The milling method of CNC milling machines

CNC milling machines, with their high precision and high automation features, have become one of the core equipment in the field of mechanical processing. Their diverse milling methods can meet the processing requirements of different parts.

 Ⅰ.Basic milling processing methods

  1.Plane milling is one of the most fundamental processing methods of CNC milling machines, mainly used for rough and finish machining of the bottom surface, top surface or step surface of workpieces. During processing, face milling cutters are used. By coordinating the rotation of the tool with the feed motion of the workpiece, the excess material on the workpiece surface is quickly removed to obtain a smooth machined surface. This method is applicable to the processing of reference surfaces for various flat plate parts and box parts, and can effectively ensure the accuracy foundation for subsequent processing.

  2.Milling slot processing covers the processing of various slot types such as straight slots, keyways, and T-slots, and is commonly accomplished with end mills or special slot milling cutters. When processing straight grooves, the end mill moves along the linear path of the workpiece, cutting the material layer by layer. To process T-slots, it is necessary to first produce straight slots and then use T-slot milling cutters for slot expansion processing. This method is widely applied in the processing of mechanical transmission parts and mold parts, such as keyways of gears and cooling water channels of molds.

  3.Side milling machining uses the side edge of an end mill to cut the side of the workpiece and is often used to process structural features such as bosses and grooves. During the processing, the cutting tool moves along the contour of the workpiece's side. By controlling the cutting depth and feed rate, the verticality and surface roughness of the side are ensured. Side milling plays a significant role in the processing of the inner cavity sides of various box parts and the bosses of bracket parts.

  4.Profiling milling Profiling milling is a type of following milling that follows the contour of a template or digital model, and is suitable for processing parts with irregular shapes. Before the popularization of numerical control technology, profiling milling was accomplished by mechanical profiling devices. Nowadays, by reading the three-dimensional model data of parts through numerical control systems and controlling the movement of cutting tools along the contour of the model, high-precision processing of complex curved surfaces and irregular parts can be achieved, such as the shape processing of automotive body panel molds and aerospace parts.

Ⅱ.Advanced milling processing methods

1. Ramping: During ramping, the cutting tool cuts into the workpiece at an oblique Angle to reduce the impact load when the tool is lowered vertically. It is often used in the processing of deep cavity parts. Compared with vertical cutting, slope milling can effectively reduce tool wear and improve the stability of processing, especially when processing materials with higher hardness, its advantages are more obvious.

2. Helical blanking (helical Plunge) helical blanking refers to the tool entering the material along a helical path. This blanking method is conducive to chip removal and can also protect the end edge of the tool. For the situation where the end mill has no center cutting ability, helical cutting can prevent tool damage caused by forced vertical cutting and is widely used in the rough machining of cavity parts.

3. Peck Milling/Trochoidal Milling: During peck milling, the cutting tool moves along a cycloidal trajectory, evenly distributing the cutting load across the cutting edge of the tool, thereby extending the tool's lifespan. This method is suitable for the efficient removal of difficult-to-machine materials, such as superalloys and titanium alloys. While ensuring processing efficiency, it can effectively control the processing deformation of parts.

4. In the process of Plunge Milling, the cutting tool is periodically inserted along the Z-axis. It is mainly used to quickly remove a large amount of excess material and is particularly suitable for rough machining of deep cavities. The processing efficiency of insert milling is relatively high. It can remove most of the excess material from the workpiece in a short time, reserving an appropriate machining allowance for subsequent fine processing.

5. Contour Milling is a process of cutting along the contour lines of a part layer by layer and is often used for the finishing of complex curved surfaces. By controlling the depth of each layer of cutting, it ensures that the surface quality of the part's curved surface is consistent with the residual height, and is widely applied in the curved surface processing of mold cavities and aerospace parts.

   
   

Ⅲ.Other special milling methods

1. Form Milling uses special tools to process complex contours. Commonly used tools include concave and convex milling cutters, which can form surface contours, fillets and circular grooves in one cutting. This method is applicable to the processing of parts with complex shapes that require high precision, such as the tooth profile of gears and the cavity contour of molds, and can effectively improve processing efficiency and accuracy.

2. Gang Milling is a type of form milling. Multiple milling cutters are installed on the same spindle to process multiple parallel surfaces or multiple grooves simultaneously. These milling cutters can have different shapes, sizes or widths, and can complete multiple processing tasks in a relatively short time, improving production efficiency. They are suitable for batch processing of complex parts.

3. Trapezoidal Milling (Straddle Milling) trapezoidal milling uses two milling cutters arranged in opposite directions to simultaneously mill both sides of the workpiece, ensuring consistent dimensional accuracy on both sides and achieving efficient symmetrical processing. This method is applicable to batch processing of structures such as symmetrical grooves and symmetrical steps, such as the symmetrical grooves of couplings and the symmetrical step surfaces of gears.