Multi-Step and Multi-Pass Trajectory Milling
In 3- to 5-axis Trajectory milling, the following terminology is used:
• Multi-step milling—The tool performs a succession of cuts at step depth increments, with the last cut being coincident with the specified trajectory.
• Multi-pass milling—The tool performs a succession of trajectory passes with horizontal offset with respect to the specified trajectory. The last pass is coincident with the specified trajectory. If multi-step milling is specified, the system creates horizontally offset slices, with the cutting passes at each step depth.
Use the following parameters to control multi-step and multi-pass Trajectory milling.
Multi-Step Trajectory Milling
Multi-step Trajectory milling can be performed by specifying either the desired STEP_DEPTH (in which case the cuts will be repeated in these step depth increments), or the desired NUMBER_CUTS. If both are specified, the higher of the two numbers of cuts will be used. The last cut will coincide with the specified trajectory.
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 The system automatically removes the first slice if it is too shallow, to reduce the risk of breaking the tool. If the depth of the first computed slice is less than (0.05*STEP_DEPTH), or is less than the absolute accuracy of the manufacturing assembly, the system discards it and starts with the second slice. |
The Start Height option on the CUT ALONG menu allows you to specify the height of the first pass. If Start Height is not specified, the top of the workpiece will be used. For Assembly machining, or workpiece with no geometry, you have to either specify the Start Height, or specify both the STEP_DEPTH and NUMBER_CUTS. In this last case, the parameters are interpreted differently: NUMBER_CUTS will determine the number of passes, and STEP_DEPTH—the offset between the passes, that is, the first pass will be offset from the specified trajectory by (NUMBER_CUTS-1)*STEP_DEPTH.
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• It is recommended not to use Start Height while defining a multi-axis Trajectory milling NC sequence. The tool orientation changes during the tool path generation and hence the start height, if specified, can produce unpredictable results, in such cases.
• The Start Height option is grayed out if neither STEP_DEPTH nor NUMBER_CUTS has been specified for the NC sequence.
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The user interface for specifying Start Height is the same as specifying Height.
Multi-Pass Trajectory Milling
Multi-pass Trajectory milling (a succession of trajectory passes with horizontal offset) can be performed by using the NUM_PROF_PASSES and PROF_INCREMENT parameters. The last pass will coincide with the specified trajectory.
Intermediate Tool Retract
When you create multi-step and multi-pass trajectory motions, you may not want the tool to move to the retract plane between the cuts. Use the CONNECTION_TYPE parameter to control the intermediate tool retracts. The values are:
• RETRACT (default)—At the end of an intermediate cut, the tool retracts, moves in the retract plane, then plunges to the start of the next cut.
• Z_LAST—At the end of an intermediate cut, the tool moves first in the XY plane and then along the Z-axis to the start of the next cut.
• Z_FIRST—At the end of an intermediate cut, the tool moves first along the Z-axis and then in the XY plane to the start of the next cut.
• SIMULTANEOUS—The tool moves directly from the end of the previous cut to the start of the next cut.