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Pay attention to the following issues when purchasing tungsten steel milling cutters:
1. End mill clamping
Most of the machining center end mills use a spring clip set clamp method, which is in a cantilever state when in use. During the milling process, sometimes the end mill may gradually protrude from the tool holder or even fall completely, causing the workpiece to be scrapped. The reason is generally because the oil film between the inner hole of the tool holder and the outer diameter of the end mill is caused by the oil film. Insufficient tightening. End mills are usually coated with anti-rust oil when they are shipped out. If non-water-soluble cutting oil is used for cutting, the inner hole of the tool holder will also adhere to a misty oil film. When the tool holder has oil film on the tool holder, the tool holder is very It is difficult to firmly clamp the shank, and the end mill is easy to loosen and fall. Therefore, before the end mill is clamped, the inner hole of the tool holder of the end mill should be cleaned with cleaning liquid, and then dried before being clamped. When the diameter of the end mill is large, even if the tool holder is clean, a knife drop accident may occur. In this case, the corresponding side locking method with a flattened notch should be used. Another problem may occur after the end mill is clamped. The end of the end mill cutter clamp is broken. The reason is generally because the tool holder has been used for too long and the port portion of the tool holder has been worn to be tapered.
2. End mill vibration
Due to the small gap between the end mill and the tool holder, the machining process may have vibration. The vibration will make the circumferential cutting edge of the end mill not uniform, and the amount of cut and expand will increase than the original value, which will affect the tool life of the machining precision. However, when the width of the groove is small, the tool can be vibrated, and the required groove width can be obtained by increasing the amount of cut. However, in this case, the large amplitude of the end mill should be limited to 0.02 mm or less, otherwise it cannot be performed. Stable cutting. The smaller the normal machining end mill vibration, the better. When tool vibration occurs, consider reducing the cutting speed feed rate. If both of them have been reduced by 40% and still have large vibrations, consider reducing the amount of knife. If the resonance occurs in the processing system, the cause may be due to excessive cutting speed, small feed speed, insufficient rigidity of the tool system, insufficient workpiece clamping force, and workpiece shape or workpiece clamping method. Measures to increase the rigidity of the tool system and increase the feed rate.
3. End mill cutting edge cutting
For CNC milling of workpiece pockets such as molds, when the cutting point is a concave part or a deep cavity, it is necessary to lengthen the extension of the end mill. If a long-edge end mill is used, it is easy to generate vibration and cause tool breakage due to the large deflection of the tool. Therefore, if only the cutting edge near the end of the tool is required to take part in the machining process, it is better to use a long-blade long-shank type end mill with a total length of the tool. When using a large-diameter end mill to machine a workpiece on a horizontal CNC machine tool, due to the large deformation caused by the tool's own weight, it should be noted that end-edge cutting is prone to problems. In the case where a long edge end mill must be used, the feed rate of the cutting speed must be greatly reduced.
4. Cutting parameters selection
The cutting speed selection depends mainly on the material of the workpiece to be machined; the feed speed selection depends mainly on the material of the workpiece being machined and the diameter of the end mill. Some tool manufacturers in foreign countries have a tool cutting parameter selection table for reference. However, the selection of cutting parameters is affected by many factors such as the machine tool, the tool system, the shape of the workpiece to be machined, and the clamping method. The cutting speed feed rate should be adjusted according to the actual situation. When the tool life is a priority, the cutting rate feed rate can be appropriately reduced; when the chip off edge condition is not good, the cutting speed can be appropriately increased.
5. Cutting method selection
The use of down-cutting helps to prevent blade damage and improves tool life. However, there are two points to note: 1 If using ordinary machine tools, try to eliminate the gap of the feed mechanism; 2 When the surface of the workpiece remains cast or forged to form an oxide film or other hardened layer, it is better to use up-cut milling.
6. Carbide end mills are used
The use range of high-speed steel end mills is relatively wide, and even if the cutting conditions are chosen slightly, there are not too many problems. While the carbide end mill has good wear resistance at high speed, it is not used in a wide range of high-speed steel end mills, and the cutting conditions must strictly meet the requirements of the tool.