Front Cover - CNC - The Hong Kong Polytechnic University

Computer Numerical Control (CNC)
a. Mirror Image
This is the function that converts the programmed path to its mirror
image, which is identical in dimensions but geometrically opposite about
one or two axes.
b. Programme Repetition and Looping
In actual machining, it is not always possible to machine to the final
dimension in one go. This function enables the looping of a portion of
the programme so that the portion can be executed repeatedly.
c. Pocketing Cycle
Pocketing is a common process in machining. This is to excavate the
material within a boundary normally in zigzag path and layer by layer. In
a pocketing cycle, the pattern of cutting is pre-determined. The user is
required to input parameters including the length, width and depth of the
pocket, tool path spacing, and layer depth. The CNC system will then
automatically work out the tool path.
d. Drilling, Boring, Reaming and Tapping Cycle
This is similar to pocketing cycle. In this function, the drilling pattern is
pre-determined by the CNC system. What the user has to do is to input
the required parameters such as the total depth of the hole, the down
feed depth, the relief height and the dwell time at the bottom of the hole.
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