Milling

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Multi-station milling machining for small and medium-sized production series, with 4-axis CNC machines.

Milling is a material removal process that allows you to obtain a wide range of surfaces (planes, grooves, shoulders, etc.) by the action of a pluteniant tool with a defined geometry. The main milling work parameters are the cutting speed, from which the cutting speed of the milling machine is obtained and the workpiece advancement. In order to make the finished piece it is necessary that this can be inscribed in the starting piece from which the overlay will be removed.

The main parameters The milling work parameters are the cutting speed from which the milling rotation speed is obtained and the workpiece feedrate:

The cutting speed depends on the material of the cutter (or the inserts forming the cutting edge) and the hardness of the material to be machined. To work with sweet steel (breaking load 490 N / mm2), today’s Widia cutting mills can work at cutting speeds of 140 m / min or up to 200 m / min if equipped with titanium nitride coatings, the speed must be reduced To work harder materials. The rotation speed (n) of the milling cutter, in rpm, is calculated by dividing the cutting speed (vc) (multiplied by 1000) for the circumference of the milling cutter in mm (Ø diameter for π):

n=vc⋅1000π⋅∅{\displaystyle n={\frac {v_{c}\cdot 1000}{\pi \cdot \varnothing }}}.

The advancement is calculated by multiplying the number of cutting edges (z) for single cutting edge (fz) for rotation speed of the cutter (n):
vf=z⋅fz⋅n{\displaystyle v_{f}=z\cdot f_{z}\cdot n}.
The feed per cut is usually 2-10 mm, for cutting edges perpendicular to the workpiece, can be increased for cutting edges with a cutting geometry of less than 90 °. From this it is understood that the advancement depends on the geometry of the cutting edges and their density, in fact, more sharp cutter blades, but larger diameters, need to rotate more slowly, so z increases but decreases. However, the sharpness of the cutter, that is, their number on the same circumference of the milling cutter, depends on the material to be machined, in particular by the type of chip it produces: if the aluminum is working, the density will be low to be able to discharge the shavings that are long And tend to tangle; The density will be average for steel, while it will be higher for cast iron that produces chips in the form of dust.

The working parameters are indicated according to the ISO Symbol:

  • Vc = cutting speed (m / min)
  • Z = number of teeth
  • N = rotation speed (rpm)
  • Fz = forward tooth (mm / (tooth × lap))
  • Fn = feed per revolution (fz × z – mm / rev)
  • Vf = increment per minute (fz × z × n; or fn × n – mm / min)
    (SOURCE WIKIPEDIA)