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( 1.3 ) Direct Numerical Control
In a Direct Numerical Control system (DNC), a mainframe computer
is used to coordinate the simultaneous operations of a number
NC machines as shown in the figures 21.2 & 21.3. The main
tasks performed by the computer are to program and edit part
programs as well as download part programs to NC machines.
Machine tool controllers have limited memory and a part program
may contain few thousands of blocks.So the program is stored
in a separate computer and sent directly to the machine, one
block at a time.
First DNC system developed was Molins System 24 in 1967 by
Cincinnati Milacron and General Electric. They are now referred
to as flexible manufacturing systems (FMS). The computers
that were used at those times were quite expensive.
/fig-2.gif)
Figure 21.2: DNC system
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/fig-3.gif)
Figure 21.3: DNC system
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