Numerical control (NC) is a method employed for controlling the motions of a machine tool slide and its auxiliary functions with an input in the form of numerical data. A computer numerical control (CNC) is a microprocessor based system to store and process the data for the control of slide motions and auxiliary functions of the machine tools.
A modern NC machine tool is a microprocessor controlled and programmed using its own programming language. Various terms are used to describe the type of control such as NC, CNC, DNC.
Basic Configuration of CNC system
- Central Processing Unit (CPU)
- Servo control
- Operator control panel
- Machine control panel
- Other peripheral devices.
- Programmable Logic Controller (PLC)
Advantages of CNC Machines:-
- High accuracy and repeatability.
- Reduced inspection.
- Easy to assembly and interchange ability.
- Less scrap and rework.
- Space savings.
- Less material handling.
- High flexibility for design changes.
- Reducing tooling.
- Better machine utilization.
- Ability for high levels of integration such as:
- Direct numerical control :DNC
- Flexible manufacturing system : FMS
- Adoptive control : AC
- Computer aided design :CAD
- Computer aided manufacturing : CAM
- Computer integrated manufacture : CIM
Application of CNC Machines
Here are few criteria to be decided on the introduction of CNC machines in any manufacturing activity.
- Number of operations per component are many.
- Complex of the operations carried out is high.
- Size of batches are medium.
- Repetation of batches is large.
- Layout cost of batches is large.
- Ratio of cutting time to non cutting time is low.
- Variety of components to be produced more
- Cost of special toolings involved is high.
- Design changes are frequent.
- Non uniform cutting condition are required.
- Setup time and inspection time are high.
- Number of dimensions to be maintained is large.
- Precision involved in component is high
Areas of Application:
CNC system has been applied to all types of machines form simple sawing machines to complex machines to complex contour grinding machines. Major areas of applications are:
- Metal cutting machines.
- Metal farming machines.
- Tool handling system.
- Work handling system.
- Inspection and quality control system.
- Welding machines.
- Heat treatment equipment.
- Assembly, testing and dispatch equipment.