Milling Parameters Specific to Thread Milling
In addition to the common milling parameters, the following parameters control the tool path generated by a Thread milling NC sequence:
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THREAD_DIAMETER
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If you have specified the thread style as Internal, this parameter indicates the major thread diameter. If the thread style is specified as External, it indicates the minor thread diameter.
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THREAD_FEED
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Specifies the thread pitch.
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THREAD_FEED_UNITS
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The possible values are TPI (threads per inch), MM (millimeter per revolution), and INCH (inch per revolution).
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THREAD_SERIES
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The possible values are: UNC, UNF, M_COARSE, M_FINE.
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TAPER ANGLE
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The thread is cut with the specified taper angle. This enables creation of tapered threads for standard or custom purposes.
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CUT_STYLE
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• THREAD_CONTINUOUS—The thread is milled in a single by continuous motion, regardless of the number of inserts on the thread tool.
• THREAD_INTERRUPTED—The thread is milled in a series of motions that may overlap. The thread motion overlap is controlled by the following parameters:
◦ THREAD_OVERLAP—Is the distance (in degrees) that a thread motion will continue beyond its end before exiting and moving to the start of the next thread motion. Type a value other than 0 (in degrees).
◦ PICKUP_OVERLAP—Is the distance (in threads or degrees) that the start of the next thread motion will overlap the end of the previous thread motion. Type a value other than 0 (in threads or degrees).
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CUT_TYPE
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This option controls where the material is relative to the tool and has two values:
• CLIMB—The tool is to the left of material (assuming clockwise spindle rotation). Corresponds to the CLIMB value of the CUT_TYPE manufacturing parameter.
• CONVENTIONAL—The tool is to the right of material (assuming clockwise spindle rotation). Corresponds to the UPCUT value of the CUT_TYPE manufacturing parameter.
The following options define the beginning and end of the cut motion:
• Start Overtravel—Specifies the initial height of the tool above the start surface at the beginning of the tool path.
• End Overtravel—Specifies the height at the end of the tool path that the tool overtravels below the end surface.
• Thread Start Angle—Specifies the angle in the XY plane that determines where the thread mill starts to cut the thread.
The following parameters enable creation of multiple passes in a single tool path for a thread milling sequence.
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INITIAL_DIAMETER
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It is the diameter of a hole prepared for thread milling and is used in the computation of number of roughing passes.
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PROF_STOCK_ALLOW
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Specifies the amount of stock left by the sequence tool path.
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THREAD_DIAMETER
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It is the value used to calculate the final diameter machined by the last profile pass, and by the spring passes. Here the external thread final diameter is THREAD_DIAMETER + PROF_STOCK_ALLOW and the internal thread final diameter is THREAD_DIAMETER - PROF_STOCK_ALLOW.
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Roughing Pass Parameters
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NUM_ROUGH_PASSES
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Together with ROUGH_INCREMENT, allows you to create multiple roughing passes. This parameter is ignored if INITIAL_DIAMETER and ROUGH_INCREMENT are specified.
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ROUGH_INCREMENT
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Specifies the amount of stock to remove with each cut for roughing passes.
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ROUGH_CUT_FEED
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The feed rate used for the profiling and roughing passes
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ROUGH_SPINDLE_SPEED
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The rate at which the spindle rotates for rough passes.
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SPINDLE_SPEED
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The rate at which the spindle rotates for roughing passes, if ROUGH_SPINDLE_SPEED is not specified.
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CUT_FEED
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The feed rate used for the roughing passes, if ROUGH_CUT_FEED is not specified.
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Profile Pass Parameters
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NUM_PROF_PASSES
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Together with PROF_INCREMENT, allows you to create multiple profiling passes horizontally offset from each other. The default value is 1. This is equivalent to a semi-finishing pass.
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PROF_INCREMENT
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Specifies the amount of stock to remove with each cut for profile passes.
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SPINDLE_SPEED
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The rate at which the spindle rotates for profile passes.
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CUT_FEED
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The feed rate used for the profile passes.
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Spring Pass Parameters
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NUM_SPRING_PASSES
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The number of spring passes when the tool moves along the final thread diameter defined by THREAD_DIAMETER parameter.
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FINISH_SPINDLE_SPEED
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The rate at which the machine spindle rotates for spring passes.
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FINISH_CUT_FEED
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The feed rate used for spring passes.
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SPINDLE_SPEED
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The rate at which the spindle rotates for spring passes, if FINISH_SPINDLE_SPEED is not specified.
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CUT_FEED
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The feed rate used for spring passes, if FINISH_CUT_FEED is not specified.
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