Using available and common modern-day machines with diverse kinematics and number of controlled axes, enhanced with a special tool and a standard CAM path, you will find a quite wide range of surfaces that can be obtained by continuous cutting. It is only necessary to recognize and skillfully use available possibilities.
Machine and S-axis of spindle rotation
Any practical application of the continuous cutting method on a CNC milling machine generally comes down to the same activities as the milling process, and the only difference is that the cutting tool must be immobilized. This immobilization consists in blocking or controlling the position of the tool rotation axis. The idea of multi-axis milling (with pivot and rotary axes) led to the development of milling machines with up to five controlled axes.
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These increasingly popular in tool shops and on production floor five-axis machines with different kinematics are devices that allow a completely free approach to the material being processed. This freedom is nothing more than six degrees of freedom control realization in space. Since working tools in the form of cutters or drills are rotary solids, six-axis designs dedicated to work with such tools were unjustified.
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The necessity of immobilizing a tool, such as a lathe knife, boring bar or a chisel, forces the introduction of a sixth axis control, and this is usually an indexed control. A smooth control of the spindle axis is used in almost every milling machine, but in special threading cycles (two-axis issue) or, for example, for the envelope milling of gears on rotary table milling machines – the user is not able to use such smooth control for other operations. In recent years, machine tools with smooth sixth axis control have become increasingly popular, mainly used for turning, boring and profiling operations (four-axis issue). Involving all six axes in a simultaneous mode will enable planing of any surface.
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This necessary sixth axis is available in most devices in indexed mode, which makes some starting point. I would like to point out that working with a fixed tool on machines that are not adapted to this must be done with a small surplus, so this machining method is dedicated mainly to finishing, and used tool should preferably generate minimum torque, because most of the machines with the possibility of indexing the spindle axis is not equipped with a brake.
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Using a special tool in the form of a standard round insert screwed to the shank in such a way that the rake plane faces downwards, a rotary planing tool is achieved (Fig. 5).
![](https://about-engineering.com/wp-content/uploads/2021/06/continuous-cutting-practical-application-5.jpg)
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![](https://about-engineering.com/wp-content/uploads/2021/06/continuous-cutting-practical-application-9a-1024x576.jpg)
![](https://about-engineering.com/wp-content/uploads/2021/06/continuous-cutting-practical-application-9b-1024x576.jpg)
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The shape of such a tool has two very important advantages. First of all, it allows direct use of some milling strategies from CAM systems, as it does not differ from a solid end mill in its geometry. Secondly, the machine does not even have to be equipped with an indexable spindle axis S.