1) 3D Contour Milling (CM) and how it’s used
3D CM is a style of machining used heavily in industries that create complex three-dimensional contour parts such as the aerospace, medical, and mold & die sectors. These contours contain a range of angles, shapes, and radii that would normally be very difficult and time consuming using conventional machining styles. When the correct tools are selected, CM also produces better surface finishes and increases productivity and tool life.
2) Tools used in this style of machining
With such complex geometries, there isn’t one tool to do it all (efficiently). Ball nose tools can be used to produce almost any feature, but that’s not to say there aren’t better/more efficient options available. Barrel/circle segment cutters are commonly used when CM. These tools have a very large radius on the OD of the tool and can be used to minimize cusp height (high spots of uncut material between passes), requiring fewer steps to attain a finish similar to a ball tool. Many times, the radius of a tool can be selected to match a specific radius on the part.
3) Axial chip thinning
Used for wide radial, shallow axial cuts, axial chip thinning occurs when using a tool with a lead angle of less than 90° (not square). This produces a larger chip and redirects cutting forces up the tool, toward the spindle. A simple way to picture this is slicing a vegetable diagonally; it produces a larger slice, and in turn, takes fewer cuts to slice it entirely compared to straight, perpendicular cuts. With cutting forces directed up and not out, the user can increase feed rate far above what a square end mill would run.
4) Advantages of 5-axis machines in CM
While it’s possible to 3D CM on a 3-axis machine, a 5-axis allows greater utilization of the cutting tool and creation of more complex/unique parts in a single setup. This is where barrel/circle-segment cutters can be used. The fifth axis allows the tool to be tilted to better match the part’s contour, minimizing cusp height while maximizing productivity.
3D CM is a style of machining used heavily in industries that create complex three-dimensional contour parts such as the aerospace, medical, and mold & die sectors.
5) Tilt angle advantage when using a 5-axis machine
A tilt angle for a ball nose tool does a few things. It gets the tip of the tool (where the surface footage is zero and shearing the material is most difficult) off the workpiece, increasing the effective diameter. Ball nose tools typically have fewer flutes at the tip of the tool, so using a tilt angle can engage all flutes, generating a better finish and spreading wear evenly on all flutes across the radius, ultimately increasing tool life. A higher flute count tool, such as the new T-Carb® 51B, will add additional flutes to share the load, increasing life and resulting in lower finish measurements.
Kyocera SGS Precision Toolswww.kyocera-sgstool.com