Wednesday, March 19, 2014

The development of the CNC machine

What are CNC machines?
Computer Numerical Control (CNC) machines are automated milling devices that are designed to make industrial components without the need for direct human assistance. Using coded instructions that are sent to an internal computer, these machines enable factories to manufacture parts accurately and quickly.

The history of CNC machining
Computerised Numerical Control or CNC as it is now known, first came about after World War II as a result of the US Air Force’s desire to produce more accurate and complex parts.  The modern machine’s advent can be traced back to the invention of the numerical controlled machine made by John T. Parsons.

First concept developed for the manufacture of helicopter blades
Alongside Frank L. Stulen, John T. Parsons first utilised computer methods to overcome machining setbacks, especially the accurate interpolation of the curves found in helicopter blades. In the process of developing smoother rotors, Parsons and Stuler generated an early version of a Numerical Control (NC) machine.

Developed with assistance of MIT
To further develop this machine, in 1949, Parsons turned to Gordon S. Brown’s Servomechanism Laboratory at the Massachusetts Institute of Technology (MIT). At MIT, a feedback system designed to gauge how far the controls had turned was developed.  
While the US Air Force halted its funding in 1953 due to expense, the project was resumed by Giddings and Lewis Machine Tool Co. who reduced expense but improved quality and efficiency.

Reduced production time from 8 hours down to 15 minutes
The first CNC machine was developed when John Runyon managed to produce punch tapes under computer control. By doing this, he managed to reduce the normal production time of 8 hours down to 15 minutes. By 1956, the US Air Force had accepted the proposal to produce a generalised programming language for NC.
The invention of CNC machines paved the way for automated tools that enabled efficient production for manufacturers. Today’s CNC machines bear little difference with the original machines in terms of concept. Both produce outputs in three dimensional directions: X and Y axes and depth.

The types of CNC machine
The types of CNC machine that exist today include the following:
CNC turning lathes –  CNC turning lathes produce parts by turning rod materials and feeding a cutting tool into the turning material.
CNC milling machines – Using a rotating cylindrical cutting tool, CNC Milling utilises a machining process similar to both drilling and cutting. The cutter in a milling machine has the ability to move along multiple axes and can create a variety of shapes, slots and holes   

CNC routers - CNC routers are similar to handheld routers but the tool paths are instead controlled via computer numerical control. CNC routers can be used for cutting various hard materials including wood, composites, aluminium, steel, plastics and foams.

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