How to adjust the rotational speed according to the diameter of the cutting tool?

Adjusting the rotational speed according to the tool diameter is indeed a crucial step in the operation of a milling machine. The core formula is: ‌ rotational speed (r/min) = 1000 × cutting speed (m/min) ÷ (π × tool diameter (mm)) ‌. Now I'll help you break it down specifically how to use it

First, determine the cutting speed

The cutting speed mainly depends on the ‌ tool material ‌ and the ‌ workpiece material ‌, for example:

high-speed steel milling cutter ‌ : processing aluminum approximately 91-244m/min, bronze 20-40m/min.

carbide milling cutter ‌ : For rough milling of No. 45 steel, the speed is approximately 20-30m/min, and for finish milling, it can reach 80-120m/min.

Second, substitute the formula to calculate the rotational speed

Suppose a ‌ carbide milling cutter ‌ is used to process no. 45 steel, with a tool diameter of 10mm and a cutting speed of 25m/min:

The rotational speed = 1000 × 25 ÷ (3.14 × 10) ≈ 796r/min. In practice, 800r/min is selected.

Iii. Pay attention to these details

The diameter of the ‌ tool has a significant impact ‌ : the smaller the diameter, the higher the rotational speed, but attention should be paid to the load-bearing capacity of the machine tool and the tool.

material hardness ‌ : The harder the material, the lower the cutting speed, and the rotational speed should also be reduced accordingly.

processing method ‌ : For rough machining, the rotational speed can be appropriately reduced; for finish machining, the rotational speed can be increased to achieve better surface quality.

Four. Let's take a practical example

high-speed steel milling cutter (D=10mm, rough milling) ‌ : cutting speed 25m/min, rotational speed ≈800r/min.

carbide milling cutter (D=20mm, finish milling) ‌ : cutting speed 100m/min, rotational speed ≈1600r/min.

Five, don't forget the feed rate

Feed rate formula: ‌Vf = fz × Z × n‌ (fz is the feed per tooth, Z is the number of teeth). For instance, for a carbide milling cutter, the fz is taken as 0.08mm/r, the number of teeth is 4, the rotational speed is 1600r/min, and the feed rate is approximately 512mm/min.

Six. Refer to these data

high-speed steel milling cutter ‌ : aluminum fz≈0.05-0.1mm/r, similar to bronze.

carbide milling cutter ‌ : for rough milling of No. 45 steel, fz≈0.1-0.2mm/r, and for finish milling, 0.05-0.1mm/r.