The importance of tool selection in machining is self-evident. Learning to choose tools can help you work more easily.
1. The most important thing in machining is the tool
When any tool stops working, it means that production stops. But it does not mean that every tool has the same importance. The tool with the longest cutting time has a greater impact on the production cycle, so under the same premise, more attention should be given to this tool. In addition, attention should also be paid to tools that require the most stringent machining tolerances for key components and machining. In addition, tools with relatively poor chip control, such as drills, grooving tools and threading tools, should also be paid attention to. Because poor chip control can cause downtime.
2. Matching with machine tools
Tools are divided into right-hand tools and left-hand tools, so it is very important to choose the right tool.
Generally, right-hand tools are suitable for counterclockwise (CCW) machine tools (looking along the spindle direction); left-hand tools are suitable for clockwise (CW) machine tools. If you have several lathes, some clamping left-hand tools and others are compatible with both left and right hands, then choose left-hand tools. For milling, people usually tend to choose more versatile tools. However, although such tools cover a wider range of processing, you will immediately lose the rigidity of the tool, increase the deflection of the tool, reduce the cutting parameters, and are more likely to cause processing vibration. In addition, the robot for changing the tool of the machine tool also limits the size and weight of the tool. If you buy a machine tool with an internal cooling hole in the spindle, please also choose a tool with an internal cooling hole.
3. Match with the material being processed
Carbon steel is the most common material being processed in machining, so most tools are designed based on optimized carbon steel processing. The blade brand needs to be selected according to the material being processed. Tool manufacturers provide a series of tool bodies and matching blades for processing non-ferrous materials such as high-temperature alloys, titanium alloys, aluminum, composites, plastics and pure metals.
When you need to process the above materials, please choose a tool with matching materials. Most brands have various series of tools, indicating what materials are suitable for processing. For example, DaElement's 3PP series is mainly used to process aluminum alloys, the 86P series is specifically used to process stainless steel, and the 6P series is specifically used to process high-hardness steel.
4. Tool specifications
A common mistake is to select a turning tool that is too small and a milling tool that is too large. Large turning tools have better rigidity; large milling cutters are not only more expensive, but also take longer to cut. In general, large tools are more expensive than small tools.
5. Choose replaceable blades or re-grinding tools
The principle to follow is simple: try to avoid re-grinding tools. Except for a few drills and face milling cutters, try to choose replaceable blades or replaceable head tools when conditions permit. This will save you labor costs and achieve stable processing results.
6. Tool materials and grades
The selection of tool materials and grades is closely related to the performance of the material being processed, the maximum speed and feed rate of the machine tool. Choose a more common tool grade for the material group being processed, usually a coated alloy grade. Refer to the "Grade Application Recommendation Chart" provided by the tool supplier. In actual applications, a common mistake is to try to solve the tool life problem by replacing similar material grades from other tool manufacturers. If your existing tool is not ideal, then changing to a similar grade from another manufacturer is likely to bring similar results. To solve the problem, you must identify the cause of the tool failure.
7. Power requirements
The guiding principle is to use everything you have. If you buy a 20hp milling machine, then select the appropriate tools and processing parameters to achieve 80% of the machine's power utilization, provided that the workpiece and fixture allow. Pay special attention to the power/speed table in the machine user's manual and select tools that can achieve better cutting applications based on the effective power range of the machine power.
8. Number of cutting edges
The principle is, more is better. Buying a turning tool with twice the cutting edges does not mean paying twice the price. In the past decade, advanced designs have doubled the number of cutting edges on grooving cutters, parting cutters, and some milling inserts. It is not uncommon to replace milling cutters with only 4 cutting edges with advanced milling cutters with 16 cutting edges. Increasing the number of effective cutting edges also directly affects the worktable feed and productivity.
9. Choose a monolithic tool or a modular tool
Small-size tools are more suitable for monolithic design; large-size tools are more suitable for modular design. For large-size tools, when the tool fails, users often hope to get a new tool by simply replacing a small and inexpensive part. This is especially true for grooving tools and boring tools.
10. Choose a single tool or a multi-function tool
The smaller the part, the more suitable it is for a composite tool. For example, a multi-function tool can perform composite drilling, turning, internal hole processing, thread processing and chamfering. Of course, the more complex the workpiece, the more suitable it is for a multi-function tool. The machine tool can only bring you benefits when it is cutting, not when it is stopped.
11. Choose a standard tool or a non-standard special tool
With the popularity of CNC machining centers, it is generally believed that the shape of the workpiece can be achieved through programming rather than relying on tools, so non-standard special tools are no longer needed. In fact, non-standard tools still account for 15% of the total tool sales today. Why? The use of special tools can meet the precise workpiece size requirements, reduce processes and shorten the processing cycle. For mass production, non-standard special tools can effectively shorten the processing cycle and reduce costs.
12. Chip Control
Remember, your goal is to produce the workpiece, not the chips, but the chips can clearly reflect the cutting state of the tool. In general, people have a prejudice against chips because most people are not trained to interpret chips. Remember the following principle: good chips do not destroy the process, and bad chips do the opposite.
Inserts are often designed with chip breakers, and chip breakers are designed based on feed rates, whether it is light cutting finishing or heavy cutting roughing.
The smaller the chip, the harder it is to break. Chip control is a big problem for difficult-to-machine materials. Although the material cannot be changed, the tool can be updated and the cutting speed, feed rate, cutting depth, tool tip radius, etc. can be adjusted. Optimizing chips and optimizing processing is the result of a comprehensive selection.
13. Programming
When faced with tools, workpieces and CNC machining machines, it is often necessary to define tool paths. Ideally, you should understand basic machine code and have an advanced CAM software package. Tool paths must take into account tool characteristics such as ramping angle, rotation direction, feed and cutting speed. Each tool has corresponding programming technology to shorten the machining cycle, improve chip cutting, and reduce cutting forces. A good CAM software package can save labor and improve productivity.
14. Choose innovative tools or conventional mature tools
At the current rate of development of advanced technology, the productivity of cutting tools can double every 10 years. Compared with the cutting parameters recommended for tools 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, which can achieve higher cutting speeds and lower cutting forces. The chipbreaker and brand are less specific to the application and more versatile. At the same time, modern tools have increased versatility and modularity, which together reduce inventory and expand tool applications. Tool development has also driven new product design and processing concepts, such as the Overlord Tool and High Feed Milling Cutter with both turning and grooving functions, which have promoted high-speed machining, minimal lubrication and cooling (MQL) machining and hard turning technology. Based on these factors and other reasons, you also need to follow the most preferred processing methods and learn about the latest advanced tool technology, otherwise there is a risk of falling behind.
15. Price
The price of a tool is important, but not as important as the production cost of the tool. Although the tool has its corresponding price, the real value of the tool is the work it performs for productivity. Usually, the cheapest tool is the one that causes the highest production cost. The price of the cutting tool accounts for only 3% of the cost of the part. So focus on the productivity of the tool, not its purchase price.
