HSM Finishing Strategies

Linear Machining is one of the most widely used finishing strategies. Linear passes are typically used to semi-finish cusps from roughing operations and to finish shallow areas. The passes are parallel in the XY-plane and follow the surface in Z-direction. You can choose their angle as well as their stepover in the horizontal direction. Cross linear-paths, at 90 degrees to the linear path, are used to finish the whole part.

Horizontal Machining strategy automatically detects all the flat areas of the part and clears them with an offsetting path at the z-level of each area, utilizing similar smoothing charcteristics as roughing. Linking is also similar to roughing with helix and profile ramping entries and smooth linking motions. Should the user require to machine these flat areas with more than one pass, any number of Z-axial offset passes can be added.

Constant-Z machining passes are generated from a set of surface contours which describe the shape of surfaces at different z-heights - like horizontal slices through the geometry. This is the best strategy for semi-finishing and finishing of steep walls. By limiting the Constant-Z passes to contact angles between 30 to 90 degrees, the steeper areas are machined, leaving the shallower area for more appropriate strategies.

Spiral machining creates a spiral tool-path from a given focal point, while keeping constant contact between the cutter and workpiece as it machines within a given boundary. A stepover defines the spacing between each coil of the pass. The focal point of the detail to be machined with spiral or radial passes is located automatically, or can be determined by the user.

Morphed machining controls the toolpath using flow boundaries and direction profiles. Morphed passes flow across the surface in a close-to-parallel formation with the shape and direction of the passes dictated by the boundaries around them. Each path echoes the shape of the one before and takes on some characteristics of the one after, thus gradually changing shape.

Radial machining provides the user with the ability to machine radial parts. Machining converges to a central point with the ability to stop short of the center of the radial passes, where they become very dense. This strategy is ideally suited for use on areas that include shallow curved surfaces and circular areas, using contact angles between 0 - 40 degrees.

A Boundary pass is created by dropping the cutter onto the surface and running it along a single boundary or a set of boundaries to produce the effect of engraving. It can be applied for engraving text, chamfering along a profile or of mold tool runner detail. Negative machining thickness can be used to machine at a constant depth below the surface being machined.

3D Corner offset machining is similar to constant stepover machining. However, rather than start from an outside boundary and work in towards the center, a set of pencil passes are created at the corners of the part. Starting from these corner passes, a tool path that maintains an equidistant surface finish is generated following the 3D form, towards the edges of the part.

3D Constant-stepover finishing strategy maintains a constant, equidistant stepover from one toolpath pass to the next, irrespective of the slope angle of the part. It creates 3D passes that are at a constant distance from each other along the surface of the part, by offsetting inwards along the surface. This strategy can be applied within any boundary or to the whole part.

The Pencil milling strategy creates tool paths along internal corners and fillets with small radii, removing material that no other strategy can reach. The pencil milling routine is used to finish corners which might otherwise have cusp marks left from previous machining operations. This is ideal for machining into corners where the surface radius is the same as the cutter.

Parallel pencil milling is an extension to pencil milling where the user can determine the number and step-over of multiple-passes, either side of the pencil tool-path. This is particularly useful when the previous cutting tool has not been able to machine all the internal corner radii to size. These multiple passes will machine from the outside in to the corner, creating a good surface finish.

While pencil milling of vertical corners can cause both the flute of the cutter and the radius to be in full contact with the material, creating adverse cutting conditions, Rest Machining strategy picks the corners out from the top down resulting in better machining technique. Steep and shallow areas are both machined in a single toolpath with different rest machining strategies.