- Jul 02, 2024
Setting the correct conditions for CNC (Computer Numerical Control) milling is essential to ensure precision, efficiency, and the longevity of both the machine and the cutting tools. CNC milling involves the removal of material from a workpiece using rotating cutting tools, and the correct settings influence the quality of the final product and the efficiency of the process. Here’s a comprehensive guide to setting CNC milling processing conditions.
1. Milling cutting speed
The milling cutting speed refers to the instantaneous speed of the selected point on the tool relative to the corresponding point on the workpiece.
Vc=πDN/1000
Vc Cutting speed, unit m/min
N Tool speed, unit r/min
D Milling cutter diameter, unit mm
The cutting speed is affected by factors such as tool material, workpiece material, machine tool component rigidity and cutting fluid. Usually, lower cutting speeds are often used to process hard or ductile metals, which are strong cutting, the purpose is to reduce tool wear and extend tool life. Higher cutting speeds are often used to process soft materials, the purpose is to obtain better surface processing quality. When a small diameter tool is used for micro-cutting on brittle material workpieces or precision parts, a higher cutting speed can also be used. For example, the milling speed of high-speed steel is 91~244m/min for aluminum and 20~40m/min for bronze.
2. Feed speed
The feed speed is another equally important factor that determines the safe and efficient processing of machine tools. It refers to the relative feed speed between the workpiece material and the tool. For multi-tooth milling cutters, since each tooth is involved in the cutting work, the thickness of the workpiece being cut depends on the feed speed. The cutting thickness will affect the service life of the milling cutter, and excessive feed speed will cause the cutting edge to break or the tool to break.
Vf = Fz * Z * N
Vf Feed speed, unit mm/min Fz Feed per tooth, unit mm/r Z Number of tool teeth N Tool speed, unit r/min
From the above formula, we only need to know the feed per tooth (cutting amount) and the spindle speed to know the feed speed. In other words, knowing the feed per tooth and feed speed, we can calculate the spindle speed.
For example, the feed of a high-speed steel milling cutter, when the tool diameter is 6 mm, the feed per tooth: aluminum 0.051; bronze 0.051; cast iron 0.025; stainless steel 0.025
3. Cutting depth
The third factor to consider during processing is the cutting depth. It is limited by factors such as the amount of workpiece material cut, the spindle power of the machine tool, the tool and the rigidity of the machine tool. Usually, the cutting depth of a steel end mill should not exceed half the tool diameter. For cutting soft metals, the cutting depth can be greater and the end mill must be sharp.