Hints for the Right Number of Teeth
In which case it is best that a milling cutter has as few teeth as possible...
The main problem of milling slots is the agglomeration of chips on the cutting edge which may lead to a plugged milling cutter. When a milling cutter is finally plugged, it can no longer transport the chips, and the feeding force of the milling machine will break it. Usually this happens – depending on the material – long before the cutting edge is worn out. So, primarily the question whereto the chips should be discharged has to be solved. Usually this will be done upwards or to the back. However, the flute should be as large as possible to transport the chips past the substance of the milling cutter. A comparison of the cross-sections of different types clearly shows that the single tooth cutter has the greatest open space (= size of the flute). This leads to the lowest risk of plugging. The more cutting edges a milling cutter has, the more the open space is being reduced. The less cutting edges a milling cutter has (and the more tapered they are), the easier it is to dip into the surface of the workpiece.
For working on materials which are mainly used for sign making like plastics (PVC, acrylic, foam plastic, etc.), derived timber products (e. g. press boards) and non-ferrous metals (soft aluminium, aluminium composite material, brass, ...), the single tooth cutter is usually better. The cutting edge erosion is less strong here than the risk of plugging.
In which case it is best that a milling cutter has as many teeth as possible...
The cutting edge is the wearing part of the milling cutter. The more cutting edges a milling cutter has, the more cutting edges share the wear. So the endurance, the life-time, if the tool will be prolonged. A milling cutter with more cutting edges has a better true running accuracy than with only one cutting edge. Due to the greater cross-sectional area of a multiple tooth cutter that is being covered by carbide, more heat will be dissipated to the collet chuck. This is especially useful if there is no other way of cooling. Another important factor is that the more cutting edges a tool has, the smaller become the chips. This leads to smoother surfaces.
A double tooth cutter is recommended when you are working on thermosetting plastics or harder sorts of aluminium (short-chipping).
We recommend multiple tooth cutters for very hard non-ferrous metals (very hard aluminium alloys, brass, ...) and for ferrous material.
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Cross-section of single tooth cutter: The single tooth cutter has a great open space |
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Cross-section of triple tooth cutter: Three cutting edges need much more space |
