General
1- Composition of a part programs.
2- Block Configuration.
3- Part programming Block format:
N G X(u) Y(w) Z F M S T
N (block number):
• Each block of information must be allocated a number.
• Ex: N0010, N0020,
• It is recommended that the blocks are programmed in increments of 10 to
allow for further block insertion.
G (code for preparatory function):
• A G code is a command to the control unit to perform some specific task
or function.
• G code is made from the G address letter and a two digit number:
G00, G01
• Some G codes remain active till replaced or cancelled. These are called
modal (retained) G codes.
• G code from group 0 are non-modal.
XYZ (position co-ordinate data):
• These letters refer to movement along the designated axes.
• Use XYZ when absolute mode is intended.
• Use U,W when incremental mode is intended.
F (feed function):
• The movement of the tool at a specified speed for cutting is called the
feedrate.
• The feedrate is defined using the F address letter followed by a numerical
value: F256
• Feedrates can be specified as either millimetre or inches movement per
minute or revolution.
• Incorrect feedrates may result in damage to the cutting tool or the work
piece.
M.nazmi ‹#›
M code (miscellaneous functions):
• are (non-standard) commands to the control unit to perform special tasks.
• M codes are defined using the M address letter and a two digit number
EX:
M03 spindle forward
S (spindle speed function):
• The rotational speed of the tool with respect to the work piece being cut
is called the spindle speed.
• Four digit number following the S code specifies the speed in RPM.
• When a move command and a S code is specified in the same block a
simultaneous execution of the command is performed.
T (tool function):
• A tool from the ATC is selected using the address letter T followed by a
number in ATC magazine position.
• To command a tool change the M06 code would precede the number of
the “new” tool required. Ex: M06 T01
4- Tool Movement
Point-to-Point
This is a rapid traverse movement that moves the slide to the next position
required.
Axes movements are not co-ordinated with each other so care must be
taken to avoid collision with clamps.
This is used for tool positioning and no cutting should be undertaken.
Line Motion (Linear interpolation)
Tool moves along the specified straight line with a given feed rate.
Line motion is used when the tool is to cut in a straight line under coordinated axis movement.
Contouring
This involves programming that is similar to line motion in that the next
position is specified and a feed rate is given but an arc movement is
achieved.
M.nazmi ‹#›
5- SAFETY
De to the great cutting forces that these machines are capable of
producing and the increased feed rates over conventional
machines, great care must be taken at all times as any fault in
the program may have disastrous effects on the machine and
the operator.
Safety Rules:
•Make sure you know how to stop the machine in case of an
emergency.
•Make sure that the machine guards are in position when
machining.
•If you suspect something is going wrong, STOP the machine
immediately.
•Isolate the machine before any adjustments.
•Do not attempt to use the machine until you are sure you can
use it correctly.
•Part programs should be proved prior to machining using a
dry run or computer simulation.
6- Program Proving
M.nazmi ‹#›
Methods of checking/verification
Graphical simulation: computer graphics are used to simulate
the workipece and the cutting tool movements. Any errors in
the program will be highlighted prior to the program being
entered into the machine and therefore the programmer is able to
edit/correct his program.
M.nazmi ‹#›
Dry Run: this method of program proving is done on the machine
tool but the component or billet to be cut is not installed. As the
tool or cutter moves in air the operator looks to see that the
cutting tool will not collide with proposed clamping and fixture
arrangements or the part.
A dry run can be done in single step mode which means that the
part program can be run block by block under the control of the
operator. All CNC machine controllers have this facility.
DATUM:
•Machine datum: defines the zero point of all axes which is fixed
by the manufacturer. We can use zero offset facility to move
this datum.
•Program/work datum is specified by the programmer when the
program is written. All subsequent measurements are then made
relative to this new “program” datum.
Z
X
M.nazmi ‹#›
Co-Ordinate Dimensioning:
There are two types of co-ordinate dimensioning systems used in CNC
programming:
•Incremental: where next position measurements are taken relative to the current
position.
- an error made in one dimension will effect subsequent measurements
- if a dimension changes then the rest of dimension will have to be
changed
•Absolute: Dimensions are always measured from the same datum position
therefore there are no build-up or accumulation of errors between dimensions.
X
Y
2
1
3
4
5
6
Incremental
Absolute
X
U
Y
1
2
3
4
5
6
1
2
3
4
5
6
M.nazmi ‹#›
W
N0000
G00
X00.0
Y00.0
Z00.0
M.nazmi ‹#›
F0000 M00
S0000 T00;
G&N programming for CNC lathe
6- Absolute and Incremental Co-ordinates
• The addresses X and Z within a program relate to a co-ordinate position
from the workpiece datum.
X axis
• The address U and W within a program relate to the individual axis
movements required to reach the new position, from the last position
reached by the tool. The address U refers to the X axis and the address
W refers to the Z axis.
Dia 30
Z axis
Dia 20
50
• Four different ways can be used to write a block within a
program:
Absolutes/ absolutes
Incremental/incremental
Absolutes/incremental
Incremental/absolutes
M.nazmi ‹#›
G01 X30 Z-50;
G01 U10 W-50;
G01 X30 W-50;
G01 U10 Z-50;
List of G Codes (Turning machine)
G00
G01
G02
G03
G04
G20
G21
G28
G40
G41
G42
G50
G70
G71
G72
G73
G74
G75
G76
G81
G90
G92
G94
G96
G97
G98
G99
positioning (rapid traverse)
liner interpolation (feed)
circular interpolation CW
circular interpolation CCW
dwell
inch data input
metric data input
reference point return
tool nose radius compensation cancel
tool nose radius compensation left
tool nose radius compensation right
work coordinate change/Max spindle speed setting
finish cycle
stock removal in turning –X
stock removal in facing-Z
pattern repeating
Peck drilling in Z axis
Grooving in X axis
multiple thread cutting cycle
deep hole drilling
diameter cutting cycle A (outer/inner)
thread cutting cycle
cutting cycle B (end face cycle)
assessed surface speed control
Assessed surface speed control cancel
feed per minute
feed per revolution
M.nazmi ‹#›
G Codes
G00 /Rapid positioning & traverse (modal)
• Executes a non cutting movement at a rapid feedrate to a specific
coordinate position in the working area (absolutes mode) or a certain
distance from previous position (increment mode).
• The two axes move completely independent off each other at the
maximum feedrate along a non vector path.
Dia.
X 30
2.0
P1
Non vector movement
G00 X30 Z2
Z 0.0
2.0
G00 Z2
X30
G00 is modal
G01 /Linear interpolation (modal)
• The G01 executes a cutting movement following a straight line at a set
feedrate. G01 X(or U) Z(or W) F
• The feedrate value programmed into the G01 command is the actual
feedrate along the proposed tool path, not the feed rates of the slide.
• On two axis movements, the machine controller will calculate the
separate feedrates for both the X and Z slides, enabling the actual
vector feedrate to equal that stated in the G01 command.
• The coordinates can be programmed in absolutes values as X and Y, or
incremental values as U and W.
• The coordinates may be programmed in mixed modes.to
M.nazmi ‹#›
Absolute:
G01
Z-25 F0.1;
X40 -Z50;
P3
P2
25 Dia
P1
25
50
40 Dia
Incremental:
G01
W-25 F0.1;
U15 W-25;
Mixed:
G01
W-25 F0.1;
X40 W-25;
Feedrate values are modal.
G02/G03 circular interpolation (modal)
• G02 executes a cutting movement following a clockwise circular path at
a set feedrate.
• G03 executes the cutting movement following an anticlockwise circular
path at a set feedrate.
• When using absolute position, X & Z values are the dimensions of the
end point of the arc in relation to the datum position of the component.
• In incremental mode, U & W are the distance the tool moves from the
start position of the arc. This can either be a plus value or a minus
value depending on the direction of the movement relative to the start
position.
G02
G02
X Z R
+/-U +/-W R
End
Absolute
Incremental
R
G03 X Z R
G03 U W R
G02 X30 Z-30 R F
Start
+X
G02 X30 W-20 R F
+Z
30 Dia
20
10
M.nazmi ‹#›
When you do not know the radius: A case for I and K
To program an arc when only the arc center is given use the address letter I and K.
• I relates to the address X and is the incremental value and direction from the start
point of the arc in the X axis to the arc center.
• K relates to the address Z and is the incremental value and direction from the start
point of the arc in the Z axis to the arc center.
Center of ARC
+X
I
+Z
End
Absolute
G02 X Z I K F;
Incremental G02 U W I K F;
Start
K
Finish
Start
I
Z
G04 /Dwell
G04 X-- (Integer time in seconds)
G04 X10
G04 U- (Real time in seconds)
G04 X10.5
G04 P-- (time in milliseconds)
G04 P2500
•
•
•
•
Used to enter a set time delay into the program.
No decimal points can be used with address P
Dwell is performed at the start of the block in which it is programmed.
G04 is non-modal
M.nazmi ‹#›
G20-G21 / Inch-Metric Data input unit
• The machine controller can be programmed in either inch unit input or
metric unit input.
G20
G21
Imperial/Inch
Metric/Millimeter
lowest value 0.0001
lowest value 0.001
• Do not switch between G20/G21 during a program
• The offsets must be set according to the units of measurement being
used.
Offsets !!!!!!!!!!!????!!
• There are two parameters that are different from tool to tool. These are radius and
length.
40
100
100-40-10
50
60
100-60-10
10
• The offset compensation table is a useful means of overcoming this problem.
G28 /Reference point return
G28 X(U) Y(W)
• The reference point is a fixed position on the machine to which the tool
can be moved. (home position)
• G28 instructs the tool to automatically move to this reference point.
• X/Y/ can be used to indicate an intermediate point through which the tool
will pass before continuing to the reference point.
M.nazmi ‹#›
• G28 moves are performed at rapid traverse rates (non-vector tool path)
Reference Point
Collision
Point
P2
G28 U0 W0
P1
when no intermediate points are
required U&W are set to zero.
P3
P2
Reference Point
P1
Dia 80
G28 X100 Z-40
To avoid this collision the tool is
sent on a path through the
intermediate point P2.
40
G50 /
1- Clamping maximum spindle speed.
2- Coordinate system setting.
3- Coordinate system shift.
1- Clamping maximum spindle speed.
G50 S____
• The value in word address S specifies the maximum spindle speed measured in
RPM.
• this command can be used in conjunction with G96 (Constant surfaces speed
control) to clamp the spindle speed to the given value.
2- Coordinate system setting.
• This command can be used to specify a user coordinate value to register as the
current position of the tool. The tool will think it is at the specified coordinates
although it has not actually moved.
M.nazmi ‹#›
20
40
30
10
20
0
10
20
10
10
20
30
40
+Z
G50 X10 Z10
3- Coordinate system shift.
• If incremental word addresses are used to specify the values then this
command shifts the coordinate axes by the specified values.
40
30
20
20
10
10
0
10
20
30
40
10
20
+Z
G50 U10 W10
G71 / Stock removal in X axis.
• G71 is a canned cycle that generates the roughing cuts needed to make a
component profile.
R
R = retract escaping
B
amount.
F= feedrate for roughing.
U1= depth of cut in X
axis (Radius value)
U2=finishing allowance
in X axis (sign & Mag)
W=finishing allowance
in Z axis (sign & Mag)
F
U1
r
F
Programmed
Path
U2
A
W
M.nazmi ‹#›
Prior to writing this command the tool is positioned at the start point. The sequence of
tool moves are as follows:
A- roughing cycle.
1- From the start position, the tool moves a distance U2 along the X axis and W along
the Z axis at a rapid feed rate.
2- the tool moves the distance U1 along the X axis towards the billet centerline at a
feed rates corresponding to the G code in the ns block.
3- the tool moves along the Z axis towards the spindle. The feedrate used is a stated
in the second block of G71.
4- at this point the tool retracts in the X and Z axis away from the work at an angle of
45 degrees at a rapid traverse. feedrates. The amount R is stated in the first block of
the G71.
5- the tool then retracts along the Z axis at a rapid feedrate until it reaches the start
point of that same diameter.
6- from this point the above cycle is repeated until the programmed shape between ns
and nf has been roughed out.
7- after all the roughing passes are completed a singled roughing profile pass is
performed at G71stated feedrate. when this single pass is complete the tool will
retract to the original starting position of the G71.
B-finishing cycle.
8- if the next block contains G70 the same tool will be used to perform the finishing
pass at feedrate and spindle speed contained between ns and nf.
• should a different tool be required to perform the finishing pass:
a) The block after nf would instruct the machine to move to a tool change
position.
b) The next block would instruct the machine to change to the tool required for
the finishing pass.
c) The next block would move the tool back to the original G71 starting
position.
d) At this point the finishing pass block would be read into the machine and
executed.
N ns …………F…..;
……….;
F …….;
S …….;
Any F or S commands between ns to nf block
N nf ……………….;
numbers will only be effective on the finishing pass.
G71 command is written in the following format:
G71 U(1) R__;
G71 P ns Q nf U(2) W_ F_;
M.nazmi ‹#›
Move commands are
specified between
program block
numbers ns to nf.
9- When the finishing pass ends the tool will retract to original G71 start position.
• In canned cycle G71 only an X axis move is permitted in the first block of the finished
profile.
• Only G00, G01, G02, G03 and G04 can be programmed between ns and nf blocks.
12
38 Dia
30
35
30 Dia
25 Dia
20 Dia
1.5 Chamfer
1 Rad
3 Rad
N0050
N0060
N0070
N0080
N0090
N0100
N0110
N0120
N0130
N0140
N0150
N0160
N0170
N0180
G00 X38 Z2;
start & finished position
G71 U1.5 R0.5;
P80 Q170 U2 W0.1 F0.15;
G01 X16 F0.3;
(ns)
Z0.5;
X20 Z-1.5 F0.05;
Z-30 F0.075;
X23;
G03 X25 Z-31 R1;
G01 X30 Z-65;
Z-74;
G02 X36 Z-77 R3;
G01 X38.5;
(NF)
G70 P80 Q170;
Finish pass
G70 /Finishing Cycle
G70 Pns Qnf
• After part profile rough cutting has been competed using G71-G72-G73 codes the
G70 can be used to perform a finishing pass/cut.
• ns = the sequence number of the start block for the finishing pass.
• nf = the sequence number of the last block for the finishing pass.
• When the finished pass is ended the tool returns to the position it was originally at
before G70 was commanded.
• F and S between the sequence numbers ns and nf will be effectively in the G70
operation.
M.nazmi ‹#›
20 Dia
1.5 Rad
32 Dia
15
N0070
N0080
N0090
N0100
N0110
N0120
N0130
N0140
N0150
N0160
N0170
N0180
15
1.5 Chamfer
15
G00 X16 Z2;
G71 U1.25 R0.5;
G71 P100 Q170 U-1.5 W0.07 F0.075;
G01 X36 F0.3;
Z0.5;
X32 Z-15 F0.05;
Z-15 F0.07;
X20 Z-30;
Z-43.5;
G03 X17 Z-45 R1.5 F0.05;
G01 X15.8;
G70 P100 Q170;
G72 /Stock removal in Z axis
• similar to G71except that the cut is applied in the Z axes.
G72 W(1) R__;
G72 Pns Qnf U__ W(2) F__;
F= feedrate.
A
r= rapid traverse.
W1= depth of cut.
U= finishing cut allowance in X axis.
R=escaping amount.
ns= sequence number of the first block of the
programmed finished shape.
nf= sequence number of the last block of the
programmed finished shape.
Programmed
U= distance and direction of the finished
Path
allowance in the X axis.
W(2)= finishing cut allowance in Z axis.
F=feedrate for roughing.
M.nazmi ‹#›
W1
F r
R
U
B
W(2)
• Only a Z axis move is allowed in the ns block.
• If the finishing pass is required to block G70 Pns Qnf is placed after the G72
command has been completed.
U
80
Dia
N0050
N0060
N0070
N0080
N0090
N0100
N0110
N0120
N0130
N0140
N0150
N0160
60
Dia
60
Dia
40
Dia
10
10
10
20
Dia
20
10
G00 X81 Z2;
G72 W2 R0.5;
G72 P80 Q150 U0.5 W1 F0.1;
G00 Z-60;
G01 X80 F0.2;
X60 W10 F0.075;
W10;
X40 W10;
W20;
X180 W11;
W1;
G70 P80 Q150;
M.nazmi ‹#›
G75 / grooving cycle.
•
G75 permits grooving in the X axis.
Q
G75 R(1);
G75 X(U) Z(W) P__ Q__ R(2) F__;
P
X(U)
R1 peck return amount.
X(U) the diameter of the depth of the
groove.
Z(W) the width of the groove.
P
stepover in the X axis measured in
microns.
Q
pecking debt in the Z axis
measured in microns.
R(2)
R(1)
z(w)
• The retract amount R(2) at the base of the groove may be impossible
unless a clearance amount has been provided. If no clearance amount
has been left the R(2) value must be set to zero or omitted from the
block.
3mm wide grooving tool
Star position X52 Z-10.5
20 Dia
50 Dia
N0060
N0070
N0080
N0090
N0100
N0110
40
G00 X52 Z-8;
G01 X20 F0.075;
G00 X52;
W-2.5;
G75 R0.5;
G75 X20 Z-40 P5000 Q2500 R0.5 F0.075;
M.nazmi ‹#›
5
G90 /outer diameter cutting cycle
• The command G90 performs the one pass cutting cycle where the cut is applied
in the x axis.
• G90 is modal.
W
X/2 U/2
P4(R)
P3(F)
G90 X(U)_ Z(W)_ F_;
P1(R)
P2(F)
• In this example both U and
W are minus.
Z
• G90 can also be used to cut tapers.
G90 X(U) Z(W) R_ F_;
P4(R)
P1(R)
U/2
P3(F)
W
• To sign of R depends on the
direction of path P1. In this example
İt is entered as a minus value.
Z
25 Dia
8
20 Dia
40
Dia
20
25
M.nazmi ‹#›
N0060
N0070
N0080
N0090
N0100
N0110
G00 X41 Z2;
G90 X35 Z-45 F0.1;
X30;
X25 Z-25;
X20;
X20 R-3.512;
X/2
R
P2(F)
G94 /end face turning cycle
W
U/2
P1(R)
P4(r)
P2(F)
• This command performs a
one pass face cutting cycle.
• The cut is applied in the Z
axis.
• G94 can also be used for
cutting taper profiles.
X
P3(F)
G94 X(U) Z(W) F_
Z
• If repetition of the move is
required only the values that
changed needs to be entered
into the next block.
W
P2(F)
G94 X(U) Z(W) R_ F_
R
X
To sign of R depends on the
direction of path P1. In this
example It is entered as a
minus value.
P3(F)
U/2
P1(R)
R
60 Dia
5
5
5
M.nazmi ‹#›
20 Dia
10 Dia
Z
N0060
N0070
N0080
N0090
N0100
N0110
N0120
N0130
N0140
N0150
N0160
N0150
G00 X61
G94 X20
Z-5;
Z-7.5;
Z-10;
Z-12.5;
Z-15;
G00 X21
Z-2.5;
Z-5;
G94 X10
Z-11 R-6;
Z2;
Z-2.5 F0.1;
Z5;
Z-7.5 R-2.5;
Spindle speed
•
this spindle speed specified by the word address S in any block of a program may
be interpreted in two ways depending on the mode selected. these are:
G96 / constant surface speed
•
•
•
•
•
•
The spindle speed is calculated so that the surface speed is always the specified
value (in S) in relation to the tool position.
The units used will depanned on whether the machine is operating using metric or
Imperial measurements.
G96 units can therefore be meters pair minutes, or feet per min.
When using G96, the work datum point must be set so that the center of rotation
meets the Z axis.
G50 code defining clamping off maximum spindle speed must be used in
conjunction with G96, so as not to overrun the safe maximum spindle speed off
the chuck.
G96 is modal.
G97 / spindle speed in Rev Per Minute
•
•
G96 S___;
G97 S__;
Once G97 is entered all subsequent spindle speeds are defined in revolution per
minutes.
G97 is the default mode at power up.
G98 / Fee per Minute
G98 F__;
• This command allows a feedrate written in the units, millimeters per minute or
inches per minute to be entered into the machine controller.
• G98 is modal therefore if a change to the feedrate is required within a program,
only the F value needs to be entered.
• G98 is the default condition at power up.
G99 / Per Revolution Feed
G99 F__;
• G99 results in feed rate of millimeters or inches per revolution depending on the
previously selected units.
• G99 is modal
M.nazmi ‹#›
M Codes:
M??
• Miscellaneous functions, called M codes, are used by the CNC control to command
on/off signals to the machine functions.
• The functions allocated are constant in most CNC machines however some can vary
from one make of the machine to the next.
• Only one M code can be programmed within each block.
M00
M01
M02
M03
M04
M05
M06
M08
M09
M10
M11
M13
M14
M25
M26
M30
M38
M39
M40
M41
M98
M99
program stop
optional stop
end of program
spindle forward (clockwise)
spindle reverse (counter clockwise)
spindle stop
automatic tool change
coolant on
coolant off
chuck open
chuck close
spindle forward and coolant on
spindle reverse and coolant on
tailstock quill extend
tailstock quill retract
program stop and reset
door open
door close
parts catcher extend
parts catcher retract
sub program call
sub program end and return
Main prog.
Sub prog. 1
Sub prog. 2
O0001
N0020
N0030
N0040
N0090
N0100
N0110
O1000
N0020
N0030
N0040
N0090
N0100
N0110
O2000
N0020
N0030
N0040
N0090
N0100
N0110
……;
……;
M98 P1000;
……;
……;
M30;
M.nazmi ‹#›
……;
……;
M98 P2000;
……;
……;
M99;
……;
……;
……;
……;
……;
M99;
7- G&N programming for CNC Milling Machine
DATUM:
•Machine datum: Sometimes referred to as the zero datum
defines the zero point of all axes which is fixed by the
manufacturer.
We can use zero offset facility to move this datum.
•Program datum is specified by the programmer when the
program is written. All subsequent measurements are then made
relative to this new “program” datum.
Z
Y
X
M.nazmi ‹#›
Co-Ordinate Dimensioning:
There are two types of co-ordinate dimensioning systems used in CNC
programming:
•Incremental: where next position measurements are taken relative to the current
position.
- an error made in one dimension will effect subsequent measurements
- if a dimension changes then the rest of dimension will have to be
changed
•Absolute: Dimensions are always measured from the same datum position
therefore there are no build-up or accumulation of errors between dimensions.
Y
X
2
1
3
4
5
6
Incremental
Absolute
X
X
Y
1
2
3
4
5
6
1
2
3
4
5
6
M.nazmi ‹#›
Y
2 holes on CL, 8 Dia x 10 deep
20
12
147
20
8
8
25
8
98
11
N0000
G00
X00.0
Y00.0
M.nazmi ‹#›
Z00.0
F0000 M00
S0000 T00;
O0001
N0010 G21;
metric measure
[BILLET X98 Y147 Z36;size of work piece
[TOOLDEF T3 D8 Z20;
define tool
[EDGEMOVE X0 Y0 Z0;
force billet datum to be at workpiece datum
/
for simulation set X datum to 20
/
this means we have room to move to the left the billet
N0015 M6 T3;
pick tool
N0020 G90;
Go home - absolute
N0040 G00 X-4 Y4 Z-25;
1st move
N0050 M03 S1500;
Spindle on
N0060 G01 X94 F120;
2nd cut
N0070 Y143;
3nd cut
N0080 X-4;
make sure no corner remains
N0090 Y139;
N0100 X93;
4rd cut complete
N0110 G00 Y140;
N0120 X4;
ready for last cut
N0130 G01 Y4;
last cut round
/
N0140 G00 Z10;
lift clear
N0150 X49 Y20;
position over 1st hole
N0150 G01 Z-10;
N0160 G00 Z10;
N0170 Y127;
Over 2nd hole
N0180 G01 Z-10;
N0190 G00 Z10;
Retract
/
N0200 Y73.5;
Over the slot center
N0210 G01 Z-5;
N0220 G91;
incremntal
N0230 X30;
N0240 X-60;
N0250 G00 z10;
N0260 G90;
N0270 M02;
N0280 M30
M.nazmi ‹#›
G00 /Rapid positioning & traverse
G00 X10 Y20 Z30
• Executes non cutting movement (point-to-point) at a rapid feed rate.
• Axis co-ordinate moves can be absolute or incremental
• G00 freezes tool radius compensation and axis movement are
independent of each other.
• G00 is modal
G01 /Linear interpolation
•
•
•
•
G90 G01 X100 Y50 F170
Executes cutting movement along a straight line at a given feed rate
Axis co-ordinate moves can be absolute or incremental
G01 is modal
F is modal and is specified as inches per minute (G20) or
millimeters per minute (G21)
G02-G03 /Circular interpolation
•G02 (CW) and G03(CCW) executes a cutting movements in circular
path.
•There are four ways to program a CW/CCW circular path:
G90 G02/03 X-- Y-- R-- F-- [can use G91]
arc end point in X&Y (absolute/incremental). R length of arc radius. F
feed rate.
G90 G02/G03 X-- Y-- I-- J-- F-- [can use G91]
I-- J-- defines the signed distance of the arc start point from the centre
point of the arc.
•For arcs exceeding 180 degree the radius value R-- must be specified
as negative.
•When X or Y are omitted the arc end point is located at the same
position as the arc start point and the arc center is commanded by I or
J, an arc of 360 degree is assumed.
M.nazmi ‹#›
G04 /Dwell
G04 X-- (time in seconds)
G04 P-- (time in 1 milliseconds)
G04 X1.5
G04 P2500
• Used to enter a set time delay into the program.
• No decimal points can be used with address P
• Dwell is performed at the start of the block in which it is
programmed.
• G04 is non-modal
G20-G21 /Data input unit
G20
G21
Imperial/Inch
Metric/Millimeter
lowest value 0.0001
lowest value 0.001
• Do not switch between G20/G21 during a program
G28 /Reference point return
G28 X-- Y-- Z-• the reference point is a fixed position on the machine to which the
tool can be moved. (home position)
• X/Y/Z can be used to indicate an intermediate point through which
the tool will pass before continuing to the reference point.
• G28 is non-modal
G40-G41-G42 /Cutter compensation
• G41/42 the tool is positioned on the left/right hand side of the part
(programmed path) as seen following the direction of movement
from behind the tool.
• G40 cancels cutter compensation
• The radius of the tool (amount compensated by) should have been
set in the machine controller.
M.nazmi ‹#›
G40-G41-G42 /Cutter compensation
• G41/42 the tool is positioned on the left/right hand side of the part
(programmed path) as seen following the direction of movement from
behind the tool.
• G40 cancels cutter compensation
• The radius of the tool (amount compensated by) should have been set
in the machine controller.
• A start-up or ramping on block must be used to allow the tool time to change
from moving along he programmed path line to following either side of the path
line. Therefore:
G41/42 must be contained in the block or specified in the previous block and A
G01 is specified in the block and the distance of the linear move must be
greater than the tool compensation
• The tool offset store in the table must not be 00
G02 or G03 can not be specified in the start-up block
G40/41/42 are modal
G40 can only be performed in a block in which a linear move (G00-G01-G28) is
performed
2 holes on CL, 8 Dia x 10 deep
20
12
147
20
8
8
25
8
98
11
M.nazmi ‹#›
Caned cycles (G73-G89) simplifies the program by replacing a number of
complex machine sequence blocks with just one block.
G98 - initial point return
G99 - R point level return
G81 /Drilling- spot boring
G90/G91 G98/G99 G81 X-- Y-- Z-- R-- K-- F--;
G90
G81 X10 Y30 Z-17 R2 F75;
G91 G99 G81 X10 Y6 Z-10 R-8 K4 F100;
•
•
•
•
•
Rapid position to XY (initial level)
Rapid traverse to R point level
Feed to depth Z
Rapid traverse to initial Z level (G98) or R point (G99).
K defines the number or repeats
G90-G91-G42 /Absolute/incremental data format
XY
R
G98
XY
G98
R
G99
G99
Z=0
Z=0
Z
Z
• Z defines the distance from the R point to the bottom of the hole in
incremental mode or the position of the hole bottom in absolute
mode.
• R defines the distance from the initial level to the R point level in
incremental mode or the position of the R point level in absolute
mode.
M.nazmi ‹#›
G82 /Drilling- counter boring
G90/G91 G98/G99
•
•
•
•
•
•
G82 X-- Y-- Z-- P-- R-- K-- F--;
Rapid position to XY (initial level)
Rapid traverse to R point level
Feed to depth Z
Dwell for value P
Rapid traverse to initial Z level (G98) or R point (G99).
K defines the number or repeats
G80 /Canned cycle cancel
• The data specified (ZPQR) is retained until it is either changed or
the canned cycle cancelled.
G73 /high speed peck drilling
G90/G91 G98/G99
•
•
•
•
•
•
•
G73 X-- Y-- Z- Q-- R-- F--;
Move rapid to XY
Move rapid to R
Feed to a depth of Q
Retract a small distance
Re-feed to a further depth of Q
Retract and repeat till Z is reached
Retract to R or initial level as specified
G 83/deep hole peck drilling
•
•
•
•
•
•
•
Rapid position to XY
Move rapid to R
Feed to a depth of Q
Retract rapid to R
Rapid traverse back to within 1mm depth of Q cut
Feed to a further depth of Q
Retract to R and repeat till a depth of Z is reached
G 84 /Tapping
G74 /Counter Tapping
G76 /Fine Boring
G 85-G86-G89 /Boring
G 87 /Back boring
M.nazmi ‹#›
G170 - G171 /circular pocket canned cycle
• The canned cycle required two blocks G170&G171
• There are three ways to program these canned cycles
G170 R0 P0 Q3 X0 Y0 Z- nI0 J0 K-24; rough cut no allowance
G171 P75 S3000 R75 F250 B J;
For 1st block
• R defines the position of the tool to start cycle
• P =0 means a roughing cycle
• Q defines the peck (vertical cut) increment
• XY defines the hole centre
• I defines the side finish allowance
• J defines the base finish allowance
• K defines the radius of the pocket (- means CCW)
For 2nd block
• P defines the cut width percentage
• S roughing spindle speed
• R roughing feed in Z
• F roughing feed in XY
• B finished spindle speed (ignored when P=0)
• J finish feed (ignored when P=0)
• When the tool has finished cutting the tool retracts 1mm in the Z axis,
moves to the centre of the circular pocket at rapid traverse, retracts again
in the Z axis.
G170 R0 P0 Q3 X0 Y0 Z-- I0.5 J0.1 K-24; rough cut WITH
G171 P75 S3000 R75 F250 B3500 J200;
finishing allowance
G170 R0 P1 Q3 X0 Y0 Z-6 I0.5 J0.1 K-24; One step finishing cycle
G171 P75 S3000 R75 F250 B3500 J200
• I&J are ignored when P=1
• S&R&F must be entered but ignored for finishing cycle
M.nazmi ‹#›
G172 - G173 /Rectangular pocket canned cycle
• The canned cycle required two blocks G170&G171
G172 I-50 J-50 K0 P0 Q3 R0 X-25 Y-25 Z-6;
Roughing cut
G173 I0 K0 P75 T1 S3000 R75 F250 B3500 J200 Z5;
For 1st block
• I defines the pocket X length (+ CW/ - CCW)
• J defines the pocket Y length
• P=0 roughing cycle
• Q defines Z peck increment
• R defines the absolute Z R point
• XYZ absolute position of the pocket corner points
For 2nd block
• I pocket side finish allowance (=0 when P=0)
• K Pocket base finish allowance (=0 when roughing)
• P is the cut width percentage
• T is the pocket tool
• S roughing spindle speed
• R roughing feed for Z
• F Rouging feed for X and Y
• B finish spindle speed
• J finish feed
• Z safety Z above R.
G172 I-50 J-50 K0 P0 Q3 R0 X-25 Y-25 Z-6; rough cut WITH finish
G173 I0.5 K0.1 P75 T1 S3000 R75 F250 B3500 J200 Z5;
G172 I-50 J-50 K0 P1 Q3 R0 X-25 Y-25 Z-6; One step finishing cycle
G173 I0.5 K0.1 P75 T1 S3000 R75 F250 B3500 J200 Z5;
M.nazmi ‹#›
G90 /Absolute command
Active when machine is first switched on
G91 /Incremental command
G94 /Feed per minute
(G29) F6= 6 inches/min
(G21) F150= 150 mm/minute
G95 /Feed per revolution of spindle
List of G Codes (Milling machine)
G00
G01
G02
G03
G04
G20
G21
G28
G40/G41/
G73-G89
G73
G74
G76
G80
G81
G83
G84
G85
G86
G87
G89
G90
G91
G94
G95
G98
G99
G170-G173
positioning (rapid traverse)
liner interpolation (feed)
circular interpolation CW
circular interpolation CCW
dwell
inch data input
metric data input
reference point return
Canned cycles
High speed peck drilling
Counter tapping
Fine boring
Canned cycle cancel
Drilling – counter boaring
Deep hole peck drilling
Tapping
Boring
Boring
Peck boring
Boring
Absolute zero command
Incremental command
feed per minute
feed per revolution
Return to initial level
Return to R point
Cirular/Rect pockets
M.nazmi ‹#›