A comprehensive guide to CNC Milling: everything you need to know about CNC milling process and components and tools of CNC milling machine
What is CNC Milling?
CNC milling is the process of using Computer Numerical Control (CNC) to move a cutting tool over a workpiece, removing material to create a 3D object. The tool used for this operation can be a drill or router, as well as other types of tools. CNC milling machines are typically used in industries such as aerospace and automotive manufacturing. They are also used in smaller shops where parts are needed quickly and on demand.
Features of CNC milling
CNC milling plays a very important role in the machining industry. What are its characteristics and what types of parts are suitable for CNC milling?
CNC milling machines and machining centers are applicable to the processing of workpieces with different structures and shapes, and can complete drilling, boring, reaming, milling plane, milling inclined plane, milling groove, milling surface (cam), tapping, etc.
2. High processing precision
CNC milling machine and machining center have high machining accuracy, which can ensure the accuracy of the workpiece in general. In addition, CNC machining also avoids the operator’s operational errors. The size of parts processed in the same batch has good dimensional consistency, which greatly improves the product quality.
3. High production efficiency
CNC milling machine and machining center have the functions of milling machine, boring machine and drilling machine, which makes the process highly centralized, greatly improves the production efficiency and reduces the workpiece clamping error. The spindle speed of CNC milling machine can realize stepless speed change, which is conducive to selecting the optimal cutting amount. CNC milling machine has fast forward, fast backward and fast positioning functions, which can greatly reduce the mobile time.
Secondly, CNC milling machine has the functions of milling machine, boring machine and drilling machine, which makes the process highly centralized and greatly improves the production efficiency. In addition, the spindle speed and feed speed of CNC milling machine are continuously variable, so it is helpful to select the best cutting amount
4. Can handle complex shapes
In addition to milling the surfaces of various parts that can be milled by ordinary milling machines, it can also milling the plane curve contour and space surface contour that cannot be milled by ordinary milling machines. This is because CNC machine tools have multiple feed coordinates. The characteristics of shaft linkage.
5. Reduce the labor intensity of operators
NC milling machine automatically completes the processing of parts according to the pre prepared processing program. In addition to operating the keyboard, loading and unloading tools, workpiece and intermediate measurement and observing the operation of the machine tool, the operator does not need to carry out heavy and repeated manual operations, which greatly reduces the labor intensity.
Which parts are suitable for CNC milling?
1. Complex shape of machined parts
Compared with ordinary milling machine, CNC milling machine has the characteristics of high machining accuracy, complex shape of machined parts, and wide processing range. According to the characteristics of NC milling machine, the content suitable for NC milling machine processing mainly includes the following categories: complex structures such as curve contour or curved surface: plane curve contour of the workpiece, that is, the part has internal and external contour lines as complex curves, and the processing surface is parallel or perpendicular to the horizontal plane. In the process of NC milling, it is generally necessary to use the two coordinate linkage of the three coordinate NC milling machine to process.
Workpiece surface generally refers to the surface where the points on the surface change in three-dimensional coordinates. It is generally designed by mathematical model. In the process of machining, the milling cutter always keeps point contact with the machining surface. The machining of curved surface parts generally uses a three coordinate NC milling machine, which often needs to be programmed with the help of a computer.
2. Workpiece structure difficult to process with ordinary milling machine:
For the parts with large size, scribing, testing quantity and difficult to observe and control, the ordinary milling machine is suitable for processing with the NC milling machine, and the NC milling machine should be selected for processing.
3. Precision and accuracy
When machining on the ordinary milling machine, it is difficult to ensure the dimensional accuracy, form and position accuracy and surface roughness of the workpiece, so the CNC milling machine should be selected for machining.
4. Parts with good consistency requirements:
In mass production, due to the high positioning accuracy and repetitive positioning accuracy of the CNC milling machine itself, it can avoid various errors caused by human factors in the processing of ordinary milling machines, so it is easy to ensure the success of the CNC milling machine. The consistency of batch parts improves the processing precision and makes the quality more stable.
CNC Milling Process
CNC milling is a process where a computer-controlled machine cuts material with a tool. The machine uses the instructions provided by the user to perform the cut, and it can be programmed to make very complex parts. CNC milling machines are used to cut metal, plastic, and other materials. These machines can also be used to make parts for consumer products such as smartphones or washing machines.
CNC Milling Operations
CNC milling operations are very similar to CNC turning operations. However, there are some key differences between the two processes.
The first and most obvious difference is that the workpiece material being cut is solid rather than a continuous section of metal (as in CNC turning).
The second difference is that tool paths for multiple cavity molds require special programming and machining strategies. These can include: dividing the mold into multiple sections; designing each section as its own individual part; calculating all possible tool paths for each section; and then combining them into an overall program file or G-code set up (which is stored on your computer’s hard drive).
For complex geometries, such as when working with large castings or forgings with tight tolerances, you may need to use more than one spindle at once—either by changing tools quickly from one spindle to another or by utilizing multiple machining centers in tandem.
CNC milling Application
CNC milling is used to produce parts for a wide range of industries, including aerospace, medical, automotive and consumer goods. CNC machining is also used in the oil and gas industry to create parts used in the drilling process.
CNC milling is well suited for producing parts with complex geometries that cannot be produced using traditional methods or molding processes. Milling machines can produce complex geometries that require precise accuracy over long distances, such as those found on medical devices or airplane wings.
What is a CNC milling machine?
A CNC milling machine is a computer-controlled machine tool that uses a variety of tools to cut, shape or finish metal or plastic work pieces.
How does it work? A typical CNC milling process begins with the loading and configuring of the appropriate CAD file on the controller’s computer. The operator then selects their desired material along with its thickness and feed rate before starting the job via an operator panel or handheld device such as an iPad® tablet. Once started, the machine will automatically home itself into position using advanced control functions while simultaneously grinding off any burrs or other imperfections left behind from machining operations during previous jobs by using an automatic reorientation mechanism (ARO). After completing all necessary pre-programmed operations under several different conditions such as variable speed feed rates or multiple axes movement directions including X/Y/Z coordinates relative to overall length measurements taken at each end point where possible; these details are recorded automatically into memory so they can be retrieved later if needed again without having to go through additional steps like those mentioned above which would take up valuable time otherwise spent elsewhere during production runs when there may not be enough available resources available at any given time during busy seasons like Christmas shopping season when demand tends increase significantly due (demand curve shift).
CNC Milling Equipment and Components
A CNC milling machine is a very sophisticated piece of equipment that can be used to cut and shape metal, plastic, or other materials. These machines are primarily used to create parts for products like cars and airplanes. However, they are also used in industrial manufacturing to produce parts such as screws and brackets.
CNC milling machines are made up of several components: the spindle (a motor that spins the cutting tool), the workpiece (or material being cut), collets (to hold the workpiece in place), tool holders (to hold cutting tools) and a computer-driven control unit that translates a program into specific movements for each component of the machine.
Milling Machine Considerations
If you plan to mill a small or medium-sized part, a vertical milling machine will likely be sufficient. These machines have the advantage of being able to provide more precise control than vertical machining centers and are also capable of milling larger workpieces.
You should consider the size and complexity of your project when deciding on which type of machine to purchase. For example, if you need to make several parts with different dimensions, then you will probably want to use a horizontal machining center because they offer greater flexibility than other types of mills in this regard.
The material that you want to machine is another factor that affects your choice between vertical versus horizontal mills: For most plastics applications (such as prototyping), horizontal mills are ideal because they tend not work very well with hard materials like metal; however, if your project involves cutting through any kind of metal then vertical machines may be preferable due to their ability handle these materials more efficiently than horizontals do.*
What are the advantages and disadvantages of CNC milling?
There are many advantages to CNC milling, including:
Quickly and precisely cutting parts.
Making complex parts.
Cutting small batches of parts (instead of one at a time).
Cutting parts that would be too expensive to make by hand.
What kinds of materials can be used in a CNC milling machine?
The computer-controlled milling machine tool can be used to produce a wide variety of parts for many different industries. Some common materials include:
Copper Alloys (brass)
How much does a CNC milling machine cost?
The cost of a CNC milling machine depends on its complexity: the more axes it has, the more expensive it will be. In addition to the price tag, you need to consider other costs that come with owning a CNC machine such as maintenance and upgrades.
If you’re just starting out in manufacturing or don’t have much experience with machinery, it’s possible that a less complex machine will suit your needs best. Consider how many pieces of metal you’ll be cutting over time and how often these parts will need to be made for optimal purchase decisions (and return on investment). If there’s no way for an inexperienced user like yourself to use this type of equipment effectively without extensive training classes or certification programs—like those offered by technical colleges—it may not be worth purchasing yet. After all, learning how best operate such machines requires both time and money which could otherwise go towards improving skills through hands-on practice instead!
A CNC milling machine is a very sophisticated piece of equipment.
The main purpose of a CNC milling machine is to remove material from a workpiece using computer-controlled cutting tools.
CNC milling machines have many uses, but they are most commonly used in the manufacturing industry for tasks such as drilling holes or forming complex shapes out of metal. The purpose behind CNC machining is to manufacture parts that are needed by other industries while using less labor and resources than traditional manual methods.
This type of manufacturing doesn’t just have industrial applications; it has applications in fields like architecture and art as well!
Analysis on the Workmanship of CNC Milling Parts
CNC milling is to complete the processing of parts by controlling the execution parts through PLC under the control command issued by the CNC system. When making parts, process analysis must be carried out in order to ensure the form and position tolerances according to the drawing requirements. First of all, determine the processing technology of the workpiece, and analyze the process, select the clamping method, and determine the cutting parameters. Then the tool is selected. Then program the machining route. The following points should be considered before determining the CNC milling route:
- ① Ensure the machining accuracy and surface quality of parts, and ensure high efficiency.
- ② The shortest processing route is possible to reduce the idle travel time and tool change times, and improve the productivity.
- ③ Reduce the deformation of parts;
- ④ Make the numerical point calculation convenient and shorten the programming time.
- ⑤ The milling method shall be reasonably selected to improve the processing quality of parts.
- ⑥ Reasonably select the starting point, cut in and cut out point and cut in and cut out mode of the tool to ensure the stability of the tool cut in and cut out.
- ⑦ The machining of hole series parts with high position accuracy requirements shall avoid the position error caused by the reverse clearance of the machine tool;
- ⑧ The machining of complex curved surface parts should be based on the actual shape, accuracy requirements, machining efficiency and other factors to determine whether it is line cutting or ring cutting, and whether it is the machining route of isometric cutting or contour cutting.
- ⑨ Ensure the safety of the machining process and avoid the interference between the tool and the non machining surface.
According to the characteristics of CNC milling, this paper lists some frequently encountered technological problems, which are analyzed and considered as the key points of technological analysis of part drawings.
- ① Whether the marking method of drawing size is convenient for programming, whether the conditions of various geometric elements constituting the contour figure of the workpiece are sufficient and necessary, whether the interrelationships of various geometric elements (such as tangency, intersection, perpendicularity and parallelism) are clear, whether there are redundant dimensions causing conflicts or closed dimensions affecting the process arrangement, etc.
- ② Whether the required machining accuracy and dimensional tolerance of parts can be guaranteed. Do not give up this analysis because of the high machining accuracy of CNC machine tools. Pay special attention to the thickness tolerance of the too thin web and flange plate. “Milling workers are afraid of milling thin” is the same for CNC milling, because the cutting tension generated during processing and the elastic yield of the thin plate are very easy to cause the vibration of the cutting surface, which makes it difficult to ensure the thickness tolerance of the thin plate, and its surface roughness will also be improved. According to practical experience, when the thickness of the sheet with large area is less than 3mm, this problem should be fully paid attention to.
- ③ Arc radius and tool radius during arc transition.
- ④ Whether the fillet radius r of the groove bottom of the part milling face or the intersection of the web and the flange plate is too large.
- ⑤ Whether the concave arc of each machining surface in the part drawing is too messy and uniform. Because there are many new problems when changing the tool more than once on the CNC milling machine, such as increasing the size of the milling tool, the number of planned stops and tool setting times, it not only brings a lot of trouble to the programming, increases the production preparation time and reduces the production efficiency, but also reduces the surface quality because frequent tool change increases the tool receiving step difference on the workpiece processing surface. Therefore, the numerical consistency of the concave arc radius on a part is very important for the CNC milling process. Generally speaking, even if complete unification cannot be sought, the arc radius shall be grouped together to achieve local unification, so as to minimize the size of milling cutter and the number of tool changes.
- ⑥ Whether there is a uniform datum on the parts to ensure the correctness of their relative positions after two clamping processes. Some workpieces need to be re installed and milled after one side is milled. Because the test cutting method commonly used in general milling machine cannot be used to connect the cutter during CNC milling, the cutter cannot be connected properly due to the re installation of workpieces (that is, the surface processed in the previous process is not aligned or the contour on the two corresponding surfaces with the same cost requirements is misaligned). In order to avoid the above problems and reduce the twice clamping error, it is better to use a unified datum positioning, so it is better to have a suitable hole on the part as the positioning datum hole. If there is no reference hole on the part, the process hole can also be specially set as the positioning reference (such as adding a process lug on the blank or setting a reference hole on the allowance to be milled off in the subsequent process). If it is true that the datum hole cannot be made, at least the finished surface should be used as the uniform datum. If this is not possible, it is better to only process one of the most complex faces, and on the other side, give up CNC milling and change to a universal milling machine.
- ⑦ Analyze the shape of parts and the heat treatment status of raw materials, whether they will be deformed during processing, and which parts are most likely to be deformed. Because CNC milling is the most taboo for workpiece deformation during processing, this kind of deformation not only can not guarantee the quality of processing, but also often causes processing can not continue, “midway waste”. At this time, it is necessary to consider taking some necessary process measures for prevention, such as quenching and tempering treatment for steel parts, annealing treatment for aluminum castings. For those that cannot be solved by heat treatment, conventional methods such as rough and finish machining and symmetrical allowance removal can also be considered. In addition, it is necessary to analyze the deformation problem after processing and what technological measures should be taken to solve it.
The purpose of process analysis is to review whether the technical requirements for the structural shape and dimensional accuracy, mutual position accuracy, surface roughness, material and heat treatment of parts are reasonable and convenient for processing and assembly; The second is to further understand the process requirements of the parts through process analysis, comprehensively consider the performance of the machine tool, select tools, cutting parameters, clamping methods, etc., the processing range and processing methods of the CNC milling machine, so as to formulate a reasonable process procedure.
The difference between CNC milling and CNC turning
When customers require to process a complex aluminum alloy part, they often require CNC processing, but generally do not mention specific processing methods. In fact, CNC processing has two different processing methods, milling and turning. Both methods are CNC machining methods, but they are not the same.
CNC refers to computer numerical control, which means to use the computer system to guide the cutting machinery to perform CNC milling and CNC turning.
Good CAD – CAM software can easily convert a 3D model into readable code of CNC machine tools. This determines the use and movement of tools, cutting paths, etc.
Although our engineers can make decisions about the proper operation of a part, it may be necessary to understand the differences.
What is the difference between NC milling and turning?
In short, CNC milling uses rotating tools, while CNC turning uses rotating parts for cutting.
Therefore, the two use different techniques to machine a component. Milling machine makes complex parts by cutting redundant metal blocks, while turning is usually used to process cylindrical parts such as shafts.
What is CNC milling?
Let’s start with milling. First of all, there are three axis CNC milling machines that are more traditional. The tool can move in 3 directions – X, Y and Z axes.
Although this places some restrictions on the geometry of the part, it is sufficient to accomplish most of the work that requires milling. Various milling cutters can provide different cutting methods, such as end milling, face milling, hollow milling, etc.
(Pictures of different types of milling cutters)
Multi axis milling allows the rotation of 4 or more axes, including tools and worktables. This increases flexibility. Five axis milling machines are common among these machines.
The size of the initial block is usually larger than the general size of the finished part. Therefore, each face can be precisely milled. Good surface finish is easy to achieve due to small tolerances.
What is CNC turning?
As mentioned earlier, CNC turning is mainly used to manufacture cylindrical parts. These can be shafts, custom hollow tubes, cones, or any other axisymmetric part.
Although five axis machining can also create cylindrical parts, turning is just more efficient.
The chuck holds the raw material (usually a round bar) in place. The chuck rotates at high speed with the spindle. The speed or RPM depends on the machine.
The single point cutting tool is connected in the turret. The turret can move back and forth when the workpiece is rotating, so that the tool contacts the metal for cutting.
This highly accurate machining method can achieve strict tolerances. This is why hole based systems are often limited and fitted because it is easier to achieve the required accuracy on the shaft.
Although these two are often packaged in the same term “CNC processing”, they are actually different. However, they can still complement each other to produce high-precision parts.
For example, it may be necessary to add the function of NC milling after turning the axis.
Since both are widely used in metal processing and manufacturing industry, it is wise to distinguish them.
This paper focuses on the CNC milling process, outlines the basic knowledge of the process, as well as the components and tools of the CNC milling machine.
CNC milling machines are very versatile and can be used for a wide range of applications. Their precision makes them ideal for complex parts that require exact dimensions and shapes. They can also be used to create objects out of metal, plastic, or even wood material with great speed and accuracy as well as help reduce waste materials due to their automated nature. However there may still be some disadvantages such as cost which could deter people from getting one unless they really need something like this machine would provide them with better quality output than any other method possible without breaking down too often (not always though).
Source: China CNC milling solutions provider – Yaang Pipe Industry (www.machinedsgn.com)