How are CNC milling conditions set?

In CNC machining, after selecting a tool, many people usually do not know how much cutting speed and speed should be selected. They just passed the experiment, and as long as there are no particular problems, they think it's ok. Doing so is very dangerous. A frequent problem is breaking the tool, or causing the material to melt or burn. Whether there is a scientific calculation method, the answer is yes.

1 milling speed

The milling speed refers to the instantaneous speed of the selected point on the tool relative to the corresponding point of the workpiece.

Vcu003dπDN/1000

VC cutting speed (M/min)

N tool speed (R/min)

D Tool diameter (mm)

Cutting speed is affected by tool material, workpiece material, part stiffness and cutting fluid. Generally speaking, lower cutting speeds are usually used to machine hard or ductile metals, which are power cutting to reduce tool wear and extend tool life. Soft materials are usually machined at higher cutting speeds for better surface quality. Higher cutting speeds can also be used when small diameter tools are used for micro-cutting brittle material workpieces or precision parts. For example, the milling speed of aluminum high-speed steel is 91~244m/min, and that of bronze is 20~40m/min.

2 Feed Rate Feed rate is another equally important factor that determines the safe and efficient machining of machine tools. Refers to the relative cutting speed between the workpiece material and the tool. For multi-tooth milling cutters, since each tooth participates in the cutting work, the cutting thickness of the workpiece depends on the feed rate. The cutting thickness will affect the service life of the milling cutter, and the feed rate will cause the cutting edge to break or the tool to break.

Vfu003dFz*Z*N

VF feed rate, unit mm/minfz feed rate per tooth, unit mm/RZ number of tool teeth n tool speed, unit R/min

From the above formula, we only need to know the feed amount (cutting amount) of each tooth and the spindle speed to know the feed amount. That is, the spindle speed can be calculated as long as the feed amount and feed amount of each tooth are known.

For example, when the cutter diameter is 6mm, the feed per tooth is 0.051 for aluminum, 0.051 for bronze, 0.025 for cast iron, and 0.025 for stainless steel

Three. The third factor to consider in depth of cut machining is the depth of cut. It is limited by the amount of workpiece material removal, machine tool spindle power, tool and machine stiffness. The depth of cut of steel cutting end mills should generally not exceed half the diameter of the tool. When cutting soft metals, the depth of cut can be greater. The end mill must be sharp when working, concentric with the end mill chuck, and minimize the overhang of the end mill during installation.