Basic Component of Numerical Control NC Technology

 

Read: What is Numerical control? Applications, Advantages, Limitation

An NC system consists following components.

• Program instruction
• Machine control unit (MCU)
• Machine controlled process (tool)

The relation between this three component is represented above

Program instruction

Program instruction is served as the input into the controller unit. It is a detailed step by step instruction which tells the machine tool what/how to do. Each instruction specify the position and movement of machine tool. This detailed set of command is coded into some type of input medium which is then interpreted by the controller unit. The most common method of inputting instruction is punched tapes.

Machine control unit (MCU)

This component consists of electronics and hardware which read and interpret the program instruction and convert each command to the action of processing equipment. The elements of control unit include of tape reader, a data buffer, signal input channel to the machine tool and the feedback channel from the machine tool. It also consists the sequence control to coordinate the whole operation of preceding element.

The tape reader is an electromechanical device which used to reading the instruction on punched tape. Then this data is read into the data buffer.  The signal output channels are connected to controls of the machine tool (servomotors). The instructions are sent to the machine tool through these channels. Then the feedback data sent back to control unit through a feedback channel. The purpose of the feedback system is that to make sure about the proper execution of the input instruction. The sequence control the all the activities of other control elements. It synchronises the operations such as the reading of punched tape, sending signal to and from machine tool.

Read : What is CNC (Computer Numerical Control)? Advantages, Limitations, Applications

Machine tool or other controlled process

It is the part of NC which perform the actual work. For example, consider an NC system designed to performs metal machining operation. In these type of NC machine, the machine tool consists of the work table, spindle, motors that control the tool, cutting tool, work fixture and other assisting equipment for the machining operation. These elements operate according to the instruction from the controller unit. For example the automatic tool changing, rotation and movement of tables and fixtures.