Why the type question matters
Ask for "an end mill" and you have named a family, not a tool. The type - square, ball nose, roughing, tapered - decides what the tool can cut and what it cannot, long before flute count or coating enters the conversation. For a buyer building a range, the types are the aisle structure of the store: each one needs its own listing, its own spec sheet and its own vocabulary. This note keeps each description to standard trade usage, so the words you read here are the words a factory will quote against.
Square end mill: the general-purpose rectangle
The square end mill carries sharp 90-degree corners at the periphery, and it does the everyday work of milling: slots, profiles, steps, pockets with square corners. Most ranges start here and stock it deepest, because a general-purpose geometry sells across every customer type. When a drawing calls for a crisp internal corner, this is the tool that makes it - and also the tool whose sharp corner is the first thing to chip in harder alloys, which is exactly why the next type exists.
Ball nose: the hemisphere
A ball nose end mill ends in a hemisphere, and it owns 3D work: contoured molds, 3D profiling, smooth finishing of curved surfaces. Because the cutting edge blends into the shape with no corner to overload, it sweeps surfaces a square tool can only step across. Mold and die shops buy it by the dozen. The family page is ball nose end mills.
Bull nose: the corner radius
A bull nose - or corner radius - end mill puts a radius between the periphery and the face. That small arc spreads the cutting forces that a sharp corner would concentrate, resists chipping, and extends the working life of the edge on harder materials. The trade-off is honest: it leaves a radius in the floor of every pocket, so drawings must either accept it or finish the corner separately. For steel, stainless and titanium work, it has become a default choice for buyers who stock by wear-out behavior rather than by price.
Roughing: the serrated periphery
A roughing end mill looks different before you read a single spec: its periphery is serrated, or corrugated, into small teeth. The serrations break chips into short segments that evacuate easily, so the tool takes deep, heavy cuts at high metal-removal rates and leaves a scalloped wall for a finishing pass to clean. It is the first half of a two-pass strategy, and the family page is roughing end mills.
Finishing: geometry for the surface
Finishing end mills are ground for fine surface finish - often more flutes, sharper geometry, and the kind of edge consistency that shows up on a measured wall rather than in a catalog sentence. In practice, buyers meet "finishing" as an intent: the last tool to touch the surface, chosen for the finish it leaves rather than the metal it moves. Flute count leans higher; the reasoning is in the flute count guide.
Tapered: the cone
A tapered end mill is a conical body with a taper angle, and it exists for walls that lean: draft angles in mold cavities, deep cavities whose walls close in as they go down, engraving with a ball taper where the tip draws fine and the body stays stiff. The taper angle is a specification line confirmed per spec, not an assumption - degrees vary by program. See the tapered end mills page.
Chamfer and corner rounding: the edge workers
Two form tools finish the perimeter of parts. A chamfer mill carries cutting geometry for 45-degree and other chamfers and for breaking sharp edges after milling. A corner rounding end mill is a full-radius form tool for fillets and radiused edges. Both are small listings with steady demand, because nearly every machined part gets its edges treated one way or another. The pages are chamfer mills and corner rounding end mills.
The map in one table
| Type | Geometry in one line | Typical work |
|---|---|---|
| Square | Sharp 90-degree corners | Slots, profiles, general milling |
| Ball nose | Hemispherical end | 3D contouring, molds, curved finishes |
| Bull nose | Radius at the corner | Harder alloys, longer-running edges |
| Roughing | Serrated periphery | High metal removal, scalloped wall |
| Finishing | More flutes, sharper geometry | Fine wall and floor finish |
| Tapered | Conical body with taper angle | Draft angles, deep cavities, engraving |
| Chamfer mill | Chamfer cutting geometry | 45-degree breaks, deburring |
| Corner rounding | Full-radius form profile | Fillets and radiused edges |
Beyond the end mill family proper sit the special shapes - slot drills for plunging, T-slot and dovetail cutters, thread mills, face mills - which the geometry index keeps in their own aisles.
How types combine on one part
A single aluminum mold block can meet five types in one cycle: a roughing pass to move metal, a square pass to square pockets, a ball nose for the contoured core, a tapered tool along the draft wall, and a chamfer mill to break every edge before the part leaves the bench. That is why ranges are built by type first and size second - a buyer who stocks all the types in the common diameters can serve nearly every job a customer brings, and can quote from a sheet where every line names its type.
For buyers: presenting the types
- One listing per type. Keep square, ball nose and the rest in separate categories with the type named in the title; mixed "end mill assorted" listings hide the line buyers search for.
- Describe to trade usage. The one-line geometry phrases above are written to be reused on product pages - geometry first, marketing nowhere.
- Spec sheet per line: type, diameter, LOC, OAL, shank, flutes, corner style, substrate, coating family. A sheet in that shape quotes without a phone call.
- Order the range deliberately. Square deepest, ball nose and bull nose next, form tools to complete the aisle - and confirm quantities and lead times in writing per the MOQ and lead time references.
If you are mapping a first range or filling gaps in an existing one, send the list of types and sizes through the quote form and the desk will return the route - catalog items or ground-to-order - for each line.