light-duty machining operations.

There's some overlap between all of these. For example, it's no problem using an end mill to machine the top surface of a small metal workpiece, but the wider and longer that surface becomes, the more reason there is to use a face mill. And some face mills can be used to cut square shoulders like a shoulder mill would, provided that shoulder is fairly shallow in depth. As stated previously, there’s a huge variety of milling cutters out there. The trick is knowing which one to use and how to apply it.

The fly mill is just one example of a milling cutter. As with drill bits, these are rotary tools used on CNC machining centers, live-tool lathes, and yes, manual milling machines. But where a drill bit's cutting edges are positioned at the very end of the tool, limiting it to axial material removal (i.e., holemaking), a milling tool also boasts cutting edges along its periphery, allowing it to remove material radially, from side to side. A huge variety of such tools exists:

Even under heavy use, the exceptional hardness of cobalt drill bits mean they maintain the sharpness of their edge longer. They even resit rusting longer than most other types of HSS bits, so tey are easier to store.

Some people talk about cobalt drill bits and HSS drill bits like they were the same thing, and others say they are completely different. This article will explain the differences between HSS and cobalt drill bits, and what those differences actually mean to you.

Shell mills or shoulder mills can be thought of as an end mill's larger, heftier cousin. They cannot plunge or ramp, but they can remove large amounts of material quickly. Due to their large size, most are indexable, often filled with dozens of carbide inserts. So are face mills, modern, multi-fluted versions of the venerable fly mill that opened this article, used to true up horizontal surfaces and make them both smooth and flat. And copy mills are similar in shape and function to ball-nosed end mills. These are a favorite of moldmaking shops, which use them to rough out large cavities before finishing with a solid carbide or modular end mill.