What is Numerical control? Applications, Advantages, Limitation

NC machine

What is NC machine?

Numerical control is defined as the form of programmable automation in which numbers letters and symbols control the operation. This instruction is designed to do a particular job. NC machines has capability to change the program for each job ie when job changes the program instruction is also changed. It is easier to change the program instruction than to modify the production equipment. This flexibility reduces the overall production cost.

Advantages and Limitation of NC

Advantages of NC
  • Greater manufacturing flexibility – NC can easily adapt to the engineering design changes and a shift in the production schedule.
  • Reduced manufacturing lead time – the job can easily and quickly set up with NC.
  • Reduced non-productive time – In case of complex machining NC seems helpful to reduce the non-productive time. Because of quick/ automatic tool changing, quick setting up, and reduced workpiece handling time.
  • Reduced fixturing – the fixture required in NC operation are simpler and less costly because NC tape does positioning instead of jig and fixture.
  • Reduced inventory - this is the result of fewer setup reduced lead time.
  • Quality control improved – No risk of human mistakes. It produces the part with high accuracy. It also reduce the man-hour for inspection.
  • Greater operator safety.
  • Reduce the scrap – the high accuracy of NC machine helps to reduce scrap material.
  • Reduced floor space requirement – since the one NC can do variety of operation it replaces several conventional machines.

Disadvantages and Limitation of conventional NC
  • High investment cost and Maintenance cost – most complex and sophisticated technology cost more than the conventional machine.
  • Require skilled operator – finding and training of NC personnel should be considered.
  • Tearing and wearing of punch tape and less reliable punch tape component.
  • Part programming mistake in punched tape.
  • No optimal feed and speed – conventional NC machine does not provide an option to change the cutting speed and feed during the operation.
Five hole and eight hole perforated paper tape as used in telegraph and computer applications
Five hole and eight hole perforated paper tape as used in telegraph and computer applications
Read : What are the basic component of Numerical Control NC technology
What is CNC (Computer Numerical Control)? Advantages, Limitations, Applications
Advantage and functions of DNC (Direct numerical control)

Applications of numerical control technology

Numerical control technology has application in a wide variety of production operation such as metal cutting, automatic drafting, spot welding, press working, assembly, inspection, etc. However, NC finds its principle application in metal machining operations. It is built to do virtually entire metal removing process. (Example for metal working Turning, sawing, Grinding, Milling, Drilling, boring).

The production jobs where the numerical control machines are most appropriate are listed below.
  • The NC technology is suitable to sequence/series of machining process.
  • Job geometry is complex, expensive. Mistakes in the process lead to high loss.
  • It is expected engineering design changes in future.
  • High metal removal is required.
  • The workpart required 100% inspection.
  • There must be close tolerance on workpart.
  • When many operations need to be done when processing. It is frequently processed in batches of small lot sizes.



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