CNC machine tools come in a huge range of not just shapes and sizes, but also in geometry types and materials. Using a combination of different tools will provide you with the best cutting results, and it is never safe to assume that a small stepover tool will suffice. In CNC milling, the cutter will rotate on the axis that is vertical to the workpiece. The cutting teeth found in these CNC machine cutting tools will be located both on the end face of the cutter as well as on the cutter body. To see professional CNC machines and how they work, visit this link.
A ball nose tool that is also known as a spherical end mill has a semi sphere at the end of the tool, and these ball nose end mills are commonly used as the preferred CNC machine cutting tools when a complex surface is worked on. To produce the end piece or product that you are working on, it is often the case that you will need to change the tools that you use in cutting. For example, you may use an end mill for the rougher cutting and 2D operations, switching over to a ball nose cutter for the finer cutting and for finishing the operation.
CNC Machine Cutting – Geometry
When analyzing the end geometry of cutting tools, you can find down-cut, up-cut, and compression; the mills have a varying number of flutes. In general, end mills will cut in a horizontal way. The difference between the up and down cuts and the compression is the way that the chips are ejected. When using a down cut, the punching chips will go only downwards; in up-cutting, the mill will eject chips upwards. The compression mill on the other hand creates a surface that is smooth both on the top as well as the bottom, and is the perfect solution for projects such as those that use laminated woods.
End mills come once again in different shapes, flat end mills cutting flat areas, but leaving a terrace-like scallop on surfaces that are not flat. The workpiece may require a large amount of different CNC machine cutting tools in order for it to be finished to perfection. For example, the stepover of the tool needs to be taken into consideration when deciding on the finish required. The stepover is the distance measured that the tool used in the cutting moves between its subsequent passes, a tool with a small stepover taking longer to cut. As well as the stepover, you will come across the term stepdown; this is the depth with which the tool will cut down in one operation. The stepdown needs to be varied depending on how hard or soft the material being cut is; harder materials require a smaller stepdown.
Flutes
CNC machine cutting tools will generally have two flutes that are up-cut spirals. However, depending on the medium you are working on it may be wise to use down-cuts instead of the normal up-cut spirals. A CNC cutting machine may have a single flute, a double flute, or may have multiple flutes. The more flutes present, the better the finish of the surface, and the higher the capacity of the feed rate.
Material
The material used for the CNC milling machine can also vary, end mills generally being made from cobalt steel alloys or tungsten carbide. Carbide tools are tougher and can be run at a higher speed, more than twice as fast as HSS tools. In general, your carbide tools will be coated to ensure that they perform better, for longer, and cut and mill your workpiece to perfection.
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