CNC cutting tools are tools used for cutting in mechanical manufacturing, also known as cutting tools. The combination of good processing equipment and high-performance CNC cutting tools can give full play to its due performance and achieve good economic benefits. With the development of cutting tool materials, various new cutting tool materials have better physical, mechanical properties and cutting performance. Has been greatly improved, the scope of application is also expanding.
CNC tool structure
1. The structure of various tools is composed of a clamping part and a working part. The clamping part and the working part of the integral structure tool are all made on the cutter body; the working part (knife tooth or blade) of the insert structure tool is mounted on the cutter body.
2. There are two types of clamping parts with holes and handles. The tool with a hole is set on the main shaft or mandrel of the machine tool by means of the inner hole, and the torsional moment is transmitted by means of an axial key or an end face key, such as a cylindrical milling cutter, a shell face milling cutter, etc.
3. Knives with handles usually have three types: rectangular shank, cylindrical shank and conical shank. Turning tools, planing tools, etc. are generally rectangular shanks; conical shanks bear axial thrust by taper, and transmit torque with the help of friction; cylindrical shanks are generally suitable for smaller twist drills, end mills and other tools. The resulting frictional force transmits the torque. The shank of many shank knives is made of low alloy steel, and the working part is made of high speed steel butt welding the two parts.
4. The working part of the tool is the part that generates and processes chips, including structural elements such as the blade, the structure that breaks or rolls up chips, the space for chip removal or chip storage, and the channel for cutting fluid. The working part of some tools is the cutting part, such as turning tools, planers, boring tools and milling cutters; the working part of some tools includes cutting parts and calibration parts, such as drills, reamers, reamers, internal surface pull Knives and taps etc. The function of the cutting part is to remove chips with the blade, and the function of the calibration part is to smooth the machined surface and guide the tool.
5. The structure of the working part of the tool has three types: integral type, welding type and mechanical clamping type. The overall structure is to make a cutting edge on the cutter body; the welding structure is to braze the blade to the steel cutter body; there are two mechanical clamping structures, one is to clamp the blade on the cutter body, and the other is It is to clamp the brazed cutter head on the cutter body. Cemented carbide tools are generally made of welded structures or mechanical clamping structures; porcelain tools are all mechanical clamping structures.
6. The geometric parameters of the cutting part of the tool have a great influence on the cutting efficiency and processing quality. Increasing the rake angle can reduce the plastic deformation when the rake face squeezes the cutting layer, and reduce the frictional resistance of the chips flowing through the front, thereby reducing the cutting force and cutting heat. However, increasing the rake angle will reduce the strength of the cutting edge and reduce the heat dissipation volume of the cutter head.
Classification of CNC tools
One category: tools for processing various external surfaces, including turning tools, planers, milling cutters, external surface broaches and files, etc.;
The second category: hole processing tools, including drills, reamers, boring tools, reamers and inner surface broaches, etc.;
The third category: thread processing tools, including taps, dies, automatic opening and closing thread cutting heads, thread turning tools and thread milling cutters, etc.;
The fourth category: gear processing tools, including hobs, gear shaping cutters, gear shaving cutters, bevel gear processing tools, etc.;
The fifth category: cut-off tools, including insert circular saw blades, band saws, bow saws, cut-off turning tools and saw blade milling cutters, etc.
Judgment Method of NC Tool Wear
1. First judge whether it is worn or not during processing, mainly during the cutting process, listen to the sound, and suddenly the sound of the tool during processing is not normal cutting, of course, this requires experience accumulation.
2. Look at the processing. If there are intermittent irregular sparks during the processing, it means that the tool has been worn out. You can change the tool in time according to the average life of the tool.
3. Look at the color of the iron filings. If the color of the iron filings changes, it means that the processing temperature has changed, which may be due to tool wear.
4. Look at the shape of the iron filings. The two sides of the iron filings appear jagged, the iron filings are abnormally curled, and the iron filings become finely divided. It is obviously not the feeling of normal cutting, which proves that the tool has been worn.
5. Looking at the surface of the workpiece, there are bright marks, but the roughness and size have not changed greatly, which is actually the tool has been worn.
6. Listen to the sound, the processing vibration will intensify, and abnormal noise will be produced when the tool is not fast. At this time, care should be taken to avoid "knife stabbing" and cause the workpiece to be scrapped.
7. Observe the load of the machine tool. If there is an obvious incremental change, it means that the tool may have been worn.
8. When the tool is cut out, the workpiece has serious burrs, the roughness decreases, the size of the workpiece changes and other obvious phenomena are also the criteria for the judgment of tool wear. In a word, seeing, hearing, and touching, as long as you can sum up one point, you can judge whether the tool is worn.
CNC tool selection principle
1. The most important thing in processing is the tool
Any tool that stops working means a halt in production. But it does not mean that every knife has the same important status. A tool with a long cutting time has a great impact on the production cycle, so under the same premise, more attention should be paid to this tool. In addition, attention should be paid to machining key components and tools with strict machining tolerances. In addition, tools with relatively poor chip control, such as drills, grooving tools, and threading tools, should also be paid attention to. Downtime can be caused by poor chip control.
2. Match with the machine tool
Knives are divided into right-handed knives and left-handed knives, so choosing the right knives is very important. In general, right-handed tools are suitable for machines that rotate counterclockwise (CCW) (as viewed along the spindle); left-handed tools are suitable for machines that rotate clockwise (CW). If you have several lathes, some that hold left-handed tools and others that are left-handed, choose left-handed tools. For milling, however, people generally tend to choose tools that are more versatile. But even though the processing range covered by this type of tool is large, you immediately lose the rigidity of the tool, increase the deflection of the tool, reduce the cutting parameters, and easily cause machining vibration. In addition, the manipulator for changing the tool on the machine tool also has restrictions on the size and weight of the tool. If you are purchasing a machine tool with an internal cooling through hole in the spindle, please also choose a tool with an internal cooling through hole.
3. Match with the processed material
Carbon steel is a common processed material in machining, so most cutting tools are designed based on optimized carbon steel processing. The blade grade should be selected according to the material to be processed. Tool manufacturers offer a range of cutter bodies and matching inserts for machining non-ferrous materials such as superalloys, titanium alloys, aluminum, composites, plastics and pure metals. When you need to process the above materials, please choose a tool with matching material. Most manufacturers have various series of cutting tools, indicating what materials are suitable for processing. For example, DaElement's 3PP series is mainly used for processing aluminum alloy, 86P series is specially used for processing stainless steel, and 6P series is specially used for processing high-hardness steel.
4. Tool specification
A common mistake is to select a turning tool that is too small and a milling tool that is too large. Large-sized turning tools have good rigidity; while large-sized milling cutters are not only expensive, but also take a long time for air cutting. In general, the price of large-scale knives is higher than that of small-scale knives.
5. Choose between replaceable blades or regrinding knives
The principle to follow is simple: try to avoid resharpening your knives. Except for a few drills and face milling cutters, try to choose replaceable blade or replaceable head cutters when conditions permit. This will save you labor expenses while obtaining stable processing results.
6. Tool material and grade
The choice of tool material and brand is closely related to the properties of the processed material, the maximum speed and feed rate of the machine tool. Choose a common tool grade for the group of materials being machined, usually coatings. Refer to the "Grade Application Recommendation Chart" provided by the tool supplier. In practical applications, a common mistake is to try to solve the problem of tool life by replacing similar material grades from other tool manufacturers. If your existing knives are not ideal, then switching to a similar brand from another manufacturer is likely to bring similar results. To solve the problem, it is necessary to determine the cause of the tool failure.
7. Power requirements
The guiding principle is to get the best out of everything. If you have purchased a milling machine with a power of 20hp, then, if the workpiece and fixture allow, select the appropriate tool and processing parameters so that it can achieve 80% of the power utilization of the machine tool. Pay special attention to the power/speed table in the machine tool user manual, and select the tool that can achieve the best cutting application according to the 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 edges doesn't mean paying twice as much. Proper design has also doubled the number of cutting edges in grooving, parting off and some milling inserts in the past decade. It is not uncommon to replace an original milling cutter with only 4 cutting edge inserts with a 16 cutting edge insert. Increasing the number of cutting edges also directly affects the table feed and productivity.
9. Choose integral tool or modular tool
Small format tools are suitable for monolithic designs; large format tools are suitable for modular designs. For large-scale cutting tools, when the cutting tool fails, users often hope to get a new cutting tool only by replacing the small and inexpensive parts. This is especially true for grooving and boring tools.
10. Choose a single tool or a multi-function tool
Smaller workpieces tend to be more suitable for compound tools. For example, a multifunctional tool that combines drilling, turning, internal boring, threading and chamfering. Of course, more complex workpieces are more suitable for multi-function tools. Machine tools are only profitable for you when they are cutting, not when they are down.
11. Choose standard tool or non-standard tool
With the popularity of numerical control machining (CNC), it is generally believed that the shape of the workpiece can be achieved through programming, rather than relying on tools, so non-standard tools are no longer needed. In fact, non-standard knives still account for 15% of the total sales of knives. Why? The use of cutting tools can meet the size requirements of the workpiece, reduce the process and shorten the processing cycle. For mass production, non-standard cutting tools can shorten the processing cycle and reduce costs.
12. Chip control
Remember, your goal is to machine the workpiece, not chips, but chips can clearly reflect the cutting state of the tool. Overall, there is a stereotype about cuttings, as most people are not trained to interpret them. Remember the following principle: good chips will not destroy the process, bad chips will do the opposite. Most of the inserts are designed with chip breakers, and the chip breakers are designed according to the feed rate, whether it is light cutting finishing or heavy cutting rough machining. The smaller the chip, the harder it is to break. Chip control is a challenge for difficult-to-machine materials. Although the material to be processed cannot be changed, new tools can be used to adjust the cutting speed, feed rate, degree of cutting, corner radius of the tool nose, etc. Optimizing chips and optimizing machining is the result of a comprehensive selection.
13. Programming
In the face of tools, workpieces and CNC machining machines, it is often necessary to define tool paths. Ideally, knowing basic machine code, has a CAM package. The toolpath needs to take into account tool characteristics such as ramping angle, direction of rotation, feed, cutting speed, etc. Each tool has corresponding programming techniques to shorten the machining cycle, improve chips, and reduce cutting forces. A good CAM software package can save labor and increase productivity.
14. Choose innovative knives or conventional mature knives
At the current rate of technological development, the productivity of cutting tools can double every 10 years. Comparing the cutting parameters of the tool recommended 10 years ago, you will find that today's tool can double the processing efficiency, but the cutting power is reduced by 30%. The alloy matrix of the new cutting tool is strong and has high toughness, which can realize high cutting speed and low cutting force. Chipbreakers and grades have low application specificity and wide versatility. At the same time, modern knives have added versatility and modularity, both of which reduce inventory and expand tool applications. The development of cutting tools has also led to new product design and processing concepts, such as Bawang cutters with both turning and grooving functions, and high-feed milling cutters, which have promoted high-speed machining, minimal-quantity lubrication (MQL) machining and hard turning technology. Based on the above factors and other reasons, you also need to follow up the processing method and learn about cutting tool technology, otherwise you will be in danger of falling behind.
15. Price
Although the price of the tool is important, it is not as important as the production cost paid for the tool. While a knife has its own price, the value of a knife lies in the duty it performs for productivity. Usually, the lower priced knives are the ones that result in higher production costs. The price of cutting tools accounts for only 3% of the cost of the part. So focus on the productivity of your knives, not their purchase price.
Post time: Jan-27-2018
