The milling cutter should be used on the CNC machining center milling machine to process planes, steps, grooves, forming appearances and blocking workpieces, etc. This has a great impact on the quality of the processed parts, so how to choose the right milling cutter? What are the principles?

The milling cutter used on the CNC machining center should be made of all cemented carbide, and the general milling machine should be made of white steel. The hardness of white steel milling cutter and cemented carbide milling cutter is softer.

Cemented carbide milling cutters have good thermal hardness, wear resistance, but poor impact resistance. If you drop the blade at will, it will break. The cemented carbide is made of powder metallurgy, the hardness can reach about 90HRA, and the thermal property can reach about 900-1000 degrees.

1. Number of milling cutter teeth

When choosing a milling cutter, consider the number of teeth. For example, a coarse-tooth milling cutter with a diameter of 100mm only needs 6 teeth, while a close-tooth milling cutter with a diameter of 100mm can have 8 teeth. The size of the tooth pitch will determine the number of cutter teeth that participate in the cutting during milling, and affect the smoothness of cutting and the requirements for machine tool cutting rate.

2, chip flutes

The rough tooth milling cutter is mostly used for rough machining because it has a larger chip pocket. Assuming that the chip pocket is not large enough, it will cause difficulty in chip coiling or increase the conflict between chips and the tool body and workpiece. At the same feed rate, the cutting load per tooth of a coarse-tooth milling cutter is larger than that of a dense-tooth milling cutter.

3, depth of cut

Depth of cut is shallow during finishing milling, generally 0.25—0.64mm. The cutting load of each tooth is small (about 0.05-0.15mm), the required power is not large, the close-tooth milling cutter can be selected, and the larger feed rate can be selected.

4. Application of rough milling

During heavy-duty rough milling, excessive cutting force can cause vibrations of the machine with poor rigidity. This chattering can cause chipping of the carbide inserts, and then shorten the tool life. The choice of coarse-tooth milling cutter can reduce the power requirements of the machine tool.

The price of milling cutters used in cnc machining centers is relatively expensive. A face milling cutter with a diameter of 100mm may cost three to four thousand yuan, so you should choose carefully. Many people who have operated cnc machining centers have encountered over-cutting problems, so how to deal with this situation?

The workpiece processing process of the cnc machining center is no longer like the traditional processing equipment, which requires uninterrupted control of the machine tool to end, control the various functional parts of the machine tool to perform messy and precise movements, and then end the processing process with high precision and efficiency. The programming of the workpiece processing program is the key to the processing of the workpiece in the machining center.

But if the programming is unreasonable or the parameter setting is improper, it will severely affect the processing accuracy and processing power of the workpiece, such as overcutting. Overcutting is a serious problem in workpiece processing, and it can cause the workpiece to be invalid when it is severe.

The front-line processing personnel have compiled a processing program that must have overcutting for some reason during CNC programming. The system can announce an alarm signal in advance during the work process, which can avoid the occurrence of overcutting. How to judge the cause of the overcut phenomenon in the CNC machining center?

1. Overcutting during arc machining of machining center

In the machining center for internal generalized arc machining, if the selected tool radius rD is too large, overcutting is likely to occur when it exceeds the required machining arc radius R. The NC machining programs are compiled according to the general track of the workpiece practice, regardless of the movement track of the tool in the actual processing process.

Because of the tool radius, the tool practice track becomes thicker and does not coincide with the programming track. In order to get the correct workpiece surface summary, it is necessary to set the tool radius compensation command between the tool track and the programming track. Otherwise, overcutting of the workpiece will be inevitable.

2. The over-cutting discrimination during straight-line processing

When the CNC machining center processes a workpiece consisting of straight segments, if the tool radius is too large, it will most likely cause overcutting, and then the workpiece will be scrapped. It can be judged by the positive or negative of the scalar product of the programming vector and the corresponding correction vector.