In metal cutting, a square-end mill is a widely used basic tool. Its cutting edge is straight and the end is a standard 90° right angle, which can handle a variety of processing tasks such as side milling, slotting, contour processing and end face finishing. Although its appearance seems simple, the design of each square-end mill embodies the comprehensive consideration of processing efficiency, precision and stability.

Selecting a tool based solely on experience or appearance is insufficient for achieving efficient and high-quality cutting. Understanding its structural composition and key geometric parameters is the prerequisite for accurate selection and efficient application. This article will systematically analyze the structural elements and core parameters of square-end mills to help engineering and technical personnel make more scientific judgments in practical applications.

1. Overview of structural composition

A standard square-end mill consists of the following parts:

Cutting Edge

The area where material removal is achieved determines the cutting performance and life of the tool.

Spiral groove (Flute)

Guide the chip discharge and assist in cooling. The shape and number of grooves directly affect the chip removal efficiency and cutting stability.

Neck

Located between the blade and the shank, some are designed as a thin neck structure to improve the deep cavity processing capability.

Shank

The part clamped in the machine tool spindle. The shank size and cylindricity are related to the concentricity and vibration control capability of the clamping system.

End Cutting Edge

Assumes the end milling and cutting functions. The end edge design has a significant impact on the milling cutter feed performance and cutting load.

2. Analysis of key specifications and parameters

1. Tool diameter (D)

The maximum outer diameter of the blade is the core parameter that determines the cutting width and spindle load. Standard specifications cover 1mm to 20mm, and common values include: 2mm, 4mm, 6mm, 8mm, 10mm, 12mm, 16mm, etc. When selecting the diameter, the machining profile size, equipment rigidity and cutting path strategy should be comprehensively considered.

2. Blade length (L1)

Refers to the effective length of the tool that can be used for cutting. Blade length is usually designed as a multiple of the tool diameter, such as 2D, 3D, or 4D (D is the tool diameter). Long blades are suitable for deep groove processing, but have low rigidity and are recommended only when necessary.

3. Total length (L)

The overall length of the tool, from the tip to the end of the shank. Affects the overhang length and processing depth. It should be reasonably selected according to the machine tool magazine limitations, clamping method and actual processing depth to avoid vibration and processing errors caused by excessive overhang.

4. Shank diameter (d)

The shank diameter must be compatible with the clamping device (such as an ER chuck or thermal expansion chuck), with common sizes including 6mm, 8mm, 10mm, 12mm, and others. Larger shank diameters offer greater clamping rigidity, enhancing the stability of high-speed machining.

5. Number of blades (N)

The number of blades affects chip removal performance, feed speed and surface quality. Common configurations are as follows:

• 2-edge: large chip removal space, suitable for high-speed processing of soft materials such as aluminum alloy;

• 3-edge: consider chip removal and strength;

• 4-edge: suitable for finishing of steel parts;

• 6-edge and above: improve unit feed rate and life, suitable for high-speed and high-load cutting.

6. Helix Angle

Typically 30°, 35°, 45°, etc., which influence the direction of cutting forces and the trajectory of chip flow.

• Small helix angle: slow chip removal but strong rigidity, suitable for hard materials;

• Large helix angle: lighter cutting, suitable for soft materials or high-speed cutting scenarios.

7. Corner Angle

Square head milling cutters usually have a standard 90° corner angle, which is used for processing features such as sharp grooves and right-angle shoulders. Although it has geometric advantages, the tip strength is low and it is easy to cause micro-chipping under impact load. If the processing conditions are severe, you can choose a variant with a **Corner Radius** design to improve chipping resistance and service life.

3. Materials and coatings: the fundamental guarantee of performance

Material type

• High-speed steel (HSS): good toughness, suitable for low-speed processing and general application scenarios.

• Integral carbide: high wear resistance and hardness, suitable for high-speed and high-precision processing, the mainstream CNC processing choice.

• Ultra-fine carbide: enhances strength and toughness, making it ideal for high-load and intermittent cutting applications.

Coating selection

Different coatings can significantly improve the tool's heat resistance, friction coefficient and oxidation resistance:

• TiN (titanium nitride): general type, improves wear resistance;

• TiAlN, AlTiN: high-temperature resistance, suitable for high-speed steel processing;

• AlCrN: excellent hot hardness, adaptable to higher cutting temperatures;

• DLC coating: excellent lubricity, suitable for aluminum alloys and non-ferrous metals.

4. Selection suggestions: practical strategies for parameter combinations

In the actual processing process, the selection of square-head milling cutters should be comprehensively judged in combination with process conditions, workpiece materials and equipment capabilities:

5. Conclusion

The square-end mill, while one of the most basic yet commonly used CNC tools, has a simple design. However, each geometric parameter, material choice, and coating selection significantly influence machining outcomes. A clear understanding of its "physique" can not only extend tool life and enhance processing efficiency but also optimize the overall quality of the entire production process.

As automation and intelligent manufacturing continue to advance, precise tool selection and optimal configuration will become essential skills for process engineers and machine operators. Mastering these begins with understanding the "body language" of the square end mill.