DMFD 3333 – CNC TECHNOLOGY
DMFD 3333 – CNC TECHNOLOGY
PROCESS PLANNING/
PROGRAMMING PROCEDURE
DMFD 3333 – CNC TECHNOLOGY
GOAL
- Completion of all instruction in the
form of a program that will result in
an error free, safe and efficient CNC
machining.
DMFD 3333 – CNC TECHNOLOGY
All planning must be approached in a logical
way and methodical way
Decision: What task to be done?
What goals?
DMFD 3333 – CNC TECHNOLOGY
PROCESS
1.
2.
3.
4.
5.
6.
7.
8.
9.
10.
11.
Study of initial information (drawings)
Material evaluation
Machine tool selection
Sequence of machining operation
Tooling selection and arrangement of cutting tool
Setup parts
Technological data
Determination of tool path
Program writing and preparation to transfer to CNC
Program testing and debugging
Program documentation
DMFD 3333 – CNC TECHNOLOGY
PROCESS
1.
2.
3.
4.
5.
6.
7.
8.
9.
10.
11.
Study of initial information (drawings)
Material evaluation
Machine tool selection
Sequence of machining operation
Tooling selection and arrangement of cutting tool
Setup parts
Technological data
Determination of tool path
Program writing and preparation to transfer to CNC
Program testing and debugging
Program documentation
DMFD 3333 – CNC TECHNOLOGY
Study of Information (Drawings)
Very important document where it physically
visual the shape, dimensions, tolerances,
surface finish and many other
requirements such as number of parts and
other secondary processes
DMFD 3333 – CNC TECHNOLOGY
Material Evaluation



Typical material is raw and unmachined:
billet, bar, plate, forging, casting etc
The size and shapes of the the material
determine the type of fixturing
Machinability: charts for recommeded
speed and feed for most common
material
DMFD 3333 – CNC TECHNOLOGY
Machining Sequence
1.
2.
3.
4.
Order of machining sequence.
Technical Skill and and machine shop
experience is important.
The machining sequence must be in
logical order.
Determine the shape of the part.
DMFD 3333 – CNC TECHNOLOGY
Machining Sequence
1.
2.
3.
4.
Order of machining sequence.
Technical Skill and and machine shop
experience is important.
The machining sequence must be in
logical order.
Determine the shape of the part.
DMFD 3333 – CNC TECHNOLOGY
Work Holding Devices
DMFD 3333 – CNC TECHNOLOGY
The method of holding the parts to be
machine on the machine so that:
1. Parts is correctly orientated
2. Dimension is not distorted
3. Locate part with respect to its datum
4. Proper locating and clamping ensures
repeated products and accuracy.
DMFD 3333 – CNC TECHNOLOGY
Work Holding devices for milling:
1. Vice
2. Angle plate
3. Direct clamping or fixtures
4. Chuck
5. Tomb stones
DMFD 3333 – CNC TECHNOLOGY
VICE
 Most commonly used for simple shape
machining
 Manually, air or hydraulically operated
 Mount on table so that it is parallel to its x
and y axis
 Movable jaw should not be used as a
datum as it moves
DMFD 3333 – CNC TECHNOLOGY
ANGLE PLATE
o
 For work that need to be held at 90 angle
to the axis
 L shaped cast iron or steel that has
tapped holes or slots to provide for
clamping purposes
 Suitable for horizontal machining centre
DMFD 3333 – CNC TECHNOLOGY
CHUCK
Three jaw chuck used to hold cylindrical
workpiece on machine table
DMFD 3333 – CNC TECHNOLOGY
DIRECT WORK MOUNTING
Used to hold big or having odd shaped
workpieces
 Bolted directly to the table
 Required ingenuity and expertise

DMFD 3333 – CNC TECHNOLOGY
FIXTURES
Used in the following cases:
 The stock require some periphery
machining
 The stock is too large to be held by a
machine vice
 Not rectangular in shape.
DMFD 3333 – CNC TECHNOLOGY
TOMB STONE
Allow multipart to be held on any or all of its
parts.
Manual or power clamping can be used
Held on rotating machine pallets so that
each side could be represented.
Increase productivity.
DMFD 3333 – CNC TECHNOLOGY
MILLING PROGRAMMING
DMFD 3333 – CNC TECHNOLOGY
TYPICAL PROGRAM
O002
Program No
N1
G20 Unit setting in different block
N2
G17 G40 G80 G49 Initial Setting and cancellation
N3 T01
Tool 1 in waiting position
N4 M06
Tool 1 into spindle
N5 G90 G54 G00 X.. Y… Z.. M3 TO2 T01 restart block
T02 into waiting position
N6 G43 Z2.0 H01 M08 Tool lgth offset coolant on
N7 G01 Z… F… Feed to Z depth
(….Cutting tool motion with tool 1)
DMFD 3333 – CNC TECHNOLOGY
N33
N34
N35
---N36
N37
N38
G00 G80 Z2.0 M09 Clear above part – coolant off
G28 Z2.0 M05 Home in Z only coolant off
M01 Optional stop
T02
Tool 2 in waiting
M06
Tool 2 in spindle
G90 G54 G00 X..Y.. S.. M03 TO3 T02 start block T03
in waiting
N39 G43 Z2.0 H02 M08 Tool lgth offsett coolant on
(N40 G43 G01 Z-…F..)
Feed to Z depth
…….Cutting motion with tool 2
DMFD 3333 – CNC TECHNOLOGY
N62 G00 G80 Z2.0 M09
N63 G28 Z2.0 M05
N64 M01
….
N65 T03
N66 M06
N67 G90 G54 G00 X.. Y.. S..M03 T01
N68 G43 z2.0 H03 M08
(N69 G01 Z-…F…..
……..Cutting motion with tool 3
…
DMFD 3333 – CNC TECHNOLOGY
N86
N87
N88
N89
%
G00 G80 Z2.0 M09
G28 Z2.0 M05
G28 X.. Y..
M30
DMFD 3333 – CNC TECHNOLOGY
Preparatory Command


Identify as G codes
To preset or to prepare the control
system to a certain desired condition or
to a certain mode or state of operation
DMFD 3333 – CNC TECHNOLOGY
Description and Purpose
e.g. N7 X200 Y10 –end position of the
cutting tool does not show coordinates
are absolute or incremental, imperial or
metric, rapid or feed… hence the block is
in complete
DMFD 3333 – CNC TECHNOLOGY
Example A
N7 G90 X13 Y10
Example B
N3 G90
N4 ….
N5…..
N6…..
N7 G00 X13.0 Y10.0
DMFD 3333 – CNC TECHNOLOGY
EXAMPLE C
N3 G90 G00
N4 …
N5 …
N6 ...
N7 X13.0 Y10.0
EXAMPLE D
N2 G90
N3 G00
N4 …..
N5 ….
N6 ….
N7 X13.0 Y 10.00
DMFD 3333 – CNC TECHNOLOGY
Will there be any difference in
motion in all the example ?
DMFD 3333 – CNC TECHNOLOGY

NO – there is no change in G codes
between block N4 and N6

One G codes in a modal will replace
another g code from the same group
DMFD 3333 – CNC TECHNOLOGY
G CODES IN A BLOCK
Several preparatory function may be used in
a single block, providing they are not in a
logical conflict with each other
DMFD 3333 – CNC TECHNOLOGY
Modality of G command
N3 G90 G00
N4 X0
N5 Y20
N6 X15 Y22
N7 X13.0 Y10.0

DMFD 3333 – CNC TECHNOLOGY
For a command to be a modal, it means it
has to remain in a certain mode until
cancel by another mode
DMFD 3333 – CNC TECHNOLOGY
Conflicting command in a block
It is impossible to have rapid motion and a
cutting motion in one block e.g G00 and
G01
- The latter will be used if accidentally used
DMFD 3333 – CNC TECHNOLOGY

Word Order in block
G codes are normally programmed at the
beginning of a block
e.g. N40 G91 G01 Z-1 F200
DMFD 3333 – CNC TECHNOLOGY
GROUPING OF COMMAND
Commands cannot be in the same block:
G00, G01, G02, G03

Any G code from a given group
automatically replaces another G code
from the same group
DMFD 3333 – CNC TECHNOLOGY
DMFD 3333 – CNC TECHNOLOGY
MICELLANEOUS FUNCTION
DMFD 3333 – CNC TECHNOLOGY
M code
– Miscellaneous function
- machine function (not all)
DMFD 3333 – CNC TECHNOLOGY
Machine Related Function
Spindle rotation
CW or CCW
Gear range change Low/medium/high
Automatic tool change ATC
Automatic Pallet change APC
Coolant operation ON or OFF
Tailstock or Quill motion IN or OUT
DMFD 3333 – CNC TECHNOLOGY
PROGRAM RELATED FUNCTION
Control of machine function
Control of the program function
DMFD 3333 – CNC TECHNOLOGY
SPECIAL MDI FUNCTION
Manual Data Input (MDI) – used to program
from the controller – simple and repetitive
process. M funcion cannot be
programmed.
DMFD 3333 – CNC TECHNOLOGY
M FUNCTION IN A BLOCK
Only ONE function in a block
Each M function is designed logically – also
common sense
DMFD 3333 – CNC TECHNOLOGY
START OF BLOCK
M03 – Spindle rotation normal
M04 – Spindle rotation reverse
M06 – ATC
M07 – Coolant mist
M08 – Coolant ON
DMFD 3333 – CNC TECHNOLOGY
END OF BLOCK
M00 Compulsory program stop
M01 Optional Stop
M02 End of program
M05 Spindle stop
M09 Coolant OFF
M30 Program end
M60 APC
DMFD 3333 – CNC TECHNOLOGY
MACHINE FUNCTION
Coolant Function: M07, M08, M09
Spindle Function: M03, M04, M05
Gear range Selection: M41, M42, M43, M44
Machine Accessories: M06, M60, M23.m24,
M98, M99
DMFD 3333 – CNC TECHNOLOGY
THANK YOU