What is CNC Machining Center?
CNC machining center, also known as gong and drum computer, is a kind of CNC machine tool. It is controlled by a CNC system. The system is developed on the basis of a CNC milling machine. It can process multiple processes such as clamping, drilling, reaming, drilling, tapping, and milling at one time, which greatly improves production efficiency.
Today, YIJIN Hardware would like to share you with a complete guide to the CNC Machining Center, CNC Machining Methods, CNC Machining Process, and the specific Steps of CNC machining.
Classification of CNC Machining Centers
According to the machining center of the spindle in the spatial direction, it can be divided into a vertical machining center and a horizontal machining center.
What Can A Vertical Machining Center Do?
The vertical machining center refers to the vertical state of the main shaft, the structure is simple, the space is small, the price is relatively low, and it is widely used. A vertical machining center is mainly suitable for processing disc and plate parts. Due to the limitation of column height and tool changer, it is difficult to process.
What Can A Horizontal Machining Center Do?
A horizontal machining center means that the spindle axis is in a horizontal state. Compared with the vertical machining center, the horizontal machining center has a complex structure, occupies a large space, and is expensive. It is suitable for the processing of box parts.
Machining of Typical Parts in CNC Machining Centers
Shell parts generally refer to parts with multiple holes, internal cavity, length, width, and height. There are many such parts in machine tools, automobiles, aircraft, and other industries, such as automobile cylinder blocks, gearboxes, lathe boxes, axle boxes, diesel engine cylinders, pump casings, etc.
Box parts generally require multi-station processing of holes, shapes, and surfaces. The wear resistance requirements, especially the geometric tolerance requirements, are relatively strict. Usually, they are processed by milling, hammering, drilling, expanding, reaming, planing, and tapping.
The number of tools is large, which requires multiple clamping, alignment, and measurement times on ordinary machine tools, resulting in a complex process, long processing cycles, high costs, and difficulty to guarantee accuracy.
This kind of part is processed in the machining center, and one clamping can complete 60~95% of the process content of the ordinary machine tool. The accuracy of each part is consistent and the quality is stable. At the same time, it can shorten the production cycle and reduce production costs.
In the processing station is more, the table needs several rotation Angle to complete the parts, usually choose the horizontal CNC machining center, when the processing station is less, and the spacing is not large, can choose the vertical CNC machining center, processing from one end.
As for the possibility of machining, if there is no overcut or machining blind area, the ball-end milling cutter can usually be used for three-coordinate linkage machining. If the workpiece has an overcut or machining blind area, such as an integral impeller, the machining accuracy is high and the efficiency is high. Low; consider using a four-coordinate or five-coordinate linkage machine.
Because complex surfaces generally through rough milling, semi-finishing milling, root cleaning, and other processes, so only a small number of cutting tools, can not give full play to the advantages of automatic tool change machining center, especially the mold type of processing, usually need rough milling, fine milling, root cleaning method.
Forming parts are irregular shape parts, most of the bracket, base, template, back mold, bracket, and so on point, line, surface mixed processing.
The rigidity of forming parts is poor, the clamping and cutting deformation is difficult to control, and the machining accuracy is difficult to guarantee. At this time can give full play to the characteristics of processing center working procedure concentration, take reasonable technological measures, one or two clampings, and complete multiple or all processing content.
Experience shows that the more complex the machining shape is, the higher the precision is required, and the machining center is used to show its advantages.
Disc, Sleeve, Plate
Disc sleeve or shaft parts with keyway or radial hole or end face with distribution hole system, such as flange shaft sleeve, shaft parts with keyway or square head, etc. Plate parts with more processing, such as all kinds of motor covers.
End face distribution hole system, disc, sleeve, plate, and other parts should choose vertical CNC machining center, with diameter hole can choose horizontal CNC machining center.
CNC Processing Technology
Aluminum Profile Cutting
Aluminum profile cutting is the most basic and common processing method in CNC processing of aluminum profiles. Since the standard size of industrial aluminum profiles is 6020mm, only aluminum profiles of different lengths or angles can be assembled into the frame.
Industrial aluminum profiles have a variety of connection methods, which need to be punched according to different connection methods. Common punching methods include through holes and stepped holes.
Through Hole: Used to fasten common bolts (semicircle head).
Step Hole: Mainly used for special connectors (built-in connectors. Fastening connection of internal connector is a common and high technology process in CNC processing of aluminum profiles.
Aluminum tapping is what we often call tapping wire. The processing of the aluminum profile is according to the technical requirements of the design drawings on the end of the aluminum profile tapping hole thread tapping processing, used for fastening the late frame connection.
CNC Milling Machine
The traditional frame assembly of aluminum profiles does not require CNC milling, but in special cases, non-standard parts are used in conjunction with the profiles, and the aluminum profiles are CNC machined according to technical needs.
6 Common Processing Methods
Rotation is mainly to rotate the workpiece and use the tool to cut the workpiece into the desired shape. The inner and outer cylindrical surfaces move on parallel rotation axes to obtain the tool.
The formation of the conical surface is when the tool moves in the oblique direction of the axial direction. The rotating surface is a profiling lathe or CNC lathe, which is fed by the control tool along a curve. Another kind of production of the rotating surface is to use a molded turning tool with lateral feed. In addition, machining thread surface, end face, eccentric shaft, etc. can also be turned.
Milling mainly relies on rotating tools. Milling is divided into horizontal milling and vertical milling. The plane of horizontal milling is composed of the cutting edge on the outer surface of the milling cutter. End milling is formed by the end face edge of the milling cutter. To obtain a higher cutting speed and better productivity, the rotational speed of the milling cutter can be increased. However, the cutting in, cutting, and impact formation of the cutter teeth of the milling cutter are prone to vibration during the cutting process, thus limiting the improvement of the quality of the machined surface.
Planing is a process in which the tool moves the workpiece in a reciprocating straight line. As a result, planning is slower and productivity is reduced. But compared with milling, the accuracy and surface roughness of planing are more stable.
Grinding processing mainly relies on a grinding wheel and tools to process workpiece, and relies on grinding wheel rotation. In the grinding process, the grinding wheel is mainly the abrasive particles on the grinding wheel to cut the workpiece surface. The grinding itself is also sharpened and gradually blunted, resulting in a decrease in cutting performance and an increase in cutting force.
5. Tooth Surface Machining
Tooth surface processing is a new type of processing method, which can be divided into two categories: one is the forming method, and the other is the expansion method. The forming method is mainly processed by an ordinary milling machine, and the tool adopts a forming milling cutter, which requires two simple forming movements of the tool’s rotary motion and linear motion. However, the machine tools that generally process the tooth surface by the unfolding method are gear hobbing machines, gear shaping machines, etc.
6. Complex Surface Treatment
For dealing with complex surfaces, CNC machine tools can be used. The cutting of the three-dimensional surface mainly adopts copy milling, CNC milling or special processing methods. The imitation milling machine must use prototypes. The profiling head of the ball head is machined with a certain pressure to keep the surface of the prototype in contact. The movement of the profiling head is converted into inductance, and the processing enlargement controls the movement of the three axes of the milling machine and forms the movement trajectory of the tool along the curved surface. Milling cutters usually use milling cutters with radii such as ball and profile heads. The emergence of CNC provides a more effective means for surface machining.
The Specific Steps of CNC Machining
- The first is the choice of CNC machine tools.
- After selecting the CNC machine, the processing method should be selected.
- Positioning method.
- Determine inspection requirements and methods.
- Then select the tool.
- Error control and tolerance control.
- Define CNC operations.
- CNC sequence.
- Determination of cutting parameters.
- Prepare the CNC machining procedure sheet.