Why CNC (Computer Numerical Control)?

Why CNC (Computer Numerical Control)?

It has been a privilege to be part of the Precision Machining
Technology Competition for the past 9 years. I am proud to have
the opportunity of working with the fine young people from all parts
of the United States. They deserve the best that the educational
system and VICA can provide to prepare them for a future in this
rapidly changing technological world and make their contribution
to the country’s economy.
My enthusiasm for VICA and the young competitors is still very
strong, however there seems to be a serious lack of preparation
for students from metalworking/manufacturing related courses in
the basic knowledge of CNC. CNC, not a new technology having
been around since 1957, is one of the key factors in the manufacture
of most products in the world today. A knowledge of CNC, for
a technology student, should rank in importance along with the
ability of speaking proper English and reading technical prints
As a former educator and now the Team Leader of the CNC VICA
competition, I feel so sorry for contestants in the Milling and
Turning who sit in front of a computer and do not know how to load
a program or the basics of CNC programming. These students are
naturally frustrated that an educational system has shortchanged
them by not realizing that metalworking technology has changed
dramatically over the past 40 years. That some schools prepare
students for the National VICA Precision Machining Competition
with 50-year-old technical knowledge is something very difficult to
The International (World) competition eliminated conventional
machine tools from the precision machining competition in 1996,
and it now consists of 100% CNC competition. To send our national
winner to the world competition without a good background
in CNC programming and machining would be a reflection on, and
a disgrace to the US educational system.
The educational community and National VICA must work
together to correct this lack of CNC knowledge and training.

The VICA CNC Programming Guide covers the basic CNC principles
and gives detailed explanation of each step in the programming
and turning a part. The time and money spent to prepare and
distribute this Guide will be wasted unless the metalworking/
manufacturing teacher is committed to introducing CNC as part of
the curriculum.

The following suggestions can be used to introduce CNC theory
and technology to metalworking/manufacturing courses:
1. Teach the basics of CNC using the VICA CNC Programming
Guide that should be supplemented by a textbook, visuals, videotapes,
etc. - COST approximately $200.00.
2. Use the VICA CNC Programming Guide and textbook along
with CAD/CAM software that allows a student to simulate the
machining of a programmed part on the computer screen. - COST
approximately $600.00.
3. Use the VICA CNC Programming Guide, textbook, CAD/CAM
software, plus a CNC Bench-Top teaching size machine. This is
by far the best method since students can actually produce a real
part that they can hold and take home to show their parents. -
COST approximately $6,000.00

For more information from a leader in CNC educational
courseware, software, and Bench-Top Teaching machines contact:
Denford Inc.
E-mail: sales@denford.com

The old argument that there are still many shops using old
technology is a fallacy used consciously or unconsciously by those
resisting changes. Over 90% of the machine tools manufactured
in the world have some form of CNC control, therefore conventional
(manual) machines should be used to provide only the basic
knowledge of machines and machining processes.

We must all do our part; State Directors, District Directors, School
Administrators, and Classroom Teachers to correct a problem long
overdue in technical education.

Steve Krar
CNC Team Leader
Precision Machining Technology
»»  CNC PROGRAMMING...“Why CNC (Computer Numerical Control)?”

Cnc Program Machining the square groove

Machining the square groove

N30 X.375
  • Y-.375 : tool rapids to position A.
N35 G01 Z-.125 F10
  • G01 linear interpolation.
  • Z-.125 tool feeds 
  • .125 below the work surface.
  • F10 feed rate set at 10 in./min.
N40 X1.625 Y-.375
  • X1.625 top groove cut to the right hand end.
  • Y-.375 measurement did not change because it was set in block N30.
N45 Y-1.625
  • Y-1.625 right hand side of the groove cut.
N50 X.375
  • X.375 bottom groove cut to the left side.
N55 Y-.375
  • Y-.375 left-hand side of groove cut; this completes the groove.
N60 G00 Z.100
  • G00 rapid traverse mode.
  • Z.100 tool rapids to
  • .100 above work surface. 

It's easy not to make a cnc program, the most important key is we know the basic origin for a programming
    »»  CNC PROGRAMMING...“Cnc Program Machining the square groove”

    Basic Computer Numerical Control Programming

    1. Identify the names and functions of some common parts of a computer.
    2. Identify and use correctly vocabulary related to CNC machining.
    3. Define CAD and CAM.
    4. Fill out a chart with information that a supervisor gives to a new employee.
    5. Analyze information from a line graph.
    6. Identify the main idea and supporting details by outlining and mapping a reading.
    7. Label the parts of a CNC machining center.Graphing  functions and  axis(  XYZ)
    8. Locate and plot  points in a two-axis Cartesian  coordinate system 
    9. Absolute position
    10. Incremental position
    11. Polar position
    12. Explore and understand G and M codes
    • Other addresses
    • Machining function
    • Program start definitions
    • Straight line programming using manual cutter radius comp
    • Basic M1 print (power point)
    • Programs end definition
    • Modals
    »»  CNC PROGRAMMING...“Basic Computer Numerical Control Programming”

    Memory Operation or Auto Mode

    Programs are registered in memory in advance. When one on these programs is
    selected and the cycle start switch on the machine operator’s panel is pressed,
    automatic operation starts, and the cycle start LED goes on.
    When the feed hold switch in the machine operator’s panel is pressed during automatic
    operation, this operation is stopped temporarily. When the cycle start switch is pressed
    again, automatic operation is restarted.
    When the RESET key on the MDI panel is pressed, automatic operation terminates and
    the reset state is entered.
    To complete this operation follow the next procedure:
    1. Press the MEMORY (AUTO) mode selection switch.
    2. Select the program from the registered programs doing the following steps:
    • Press PROG to display the program screen.
    • Press “+” soft key.
    • Press “DIR” soft key and the program library will be displayed.
    • Enter a program number using the numeric keys.
    • Press the O SRH soft key.
    3. Press the cycle start switch on the machine operator’s panel. Automatic operation
    starts, and the cycle start LED goes on. When automatic operation terminates, the
    cycle start LED goes off.
    4. To stop or cancel memory operation midway through, follow the steps below:
    • Stopping memory operation.
    Press the feed hold switch on the machine operator’s panel. The feed hold LED
    goes on and the cycle start LED goes off. The machine responds as follows:
    When the machine was moving, feed operation decelerates and stops.
    When dwell was being performed, dwell is stopped.
    When M, S, or T was being executed, the operation stopped after M, S, or T is finished.
    • Terminating memory operation.
    Press the RESET key on the MDI panel
    Automatic operation is terminated and the reset state is entered. When a reset is
    applied during movement, movement decelerates then stops.
    »»  CNC PROGRAMMING...“Memory Operation or Auto Mode”


    In the MDI mode, a program consisting of up to 10 lines can be created in the same
    format as normal programs and executed from the MDI panel. MDI operation is used for
    simple test operations.
    In order to complete this operation, follow the next procedure:
    1. Press the MDI mode selection switch.
    2. Press the PROG function key on the MDI panel to select the program screen.
    3. Prepare a program to be executed by an operation similar to normal program editing.
    M30, specified in the last block can return control to the beginning of the program
    after operation ends. Word insertion, modification, deletion, word search,
    address search, and program search are available for programs created in the MDI
    4. To entirely erase created program in the MDI mode, use one of the following methods:
    • Enter address, and then press the DELETE key on the MDI panel.
    • Alternatively, press the RESET key.
    5. To execute a program, set the cursor on the head of the program. Push CYCLE
    START button on the operator’s panel. By this selection, the prepared program will
    start. When the program end (M02, M30) or ER (%) is executed, the program will
    be erased and the operation will end. By command of M30, control returns to the
    head of the prepared program.
    6. To stop or terminate MDI operation in midway through, follow the next steps:
    • Stop MDI operation.
    Press the feed hold switch on the machine operator’s panel. The feed hold LED
    goes on and the cycle start LED goes off.
    • Terminate MDI operation.
    Press the reset key on the MDI panel. Automatic operation is terminated and the
    reset state is entered. When a reset is applied during movement, movement decelerates
    then stops.

    Learn to read program cnc lathe machine

    If you look at the structure of a program cnc, What comes to your mind? Can you know how to read the program. Here I will explain my little knowledge about the structure of the program cnc.  

    N005 G97 S250 M03
    N010 T0101
    N015 G00 X2.875 Z.1 M08
    N020 G01 Z-2.0 F.008
    N025 X3.1
    N030 G00 X8.0 Z3.0 M09
    N035 M30

    The program can we describe as follows:
    1. O0001 All Fanuc programs begin
    2. N005  N words are sequence numbers for command identification
    • Turn Spindle On
    1. G97 Turn Spindle On Select RPM mode
    2. S250 Select speed
    3. M03 Turn spindle on in forward direction
    • Index Turret
    1. N010 T0101 Turret index command selects tool station and offset
    • Move Into Position
    1. N015 G00
    2. X2.875 Approach X position
    3. Z.1 Approach Z position
    4. M08 Turn on coolant
    • Feed Along Diameter
    1. N020 G01 Select cutting mode
    2. Z-2.0Z end point
    3. F.008 Cutting feedrate
    4. Feed Up Face
    5. N025 X3.1 Ending X position
    • Move Away
    1. N030 G00 X8.0 Z3.0
    2. M09 Turn off coolant
    3. N035 M30 End of program command

    Maybe that's all I can give about how to read a cnc programming, please If there is any deficiency is added.
    Till we meet again with my upcoming article
    »»  CNC PROGRAMMING...“Learn to read program cnc lathe machine”

    Drill and Facing in the process of machining centers

    From Blogger Pictures
    Meet again with my post, this time I want to discuss about the drill and facing. I find obstacles to use of the tool joint and drill facing (can be seen in the image above). At the same drill a hole through it is with the process of facing. Obstacle I faced was the age of the tools that I use can not last long (often broken)
    Maybe it could be seen from the program like this:


    Z Zero To position contained in facing
    Material is Aluminium casting

    For that through this post I want to ask for help in finding a solution to the master's or designer of CNC tool
    »»  CNC PROGRAMMING...“Drill and Facing in the process of machining centers”

    how to indicate command dimensions for moving the tool

    How to indicate command dimensions for moving the tool
    Command for moving the tool can be indicated by " Absolute Command or Incrimental Command "

    Absolute Command
    The tool moves to a point at "the distance from zero point af the coordinate system" that is to the position of the coordinate values
    For milling:
    Command specifying movement from point A to point B
     G90 X10.0 Y30.0 Z 5.0;
    ( X10.0 Y30.0 Z5.0 is Coordinate of poin B )

    For Lathe cutting:

    Command specifying movement from point A to point B
    X30.0 Z70.0  ( coordinate of point B )

    "Incrimental command" I will discuss in future posts
    »»  CNC PROGRAMMING...“how to indicate command dimensions for moving the tool”

    Speed and Speed Cut Feeds

    Speed and Speed Cut Feeds
    Cutting Speed (Vc)
    Vc = (p x d x n) / 1000 (m / min)
    d = Diameter Things Work
    n = Number of rounds per minute (rpm)
    p = Phi = 3.14
    Vc Influenced by: a) Material, b) Types of cutting tools,
    c) Speed feeds, d) Depth feeds
    Speed feeds (F)
    F (mm / min) = n (rev / min) x f (mm / rev)
    Where: n = (Vc x 1000) / p x d (rev / min)
    F = in mm / rotation or mm / min
    »»  CNC PROGRAMMING...“Speed and Speed Cut Feeds”

    History of CNC machine

    CNC stands for Computer Numerically Controlled,
    machine tools are equipped with control systems
    computer-based reading instruction code capable of N and G (Gkode)
    which regulates the working system machine equipment, namely a
    powered mechanical equipment used to make
    component / workpiece. Machine tools are CNC machine
    tool equipped with a variety of cutting tools that can be
    make precise workpieces and can do
    interpolation / insertion directed by numerical (based on
    number). Operating system parameters / CNC working system can be changed
    through software programs (software load program) is appropriate.
    The presence of CNC machines starting from the development system
    Numerically Controlled (NC) in the late 1940s and early years
    Found in 1950 by John T. Parsons, in cooperation
    Company Servomechanism MIT. The presence of CNC machine
    preceded by the discovery of NC machines which have the feature parameters
    operating system can not be changed. CNC System on
    initially use this type of hardware (hard ware), NC, and
    computers used as a tool compensation calculations and
    sometimes as a tool for editing.
    At first CNC machines still use paper
    hole as a medium for transferring G and M code to the system
    control. After 1950, found a new method of transferring data
    using RS232 cables, floppy disks, and last by
    Computer Network Cables (Computer Network Cables) could even
    controlled via the internet.
    Lately, CNC machines have been developed
    stunning, which changed the manufacturing industry during this
    using human labor to full automation. Expanding
    CNC machine, the workpiece can be made complicated sekalkipun
    easily in large numbers.
    We all know that the manufacture of components / spare
    precision parts of a machine with manual machine tools
    not easy, though done by a machine operator
    advanced tooling solution even if it takes
    long. If there is consumer demand to make components
    High-tech in large quantities in short time,
    with quality as good, it would be difficult to achieve when
    using manual tools. Moreover, when the shape of objects
    ordered more complicated, the harder it would be completed within
    brief. Completion of the old product would be economically
    increase production costs, product price will be
    increasingly expensive, so more and more difficult to compete with products
    »»  CNC PROGRAMMING...“History of CNC machine”

    Insert Turning With Chip Breaker.Pdf

    Our knowledge of the process feeds contributed in PDF files with the title of Turning Insert with chip breaker.
    The process feeds in a machining process is very influential with the inserts that we use. In addition we need to know is Is it already there Insert the chip breaker or not
    »»  CNC PROGRAMMING...“Insert Turning With Chip Breaker.Pdf”

    CNC Mechine language and Basic ISO CNC code

    Still in the discussion of CNC base. To post this time I can be from one of my friends blogs. I think it is very good because it is packed in PDF files with title MY CNC. Hopefully useful to all friends
    we just see PDF file below:
    »»  CNC PROGRAMMING...“CNC Mechine language and Basic ISO CNC code”

    Function G Code on CNC Machining Center Machine

    CNC MACHINE (Computer Numerical Control) machine is controlled by the computer with commands in the code of letters and numbers.
    For the first post I tried to introduce the function G code on a CNC Machining Center machines.
    Below is a list of the names of the existing G Code:
    1. G00 Positioning
    2. G01 Linear interpolation
    3. G02 Circular interpolation CW
    4. G03 Circular interpolation CCW
    5. G04 Dwell
    6. G05 High-speed continuous cutting
    7. G07 SINE interpolation
    8. G09 Exact stop check
    9. G10 Offset value setting / work zero offset setting
    10. G17 XY plane selection
    11. G18 ZX plane selection
    12. G19 YZ plane selection
    13. G20 Inch data input
    14. G21 Metric data input
    15. G22 Stored stroke limit on
    16. G23 Stored stroke limit off
    17. G27 Zero return check
    18. G28 Automatic Zero Return
    19. G29 Return from reference point
    20. G30 Return to 2nd/3rd/4th reference point
    21. G31 Skip cutting
    22. G33 Thread cutting
    23. G40 Cutter compesation cancel
    24. G41 Cutter compensation left side
    25. G42 Cutter compensation right side
    26. G43 Tool length offset (+)
    27. G44 Tool lenght offset (-)
    28. G45 Tool offset increase
    29. G46 Tool offset decrease
    30. G47 Tool offset double increase
    31. G48 Tool offset double decrease
    32. G49 Tool lenght offset cancel
    33. G54 Work coordinate system 1
    34. G55 Work coordingte system 2
    35. G56 Work coordinate system 3
    36. G57 work coordinate system 4
    37. G58 Work coordinate system 5
    38. G59 Work coordinate system 6
    39. G60 Single direction positioning
    40. G61 Exact stop check mode
    41. G62 Automatic corner override effective
    42. G64 Cutting mode
    43. G65 Custom macro simple call
    44. G66 Custom macro modal call
    45. G67 Custom macro modal call cancel
    46. G73 Peck drilling cycle
    47. G74 Counter tapping cycle
    48. G76 Fine boring cycle
    49. G80 Canned cycle cancel
    50. G81 Drilling cycle
    51. G82 Drilling cycle/counter boring
    52. G83 Peck drilling cycle
    53. G84 Tapping cycle
    54. G85 Boring cycle
    55. G86 Boring cycle
    56. G87 Back boring cycle
    57. G88 Boring cycle
    58. G89 Boring cycle
    59. G90 Absolute programming
    60. G91 Incremental programming
    61. G92 Programming of absolute zero point
    62. G94 Feed per minute
    63. G95 Feed per revolution
    64. G98 Return to initial point level in canned cycle
    65. G99 Return to R point level in canned cycle

    »»  CNC PROGRAMMING...“Function G Code on CNC Machining Center Machine”