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Side and face milling

​Side and face milling cutters can handle long, deep, open slots in a more efficient manner, and provide the best stability and productivity for this type of milling. They can also be built into a “gang” to machine more than one surface in the same plane at the same time.


How to apply

​Application checklist and hints

  • Choose cutter size, pitch and position so that at least one edge is in the cut at all times.
  • Check chip thickness to achieve the optimum feed per tooth.
  • In demanding milling, check the requirements for power and torque.
    Stiff arbors and overhang are very important in applications in which arbors have a free end.
  • Fixture and arbor support must be strong to handle up-milling cutting forces.




  • First choice method.
  • Use a firm stop in the direction of tangential cutting forces to prevent them from forcing the workpiece down against the table. The feed direction corresponds with the cutting forces, which means that rigidity and eliminating backlash are also important, since the cutter has a tendency to climb.


  • Alternative in applications where problems arise due to insufficient rigidity, or when working on exotic materials.
  • Solves problems generated by weak set-ups and chip jamming in deeper grooves.


  • Good complement for weak set-ups and when available power and torque are low.
  • Position the flywheel as close to the tool as possible.
  • Strengthening the workpiece mounting is always a good investment.


Milling open slots using side and face milling cutters


Calculating feed per tooth
A critical factor in peripheral milling using side and face milling cutters, like CoroMill 331, is achieving a suitable feed per tooth, fz. Insufficient values cause serious disadvantages, so that extra care should always be taken when calculating this.

The feed per tooth, fz, should be decreased for deeper slots and increased for shallower ones in order to maintain the recommended maximum chip thickness.





When full slotting with a CoroMill 331 with an insert size 05 and geometry PL, maximum chip thickness should be 0.10 mm which equals:

Note: Because two inserts work together to cut the full slot width, feed is calculated using half the number of inserts zn.


Depth of cut
In general, a CoroMill 331 will machine slots to a depth ae of 4 x width ap. For deeper slots, a special cutter can be ordered. If deeper slots are to be machined, feed per tooth should be decreased. If the slot is shallower, increase feed.

Note: The depth of a slot can be limited by the diameter of the arbor boss, the deformation strength of the driving keys, and the capacity of the chip pockets.


Fly-wheel – on horizontal machines


​Only a few teeth are engaged at any one time in side and face milling
operations, which can generate heavy torsional vibrations due to the
intermittent machining. This is detrimental to the machining result and to

  • Employing a fly-wheel is often a good solution for reducing these vibrations.
    Problems caused by insufficient power, torque and stability in the machine are often solved by the correct use of fly-wheels.
  • The need for a fly-wheel is greater in a small machine with low power, or in a machine with greater wear, than in a larger, more stable and powerful machine.
  • Position the fly-wheel as close to the tool as possible.
  • Using a fly-wheel results in smoother machining, which in turn leads to a reduction in noise and vibration, and a longer tool life.
  • In addition to up-milling, a fly-wheel can be fitted to the arbor on which the milling cutter is set up.
  • In order to further improve stability when side and face milling, use the
    largest possible fly-wheel that the application permits.
  • Combining a number of round carbon steel discs, each with a centre hole and key groove to fit the arbor, remains the best method for constructing a fly-wheel.
  • The effect of the weight of a fly-wheel increases as the diameter of the
    fly-wheel increases. This means that if circumstances permit a large
    diameter, the weight of the fly-wheel can be reduced.
  • Fly-wheel weight can, if necessary, be distributed over several fly-wheels where space permits.
  • Higher spindle speeds and a larger cut reduce the need for a fly-wheel.
  • Use the smallest possible milling cutter diameter – spindle speed can be increased for a particular cutting speed.


Gang milling using cutters mounted in a staggered pattern


​One of the keyways is displaced from the centre-line by half a pitch.

​CoroMill 331 cutters, CoroMill 329, T-Max Q-cutter and CoroMill 328 versions that have bore mounting with keyways can be arranged in a staggered pattern for milling more than one slot at the same time.

Displacing the cutters half a pitch in relation to each other assists in avoiding
vibration. This also reduces the need for fly-wheels.


Milling of narrow and shallow slots and grooves


​The CoroMill 327/328 cutters have multiple edge inserts that are available in shapes to fit most types of small grooves.

Common applications include the machining of internal circlip and sealring grooves, and of small straight or circular external grooves, particularly on components that cannot be rotated.


Internal grooving


  • A smooth entrance should be programmed when using circular milling.
  • Consider the relationship between the cutter diameter and the hole diameter, Dc/Dw. The smaller the relationship, the larger the engagement will be.


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