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Why CNC?
Competition between manufacturing firms is increasingly dictated by
quality, cost, variety and Servicing.
Achieving the highest possible efficiency in manufacturing can only
produce each one of these attributes of a successful product.
Why CNC?
For the parts having complex contours, that cannot be manufactured by
conventional machine tools.
For small lot production, often for even single (one off) job production,
such as for prototyping, tool manufacturing, etc.
For jobs requiring very high accuracy and repeatability.
Why CNC?
For jobs requiring many set ups and/or the set ups are very expensive.
The inspection cost is a significant portion of the total manufacturing
cost.
Why CNC?
For the parts having complex contours, that cannot be
manufactured by conventional machine tools.
What is CNC?
NUMERICAL CONTROL is a method of automatically operating a
manufacturing machine based on a code of letters, numbers, and special
characters.
What is CNC?
The program is translated into the appropriate electrical signals for
input to motors that run the machine.
CNC stands for Computer Numerical Control.
It is the technology of controlling a machining operation using a computer program, which is called Numerical Control (NC) Program.
In other words, a computer rather than a person will directly control the machine tool.
The most important computerized machine tools that are used extensively in the industry are:
CNC Turning (Lathe) machine
CNC Milling machine
Increased speed at which parts are produced (mass production).
Producing the same quality for all work parts.
Better dimensional accuracy which gives exact and correct dimensions.
Less scrap.
Basically there are two common
coordinate systems:
Cartesian coordinate
system
Polar coordinate
system
When dealing with three dimensions (3D), the three dimensional coordinate system is
used; see the Figure below
The angle is positive if it is measured in counterclockwise direction starting from positive X-axis; Fig. 1.5-A.
Locate points P1 through P4 on the
coordinate system shown in Fig. 1.4
P1 X = 80 Y = 60
P2 X = -80 Y = 20
P3 X = -50 Y = -60
P4 X = 60 Y = -70
X A
xis
-
+
3.000
X3.0
Universal style slant bed turning center
X is DIAMETERIf you want to turn a 3.0 inch diameter…
X3.0 will be the commanding word
X A
xis
-
+
3.000
X3.0
X is DIAMETER
Once again:X is always the diameter-controlling axisZ is always the length controlling axis
Also:X+: always gets bigger in diameterZ+: always away from the spindle
Though some machine tool builders reverse the polarity of the X axis
EXAMPLE:
O2456;
N10 G17 G21 G40 G90 ;
N20 M06 T01;
N30 M03 S2000;
……………………..
……………………..
……………………..
PROGRAM NUMBER
BLOCK
WORD
SEQUENCE NUMBER OR BLOCK IDENTIFICATION NUMBER
N10