For CNC milling parts, the quality of the finished workpiece is crucial. Selecting the right cutting tools and determining the appropriate cutting parameters are key factors in CNC milling. Programming staff must accurately master the basic principles of tool selection and cutting parameters. Additionally, the characteristics of each part’s machining process should be highly valued.
Common Types of Milling Cutters
The variety of workpiece materials and forms results in different types and forms of milling cutters.
Milling cutters can be classified by material (high-speed steel, alloy steel, diamond, ceramic, cubic boron nitride) and by structure (integral and insert types). Insert types can be welded or machine-clamped.
By cutting head shapes, they can be classified into ball-end, flat-end, tapered, T-shaped, etc.
Factors Influencing Cutting Tools Selection
Choosing the right milling cutter depends on the properties of the workpiece material (e.g., ferrous, non-ferrous metals, composites, polymers).
Factors like hardness, toughness, rigidity, and wear resistance must be considered. The main machining capabilities depend on the CNC machine, so the choice of tools should also consider the machine’s characteristics, minimizing tool numbers to complete multiple processes in one setup.
Common Uses of CNC Milling Tools
End Mills: Suitable for shaping bosses or grooves on the workpiece surface, and for roughing, finishing, and cleaning operations.
Keyway Milling Cutters: Ideal for machining various slots and keyways.
Ball End Mills: Suitable for surface finishing with small cutting volumes. Generally not used for large shapes due to low efficiency.
Face Mills: Mainly used for machining large flat workpieces.
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How to Select Cutting Tools for CNC Milling
The principles for selecting milling cutters include ease of installation and adjustment, ensuring machining accuracy, and extending tool life. The geometric shape of the workpiece is a critical consideration when choosing milling cutters, as improper selection can severely impact machining quality and result in defective products.
Determining Cutting Parameters for CNC Milling
CNC milling achieves workpiece machining through cuts in different directions. Cutting parameters such as cutting speed, depth of cut, and width of cut significantly affect machining speed, quality, and tool life. Different conditions require different cutting parameters, balancing machining quality, efficiency, and tool wear.
1 Determining Cutting Speed
Cutting speed selection considers workpiece hardness, tool material, and tool life. Lower cutting speeds are recommended for roughing operations with large cutting depths to reduce temperature and extend tool life. Higher cutting speeds can be used for finishing operations to ensure surface accuracy and efficiency.
2 Determining Feed Rate
Feed rate, the depth cut per minute, typically ranges from 100 to 200 mm/min. Lower feed rates are recommended for high-speed steel tools or deep-hole machining, usually between 20 to 50 mm/min.
3 Determining Depth of Cut
The depth of cut (width of cut) affects operational safety and tool and machine life. Excessive depths can cause tool collisions, damaging tools or machines. Within a certain range, choosing the maximum tolerable depth can reduce the number of passes and improve production efficiency.
Conclusion
CNC milling machines have high requirements for their cutting tools, which must have high precision, strength, and rigidity and be easy to install and adjust. Different tools have various lengths of shank and shapes of cutting heads.
When selecting tools, factors such as the milling machine’s clamping capability, workpiece material properties, and processing methods must be considered. Tools with shorter shanks should be chosen whenever possible to maximize rigidity, meet machining accuracy requirements, and extend tool life.
