Machining parameters for milling operations will influence the efficiency and quality directly, so it’s necessary for optimization of CNC milling parameter, definition of each parameter, selection principle and recommended values are listed in this article for your reference.
The optimization of milling process parameters is closely related to the CNC milling accuracy, the improvement of the surface quality and productivity. Milling parameters mainly includes:
1) Milling spindle speed (V): the linear speed of a specific point on the cutting edge in the main motion during milling.
V=π*dn/1000 (d: milling cutter diameter, mm; n: spindle or cutter rotary speed, r/min)
2) Feed rate (F): the unit displacement of the milling cutter relative to the workpiece in the feed direction. The feed rate of CNC milling will affect the machining accuracy, surface quality, deformation of the workpiece, and cutting tool life.
Feed per revolution (f): the displacement of the milling cutter in the feed direction relative to the workpiece per revolution
Feed per tooth (fz): the displacement of each tooth in the feed direction relative to the workpiece in each rotation of the milling cutter
Feed per minute (Vf): the displacement of the milling cutter in the feed direction relative to the workpiece per minute of rotation
Vf = fn =fz *z * n (n: milling speed; z: number of milling teeth)
3) Milling cutting width (W): the dimension of milling layer measured perpendicular to the axis of milling cutter and the feed direction of workpiece
4) Milling cutting depth (D): the dimension of milling layer measured in the direction parallel to the axis of milling cutter
Note: The selection principle of machining parameters for milling operation is to give full play to the working efficiency and cutting performance of the machine tool on the premise of ensuring the machining quality. Under the condition that the rigidity of the process system allows, choose larger milling depth and width as much as possible, then choose larger feed per tooth, and finally calculate the milling speed.
1)The optimization/selection of milling width and depth
The cutting width and depth options will affect the tool life, often selected based on the machining procedure, efficiency and quality. In rough machining, larger cutting depth and width are recommended, while in finishing machining, less depth and width are better. For end mills, the end mill diameter is usually 1.1 to 1.6 times the milling width. For cylindrical milling cutters, the milling depth shall be less than the length of the milling cutter.
2)The optimization/selection of feed
Feed rate per tooth is an important index to measure milling efficiency. In rough milling, the feed rate is mainly affected by the cutting force, while in semi-finishing milling and finishing milling, it is mainly limited by the surface roughness.
Recommended feed per tooth of milling cutter (mm/z):
3)The optimization/selection of spindle speed
The speed will be influenced by workpiece material, milling part hardness, cutter material, and more factors.
Recommended speed table: