RECAP – Class 4 Controller
Program of unit Machine tool
instructions
1. Development of machine tools
2. Machine tool capabilities
3. Machine tool categories – Chip, non-chip producing,
New Gen and Multi-tasking machines
4. Development of NC systems
5. Basic components of NC system – Program, Controller
and Machine
6. Problems with Conventional NC – Punched tape, reader
and controller
Email: Classification of NC Machine Tools
,Classification of NC Machine Tools
1. Based on motion type 4. Based on power supply
❖Point to point ❖ Electric
❖Straight cut ❖ Hydraulic
❖Contouring ❖ Pneumatic
2. Based on control loops 5. Based on contact
❖ Direct contact machine
❖Open loop system
❖ Indirect contact machines
❖Closed loop system
3. Based on positioning system
❖Absolute system
❖Incremental System
Email: Classification of NC Machine Tools
, Based on motion type
1. Point to point or Positioning NC system
• In PTP, the objective of the machine tool control system is to move the cutting tool
to a predefined location.
• The speed or path by which this movement is accomplished is not important in
PTP NC. Once the tool reaches the desired location, the machining operation is
performed at that position. Example: NC Drill press
• Positioning systems are the simplest machine tool control systems and are
therefore the least expensive of the three types.
Email: Classification of NC Machine Tools
, 2. Straight-cut NC
• Straight-cut control systems are capable of moving the cutting tool parallel to one of the
major axes at a controlled rate suitable for machining. It is therefore appropriate for
performing milling operations to fabricate workpieces of rectangular configurations.
• With this type of NC system it is not possible to combine movements in more than a single
axis direction. Therefore, angular cuts on the workpiece would not be possible.
• A NC machine capable of straight cut movements is also capable of PTP movements.
Email: Classification of NC Machine Tools
Program of unit Machine tool
instructions
1. Development of machine tools
2. Machine tool capabilities
3. Machine tool categories – Chip, non-chip producing,
New Gen and Multi-tasking machines
4. Development of NC systems
5. Basic components of NC system – Program, Controller
and Machine
6. Problems with Conventional NC – Punched tape, reader
and controller
Email: Classification of NC Machine Tools
,Classification of NC Machine Tools
1. Based on motion type 4. Based on power supply
❖Point to point ❖ Electric
❖Straight cut ❖ Hydraulic
❖Contouring ❖ Pneumatic
2. Based on control loops 5. Based on contact
❖ Direct contact machine
❖Open loop system
❖ Indirect contact machines
❖Closed loop system
3. Based on positioning system
❖Absolute system
❖Incremental System
Email: Classification of NC Machine Tools
, Based on motion type
1. Point to point or Positioning NC system
• In PTP, the objective of the machine tool control system is to move the cutting tool
to a predefined location.
• The speed or path by which this movement is accomplished is not important in
PTP NC. Once the tool reaches the desired location, the machining operation is
performed at that position. Example: NC Drill press
• Positioning systems are the simplest machine tool control systems and are
therefore the least expensive of the three types.
Email: Classification of NC Machine Tools
, 2. Straight-cut NC
• Straight-cut control systems are capable of moving the cutting tool parallel to one of the
major axes at a controlled rate suitable for machining. It is therefore appropriate for
performing milling operations to fabricate workpieces of rectangular configurations.
• With this type of NC system it is not possible to combine movements in more than a single
axis direction. Therefore, angular cuts on the workpiece would not be possible.
• A NC machine capable of straight cut movements is also capable of PTP movements.
Email: Classification of NC Machine Tools
