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Milling cutters are cutting tools used in milling machines or machining centres. They are used to remove material by their movement within the machine (eg: a ball nose mill) or directly from the cutters shape (a form tool such as a Hobbing cutter).
Slot drills
Slot drills (top row in image) are generally two (occasionally three) fluted cutters that are designed to cut on their end as well as the flutes. They are so named for their use in cutting keyway slots. When used for plunge cutting (vertically down as when drilling), one of their frontal cutting edges should be across the center for the correct cutting action to occur as shown in the image opposite, with the end view of the slot drill. Slot drills are mostly used only when it would be too time consuming to pre-drill a hole for an endmill and there isn't enough room for the end mill to plunge using a helical motion. That is because slot drills don't drill very well; the cutting edge that crosses the center of the mill (center-cut) actually spins the wrong way on the part of it that crosses the center.
End mills
End mills (middle row in image) are generally HSS cutting tools with three or more flutes. They are intended for bulk metal removal with their flutes and unless they are ground with cutting edges that cross the axis (as those in the image show) then they are only suitable for side cutting. However, you can perform plunge cuts with them if you instead of simply drilling down into the workpiece, perform a three-axis helical motion. That way on the side cutters will be in cutting due to the extreme precision the mill is produced with.
Early endmills and most large endmills have a recessed center at each end of the cutter to facilitate resharpening, this results in the full cutting edge being unavailable. The image at right shows two end views (center row) of an endmill that illustrate this. Some endmills also have rounded corners, either concave radii (fillet endmills), or convex radii (bullnose).
Ball nose cutter
Ball nose cutters (lower row in image) are similar to slot drills but the end of the cutters are shaped as hemispherical cutting edges. They are ideal for machining 3 dimensional contoured shapes in machining centres, for example in molds and dies.
Slab mill
Slab mills are (were) used in horizontal or universal milling machines to machine large broad surfaces quickly. They have been superseded by the use of Carbide tipped face mills that are then used in vertical mills or machining centres.
Side and face cutter
The side and face cutter is designed with cutting teeth on its side as well as its circumference. They are made in varying diameters and widths depending on the application. The teeth on the side allow the cutter to make unbalanced cuts (cutting on one side only) without deflecting the cutter as would happen with a slitting saw or slot cutter (no side teeth).
Involute gear cutter
The image shows a Number 4 cutter from an involute gear cutting set. There are 7 cutters (excluding the rare half sizes) that will cut gears from 12 teeth through to a rack (infinite diameter). The cutter shown has markings that show it is a
- 10 DP (diametrical pitch) cutter
- That it is No. 4 in the set
- that it cuts gears from 26 through to 34 teeth
- It has a 14.5 degree pressure angle
Hobbing cutter
These cutters are a type of form tool and are used in hobbing machines to generate gears. A cross section of the cutters tooth will generate the required shape on the workpiece, once set to the appropriate conditions (blank size). A hobbing machine is a specialised milling machine.
Face mill (carbide tipped)
A face mill consist of a cutter body (with the appropriate machine taper) that is designed to hold multiple disposable carbide or ceramic tips (or inserts).
These tips may be rotated within the holder to present a fresh face to the workpiece, this increases the life of the tip and thus their economical cutting life. The tips are not designed to be resharpened and are selected from a range of types that may be determined by various criteria, some of which may be: tip shape, cutting action required, material being cut.
Woodruff cutter
'Woodruff cutters are used to make the seat for woodruff keys. These keys are used to retain pulleys on shafts and are shaped as shown in the image.
"Milling cutter"