August 2011 - Haas Automation, Inc.

(signals mill to proceed) and the following step(s) as one. If more than one step is
required, use an L command. In order to spiral mill, mill feedrate must be calculated
so rotary unit and mills axis stop at the same time.
In order to calculate the mill feed rate, the following information needs to be addressed:
1. The angular rotation of the spindle (this is described in the part drawing).
2. A feed rate for the spindle (arbitrarily select a reasonable one, for example,
five degrees (5 o ) per second).
3. The distance you wish to travel on X-axis (see part drawing).
For example, to mill a spiral that is 72 o of rotation and move 1.500” on the X-axis at
the same time:
1. Compute the amount of time it will take the rotary unit to rotate through the
angle
# of degrees / (feed rate of spindle) = time to index
72 degrees / 5° per sec = 14.40 seconds for unit to rotate.
2. Compute the mill feed rate that will move the X distance in 14.40 seconds
(length to travel in inches/# of seconds of rotation) x 60 seconds = mill feed
rate in inches per minute.
1.500 inches/14.4 seconds = 0.1042 inches per second x 60 =
6.25 inches per minute.
Therefore, if the indexer is set to move 72 o at a feed rate of 5 o per second you will
have to program the mill to travel 1.500 inches with a feed rate of 6.25 inches per
minute for the spiral to be generated. The program for the Haas control would be
as follows:
STEP STEP SIZE FEED RATE LOOP COUNT G CODE
(see previous feed rate table)
01 0 080.000 (HRT) 1 [94]
02 [72000] [5.000] 1 [91]
03 0 080.000 (HRT) 1 [88]
04 0 080.000 (HRT) 1 [99]
The mill program would look like this:
N1 G00 G91 (rapind in incremental mode)
N2 G01 F10. Z-1.0 (feed down in Z-axis)
N3 M21
(to start indexing program above at step one)
N4 X-1.5 F6.25 (index head and mill move at same time here)
N5 G00 Z1.0 (rapid back in Z-axis)
N6 M21
(return indexer Home at step three)
N7 M30
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