NC machines :-
"NC machines also known as Numeric Control Machines are the machines that are automatically operated without any human interference by commands which are received into their processing units and are called NC or Numeric Control Machines". The commands which is received by NC machines are given in the form of coded instructions which are expressed not easily through numerals . So, along with numerals letters , punctuation marks and other symbols are also required . The commands or instructions which are given to machines are fed through an external medium such as punch card , punch tape , magnetic tape and etc.
The programming which is done in the form of code contains the required data for the production of components , dies , blocks is punched on the tape . The data which is in present in the tape is in the form of binary codes or digits . Tape reader is also placed in machines that reads the data and is stored into the memory storage of the machine or control system which is also called "Buffer storage". Further then the program is run into machine step by step. Therefore, when the machine is working on one instruction block , the next block is read from the tape reader and thus stored in the memory of NC machine memory or control system for next process. When the one function is completed in machine , the next command or information from storage or "Buffer storage" is then instantaneously sended to the active storage of machine, thus ensuring the continuous running of program in machine.
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NC machine System |
The tape reader in machine then sends the corresponding data to decoder section of control system. The decoder then further generates the pulse for all the start and end points given to system. Further then the signals generated are further amplified and then redirected to Stepper motor , which as a result runs or operates the machine element. The feedback about the program which is running inside is taken from transducers which are placed in system, The feedback which is receiving is then compared with the input signals and further the error signals are generated to operative unit , and is done till output matched with input. The tape in system has to run repeatedly depending upon the number of units to be produced . In case if you want to change or modify the program , the tape which is placed in machine has to discard and replace with the new and modified program which you want to run into machine.
Features of NC machines:-
In addition to the NC machines it has the following Features :-
- The machine is controlled with help of numeric data or binary codes.
- The precision , reliability and high degree of accuracy is achieved in it.
- The material removal rate and capacity is high in this system.
- Productivity is also high.
- Tool life is also increased in this system.
- Due to accuracy less need of inspection.
- Planning and scheduling is also done in better way.
Disadvantages of NC machines :-
NC machines also have some major drawbacks associated with it which are as follows:-
- Tape readers which use in machine are not reliable for use.
- In this system maintenance cost is too high.
- Initial investment is also high.
- The punched tape which we use gets damaged after repeated use.
- If we need to modify or edit program it is not possible , for that we have to remove punch card from machine.
- For operating this system highly skilled or trained person is required.
By keeping in mind that this NC machine has major drawbacks, modification is done in this area and new machine with some changes is introduced which is named as CNC (Computer numerical Control) Machine.
