When milling complex workpieces on the milling machining center, the use of CNC end mills should pay attention to the following issues.
1. Clamping of end mills: Most of the end mills used in machining centers are clamped in a spring clamp set and are in a cantilevered state when in use. In the milling process, sometimes the end mill may gradually extend from the tool holder, or even completely fall off, resulting in the scrapping of the workpiece, which is generally due to the presence of oil film between the inner hole of the tool holder and the outer diameter of the shank of the end mill, resulting in insufficient clamping force. End mill cutters are usually coated with anti-rust oil, if cutting with non-water-soluble cutting oil, the inner hole of the tool holder will also be attached to a layer of foggy oil film, when the shank and the tool holder are on the oil film, the tool holder is difficult to firmly clamp the shank, in the processing of the end mill cutter is easy to loosen and fall off. Therefore, before clamping the end mill, the shank of the end mill and the inner hole of the tool holder should be cleaned with cleaning liquid and dried before clamping. When the diameter of the end mill is large, even if the shank and the tool holder are clean, it may still happen that the tool is dropped, then the shank with the cutting notch and the corresponding side locking method should be used. Another problem that may occur after the end mill is clamped is that the end mill is broken at the tool clamp port during processing, the reason is generally because the tool clamp has been used for too long, the tool clamp port has worn into a cone.
2. Vibration of the end mill: Because there is a small gap between the end mill and the tool holder, the tool has the possibility of vibration during the machining process. Vibration will make the end mill circumferential edge of the eating amount is not uniform, and the cutting expansion than the original value increases, affecting the machining accuracy and tool life. However, when the groove width is small, it is possible to make the tool vibrate purposely to obtain the required groove width by increasing the cutting and expanding volume, but the maximum amplitude of the end mill should be limited to less than 0.02mm in this case, otherwise stable cutting cannot be carried out. The smaller the vibration of the end mill in normal machining, the better. When the tool vibration occurs, consider reducing the cutting speed and feed rate, if both have been reduced by 40% there is still a large vibration, then consider reducing the amount of tool eating. If resonance occurs in the machining system, the reason may be that the cutting speed is too large, the feed rate is small, the tool system is not rigid enough, the workpiece clamping force is not enough and the shape of the workpiece or the workpiece clamping method, etc. At this time, measures should be taken to adjust the cutting amount, increase the rigidity of the tool system, and improve the feed rate.