Surface Machining using the Zig-Zag Cycle

Another way to machine the interior of a pocket is using the Zig-Zag cycle. It uses a back-and-forth "zig-zag" tool motion to rough or finish an area within a closed boundary. This cycle can be used to rough and finish a pocket with "islands". When the tool encounters an island in the pocket, it cuts around the island boundary, leaving material equal to the Stock Allow value on the island. When a pocket with islands has been roughed using the Zig-Zag cycle, it is usually desirable to finish the islands using a Contouring cycle. Rapid curve links at begin of the pocket profile can be used to support multiple plunge points. Multiple points are linked via rapid curve links before the pocket profile. Whenever a plunge move is required, the closest rapid point is picked. Target loop is also resorted so that its start point is closest to the selected plunge point. An optional surface Finishing Allowance can be set in the Work Step Surface section on the 3D Cycle Data dialog.  

The pocket boundary is normally defined by the selected Path Curve ID or, in case "None" is selected there, automatically computed by the system. Islands can be defined in two different ways. They can be defined within the same curve together with the pockets boundary profile, or you can create individual islands curves and assign them as Check Curves on the 3D Cycle Data Tab. See the Pockets & Islands topic for more information.

The Zig-Zag cycle provides the following advantages:

• control over the cutting direction via the Cut Angle parameter.

• machining of islands, without removing the tool from the workpiece.

• multiple surface machining within the specified pocket boundary (surface machining).

However, the Zig-Zag cycle has two disadvantages

• less control over the surface finish on vertical or nearly vertical walls  (surface machining).

• increased tool path calculation times.