Numerically controlled systems operated automatically based on the program fed into the tape. These machines increased productivity; however, they also came with various limitations. These issues made it hard for any developments to be made on the NC machines. The introduction of computers in NC machining created room for further development, and this came to be known as computer numerical machines (CNC) machines. To appreciate the benefits and efficiency of the CNC machines, it is important to understand the limitations of NC machines.
Unreliable Tape and Tape Reader
The tape reader in NC machines reads the instructions on the programs. The punched tape is what feeds the reader. The problem with this kind of operation is that the tape reader is highly unreliable. This is because it is prone to breakdowns. In older CNC machines, the tape and the reader are still used, but only to feed the memory of the computer. The tape is no longer needed once the program is saved. This means that the tape reader and the tape which come with numerous maintenance issues are removed. Modern CNC machines have done away with the tape and tape reader. The instructions are now fed directly through the computer's panel control.
The NC machines have a controller unit that is hardwired. NC machines employed mechanical relays and vacuum tubes as their main controller set. The complexity of these sets made it very hard to make changes to any of the programs. Today, CNC machines use high density circuits. This makes it much easier to make changes and store them in a new program. It is also possible to introduce more control options. This means that updates can be done at a lesser cost. Again, the risk of obsolescence is eliminated in CNC machining.
Limited Level of Automation
The latest CNC machines are able to automatically survey the quality of tasks being performed. This information is then relayed to other components in the machining process such as loading and unloading. The CNC machine is also intelligent enough to notice any defects and deviations from the intended design. It is also equipped to make corrections in real time. In most cases it will replace dull tools or notify the user about these problems. This level of automation is the key difference between NC and CNC machines. NC machines are designed to operate in parameters of direct and simple commands. CNC machinery is able to analyze information and adapt to different circumstances.