computer numerical control is the control of a machine tool using numbers and letters

8/7/2019 Computer Numerical Control is the control of a machine tool using numbers and letters

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Computer Numerical Control is the control of a machine tool using numbers

and letters.

It is a system in which programmed numerical values are directly inserted and

stored on

some form of input medium, and automatically read and decoded to cause acorresponding movement in the machine which it is controlling

advantages

H igh degree of quality due to accuracy, repeatability, and freedom from

operator-

introduced variations.

R educed scrap. Errors due to operator fatigue, interruptions, and other factors

are less

likely to occur.

Simplified inspection. Once the first piece has passed inspection, minimal

inspection is

required on subsequent parts

L ower tooling costs due to less need for complex jigs and fixtures.

R educed lead time.

Complex machining operations are more easily accomplished due to advanced

machine

contro

disadvantages

Tools on NC machines do not cut metal any faster than conventional machines.

NC does not eliminate the need for expensive tools.There is also a greater initial

cost

involved with the NC machine.


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NC will not totally eliminate errors. Operators can still fail to push the correct

buttons,

make incorrect alignments, and fail to locate parts properly in a fixture.

Selection and training of programmers and maintenance personnel is required

History

1 9 4 7 - John Parsons began experimenting with the idea of generating thru-axis

curve data

and using that data to control machine tool motions.

1 9 4 9 - A contract was granted to the Parsons Corporation to search for a

speedy

production method.

1 9 5 2 - MI T successfully demonstrates a model of the NC machine of

today. The machine

successfully made parts with simultaneous thru-axis cutting tool movements.

MITcoined

the term "numerical control".

1 9 5 5 - Commercial models of NC machines displayed for customer acceptance.

1 9 5 7 - NC accepted by industry; several are installed and in use.

Turning is the process whereby a single point cutting tool is parallel to the surface. It can be done manually,

in a traditional form of lathe, which frequently requires continuous supervision by the operator, or by using a

computer controlled and automated lathe which does not. This type of machine tool is referred to as

having computer numerical control, better known as CNC. and is commonly used with many other types

ofmachine tool besides the lathe.
http://en.wikipedia.org/wiki/Computer_numerical_controlhttp://en.wikipedia.org/wiki/Machine_toolhttp://en.wikipedia.org/wiki/Computer_numerical_controlhttp://en.wikipedia.org/wiki/Machine_tool


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When turning, a piece of material (wood, metal, plastic, or stone) is rotated and acutting tool is traversed

along 2 axes of motion to produce precise diameters and depths. Turning can be either on the outside of the

cylinder or on the inside (also known asboring) to produce tubular components to various geometries.

Although now quite rare, early lathes could even be used to produce complex geometric figures, even

the platonic solids; although until the advent of CNC it had become unusual to use one for this purpose for

the last three quarters of the twentieth century. It is said that the lathe is the only machine tool that can

reproduce itself.

The turning processes are typically carried out on a lathe, considered to be the oldest machine tools, and

can be of four different types such as straight turning, taper turning,profilingorexternalgrooving. Those

types of turning processes can produce various shapes of materials such asstraight, conical, curved,

orgroovedworkpiece. In general, turning uses simple single-point cuttingtools. Each group of workpiece

materials has an optimum set of tools angles which have been developed through the years.

The bits of waste metal from turning operations are known as chips (North America), orswarf(Britain). In

some areas they may be known as turnings.

CNC Turning is the most simple and important process used for plastic

machining. It is utilized where the precision tool generates materials afterinserting the single cutter point into the material turning. The cutting procedure isexecuted through a cutting tool that is applied either at the right angle to the axisor parallel of the work piece.

It is done through exercising pressure on the work piece or the weaker materialto form the flexible shapes of the material. Sometimes through ComputerNumerically Controlled lathe, the cut surface is formed by executing the helicalfeed as it results in rotation.The cutting tool is used until the precise depth and dimension is achieved. CNCTurning can be done on both sides, inside or outside as far as the needs and

specifications require. Parts that are too large to balance and cause difficulty inrotating around one center point, are worked on a machining center featuring a Uaxis. The turning length is about 1000mm between centers with a speed range of4,000 revolutions per minute and 46kW drive power.The CNC turning process cuts the plastic into various shapes like pointed, simpleplain surface, tapered ends, contour, curve, fillet and radius profiles withthreaded surface. These cut and turned pieces are used to create shafts, rods,bushes, pulleys and much more. This turning process applies well to the most
http://en.wikipedia.org/wiki/Tool_bithttp://en.wikipedia.org/wiki/Tool_bithttp://en.wikipedia.org/wiki/Boringhttp://en.wikipedia.org/wiki/Boringhttp://en.wikipedia.org/wiki/Boringhttp://en.wikipedia.org/wiki/Platonic_solidshttp://en.wikipedia.org/wiki/Platonic_solidshttp://en.wikipedia.org/wiki/Swarfhttp://en.wikipedia.org/wiki/Swarfhttp://en.wikipedia.org/wiki/Tool_bithttp://en.wikipedia.org/wiki/Boringhttp://en.wikipedia.org/wiki/Platonic_solidshttp://en.wikipedia.org/wiki/Swarf


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rigid materials like Aluminum, Stainless Steel, Copper, Nylon, Polycarbonate,Acrylic, Brass, Teflon, Titanium, ABS, PVC, etc., that can be controlled with thesoftware program tooling. The CNC turning is more economical than the CNCmilling as it reduces the cost of production by minimizing the design elements.However, this also puts a limitation to the flexibility of designs.

CNC turning has various advantages as the turning tools are said to delivercomponents at a faster production rate with optimum manufacturing accuracy. Infact, the automation of the CNC turning process allows reaching tight dimensionaltolerances in every piece. Some more advantages include the high level of partsuniformity or consistency, attainment of optimum cycle times for all componentsand quick execution of larger volume. Example of parts made by CNC turninginclude Robot Parts, Shift knobs, Motorcycle Parts, Auto Parts, Toy Parts, Knobs,etc., And parts made through this.
http://www.tamshell.com/plastic-turning.htmhttp://www.tamshell.com/plastic-turning.htm

computer numerical control is the control of a machine tool using numbers and letters

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