Figure 2-19.CNC programming station.
In CNC, the machinist begins with a blueprint, other
drawing, or sample of the part to be made. Then he or
she uses a keyboard, mouse, digitizer, and/or light pen
to define the geometry of the part to the computer. The
image appears on the computer screen where the ma-
chinist edits and proofs the design. When satisfied, the
machinist instructs the computer to analyze the geome-
try of the part and calculate the tool paths that will be
required to machine the part. Each tool path is translated
into a detailed sequence of the machine axes movement
commands the machine needs to produce the part.
The computer-generated instructions can be
stored in a central computers memory, or on a disk,
for direct transfer to one or more CNC machine tools
that will make the parts. This is known as direct
numerical control (DNC). Figure 2-20 shows a
Figure 2-20.Direct numerical control station.