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NC Programming
IML 332E:
332E: NC Programming
Each NC program includes the following:
1. A declaration of the program number
2. Statements defining the origin of the coordinate system and the
kind of coordinates (incremental or absolute) used to describe the
the
tool position or be seen from this example program
3. Statements defining operations, other than tool movements, to be
performed by the NC machine, such as turning the coolant and
spindle on or off, setting the spindle speed and feed rate, and
changing or selecting tool(s)
4. Statements defining the movement and position of the tool
5. Statements defining operations to be performed by the control "Stop
reading and execution," "Stop reading and execution and d mill at
at
initial memory," and "Call a subprogram"
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A Sample NC Program
IML 332E:
332E: NC Programming
2
1
NC Coordinate Systems
IML 332E:
332E: NC Programming
Assume:
Directions are assigned
as if the tool is moving
w.r.t. the workpiece.
3
Setting origin of the Coordinate System:
System:
G50 (Turning
(Turning)) & G92 (Milling
(Milling)) IML 332E:: NC Programming
IML 332E NC Programming
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2
N-Code Words
Milling
IML 332E:
332E: NC Programming
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N-Code Words
Lathe
IML 332E:
332E: NC Programming
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3
G-Codes 1
Milling
IML 332E:
332E: NC Programming
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G-Codes 1
Lathe
IML 332E:
332E: NC Programming
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4
M-Codes
Milling
IML 332E:
332E: NC Programming
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Setting up Coordinate System: G28 & G92
IML 332E:
332E: NC Programming
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5
Rapid Positioning: G00
IML 332E:
332E: NC Programming
G00XxYyZz
G91G00XxYyZz
G00UuWw
where x, y, and z are the coordinates of
the destination point.
(milling , incremental)
(turning, incremental)
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Linear Interpolation: G01
IML 332E:
332E: NC Programming
G01XxYyZzFf
where x, y, and z are the coordinates of
the destination point and f is the feed value
in mm/min or in/min.
G91G01XxYyZzFf (milling , incremental)
G01XxZzFf
G01UuWwFf
(turning, absolute)
(turning, incremental)
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6
Circular Interpolation:
Interpolation: G02 &G03
IML 332E:
332E: NC Programming
In the XX-Y plane:
G17G02XxYy
RrFf
Ff
G17G02XxYyRr
G17G03
XxYyIiJj
IiJjFf
Ff
G17G03XxYy
In the YY-Z plane:
G19G02YyZz
RrFf
Ff
G19G02YyZzRr
G19G03
YyZzJjKk
JjKkFf
Ff
G19G03YyZz
In the ZZ-X plane:
G18G02XxZz
RrFf
Ff
G18G02XxZzRr
G18G03
XxZzIiKk
IiKkFf
Ff
G18G03XxZz
where
G17, G18 and G19 define XX-Y, ZZ-X and YY-Z planes, respectively.
G02 and G03 define rotation in CW and CCW directions
x, y, z denote coordinates of the destination point
i, j, k denote incremental coordinates from the center of the initial
initial tool position.
R denotes radius of the circle
Complete Circle:
G02G17IiJj
G03G17IiJj
G02G18IiKk
G03G18IiKk
G02G19JjKk
G03G19JjKk
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Circular Int.:
G02 &G03
IML 332E:
332E: NC Programming
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7
G02 &
G03
IML 332E:
332E: NC Programming
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G02 & G03
IML 332E:
332E: NC Programming
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8
Dwelling at the
current position:
position: G04
IML 332E:
332E: NC Programming
G04Xn
G04Pn
G04Un (lathe only)
- Cutter stops at current
location for n seconds
- Automatic deceleration
and acceleration
- G04 makes a sharp
corner.
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Tool Radius
Compensation
IML 332E:
332E: NC Programming
G40: Cancel
G41: Left HS comp.
G42: Right HS comp.
D: Radius offset code
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9
Tool Radius Compensation - 2
IML 332E:
332E: NC Programming
G10PpRr
causes to input an offset value of r into offset register # p.
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Tool Radius
Compensation - 3
IML 332E:
332E: NC Programming
Prevention of UnderUnder-cutting
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10
Tool Nose
Vectors (Lathe)
IML 332E:
332E: NC Programming
Different cutter
compensation vectors
must be applied with
different types of cutting
tools.
G40: Cancel
G41: Left HS
G42: Right HS
T: Offset code
4 digits, the first 2 digits
define the turret position
(tool #); the last 2 digits
define the offset number
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Tool Offsets:
Lathe
IML 332E:
332E: NC Programming
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Cyclic Operations
(Milling)
IML 332E:
332E: NC Programming
G80: Cancel cycle
function
...Default function (when
power is turned on)
G81: Spot drilling cycle
G82: Counter boring cycle
G83: Peck drilling cycle
G84: Tapping cycle
G85: Boring cycle
G86G86-G89: Special boring
cycle
Retreating Motions:
G98: tool returns to the initial
point level
G99: tool returns to the R
point level
G90 & G91 modes possible 23
Spot Drilling:
G81
IML 332E:
332E: NC Programming
G81XxYyZzRrFfLl’
G81XxYyZzRrFfLl’
x, y: coordinates of
the hole
z: coordinate of the
hole bottom
r: z coordinate of the
point R
f: Feed rate
l’: # of times the
subroutine to be
repeated
When l’l’ is omitted,
default value for l’l’ is
1.
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12
G81 Example
IML 332E:
332E: NC Programming
00001;
N1G90G
90G92X
92X-4.Y
4.Y0Z3.M
3.M03S
03S35;
N2G91G
0.9R4.Z-0.9R
81X4.Z
99G81X
91G99G
2.9F
2.9F2.0L
2.0L4;
N3Y3.L
3.L2;
N4X-4.L
4.L3;
N5Y-3.;
N6G00Z
00Z2.9;
N7G8lX
8lX3.0Z
3.0Z-1.2R
1.2R-0.9;
N8X6.0;
N9G90G
90G00X
00X-4.Y
4.Y0Z3.M
3.M05;
N10M
10M30;
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IML 332E:
332E: NC Programming
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13
Peck Drilling:
G83
IML 332E:
332E: NC Programming
G83XxYyZzQqRrFfLl’
G83XxYyZzQqRrFfLl’
x, y: coordinates of the
hole
z: hole depth
r: z coordinate of the
point R
q: depth of cut for each
peck drill
f: Feed rate
l’: # of times the
subroutine to be
repeated
When l’l’ is omitted,
default value for l’l’ is 1.
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Boring Cycle:
G85
IML 332E:
332E: NC Programming
G85XxYyZzRrFfLl’
G85XxYyZzRrFfLl’
x, y: coordinates of the
hole
z: hole depth
r: z coordinate of the
point R
f: Feed rate
l’: # of times the
subroutine to be
repeated
When l’l’ is omitted,
default value for l’l’ is 1.
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14
Turning: Cycle Motion: G90
IML 332E:
332E: NC Programming
G90XxZzIiFf
G90UuWwIiFf
x/2, z: coordinates of the destination point
u/2, w: incremental coordinates of the destination point from the
the start point
i: incremental coordinates measured from B to point A
f: feed rate
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Example:
IML 332E:
332E: NC Programming
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15
Facing Cycle: G94
IML 332E:
332E: NC Programming
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Thread Cutting Cycle: G92
IML 332E:
332E: NC Programming
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Example: Cutting M24x3 Thread
IML 332E:
332E: NC Programming
The following program will cut the thread shown in Fig. 22-28.
Seven threading cycles (statements N31 to N37) are needed here to
to
cut the thread.
………….
………….
....G21....
..…
..…
N31G92X23.0ZN31G92X23.0Z-40.0F3.0*
N32X22.3*
N33X21.8*
N34X21.4*
N35X21.1*
N36X20.8*
N37X20.752*
………….
………….
* means end of block
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Repetitive Turning
Cycle: G71
IML 332E:
332E: NC Programming
G71PpQqUuWwDdFfSsTt
Np...
Np...
…….
…….
…….
…….
Nq…
Nq…
G70PpQq
…….
…….
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17
Cycle Operations in Lathe: G72
IML 332E:
332E: NC Programming
G72PpQqUuWwDdFfSsTt
Np...
Np...
…….
…….
…….
…….
Nq…
Nq…
G70PpQq
…….
…….
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TRENDS
Application of G71
IML 332E:
332E: NC Programming
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Patterns Repeating:
G73
IML 332E:
332E: NC Programming
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Patterns Repeating: G73
IML 332E:
332E: NC Programming
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Repetitive Threading
Cycle: G76
IML 332E:
332E: NC Programming
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Codes Specifying Miscellaneous Functions
& SUBPROGRAMS
IML 332E:
332E: NC Programming
M Code (Miscellaneous Function Code)
M98P
98PpLl’ (call a subprogram numbered with p and l’l’ number of times)
M99P
(last statement of a subprogram, p line number to return in the
99Pp
main program, 4 digits)
S Code (Spindle Speed)
T Code (Tool # or Turret position)
40
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