Understanding NC Machine Tools
NC (Numerical Control) machine tools are a crucial part of modern manufacturing processes. They operate based on a series of coded instructions that dictate how the machine should perform various tasks.

What are Coded Instructions?
- Coded instructions are the fundamental elements of NC technology.
- These instructions are typically written in a programming language called G-code.
- Each line of G-code corresponds to specific movements or actions the machine should execute, such as cutting, drilling, or milling.

How Do They Work?
- The coded instructions are fed into the machine's controller, which interprets them.
- The controller translates these codes into mechanical movements, guiding the machine's tools along predetermined paths.
- This allows for high precision and repeatability in manufacturing processes.

Advantages of Coded Instructions
- **Automation**: The use of coded instructions allows for the automation of complex machining tasks, reducing human intervention.
- **Precision**: Coded commands enable accurate execution of designs, ensuring consistent quality in production.
- **Flexibility**: Adjusting the code allows easy modifications to the manufacturing process without needing to change the machine setup.

Conclusion
In summary, the operation of NC machine tools fundamentally relies on a series of coded instructions. This method not only enhances efficiency and precision but also provides the flexibility needed in modern manufacturing environments. Therefore, option 'C' is the correct answer for understanding NC machine tools.