4. CNC TECHNOLOGY
• The CNC stands for Computer Numerical Control
• Instructions are stored as a program in micro-computer
attached to the machine.
• Refers to a computer controller that controls the
movement of every axis of the machine
• Using G and M codes instructions
• Drives the spindle or machine tool into a raw material to
fabricate or to remove the unwanted material from work
piece more accurately without human intervention.
• The computer will also handle much of the controllogic of
the machine, making it more adaptable than earlier hard-
wired controllers.
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7. HISTORY
The birth of NC is generally credited to John T. Parsons, a
machinist and salesman at his father's machining company,
Parsons Corp.
1949
US Air Force asks MIT to develop a "numerically controlled"
machine that are programmable milling machine.
1947
Using punched cards he was able to control the position of a
machine in an attempt to machine helicopter blade.
1952
Prototype NC machine demonstrated (punched tape input)
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8. HISTORY
1959
Machining centers and turning centers that could perform
multiple machining processes was developed.
1980-
CNC machines (computer used to link directly to controller)
1990-
DNC: external computer “drip feeds” control programmer to
machine tool controller
Modern NC machine has a computer on board, Computer
Numerical Control (CNC). They can run unattended at over
20,000 rpm (spindler speed) with a feed rate of over 600 ipm
and an accuracy of .0001..
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9. NC
• A control system which primarily processes numeric
input.
• Limited programming capability at the machine tool.
• Limited logic beyond direct input.
• These types of systems are referred to as “hardwire
controls” and were popular from the 1950’s to
1970’s.
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11. CNC
• A numerical control system in which the data
handling, control sequences, and response to
input is determined by an on-board computer
system at the machine tool.
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13. CNC APPLICATIONS
To manufacture complex curved geometries in 2D
or 3D was extremely expensive by mechanical
means (which usually would require complex jigs to
control the cutter motions)
Machining components with repeatable accuracy
Unmanned machining operations
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