The use of a computer for controlling the Numerical Control (NC) machine through a coded alpha-numeric system is called Computer Numerical Control (CNC). CNC system is operated by computer programmed data. It has its applications in many industries such as aerospace, agriculture, construction, automotive for the production of surgical equipment, automobile frames, airplane engine, etc.
CNC Machining Software
Different software applications are used for operating the CNC machining system. The aim is to enhance the optimization, accuracy, and precision of the designed part. These software applications are CAD, CAE, CAM:
Computer-aided design (CAD) software
The applications which are employed to create 2D and 3D metal parts and technical specifications and documentation of the parts. The models prepared by the CAD are used by CAM program to generate machine programs for the production of solid parts through CNC machining process.
Computer-aided manufacturing (CAM) software
The applications that create a machine program on the basis of information extracted from CAD program. CAM software is used to operate the CNC machine and manipulate tooling to create the custom-designed parts.
Computer-aided engineering (CAE) software
Software used in engineering analysis applications including planning, simulation, design, manufacturing, and diagnosis which are employed for the evaluation and modification of product design.
Parts of CNC machine
The main parts of the CNC machine are the following:
- Input Devices
An Input device is used to enter the part program in the CNC machine. They’re most commonly used input devices are magnetic tape reader, punch tape reader, and computer via RS-232-C communication.
- Machine Control Unit (MCU)
MCU is a major part of the CNC machine. All the controlling actions of the CNC machine are performed via MCU. Its functions include:
- To read the coded commands enter into it.
- To decode the coded commands.
- To apply interpolation (linear, helical, and circular) to create axis motion instructions.
- To enter the axis motion instructions to the amplifier circuits in order to drive the axis mechanism.
- To receive feedback signals of speed and position of individual drive axis.
- To apply the auxiliary control functions including tool change and coolant or spindle on/off.
- Machine Tool
Machine tools are controlled by CNC controls. Each type of machine tool has a slide table and a spindle for regulating the speed and position. The machine table is regulated in the X and Y axis while the spindle is regulated in Z-axis.
- Driving System
Drives provide a regulated motion to the CNC elements. The CNC machine drive system comprised of drive motors, ball lead screw, and amplifier circuits. The MCU enters the signals of all axes to the amplifier circuits. The control signals are then amplified to simulate the drive motors. The simulated drive motors revolve the ball lead screw in order to position the machine table.
- Feedback System:
The feedback system is also called the measuring system. It composed of transducers that act as a sensor. There are speed and position transducers that constantly monitor the speed and position of the cutting tool at any particular instant. These transducers provide signals to MCU which uses the difference between feedback signals and reference signals to create the control signals for the correction of speed and position error.
- Display Unit:
A monitor that displays the commands, programs and other useful data of CNC machine.