4. Comparing NC with Conventional
System
• As compared to a conventional machine tool , a
NC system replaces the manual actions of the
operator.
• In conventional machining operations, a part is
produced by moving a cutting tool on a work
piece by means of hand wheels by an operator.
• On the other hand, operators of NC machine tool
need not he a skilled machinist. They only need
the monitoring operations of the machine.
6. Elements of NC system
1. Part program software
2. Machine Control Unit
a. Input or Reader Unit
b. Memory
c. Processor
d. Output Channels
e. Control Panel
f. Feedback channels
3. Machine tool
17. Classification of CNC Machines
• According to the structure of control system
used
1. Analog system
2. Digital system
18. Classification of CNC Machines
• According to the type of control system used
1. Closed loop system
2. Open loop system
19. Classification of CNC Machines
• According to the type of tool motion control
system used
1. Point to point positioning system
2. Continuous path system
a) Straight cut system
b) Contouring system
20. Classification of CNC Machines
• According to the programming mode used
1. Closed loop system
2. Open loop system
21. Classification of CNC Machines
• According to the controller design
1. Hybrid CNC
2. Straight CNC
