A milling cutter is a rotating tool with one or more teeth used for milling processing. During operation, each cutting tooth intermittently cuts off the remaining amount of the workpiece. Milling cutters are mainly used for machining flat surfaces, steps, grooves, formed surfaces, and cutting workpieces on milling machines. The author believes that when choosing a milling cutter, attention should be paid to both the milling cutter body and the tool holder: 1. Is the milling cutter used on a CNC machining center or a regular milling machine. 2. Materials and hardness processed by milling cutters. 3. The specifications of the milling cutter, such as blade length, full length, blade diameter, shank diameter, etc. If it is used on CNC machining centers, it should be made of solid hard alloy. White steel can be used on ordinary milling machines. Compared to hard alloy milling cutters, white steel milling cutters have softer hardness. High speed steel cutters are cheap and have good toughness, but their strength is not high, making them easy to break. Moreover, their wear resistance and thermal hardness are relatively poor. The thermal hardness of high-speed steel milling cutters is about 600 degrees, and the hardness is about 65HRC. It is obvious that when using white steel to mill harder materials, if the coolant is not in place, it is easy to burn the cutter. This is one of the reasons for the low thermal hardness. Hard alloy milling cutters have good thermal hardness and wear resistance, but their impact resistance is poor. The cutting edge can shatter easily when dropped. Hard alloy is a material made by powder metallurgy, with a hardness of around 90HRA and a thermal resistance of around 900-1000 degrees. So, white steel is suitable for ordinary milling machines, and alloy milling cutters are used in CNC machining centers.