1. Know the Code…
Students will participate in an activity that will help them understand CNC programming and how machines read programmed information.
CHSE-Lance Tatro 2010

2. Objectives for this lesson…
By the end of the lesson, students should be able to:
Identify the values of typical CNC code used in simple programming.
Know the roll of G code as used in Numerical control programming language
Know the roll of M code as used in Numerical control programming language
Interpret a simple code used for a CNC Mill
CHSE-Lance Tatro 2010

3. Review… Q. How are points named?
Q. What is the first number, second, third?
Q. Do you need to name all the points on your design? If so, why?
CHSE-Lance Tatro 2010

4. Vocabulary Terms…
G-Code, or preparatory code or function, are functions in the Numerical control programming language. The G-codes are the codes that position the tool and do the actual work
M Codes control the overall machine, causing it to stop, start, turn on coolant, etc.
S Code controls the speed of the spindle (cutter).
CHSE-Lance Tatro 2010

5. M-Code (S)
(*) M codes control the overall machine, causing it to stop, start, turn on coolant, etc.
CHSE-Lance Tatro 2010

6. Partial list of M-Codes
M00=Program Stop (non-optional)
M01=Optional Stop, machine will only stop if operator selects this option
M02=End of Program
M03=Spindle on (CW rotation)
M04=Spindle on (CCW rotation)
M05=Spindle Stop
M06=Tool Change
M07=Coolant on (flood)
M08=Coolant on (mist)
M09=Coolant off
M10=Pallet clamp on
M11=Pallet clamp off
M30=End of program/rewind tape (may still be required for older CNC machines)
CHSE-Lance Tatro 2010

7. Example…. An example of an M-Code might be
M01 This would indicate the “Optional Stop” function of the machine. This function will only take place if the operator selects to do so.
CHSE-Lance Tatro 2010

8. G-Codes
G Code (s), or preparatory code or function, are functions in the Numerical control programming language. The G-codes are the codes that position the tool and do the actual work.
CHSE-Lance Tatro 2010

9. G-Codes for a typical Milling Machine
Positioning in Rapid
G01
Linear Interpolation
G02
Circular Interpolation (CW)
G03
Circular Interpolation (CCW)
G04
Dwell
G07
Imaginary axis designation
G09
Exact stop check
G10
Program parameter input
G11
Program parameter input cancel
G12
Circle Cutting CW
G13
Circle Cutting CCW
G17
XY Plane
G18
XZ Plane
G19
YZ Plane
G20
Inch Units
G21
Metric Units
G22
Stored stroke limit ON
G23
Stored stroke limit OFF
G27
Reference point return check
G28
Automatic return to reference point
G29
Automatic return from reference point
G30
Return to 2nd, 3rd, 4th reference point
G31
Skip function .
G33
Thread cutting
G34
Bolt hole circle (Canned Cycle)
G35
Line at angle (Canned Cycle)
G36
Arc (Canned Cycle)
G40
Cutter compensation Cancel
G41
Cutter compensation Left
G42
Cutter compensation Right
G43
Tool Length Compensation (Plus)
G44
Tool Length Compensation (Minus)
CHSE-Lance Tatro 2010

10. More G-Code… G60 Single direction positioning G61
Exact stop check mode
G62
Automatic corner override
G63
Tapping mode
G64
Cutting mode
G65
Custom macro simple call
G66
Custom macro modal call
G67
Custom macro modal call cancel
G68
Coordinate system rotation ON
G69
Coordinate system rotation OFF
G70
Inch Units
G71
Metric Units
G72
User canned cycle
G73
High-Speed Peck Drilling Cycle
G74
Counter tapping cycle
G75
G76
Fine boring cycle
G77
G78
G79
G80
Cancel Canned Cycles
G45
Tool offset increase
G46
Tool offset decrease
G47
Tool offset double increase
G48
Tool offset double decrease
G49
Tool Length Compensation Cancel
G50
Scaling OFF
G51
Scaling ON
G52
Local coordinate system setting
G53
Machine coordinate system selection
G54
Workpiece Coordinate System
G55
Workpiece Coordinate System 2
G56
Workpiece Coordinate System 3
G57
Workpiece Coordinate System 4
G58
Workpiece Coordinate System 5
G59
Workpiece Coordinate System 6
CHSE-Lance Tatro 2010

11. Example…
G50 S2000 This code would indicate to the machine to set the spindle speed to 2000 RPMs (Revolutions Per Minute)
G50 = Define the Spindle Speed
S Spindle Speed of 2000 RPMs
CHSE-Lance Tatro 2010

12. Supplementary Codes (Control)
X absolute position
Y absolute position
Z absolute position
A position (rotary around X)
B position (rotary around Y)
C position (rotary around Z)
U Relative axis parallel to X
V Relative axis parallel to Y
W Relative axis parallel to Z
M code (another "action" register or Machine code(*)) (otherwise referred to as a "Miscellaneous" function")
F feed rate
S spindle speed
N line number
R Arc radius or optional word passed to a subprogram/canned cycle
P Dwell time or optional word passed to a subprogram/canned cycle
T Tool selection
I Arc data X axis
J Arc data Y axis.
K Arc data Z axis, or optional word passed to a subprogram/canned cycle
D Cutter diameter/radius offset
H Tool length offset
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13. Example…
G01 X-1.25 Y0.75
This would tell the machine that it will be moving in a linear movement to the coordinate -1.25,.75 on the X-Y grid.
CHSE-Lance Tatro 2010

14. Forming The Letter “Z” G00 X0.1 Y0.75 Initial move to start point
G00 Z Plunge the Z axis into the material
G01 X1.0 Y0.75 Linear move to point (1.0,.75)
G01 X0.0 Y Linear move to point (0.0,-.75)
G01 X1.1 Y Linear move to point (1.1,-.75)
G00 Z0.5 Retract the Z axis
M02 Stop the program
CHSE-Lance Tatro 2010

15. Practice Code Line Code Description N01 M216 N02 G00 X20 Z20 N03
N02
G00 X20 Z20
N03
G50 S2000
N04
M01
N05
T0303 M6
N06
G96 S854 M42 M03 M08
N07
G00 X1.1 Z1.1
N08
G01 Z1.0 F.05
N09
X0.0
N10
G00 Z1.1
N11X1.0
Rapid feed up until the tool is standing at the finished OD
N12
G01 Z0.0 F.05
N13
M05 M09
N14
G28 G91 X0
N15
M215
N16
M30
CHSE-Lance Tatro 2010

16. Answer Descriptions to Sample Code
Line
Code
Description
N01
M216
Turn on load monitor
N02
G00 X20 Z20
Rapid move away from the part, to ensure the starting position of the tool
N03
G50 S2000
Set Maximum spindle speed
N04
M01
Optional stop
N05
T0303 M6
Select tool #3 from the carousel, use tool offset values located in line 3 of the program table, index the turret to select new tool
N06
G96 S854 M42 M03 M08
Variable speed cutting, 854 rev/min, High spindle gear, Start spindle CW rotation, Turn the mist coolant on
N07
G00 X1.1 Z1.1
Rapid feed to a point 0.1" from the end of the bar and 0.05" from the side
N08
G01 Z1.0 F.05
Feed in horizontally until the tool is standing 1" from the datum
N09
X0.0
Feed down until the tool is on center - Face the end of the bar
N10
G00 Z1.1
Rapid feed 0.1" away from the end of the bar
N11X1.0
Rapid feed up until the tool is standing at the finished OD
N12
G01 Z0.0 F.05
Feed in horizontally cutting the bar to 1" diameter all the way to the datum
N13
M05 M09
Stop the spindle, Turn off the coolant
N14
G28 G91 X0
Home X axis in the machine coordinate system, then home all other axes
N15
M215
Turn the load monitor off
N16
M30
Program stop, pallet change if applicable, rewind to beginning of the program
CHSE-Lance Tatro 2010

17. Independent Practice
For your assignment, you will use the coordinates developed in the “Developing CNC Code” lesson to write a complete code. You can use the practice code from this lesson and your coordinates from the previous lesson to complete the independent practice assignment.
Look at the code we used for the letter “Z” and use that information to help you develop your code.
CHSE-Lance Tatro 2010

18. Teacher Information Sheet
Description:
Student will be introduced to CNC code writing, and learn to decipher a simple code using information learned in this lesson.
Materials Needed:
1. Paper
2. Pencil
3. Computer W/PowerPoint
4. Worksheet/Handouts
References:
STANDARDS
CTE/Technology & Engineering Education Standard:
CTE/Manufacturing and Product Development Industry Sector
Foundational Standards:
1.1 Mathematics 5.0
2.4 Listening and Speaking
4.0 Technology 4.1; 4.2; 4.5
5.0 Problem Solving and Critical Thinking 5.1; 5.2
10.0 Technical Knowledge and Skills 10.3; 10.5
Pathway Standards: C7.0; C7.3; C8.0
Teacher Performance Expectations: TPE 1, TPE2, TPE 3, TPE 5, TPE7, TPE 9, TPE10, TPE 12
SDAIE Strategies: modeling, bridging, contextualization
CHSE-Lance Tatro 2010