Get the ramp angle from the depth and length of an entry move, and check it against the maximum ramp angle the cutter can take. Steep ramps break small end mills.
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Request a Proposal →When an end mill enters the material at an angle (ramping or helical entry), the centre of the tool cuts material. The maximum ramping angle depends on the tool's centre-cutting capability and the axial depth per revolution.
3-5 deg is safe for most end mills. Some high-performance ramping end mills can handle 7-10 deg . Indexable tools are more limited (1-3 deg ) because the centre insert is not designed for heavy axial cutting. Always check the manufacturer's specification.
The tool centre -- which has zero surface speed -- is forced to cut full material. This causes extreme thrust force, tool deflection, poor hole quality, and likely tool breakage. The tool essentially acts as a drill without the proper drill point geometry.
Helical ramping distributes the load more evenly and is preferred for blind holes. Linear ramping is simpler to program and works for open pockets. Both methods must respect the tool's maximum ramp angle.
Enter the axial depth per pass (ap) and the tool diameter. The calculator shows the ramping angle and the recommended maximum. For most end mills, keep the ramp angle below 5 deg . Use helical entry for tight bores.
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RAMPING INTO THE CUT? Ramp limits are set by the cutter's core, which is a spec worth confirming rather than assuming. See what to specify when ordering a milling cutter.
A ramp angle your cutter cannot survive is a broken cutter, not a slow one. Centre-cutting geometry, core diameter and flute count decide what is safe. Send the angle and the material.