RAHUL KUMAR MEC

8/7/2019 RAHUL KUMAR MEC

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TERM PAPERMEC 104

Topic :

C

NC PROGRAMMING

Course instructor: Mr Acchidanand

DubeyStudents name: Rahul Kumar

Section: G4001

Roll No.: A-71

Reg. No.: 11005005

Course code: 1208D

Course name: B.Tech-

M.Tech(Duel Degree)ME



Acknowledgement:

I declare that this term paper is my own work. I have not copied it

from anybody. I have taken help from my friends

and internet . I thank them for helping me in my term paper.



Contents:

1: Introduction to CNC PROGRAMMING

2: History

3: Description

4: Programming concept

5: C-Axis

6: Program Editor



INTRODUCTION

Numerical control ( NC ) refers to the automation of

machine tools that are operated by abstractly

programmed commands encoded on a storage medium,as opposed to manually controlled via hand wheels or

levers, or mechanically automated via cams alone. These

early servomechanisms were rapidly augmented with

analog and digital computers, creating the modern

http://en.wikipedia.org/wiki/Automation

http://en.wikipedia.org/wiki/Machine_tool

http://en.wikipedia.org/wiki/Automation

http://en.wikipedia.org/wiki/Machine_tool



computer numerical controlled ( CNC ) machine tools

that have revolutionized the manufacturing process. In

modern CNC systems, end-to-end component design is

highly automated using CAD / CAM programs. The programs produce a computer file that is interpreted to

extract the commands needed to operate a particular

machine via a postprocessor, and then loaded into the

CNC machines for production

HISTORY

►CNC ARRIVES

http://en.wikipedia.org/wiki/Computer-aided_design

http://en.wikipedia.org/wiki/Computer-aided_manufacturing

http://en.wikipedia.org/wiki/Computer-aided_design

http://en.wikipedia.org/wiki/Computer-aided_manufacturing



Many of the commands for the experimental parts were programmed "by hand" to produce the punch tapes that were used as input. During the development of Whirlwind , MIT's real-time computer, John Runyon coded

a number of subroutines to produce these tapes under computer control. Users could enter a list of points and speeds, and the program would generate the punch tape.In one instance, this process reduced the time required to

produce the instruction list and mill the part from 8 hoursto 15 minutes. This led to a proposal to the Air Force to

produce a generalized "programming" language for numerical control, which was accepted in June 1956.

►CAD MEETS CNC

While the Servomechanisms Lab was in the process of developing their first mill, in 1953 MIT's MechanicalEngineering Department dropped the requirement that undergraduates take courses in drawing. The instructorsformerly teaching these programs were merged into theDesign Division, where an informal discussion of computerized design started. Meanwhile the ElectronicSystems Laboratory, the newly rechristened Servomechanisms Laboratory, had been discussingwhether or not design would ever start with paper diagrams in the future.

►PROLIFERATION OF CNC

The price of computer cycles fell drastically during the1960s with the widespread introduction of useful

http://en.wikipedia.org/wiki/Punch_tape

http://en.wikipedia.org/wiki/Whirlwind_(computer)

http://en.wikipedia.org/wiki/Punch_tape

http://en.wikipedia.org/wiki/Whirlwind_(computer)



minicomputers. Eventually it became less expensive tohandle the motor control and feedback with a computer

program than it was with dedicated servo systems. Smallcomputers were dedicated to a single mill, placing the

entire process in a small box. PDP-8's and Data GeneralNova computers were common in these roles. Theintroduction of the microprocessor in the 1970s further reduced the cost of implementation, and today almost allCNC machines use some form of microprocessor tohandle all operations.

http://en.wikipedia.org/wiki/Minicomputer

http://en.wikipedia.org/wiki/PDP-8

http://en.wikipedia.org/wiki/Data_General_Nova


http://en.wikipedia.org/wiki/Microprocessor

http://en.wikipedia.org/wiki/Minicomputer

http://en.wikipedia.org/wiki/PDP-8



http://en.wikipedia.org/wiki/Microprocessor



DESCRIPTION

Modern CNC mills differ little in concept from the original

model built at MIT in 1952. Mills typically consist of atable that moves in the X and Y axes, and a tool spindlethat moves in the Z (depth). The position of the tool isdriven by motors through a series of step-down gears inorder to provide highly accurate movements, or inmodern designs, direct-drive stepper motors. Closed-loopcontrol is not mandatory today, as open-loop controlworks as long as the forces are kept small enough.

As the controller hardware evolved, the mills themselvesalso evolved. One change has been to enclose the entiremechanism in a large box as a safety measure, often withadditional safety interlocks to ensure the operator is far enough from the working piece for safe operation. Most new CNC systems built today are completely electronically controlled.

CNC-like systems are now used for any process that canbe described as a series of movements and operations.These include laser cutting, welding, friction stir welding,ultrasonic welding, flame and plasma cutting, bending,spinning, pinning, gluing, fabric cutting, sewing, tape

LATE MODEL DIAGRAM

http://en.wikipedia.org/wiki/Stepper_motor

http://en.wikipedia.org/wiki/Laser_cutting

http://en.wikipedia.org/wiki/Welding

http://en.wikipedia.org/wiki/Ultrasonic_welding

http://en.wikipedia.org/wiki/Plasma_cutting

http://en.wikipedia.org/wiki/Stepper_motor

http://en.wikipedia.org/wiki/Laser_cutting

http://en.wikipedia.org/wiki/Welding

http://en.wikipedia.org/wiki/Ultrasonic_welding

http://en.wikipedia.org/wiki/Plasma_cutting





TOOLS WITH CNC VARIANTS

• Drills

• Lathes

• Milling machines

• Sheet metal works (Turret Punch)

• Wire bending machines

• Hot-wire foam cutters

• Surface grinders

• Cylindrical grinders

• Induction hardening machines

http://en.wikipedia.org/wiki/Drill

http://en.wikipedia.org/wiki/Lathe_(tool)

http://en.wikipedia.org/wiki/Milling_machine

http://en.wikipedia.org/wiki/Sheet_metal

http://en.wikipedia.org/wiki/Hot-wire_foam_cutter

http://en.wikipedia.org/wiki/Surface_grinder

http://en.wikipedia.org/wiki/Induction_hardening

http://en.wikipedia.org/wiki/Drill

http://en.wikipedia.org/wiki/Lathe_(tool)

http://en.wikipedia.org/wiki/Milling_machine

http://en.wikipedia.org/wiki/Sheet_metal

http://en.wikipedia.org/wiki/Hot-wire_foam_cutter

http://en.wikipedia.org/wiki/Surface_grinder

http://en.wikipedia.org/wiki/Induction_hardening



Programming Concepts

This section contains programming concepts for the

beginning programmer. You must master these conceptsand be familiar with the terminology in order to write programs.

Programs. A program is the set of instructions that theCNC uses to direct the machine movements. Each line of instructions is called a block. Each block runsindependently, thus allowing the program to be stepped along, one block at a time.

Axis Descriptions

The machine moves along its axes of motion. Allmovements along an axis are either in a positive or negative direction. Not all machines use the same systemto identify axes. The descriptions used in this manual arecommonly used to identify 3-axis mills.

NOTE:

To visualize machine movements correctly, imagine toolmotion rather than table motion.

X Axis

Table movement along the X-axis is to the left and right.Positive motion is table movement to the left; negative

motion is table movement to the right.

Y Axis



Table movement along the Y-axis is inward and outward.Positive motion is table movement outward; negativemotion is table movement inward.

Z Axis

Spindle movement along the Z-axis is upward and downward. Positive motion is tool movement upward (away from the workpiece); negative motion is toolmovement downward (into the workpiece).

Defining Positions

The intersection of the X-, Y-, and Z-axes is the reference point from which to define most positions. This point isthe X0, Y0, and Z0 position. Most positions are identified by their X, Y, and Z coordinates. A position two inchesleft, three inches back, and four inches up has an X coordinate of X -2.0, a Y coordinate of Y3.0, and a Z coordinate of Z4.0

Edit Keys:

This area contains the SHIFT (left), ENTER (right) and thecursor control keys (ARROWS).

Alphanumeric Keys

Alphanumeric keys allow you to enter positioncoordinates (XYZ moves) and program G, M, S, and T codes. Some keyfaces have two characters, a large onein the middle of the key and a smaller one in the upper-



left corner. The large characters are Primary characters.The smaller characters are SHIFT key characters.

To type a primary character, press the key that contains that

character. To type a SHIFT key character:

1. Press SHIFT. You do not need to hold down the key, it remains on until you press the next key.

2. Press the key that displays the required character inthe upper-left corner.

Powering On the CNC

1. Turn on the CNC according to the builder’s instructions.When the power switch is turned on, the CNC completely resets.

2. Turn the power switch ON. The startup screen activatesand prompts you to Press F10 to continue.

3. Press (F10). The CNC displays the Software Optionsmenu.

4. Highlight 1. CNC Control and press ENTER to activateManual Mode.



Shutting Down the CNC:

1. Press E-STOP to disengage the servos and revert toManual Mode.

2. Press EXIT (SHIFT+F10) to display the Software Optionsmenu.

3. Follow the builder’s instructions for turning off the CNC.Emergency Stop (E-STOP)

Press E-STOP to take all axes and spindle servos offline.This ends all machine movement.

To reset E-STOP, pull out and turn the rotary switchclockwise in the direction of the arrows. The switchmakes a clicking sound when it resets.

Resetting E-STOP does not automatically reactivate theservos. The servos must be reset to move the machine.Press servo reset to restart the servos.

Activating/Resetting the Servos

For safety reasons, the CNC powers up with the servomotors disengaged. While the servos are off, the CNCcannot move the machine. The CNC displays the

message SERVO OFF! when the servos are disengaged.The servos are also disengaged when you press E-STOP,or if the machine attempts to travel beyond a limit switch.

Reset the servos as follows:



1. If a limit switch disengaged the servos, manually reposition the machine inside its normal range of travel.

2. Press E-STOP to display MESSAGE: E-STOP IN-SERVO

OFF!.

3. Rotate the E-STOP switch in the direction of the arrowsto reset it. The E-STOP switch makes a clicking sound when it resets.

4. Press SERVO RESET to display MESSAGE: SERVODELAY, PLEASE WAIT… while the CNC resets the servos.The message disappears when the servos reset.

‘C’ AXIS:

The CNC allows activating axes and spindles as C axis,that interpolated with a linear axis makes it possible tomill the cylindrical surface or the face of a turning part.

Although the machine may have several axes or spindledefined as "C" axis, only one of them may be active.

C· axis on a lathe.

On a lathe, it is most common to activate the spindle as·C· axis and use a live tool to machine the part.

·C· axis on a milling machine.

On a milling machine, it is most common to activate arotary axis as ·C· axis and use the spindle to machine the

part.



Configuration of a ·C· axis.

To activate an axis or spindle as "C" axis, it must havebeen defined as such by the machine manufacturer. To

know whether an axis or spindle may be activated as a·C· axis, refer to parameter CAXIS in the machine

parameter table or to its variable.

PROGRAM EDITOR:

Activating the Program Editor

Program blocks are written using the Program Editor. TheProgram Editor can be activated from the Manual screen,Program Directory, or Draw Graphics. When you activatethe Program Editor, the selected program opens for editing. Activating Edit Mode from the Manual Screen Toactivate the Edit Mode from the Manual screen:

1. With the appropriate program loaded, press EDIT (F3).The Edit Screen activates and Ins (F3) highlights.

Activating Edit Mode from the Program Directory

To activate the Edit Mode from the Program Directory:

1. Highlight a program in the Program Directory.



2. Press EDIT (F8). The Edit screen activates and Ins (F3)highlights. Activating Edit Mode from Draw Graphics

To activate the Edit Mode from Draw Graphics:

Press Edit (F2). The Edit screen activates and Ins (F3)highlights. You can write and edit programs from the Edit Screen. The Edit screen provides the following options:

Program Name The name of the program listed on thescreen. Cursor Location Indicates where text will beinserted (Line:Column). Soft Key Labels These labelsdefine soft key functions. Some soft keys, when pressed,

activate pop-up menus that

contain additional features. (edited) Marker The (edited)marker indicates that the program has been edited and the edits have not been saved. Marked Block Highlighted block(s) to which the activated editing feature (cut,

paste, delete, etc.) will be applied.

Marking Programming Blocks

For many editing features, you must mark the affected program

blocks before the edit is performed. To mark program blocks:

1. In Edit Mode, place the cursor at the beginning of thefirst block to be marked.

2. Press EDITING (F8). The soft key highlights and theEditing Pop-Up Menu activates.



3. Highlight Mark block. Press ENTER. The block ismarked.

4. Use ARROWS to mark the appropriate blocks.

Unmarking Program Blocks

1. In Edit Mode, press EDITING (F8). The soft key highlights and the Editing Pop-Up Menu activates.

2. Highlight Mark block. Press ENTER. Previously marked blocks will no longer be highlighted.

Saving Edits

The Program Listing displays edits as soon as they aremade, but the edits are not saved until you exit theProgram Editor. If the program contains unsaved edits,the (edited) Marker is displayed next to the ProgramName.

To save edits:

1. In Edit Mode, press Exit (F10). The CNC returns to theProgram Directory or Draw Graphics screen and saves all



edits. Canceling Unsaved Edits If edits have not beensaved, they can be canceled.

To cancel unsaved edits:

1. In Edit Mode, press SHIFT and then press Quit (SHIFT +F10).

2. The message WARNING: Program has been edited.Sure you want to Quit? is displayed on the screen, and the soft keys change. Press Yes (F1) to cancel edits and

return to the Program Directory. Press No (F2) to returnto the Edit Mode. Deleting a Character To delete acharacter:

1. In Edit Mode, use ARROWS to place the cursor on thecharacter you want to delete.

2. Press Del (F2) to delete the character .

Deleting a Program Block

There are two ways to delete program blocks from a Program

Listing.

Use the DelBlk (F4) soft key to delete blocks one at atime.

Use the BLOCK operations Delete feature to deleteseveral blocksat a time.

To delete a program block using the DelBlk (F4) soft key:



1. In Edit Mode, place the cursor on the program block tobe deleted.

2. Press DelBlk (F4). The CNC deletes the block.

To delete program blocks using the BLOCK operations Delete

feature:

1. In Edit Mode, mark the blocks to be deleted.

2. Press EDITING (F8). The soft key highlights and theEditing Pop-Up Menu activates.

3. Highlight BLOCK operations. Press ENTER. The Block Operation Pop-Up Menu activates.

4. Highlight Delete. Press ENTER. The CNC deletes themarked blocks.

Undeleting a Block:

You can restore deleted blocks with the Undelete Block feature. The

last block deleted is the first block restored. There are two ways to

restore a block.

To restore a block using the EDITING (F8) Pop-Up Menu:



1. In Edit Mode, place the cursor at the point where therestored block will appear.

2. Press EDITING (F8). The soft key highlights and the

Editing Pop-Up Menu activates.

3. Highlight Undelete Block. Press ENTER. The last linedeleted from the program is displayed at the cursor.

To restore a block with the SHIFT soft key menu:

1. In Edit Mode, place the cursor where the restored block will appear.

2. Press SHIFT and then press UnDelBk (SHIFT + F4). Thelast line deleted from the program is inserted at thecursor.

NOTE:

Up to 128 consecutively deleted blocks can be restored.

Canceling Edits to a Program Block

Use the Restore Block feature to cancel edits made to a program block



and restore the block to its original form. The featuremust be activated

before the cursor has been moved to another block.

To cancel edits to a program block:

1. In Edit Mode, place the cursor on the program block tobe restored.

Press EDITING (F8). The soft key highlights and the

Editing Pop-Up

Menu activates.

2. Highlight Restore Block. Press ENTER. The CNC cancelsthe edits

and restores In Edit Mode, place the cursor on the

program block to be restored.

Press EDITING (F8). The soft key highlights and theEditing Pop-Up

Menu activates.

Highlight Restore Block. Press ENTER. The CNC cancels

the edits

the original block.

Inserting Text without Overwriting Previous TextUse Ins(F3) to activate the Insert Mode. In Insert Mode, the CNCinserts typed text at the cursur



To insert text into a program without overwriting previously

entered text:

1. In Edit Mode, press Ins (F3).

2. Place the cursor where you want to insert the text.Type the new text.

The new text is inserted at the cursor. The CNC does not delete previously typed text as you type.

Inserting Text and Overwriting Previous Text

To insert text into a program while overwriting previously entered

text:

1. In Edit Mode, press Ins (F3) to cancel the Insert Mode.The soft key

will no longer be highlighted.

2. Place the cursor where the text will be inserted. Typethe new text.

The new text is inserted at the cursor. The CNC deletes previously

typed text as you type.





2. Highlight End of program. Press ENTER. The cursor advances to the

last block of the program.

– or –

Highlight Start of program. Press ENTER. The cursor returns to the

first block of the program.

Searching the Program Listing for Selected Text

Use Find Word and Find Next to search blocks for selected text. Type

the text to be found.

To find all references of text in a program:

1. In Edit Mode, place the cursor at the beginning of the program. (FindWord and Find Next search forward in the program only.)

2. Press MOVE (F7). The soft key highlights and the MovePop-Up

Menu activates.

3. Highlight Find Word. Press ENTER.

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RAHUL KUMAR MEC