The most amazing part of the machinery is that it can bring great convenience to daily life. From cars to small kitchen knives, do you know how their parts are processed? YIJIN Hardware engineers take you through 5 of the most common precision CNC machining.
1. CNC Turning
CNC turning is a method of cutting a workpiece on a lathe using the rotation of the workpiece relative to the tool. CNC turning is the most basic and common cutting method. Most workpieces with revolving surfaces can be processed by turning methods, such as inner and outer cylindrical surfaces, inner and outer conical surfaces, end faces, grooves, threads, and rotary forming surfaces. Common CNC lathes can be divided into horizontal lathes, floor lathes, vertical lathes, turret lathes, and copy lathes, most of which are horizontal lathes.
Due to the development of modern science and technology, various high-strength and high-hardness engineering materials are more and more used, and traditional turning technology is incompetent or impossible to process some high-strength and high-hardness materials. CNC turning technology makes it possible and has achieved obvious benefits in production.
Introduction to the Characteristics of CNC turning
High Efficiency of CNC Turning
CNC turning has higher efficiency than grinding. CNC turning often adopts a large cutting depth and high workpiece speed, and its metal removal rate is usually several times that of grinding. In CNC turning, a variety of surface machining can be completed in one clamping, while grinding requires multiple installations, so the auxiliary time is short and the positional accuracy between the machined surfaces is high.
Suitable for Small Batch Flexible Production Requirements
The CNC lathe itself is a flexible processing method with a wide range of processing. The CNC lathe is easy to operate and the CNC turning and clamping are fast. Compared with grinding, the CNC turning can better meet the requirements of flexible production.
CNC Turning Allows Parts to Obtain Good Overall Machining Accuracy
Most of the heat produced in CNC turning is taken away by the cutting oil, and there will be no surface burns and cracks like grinding. CNC turning has excellent machined surface quality, and accurate machining roundness, and can ensure high positional accuracy between machined surfaces.
2. CNC Milling
The so-called milling is the process of machining parts with a milling cutter on a CNC milling machine. CNC milling is a widely used cutting method, which uses the rotation (main motion) of the milling cutter and the movement of the workpiece (feed motion) to process the workpiece on the CNC milling machine. Milling can be performed on horizontal milling machines, vertical milling machines, gantry milling machines, tool milling machines, and various special milling machines. For small and medium-sized parts produced in small batches, horizontal milling machines and vertical milling machines are the most commonly used. The precision of CNC milling is high, the dimensional tolerance level of the workpiece is generally up to IT9 ~ IT7, and the surface roughness is generally Ra value of 6.3 ~ 1.6um. In cutting processing, the workload of the CNC milling machine is second only to the CNC lathe.
Application Scope of CNC Milling
CNC milling has a wide range of processing. Milling is mainly used for processing plane, step surface, bevel, groove, forming surface, gear and cut off, etc., can also be drilled and boring.
3. CNC Laser Machining
Laser cutting: It is controlled by the CNC program or made into a cutting robot. As a precise machining method, laser cutting can cut almost all materials, including two-dimensional or three-dimensional cutting of thin metal sheets.
Laser cutting uses a focused high-power-density laser beam to irradiate the workpiece so that the irradiated material rapidly melts, vaporizes, ablates, or reaches the ignition point, and at the same time, the molten material is blown away with the help of high-speed airflow coaxial with the beam, so as to realize the cutting of the workpiece.
After the material is laser-cut, the width of the heat-affected zone is very small, and the properties of the material near the cutting seam are hardly affected, and the workpiece deformation is small, the cutting precision is high, the geometrical shape of the cutting seam is good, and the cross-sectional shape of the cutting seam is a relatively regular rectangle.
4. 5-Axis CNC Machining
5-axis CNC machining can realize milling, boring, drilling, twisting, tapping, and other processes. Due to the high versatility of 5-axis CNC machining, it is used to manufacture complex precision parts. Such as medical parts for artificial limbs or bones, aerospace parts, titanium parts, oil and gas machinery parts, military products, etc.
5. Complex Surface Processing
For the machining of complex surfaces, CNC machine tools come in handy. The machining of three-dimensional curved surfaces mainly adopts the methods of copy milling and CNC milling or special processing methods. Copying milling must have a prototype as a die. During processing, the profiling head of the ball head is always in contact with the prototype surface with a certain pressure. The movement of the profiling head is transformed into inductance, and the processing amplification controls the movement of the three axes of the milling machine, forming the trajectory of the cutter head moving along the curved surface. The milling cutters mostly use ball-end milling cutters with the same radius as the profiling head. The emergence of numerical control technology provides a more effective method for surface machining.
Advantages of CNC Machining
Compared to traditional manual machining, CNC machining is much faster. As long as the computer code is correct and conforms to the design, the finished product has high dimensional accuracy and small errors.
CNC manufacturing is an ideal rapid prototyping manufacturing method. It can also be used to manufacture end-use products and components but is usually only cost-effective in low-volume, short-run production runs.
Precision CNC Machining Steps
- Reasonable Choice of Machine Tool: The application of CNC machine tools to deal with the deep processing of parts should focus on the texture, properties of the blanks, as well as contours and complex programs of the parts. In addition, size, machining accuracy, number of parts, and whether heat treatment is required are all things that factories need to consider.
- Technological Analysis of CNC Machining Parts: The technological analysis of CNC machining involves a very wide range, often requiring part drawings, dimensional data, and programming principles. The dimensions on the drawings should be extremely standardized and suitable for CNC equipment applications. Specifically, the same reference size can be quoted or the coordinate size can be given directly. This operation can ensure that subsequent programming is more scientific and stable.
- Choice of Machining Method: The selection principle of the machining method is to ensure the machining accuracy and surface roughness of the machined surface. Since there are many processing methods for the same level of precision and surface roughness, the shape, size, and heat treatment of the parts can be combined in the selection. In addition, productivity and economics are also issues that factories need to think about.
- Determination of Processing Plan: For the surface machining of precision parts, rough machining, semi-finishing, and finishing are often used, and the streamlined operation will make the parts more perfect. From the blank to the real part, the key lies in the selection of equipment and the precision of the drawings. The designer needs to consult with the construction personnel and formulate a thorough processing plan.
- Process and Step: CNC machine tools process parts, the process will be more concentrated, and all the processes can be completed in one clamping. The focus of CNC machining is to consider whether the machined parts can be completed by a CNC lathe or milling machine, or whether it requires the coordination of multiple types of equipment.
- Parts Installation and Fixture Selection: The installation of parts and the selection of fixtures should follow a basic point: the three benchmarks of design, technology, and programming are unified.
- Selection of Tools and Determination of Cutting Amount: Precision CNC machining is inseparable from matching high-quality tools. From traditional machine tools, lathes, and milling machines, manual sharpening is required, and now mechanical equipment has the advantages of automatic sharpening. When programming, the operator should pay attention to the processing capacity of the machine tool, the content of the process, the material of the workpiece, and other factors.
- Selection of Cutting Oil: Cutting oil can lubricate and ensure smooth processing, and it is also an essential and important item for the daily maintenance of machinery and equipment. The selection of cutting oil can be based on the material of the workpiece, and also can be based on the type of equipment, process method, tool performance, and other factors.
Notes for CNC Machining Center
The Location of The CNC Machine: In precision CNC machining, there are often some problems due to the placement, such as the very common vibration source phenomenon.
The operation of CNC machine tools should have two basic conditions: stable power supply and flat ground. In many workshops due to uneven ground or machine tool base damage, unstable placement in processing will produce a large vibration source sense, which is not conducive to the deep processing of parts. In the long run, this can also cause damage to machinery and equipment.
Voltage, Power Supply: Industrial power is 380 Ford high voltage, which is one of the riskiest and most efficient power applications. CNC machining centers in the implementation of cutting and other operations, often need to consume a lot of electrical energy. At this point, the operator needs to ensure that the machining center can operate normally and ensure the stability of the current supply. The specific operation should start from two aspects: First, check the safety and stability of the peripheral power supply. Second, the power supply voltage fluctuation should be within the allowable range of the machine tool factory, and should not exceed it.
Ambient Temperature: According to normal practice, when the CNC machining center processes parts, the ambient temperature should be kept at about 0-45°, and the humidity should preferably be less than 75%.