How to choose the best cutting tool for CNC machine tools? What are the tips?

Choosing the best cutting tool is critical to the success of machining production companies. This is also a constant and repeated work, and will directly affect the product machining cycle and factory competitiveness.

A tool company has 40,000 tools with only inch specifications! You can see from the numerical comparison how difficult it is to choose the most suitable tool! Of course, many people say that we use whatever knives are available in the factory, but if you know more about choosing knives, you will be more efficient and save money. Then the boss will not give you a raise and who will give you a raise!

When selecting a tool, it is necessary to consider the compatibility with the machine tool, and use the shortest time and the lowest cost to process the highest quality parts.

We will discuss how to choose a tool from the following 15 aspects!

1. The most important tool

Any tool stops working, it means that production has stopped. But it does not mean that every tool has the same important status. The tool with the longest cutting time has a greater impact on the production cycle, so under the same premise, this tool should be given more attention. In addition, attention should be paid to the most stringent tools for machining key components and advance cnc machining tolerances. In addition, tools with relatively poor chip control, such as drills, grooving tools, and threading tools, should also be focused on. Poor chip control can cause downtime.

2. Match with the machine tool

There are right-handed and left-handed knives, so choosing the right tool is very important. Generally, right-hand tools are suitable for machine tools that rotate counterclockwise (CCW) (viewed along the main axis); left-hand tools are suitable for machine tools that rotate clockwise (CW). If you have several lathes, some of which hold left-hand tools, and others are compatible with left and right hands, then please choose left-hand tools. As for milling, people usually tend to choose more versatile tools. However, although this type of tool covers a larger machining range, it also makes you immediately lose the rigidity of the tool, increase the deflection of the tool, reduce the cutting parameters, and more easily cause machining vibration. In addition, the manipulator of the machine tool to change the tool also has restrictions on the size and weight of the tool. If you are buying a machine tool with an internal cooling through hole for the spindle, please also choose a tool with an internal cooling through hole.

3. Match with the processed material

Carbon steel is the most common material to be processed in machining, so most tools are based on optimized carbon steel machining design. The blade grade should be selected according to the processed material. Tool manufacturers provide a series of tool bodies and matching blades for machining non-ferrous materials such as high-temperature alloys, titanium alloys, aluminum, composite materials, plastics and pure metals. When you need to process the above-mentioned materials, please choose a tool that matches the material.

4. Tool specifications

A common mistake is that the size of the selected turning tool is too small and the size of the milling cutter is too large. Large-size turning tools have better rigidity; large-size milling cutters are not only more expensive, but also take longer to cut. In general, the price of large-size tools is higher than that of small-size tools.

5. Choose between replaceable blade or re-grinding tool

The principle to follow is simple: try to avoid grinding tools. Except for a few drill bits and face milling cutters, if conditions permit, try to choose replaceable blade type or replaceable head type tools. This will save you labor costs and obtain stable machining results.

6. Tool materials and grades

The choice of tool material and grade is closely related to the performance of the material being processed, the maximum speed and feed rate of the machine tool. Choose more general tool grades for the processed material group, usually coating alloy grades. Refer to the “Grade Application Recommendation Chart” provided by the tool supplier. In practical applications, a common mistake is to replace similar material grades of other tool manufacturers to try to solve the tool life problem. If your existing tool is not ideal, then changing to another manufacturer’s brand close to it is likely to bring similar results. To solve the problem, the cause of the tool failure must be clarified.

7. Power requirements

The guiding principle is to make the best use of everything. If you have purchased a milling machine with a power of 20hp, then, if the workpiece and fixture allow it, select the appropriate tool and machining parameters to enable it to achieve 80% of the power of the machine. Pay special attention to the power/tachometer in the machine tool user manual, and select the tool that can achieve better cutting applications according to the effective power range of the machine power.

8. Number of cutting edges

The principle is, the more the better. Buying a turning tool with twice the cutting edge does not mean paying twice the cost. In the past ten years, advanced designs have doubled the number of cutting edges for grooving knives, cutting knives, and some milling inserts. It is not uncommon to replace the original milling cutter with only 4 cutting edges with advanced milling cutters with 16 cutting edges. The increase in the number of effective cutting edges also directly affects the table feed and productivity.

9. Choose integral tool or modular tool

Small size cutters are more suitable for overall design; large size cutters are more suitable for modular design. For large-size tools, when the tool fails, users often hope to regain a new tool just by replacing small and inexpensive parts. This is especially true for grooving and boring tools.

10. Choose a single tool or a multi-function tool

The smaller the workpiece, the more suitable the compound tool is. For example, a multifunctional tool can combine drilling, turning, inner hole machining, thread machining and chamfering. Of course, the more complex the workpiece, the more suitable it is for multifunctional tools. The machine tool can only bring you benefits when it is cutting, not when it is down.

11. Choose standard tools or non-standard special tools

With the popularity of advance CNC machining centers, it is generally believed that the shape of the workpiece can be realized through programming instead of relying on tools. Therefore, non-standard special tools are no longer needed. In fact, non-standard tools still account for 15% of total tool sales today. why? The use of special tools can meet the requirements of precise workpiece size, reduce procedures and shorten the machining cycle. For mass production, non-standard special tools can shorten the machining cycle and reduce costs.

12. Chip control

Remember, your goal is to machine the workpiece, not chips, but the chips can clearly reflect the cutting state of the tool. Generally speaking, people have prejudices about cutting chips, because most people are not trained to interpret cutting chips. Remember the following principles:

Good chips will not damage machining, bad chips are just the opposite.

The inserts are mostly designed with chipbreakers, and the chipbreakers are designed according to the feed rate, whether it is light cutting finishing or heavy cutting roughing.

The smaller the chip, the harder it is to break.

For difficult-to-machine materials, chip control is a big problem. Although the material to be processed cannot be replaced, the tool can be updated, and the cutting speed, feed rate, depth of cut, tool tip fillet radius, etc. can be adjusted. Optimizing chips and optimizing machining is the result of a comprehensive selection.

13. Programming

Faced with tools, workpieces and CNC machining machines, it is often necessary to define tool paths. The ideal situation is to understand the basic machine code and have advanced CAM programming software. The tool path must take into account the tool characteristics, such as ramp angle, rotation direction, feed, cutting speed, etc. Each tool has a corresponding programming technology to shorten the machining cycle, improve the chip, and reduce the cutting force. Good CAM programming software can save labor and improve productivity.

14. Choose innovative tools or conventional mature tools

With the current development speed of advanced technology, the productivity of cutting tools can double every 10 years. Comparing the cutting parameters of the tools recommended 10 years ago, you will find that today’s tools can double the machining efficiency, but the cutting power is reduced by 30%. The new tool alloy matrix is stronger and tougher, enabling higher cutting speeds and lower cutting forces. Chipbreakers and grades are less specific to the application and more versatile. At the same time, modern tools have also increased versatility and modularity, which together reduce inventory and expand tool applications. The development of cutting tools has also led to new product design and machining concepts, such as overlord cutters with both turning and grooving functions, high-feed milling cutters, high-speed machining, micro-lubrication cooling (MQL) machining, and hard turning technology. Based on the above factors and other reasons, you also need to follow up the most preferred advance cnc machining method and learn about the latest advanced tool technology, otherwise you will be in danger of falling behind.

15. Price

Although the price of cutting tools is important, it is not as important as the production cost paid by cutting tools. Although knives have their corresponding prices, the true value of knives lies in their duties for productivity. Generally, the tool with the lowest price is the tool with the highest production cost. The price of cutting tools only accounts for 3% of the cost of the parts. So pay attention to the productivity of the tool, not its purchase price.

Machining is developing into a professional science, but experience is still irreplaceable. As a feedback to customers, the service of tool vendors is free, and they can even provide tool trial cutting for free. The experienced experts of the tool supplier can provide the best and instructive help for the user to choose the tool.