CNC Milling Process
CNC machining is a fully automated manufacturing process that uses computer software to regulate a machine’s motion and functionality. The term CNC refers to computer numerical control. It is a subtractive process in which the material from the workpiece is removed to generate parts of various shapes and geometry.
This manufacturing method was developed in the 1950s, and manufacturers began using it in the 1980s for various applications. Since then, it has continuously evolved and become a more reliable and accurate manufacturing approach.
The CAD design is used as a blueprint of required parts and products, which later CNC machining gives the exact result with the help of Instructions that guide the CNC machine through the production process. Many products currently exist in the market today were created by the CNC machining process.
Various CNC machining processes, including CNC milling, turning, drilling, routing, and more, will be covered in this article.
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CNC Milling Process
The starting step in the CNC milling process is to place the workpiece within the CNC machine’s holding mechanism. Next, the spindle is equipped with milling tools. Either vertical milling or horizontal milling can be selected for machining through the software. The operator starts the program, and the milling process begins.
The provided instruction dictates the workpiece to shift, rotate, and be positioned for the work of the machining tool. The feeding takes place by either a rotating tool, workpiece, or combination.
The initial step in milling involves making a series of tiny cuts to approximate the desired shape. Following that, the tool makes many passes over the workpiece to preserve the precision of each feature. For Complex shapes, the tool moves over the workpieces many times, and sometimes multiple tool setups might be required.
According to the type of CNC machine, the milling cutter can operate along 3, 4, 5, or 6 axes. It can create many shapes, holes, grooves, slots, and other features. According to the CAD design, CNC milling gets completed by moving the tool along various axes; X and Y denote horizontal movement, Z denotes vertical movement, and W denotes diagonal movement.
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Types of Milling Processes
The versatility of CNC milling makes it suitable for large-scale production, customized parts, and prototyping. There are four common categories of milling operations.
1. Face Milling
It involves cutting a flat surface right to the cutting axis. Cutting teeth serve various specialized purposes and are found on the tool face and periphery. It produces a clean surface finish whether milling is done vertically or horizontally.
2. Plain milling
The plain milling is carried out by making the cutter axis parallel to the surface of the workpiece. For plain milling, the workpiece needs to be mounted parallel to the milling machine table.
Narrow cutters are used for deep cuts in plain milling, whereas wide cutters are used for broad surfaces. Cutting tools start by setting the coarse-toothed cutter with slow cutting speeds and quick feed rates to achieve the approximate geometry. Followed by high cutting speed and slow feed to accurately shape the material.
3. Angular Milling
Angular milling refers to machining a flat surface, where tools make certain angles to the surface, such as 45°, 50°, 55°, or 60°are the typical angles. Angular milling is the best way to create angular surfaces, grooves, and chamfers. During the process, a side milling cutter is used to rough out the groove, and an angle milling cutter is used to complete the angular sides and base.
4. Form milling
form milling is used to mill uneven surfaces like curve planes. Thanks to formed milling, several complex pieces had to be made in convex, concave, hemispherical, or other challenging shapes.
Some Specialized Milling Operations
There are different milling operations for specific operations, such as gear milling, gang milling, profile milling, and straddle milling.
| Milling Operation | Description |
| Gear Cutting | Cutters with specific shapes and sizes are used in gear cutting based on specific gear designs. This operation is used to make gear teeth for spur, helical, herringbone, and worm gears. |
| Gang Milling | As the name suggests, gang milling refers to several milling operations using multiple cutters. It produces complex shapes where different cuts are needed, such as flat and angular grooves. |
| Profile Milling | It is applicable in the making of vertical or slanted surfaces. In this process, cutting tools might be parallel or perpendicular to the working surface of the workpiece. |
| Straddle Milling | Two milling cutters get installed on the same arbor during the machining technique known as “straddle milling.” It is utilized to simultaneously machine two sides of the workpiece. |
Specialized milling operations
CNC Turning Process
CNC turning process
CNC turning is a fully computer-controlled manufacturing process in which a round workpiece spins and a tool is fed into it. Material outside the workpiece is removed during turning and fed into the tool to produce the desired form. The computer program ultimately controls the removal procedure.
The four main steps of the CNC turning process are the creation of a digital representation (CAD), the generation of machining code from CAD files, the configuration of the CNC lathe, and the production of turned parts based on input from the computer.
The chuck is initially fastened to the raw material bar and starts rotating at the input speed. After that, the material is fed into the cutting tool to begin the creation of the desired shape. Manual monitoring is still necessary to ensure exact shape and tight tolerance, even if the CNC turning process is numerically controlled.
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Types of CNC Turning
Different types of CNC turning operations are used to create specific features and shapes.
| Turning Operation | Description |
| Taper turning | It is the process of gradually reducing or increasing the diameter of a cylindrical workpiece to produce a conical surface. |
| Step-up turning | It involves a sudden increase or decrease in the diameter. |
| contour turning | The cutting tool axially follows a trajectory with a predefined geometry. |
| Grooving | A narrow cut called a “groove” is made around the workpiece’s cylindrical surface within the specific segment. |
| Threading | A tool is moved along the side of a cylindrical workpiece to create continuous helical grooves. |
| Boring | It is related to internal turning, increasing the hole diameter’s accuracy, where a pre-formed hole is enlarged through this process. |
Different types of CNC turning processes
CNC Drilling Process
CNC drilling process
Using a multi-point drill bit, cylindrical holes are carved out of the workpiece during the CNC drilling process. The procedure involves the CNC machine feeding the drill bit perpendicularly onto the workpiece.
When the drill bit feeds the workpiece, it creates vertically aligned holes with the same diameter as the drill bit. Some applications also need angular holes. In that case, special configurations of drill bits are employed. Drilling is also used in reaming, tapping, counterboring, and countersinking.
CNC Mill-Turning Process
CNC turn-mill process
Whereas turning rotates the workpiece and milling rotates the cutting tools, CNC mill-turning machines have both milling and turning tools. They are configured to be utilized fast and concurrently in response to input commands from a computer.
A mill-turn center machine is employed for the turning-milling operation, essentially a hybrid system that executes both turning and milling operations simultaneously without switching the apparatus. In contrast to the standard CNC machining technique, this method removes the need for frequent machine changes and simplifies manufacture since complex geometries necessitate both methods.
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Conclusion
Milling, turning, and drilling are the three most widely used CNC machining processes. Each process involves the removal of the material from the workpiece to create the desired shape with different tool setups and feeding styles.
Using the CNC machining process, different prototypes, customized parts, and products can be made with a tight tolerance in a short time. The right machining process is a complex task, and it is crucial to create the exact shape as designed in computer software. However, It will not be difficult while collaborate with Prolean. Prolean has advanced CNC machines with expert engineers and operators to provide the best result for your CNC machining projects.
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FAQ’s
What is the lowest thickness that can implement into the design to prevent warpage from CNC machining processes?
We recommend a minimum thickness of 0.5mm for metal and 1mm for plastic. The value, however, is heavily dependent on the size of the parts to be manufactured. For example, if your parts are much smaller, you may need to increase the minimum thickness limit to prevent warpage, and for large parts, you may need to lower the limit.
Why choose CNC milling?
CNC machines can quickly make highly precise parts because they rely on computer control. It allows the production of prototypes, customized parts, and complete products for various industries.
What are the applications of CNC machining processes?
Different components from the automotive, aircraft, agriculture, defense, electrical, electronics, hardware, home appliance, and many other industries can be machined using CNC operations.
What benefits does CNC turning offer?
The precise creation of complex shapes and better material use provided by the CNC turning process are two of its many advantages. Additionally, CNC turning allows for the quick production of very accurate parts. Overall, it’s a flexible strategy.
What are the Advantages of Using the Turning-milling process?
Turning-milling generates accurate parts using the same machining setup, which reduces production time instead of performing independently, necessitating separate setup, instructions, and tool arrangements.
Danke für den guten Artikel zu CNC. Fräsen ist eine tolle Technik. Ich habe schon so einige Projekte damit umgesetzt.