How To Select Cutting Tools For CNC Machining?

Precision CNC machining of a metal component by Yonglihao Machinery cutting tool

In the process of CNC machine tool machining parts, the selection of CNC tools is essential to the machining process. It is key to the process of making the parts. Choosing the right tool will not only affect the speed at which the part is machined. Choosing the right CNC tool reduces part distortion. It improves manufacturing quality and speeds up part machining. It also increases productivity and extends the life of tools and equipment. It reduces the number of tool changes and improves the efficiency and accuracy of CNC machines. This increases the competitiveness of the company’s products and ensures sustainable growth. In the next section, Yonglihao Machinery will show you how to choose the right tool for your CNC machine tool.

Table of Contents

Understanding Different Types of CNC Cutting Tools

There are several ways to categorize CNC cutting tools. Commonly used CNC cutting tools include end, circular, and ball end mills. Each type of tool has its specific purpose.

According to the structure of the tool, it can be divided into (1) integral type; (2) inlaid type with welded or machine-clamped coupling, of which the machine-clamped type can be further categorized into non-inverted and indexable two; (3) special type, including, for example, composite tools, vibration-damping tools and so on.

The materials used in the manufacture of tools can be divided into (1) high-speed steel tools; (2) carbide tools; (3) diamond tools; and (4and ) other materials, such as cubic boron nitride tools, ceramic tools, and so on.

The cutting process can be divided into ① turning tools, divided into cylindrical, bore, thread, cutting tools and other kinds of; ② drilling tools, including drills, reamers, taps, etc.; ③ boring tools; ④ milling tools and so on.

To meet the requirements of CNC machine tools, in recent years the number of adjustable and durable tools has reached 40% to 90% of the total number of CNC machine tools. CNC machine tools have some key differences from ordinary ones. They have good rigidity, high precision, and long life. They are also easy to replace. In addition, It also has standardization, serialization, and other features. These make programming and tool management easier.

Variety of Yonglihao Machinery CNC cutting tools

Factors to Consider When Choosing CNC Tools

In the process of CNC machining, tool selection can refer to the following key factors:

1. Workpiece material: The workpiece material will determine the choice of tool material and geometric parameters of the cutting part. It also affects the machining accuracy of the final part and the functional performance of the product

2. Nature of production: The nature of production here refers to the batch size of the part, mainly from the cost of processing to consider the impact of tool selection. For example, using special tools in mass production may be cost-effective. But, in single-piece or small-batch production, it’s better to use standard tools.

3. Machining accuracy: Machining accuracy affects the type of finishing tool selection and structural shape, such as the final processing of the hole according to the accuracy of the hole can be drilled, reamed drill, reamer or boring tool, and other ways to process.

4. Machining program: Different machining programs may choose different machining tools. For example, some large holes can be processed using drilling and reaming drills, can also be processed using a boring tool, you can also use a milling cutter for processing.

5. Cutting parameters: Different materials require different cutting parameters. For example, when machining free-form surfaces (e.g. molds), the cutting speed of a ball-end tool is zero. Therefore, the cutting line distance is usually set to dense to maintain accuracy. For this reason, ball-end tools are usually used for surface finishing.

6. Workpiece size and shape: The size and shape of the workpiece also affect tool selection. For example, end mills process the edges of flat parts. To mill flat surfaces, use carbide insert milling cutters. For high-speed milling, convex or fluted cutters should be selected. For rough surface machining, use corn milling cutters with carbide inserts. They can also be used for rough-hole machining.

7. Machining surface accuracy: Roughness affects tool shape and cutting dosage. For rough milling, use a coarse tooth cutter. For fine milling, use a fine tooth cutter. For rough surface or hole machining, use a corn milling cutter with carbide inserts.

Yonglihao Machinery specialized CNC cutting tools for advanced manufacturing

Tool Configuration and Setup

In the general production process, setting up and installing good tools is crucial for producing parts. To complete multiple machining processes in a single clamping of the workpiece, shorten the auxiliary time, and reduce the error caused by installing the workpiece several times, an automatic tool changer can be used.

First, the machining tools should be mounted individually in standard tool holders. Then, after being pre-sized outside the machine, they are somehow placed in the tool magazine. 

When changing tools, the first tool is picked up from the tool magazine. The tool changer then removes the tool from the magazine or spindle and replaces it. It loads the new tool into the spindle and puts the old tool back into the tool magazine. The tool magazine has a large capacity and can be mounted on the side or above the spindle housing.

The CNC machine has an automatic tool changer with a tool magazine. It has only one spindle in the spindle box. The parts of the spindle must be tough to meet the needs of precision machining. In addition, the tool magazine contains many tools. This allows multi-process machining of complex parts. The adaptability and efficiency of the machine tool is greatly improved. Automatic tool change systems with tool magazines are suitable for CNC drilling centers and machining centers.

Advanced Yonglihao Machinery CNC cutting tool head for high precision machining

Advanced Tool Selection Strategies 

In CNC machining, tools are considered a critical component of the production process. The general selection principles for critical tools are ease of installation, ease of adjustment, robustness, and machining accuracy. To meet the machining requirements, choose a shorter shank. This will improve tool rigidity. When selecting the tool, the size of the tool should be adapted to the surface size of the workpiece to be machined. For roughing non-smooth surfaces or hole surfaces, you can use carbide insert milling cutters. For certain 3D surfaces and variable beveled contours, you can use spherical, ring, taper, and trapezoidal cutters, among others. In the surface processing, should be selected ball tool, and the radius of the ball tool should be less than the minimum curvature radius of the surface. The end-cutting speed of a ball-ended tool is zero. To ensure accuracy, the cutting rows are very close to each other. In terms of surface quality and cutting efficiency, flat-end tools are superior to ball-end tools. Therefore, after ensuring the machining accuracy, then select the flat-end tool for roughing or finishing. Tool selection also needs to be adjusted according to specific machining tasks. In high-volume production, you can pick high-quality tools with good wear resistance. These tools may cost more. But, they can greatly cut the overall machining costs by boosting quality and efficiency.

Maintenance & Care for CNC Tools

The maintenance of CNC tools is also an important part of the machining process. In the whole process of machining parts, the need to do as well as possible in the following areas:

Regularly clean the tool: In the production process, the surface of the tool is easy to adhere to the cutting fluid, oil and metal shavings, and other impurities, these impurities will not only affect the cutting performance of the tool but also may cause damage to the machine tool. Therefore, the tool should be cleaned regularly to keep its surface clean.

Regularly check tools for wear and replace them as appropriate: You can use the number of times a tool is used or the length of time it is on the job to plan a tool replacement cycle so that it can be replaced promptly.

Reasonable storage by the requirements: Store knives in a dry, ventilated, dust-free place. Avoid direct sunlight and moisture. At the same time, tools should be categorized and stored to avoid confusion and damage. Good maintenance and preventive measures are therefore important. They prolong tool life and also improve the quality of parts machining.

Multiple CNC cutting inserts from Yonglihao Machinery optimized for various machining operation

Conclusion

Metal-cutting tool materials are now categorized into five main groups. They are high-speed steel, cemented carbide, ceramics, cubic boron nitride, and polycrystalline diamond. When turning or milling high-strength steel, titanium alloy, and stainless steel parts, it is recommended that you use carbide tools with better wear resistance.

In the roughing stage, hard, imprecise tools should be used to remove excess parts of the blank material.

During the semi-finishing and finishing stages, durable, precision tools are used to ensure the accuracy and quality of the part.

Use the least accurate tools in the roughing stage and the most accurate tools in the finishing stage. If roughing and finishing selection of the same tool, it is recommended that roughing selection of finishing eliminated from the tool, because finishing eliminated most of the tool wear for the edge of the slight wear, coating wear repair light, continue to use will affect the machining quality of the finishing process, but the impact on the roughing is small.

Nowadays, CNC tooling is rapidly evolving and changing. More and more tool types are coming. When we choose tools, we need to keep learning new tooling knowledge and mastering new cutting technology. Yonglihao Machinery has lots of experience and expertise in the industry. It can provide you with the best solutions. For more information, please feel free to contact us, we will be happy to serve you.

FAQ

In CNC machining, when we find that tools are worn, parts are oversized, machining efficiency becomes lower, and the surface finish of the machined parts is reduced, we may need to change tools to ensure that the quality of the parts machined meets the requirements of the drawings.

The tool’s geometry, material, and how it’s made directly determine the part’s accuracy and surface quality. Different CNC cutting tools have different impacts on the final product’s quality. For example, a high-precision tool can ensure that the part’s dimensions and shapes are within the allowed range. High-quality tool materials can reduce wear in machining and ensure a good surface finish.

Yes, the same tool can be used for different materials because some lathe tools are universal. For example, carbide tools are suitable for ferrous and non-ferrous workpieces. However, some cannot. For example, HSS lathe tools only work for soft materials, like aluminum.

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