Clamping of milling cutter

Most of the milling cutters used in the machining center are in the form of spring clips, and they are in cantilever form when used. During the milling process, sometimes the milling cutter may gradually protrude from the tool holder, so that the workpiece is scrapped. The reason is generally due to the presence of an oil film between the inner hole of the tool holder and the outer diameter of the milling cutter shank, forming a clamp. Due to lack of strength. The milling cutter is generally coated with anti-rust oil when it leaves the factory. If non-water-soluble cutting oil is used for cutting, a misty oil film will also be attached to the inner hole of the tool holder. It is difficult to firmly clamp the tool holder, and the milling cutter is easy to lose during processing. Therefore, before the milling cutter is clamped, the shank of the milling cutter and the inner hole of the cutter holder should be cleaned with cleaning fluid, and then dried before clamping.

When the diameter of the milling cutter is large, even if the tool holder and the tool holder are clean, accidents may still occur. At this time, the tool holder with a flat notch and the corresponding side locking method should be selected. After the milling cutter is clamped Another problem that may appear is that the milling cutter is broken at the tool holder port during processing. The reason is generally that the tool holder has been used for too long and the tool holder port has been worn into a cone. At this time, a new tool holder should be replaced. .

Vibration of milling cutter

Due to the slight gap between the milling cutter and the tool holder, the tool may vibrate during the machining process. Vibration will make the cutting amount of the circumferential edge of the milling cutter uneven, and the cutting and expansion amount will be larger than the original value, which will affect the machining accuracy and tool life. However, when the width of the machined groove is too small, the tool can be vibrated purposefully, and the required groove width can be obtained by increasing the amount of cutting and expansion, but in this case, the maximum amplitude of the milling cutter should be below 0.02mm, otherwise it is impossible to Make stable cuts. The smaller the vibration of the milling cutter in normal machining, the better.

When tool vibration occurs, consider reducing the cutting speed and feed rate. If there is still a large vibration after both have been reduced by 40%, you should consider reducing the amount of cutting. If there is resonance in the machining system, the reason may be that the cutting speed is too high, the feed speed is just too small, the tool system is just not enough, the clamping force of the workpiece is not enough, and the shape of the workpiece or the method of clamping the workpiece and other factors, it should be accepted at this time. Adjust the cutting amount, increase the rigidity of the tool system, increase the feed speed and other measures.

How to use the milling cutter

End cutting of milling cutter

During the CNC milling of workpiece cavities such as molds, when the cutting point is a concave part or a deep cavity, it is necessary to lengthen the protrusion of the milling cutter. If a long-edge milling cutter is used, due to the large deflection of the tool, it is easy to generate vibration and cause the tool to break. Therefore, in the process of machining, if only the cutting edge with the similar end of the tool is required to participate in the cutting, it is best to use a short-edged and long-shank type milling cutter with a longer overall length of the tool. When using a large-diameter milling cutter to process a workpiece on a horizontal CNC machine tool, the deformation caused by the self-weight of the tool is large, and more attention should be paid to the problem of excellent end-edge cutting. In the case where long-edged milling cutters must be used, the cutting speed and feed rate need to be greatly reduced.

The selection of cutting speed mainly depends on the material of the workpiece to be machined; the selection of feed rate mainly depends on the material of the workpiece to be machined and the diameter of the milling cutter. The tool samples of some foreign tool manufacturers are attached with a tool cutting parameter selection table for reference. However, the selection of cutting parameters is also affected by many factors such as the machine tool, tool system, the shape of the workpiece to be processed, and the clamping method. The cutting speed and feed rate should be adjusted according to the actual situation.

When the tool life is the priority factor, it is suitable to reduce the cutting speed and feed speed; when the chip separation is not good, it can be suitable to increase the cutting speed.

The choice of cutting method

Using down milling is beneficial to prevent edge protection and improve tool life. But there are two points to pay attention to:

If ordinary machine tools are used for processing, the gap of the feeding mechanism should be eliminated;

When the surface of the workpiece has an oxide film or other hardened layer composed of casting and forging processes, it is advisable to use up milling.