What is an End Mill Used for?

End mills are the most commonly used milling cutters on CNC machine tools. There are cutters on the cylindrical surface and end face of the end mills. They can be cut simultaneously or separately. Mainly used for face milling, groove milling, step milling and copy milling.

There are many types of milling cutters , ordinary milling machines and

Most of the end mills for machining centers use spring clips, which are in a cantilever state when used. During the milling process, sometimes the end mill gradually protrudes from the holder, or even completely falls, causing the workpiece to be scrapped. The reason is generally between the inner hole of the holder and the outer diameter of the end mill shank. Oil film is present, resulting in insufficient clamping force. End mills are usually coated with anti-rust oil when they leave the factory. If water-insoluble cutting oil is used for cutting, a layer of misty oil film will also adhere to the inner hole of the tool holder. It is difficult to clamp the shank firmly, and the end mill is easily loosened during processing. Therefore, before the end mill is clamped, the end mill cutter shank and the inner hole of the clamp should be cleaned with a cleaning liquid, and then dried.

When the diameter of the end mill is large, even if the tool holder and the holder are clean, a tool accident may occur. At this time, a tool holder with a flat 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 holder port during processing. The reason is generally because the tool holder is used for a long time and the tool holder port has been worn into a cone. At this time, The tool holder should be replaced with a new one ^[2]

Because there is a slight gap between the end mill and the tool holder, the tool may vibrate during processing. Vibration will make the cutting amount of the peripheral edge of the end mill uneven, and the cutting expansion will be larger than the original value, which will affect the machining accuracy and tool life. But when the width of the processed groove is too small, the tool can also be purposefully vibrated and the required groove width can be obtained by increasing the cutting expansion. However, in this case, the maximum amplitude of the end mill should be limited to 0.02mm or less. Otherwise, stable cutting cannot be performed. The smaller the end mill vibration during normal machining, the better.

When the tool vibration occurs, you should consider reducing the cutting speed and feed rate. If both still have a large vibration after 40% reduction, you should consider reducing the amount of knife.

If there is resonance in the processing system, the reasons may be caused by excessive cutting speed, low feed speed, insufficient rigidity of the tool system, insufficient clamping force of the workpiece, and the shape of the workpiece or the clamping method of the workpiece. Measures such as increasing the rigidity of the tool system and increasing the feed rate.

In the numerical control milling processing of workpiece cavities such as molds, when the cutting point is a concave portion or a deep cavity, the extension of the end mill needs to be increased. If a long-edge type end mill is used, it is easy to generate vibration and cause tool breakage due to the large deflection of the tool. Therefore, in the processing process, if only the cutting edge near the end of the tool is required to participate in cutting, it is best to choose a short-edged long-shank end mill with a longer total tool length. When using a large-diameter end mill on a horizontal CNC machine to process a workpiece, due to the large deformation caused by the tool's own weight, more attention should be paid to the problems that are easy to occur in end-edge cutting. When a long-edge type end mill must be used, the cutting speed and feed speed must be greatly reduced.

Cutting speed of end mill

The choice of cutting speed mainly depends on the material of the workpiece; the choice of feed speed mainly depends on the material of the workpiece and the diameter of the end mill. The cutting tool selection table of some cutting tool manufacturers from abroad is attached for reference. However, the selection of cutting parameters is also affected by various factors such as the machine tool, the tool system, the shape of the workpiece being processed, and the clamping method. The cutting speed and feed speed should be appropriately adjusted according to the actual situation.

When the tool life is a priority factor, the cutting speed and feed speed can be appropriately reduced; when the chip off-edge condition is not good, the cutting speed can be appropriately increased.

End mill

Adopting down milling is helpful to prevent cutting edge damage and increase tool life. However, there are two points to note: If using ordinary machine tools, you should try to eliminate the gap of the feed mechanism; When the oxide film or other hardened layer formed by the casting and forging process remains on the surface of the workpiece, reverse milling should be used.

End mill cutter material

The use range and requirements of high-speed steel end mills are relatively wide, and even if the choice of cutting conditions is slightly inappropriate, there will not be too many problems. Although hard alloy end mills have good abrasion resistance during high-speed cutting, they are not as widely used as high-speed steel end mills, and the cutting conditions must strictly meet the requirements of the tool ^[3] .