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
(blueprints).
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
understand.
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.
1-800-886-9750
www.denford.com
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”

    FADAL AUTOMATIC OPERATION MODES " MDI "

    AUTOMATIC OPERATION MODES
    " MDI " OPERATION 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
    mode.
    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.
    »»  CNC PROGRAMMING...“FADAL AUTOMATIC OPERATION MODES " MDI "”
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