• What is a CNC Machine?

• CNC : Computerised Numerical Control

• Conventionally, an operator decides and adjusts various machines parameters like feed , depth of cut etc depending on type of job , and controls the slide movements by hand. In a CNC Machine functions and slide movements are controlled by motors using computer programs.

CNC Machines

Definition of Numerical Control M/C

E.I.A : -(Electronic Ind. Association) defines NC Control as‘’A system in which actions are controlled by direct insertion of numerical data or at least some portion of this data.” In simpler language NC means control by number. The input information's for controlling the machine tool motions is provided through punched paper tape or Magnetic tapes in a coded language.

E.I.A -Electronic Ind. Association.ISO -International standard Organization.ASCII -American standard code for Information Interchange.

CNC :-Computerised Numerical ControlComputerised Numerical Control is a numerical

control system that utilizes a dedicated stored programmed. Computer is used to perform some or all basic function. Numerical control is a programmable automation in which process is controlled by Numbers, Letters, and symbols. (Computer +NC= CNC).

Some of the typical function of CNC M/C are:-• Machine Tool Control.• In Process Compensation.• Graphics.• Diagnostics.• Number of CNC M/C Axis : 2,3,4,-------------------24axis.

DNC :- Direct Numerical Control.Direct Numerical Control is a manufacturing system in which number of M/C are controlled by a computer through direct connection and in real time. One computer can be used to control 100 separate machines and it is designed to provide instructions to each M/C tool on demand.

Benefits of DNC1. NC. Without punched tapes.2. Greater computation & Flexibility.3. Convenient storage of NC Part Programme in computer

file. (General format of Programme as C.L. file.) 4. Data collection function like shop floor Control etc.

(Processing & Reporting of shop performance.) 5. Direct conversion of data from CAD to NC Programme.6. Increases Productivity.7. Save time.8. Post Processing.

CNC Machines- Advantages/DisadvantagesAdvantages:

• High Repeatability and Precision e.g. Aircraft parts • Volume of production is very high • Complex contours/surfaces need to be machined. E.g.

Turbines• Flexibility in job change, automatic tool settings, less scrap• More safe, higher productivity, better quality• Less paper work, faster prototype production, reduction in

lead times Disadvantages:

• Costly setup, skilled operators• Computers, programming knowledge required• Maintenance is difficult

Conditions Suitable for Introducing CNC M/C.• Labour cost of the component--------------- High.• Size of batches ----------------------------------- Small.• Repetation of batches-------------------------- Often.• Complexity of the operation Carried out-- High.• Number of operation per Component------ Many.• Time lag between operation ------------------ Low.• Ratio of cutting time to non cutting time --- Low.• Variety of Components to be produced ---- More.• Design changes------------------------------------ Frequent.• Non uniform cutting conditions -------------- Required.• Cost of special tooling involved--------------- High.• Skill required by the operator ---------------- High.• Set-up time /Inspection time----------------- Low.• Number of dimensions to be maintained-- Many• Precision involved in the components------ High.

MACHINE TYPES

1. Group 1: -M/C Tools with rotating tool i.e. Milling M/C, Drilling M/C, Boring M/C , Tapping M/C

2. Group 2: -M/C Tool with Rotating work piece i.e. Lathe.

3. Group 3: -Non Rotating work Piece and non rotating tool i.e. Shaper, Planer, EDM, Wire cut.

4. Group: -Other than above Z Categories i.e. NC Drafting.

Classification of Controllers

1. Point to Point type (P-Type)A. )Only Positioning.B.) No Control over Feed speed.C.) Semi Automatic Drilling M/C Spot Welding M/C etc.

2. Position Control (2PL)

3. 2L/3L Controllers.

4. Continuous Control (C-Type Controllers)A.) 2CL-

a.) 2 ½ Axis Controllers.b.) Simultaneous Control of two Axis + Feed control of one Axis.c.) Can make 2-D Fig. Like Circle, Arc Ellipse.

B.) 3Ca.) 3 Axis Simultaneousb.) Can do interpolation in 3 DimensionsC.) Can Produce SphereD.) Most Suitable for Production Operations

Motion and coordinate system for NC machine

Z-axis: Always aligned with the spindle that imparts cutting power. This spindle might rotate the work-piece as in a lathe, it might rotate a tool as in a milling machine. It is perpendicular to work-holding surface if there is no such spindle. Positive motion in z axis tends to increase the separation between the work-piece and the tool

X axis: Positioning the moving element, parallel to the work-holding surface, horizontal (if possible). On machines with rotating work-pieces, it is radial and parallel to the cross-slide On machines with rotating tools,1.If the Z-axis is horizontal, the positive x motion is to the right when

looking from the spindle to the work-piece. 2. If the z axis in vertical, the positive x axis is to the right when looking

from the spindle to the column On machines with non-rotating work-pieces and non-rotating tools, the x axis is parallel to and directed toward the principal cutting direction

Y-axis: be in such a direction as to complete a right-handed Cartesian coordinate system

What , if you have Multi spindle M/C

Select principle spindle as Primary ‘Z’ axis and other slides/quills are termed as secondary tertiary motion axis.

Axis Rotator Axis A,B,C

Principal: X,Y,ZSecond: U,V,WTertiary: P,Q,R

Fanuc used: - ’U,V,W’ to designates Incremental Movement in ‘X,Y,Z direction. ‘X,Y,Z is used to designates Absolutes Motion.

Axes convention

Axes convention The tool can be moved to any position in a 3 dimensional cartesian co-ordinate system. The Z axis is along the spindle axis. The X and Y axes are perpendicular to Z.

VMC (Vertical Machining Center)

HMC (Horizontal Machining Center)

Open Loop Control SystemA Control system in which the final output value is not directly measured

and checked against the desired value is know as open loop control system.In open loop control system, there is no feedback device to measure the

actual position of tool slide or work table. Hence it can not be compared & verified with Positional value given in command.

Closed Loop Control SystemA control system in which the displacement of machine slide is balanced

signal received from feed back devices is known as closed loop control system. There are two input signals to drive a motor. One is command signal due to which the servo motor is driven. As soon as the displacement takes another signal is generated by the position sensor known as transducer to know that whether the position has-been achieved or not. This actual position signal is feed to the comparator device, which compares it with command signal and produces an electrical signal proportional to the difference between the two. This signal is feed to the servo motor through an amplifier to move the machine slide in a direction to reduce the difference. This loop is followed again and again till the difference between the two signals (input and feedback) becomes of zero amplitude.

Open-loop Control• Stepper motor is used, having a predefined amount of revolution.• Current pulses are send from MCU to individual motors.• Movement/rotation depends on number of pulses send.

Advantages:• Position is maintained just by keeping track of number of revolutions.• Can produce a movement of 1/1000th of an inch, for a single pulse.• Cheap and less complex.• Easy to maintain.

Drawback:• Assumption: Motor movement is precise, i.e. motor is moving the exact

amount depending on the number of pulses.• No way to correct errors, because no feedback.• This control is not suitable for large machines requiring greater power

because of limitation of stepper motor to generate high torque.

• Closed-loop Control• Direct current (DC) motors are used.• Can generate high levels of torque.• Can be reversed.• Unlike stepper motors, it cannot achieve very precise

movement.• Separate positions sensors are required.• Position information is fed back as a signal to the controller.• Major advantage: because of feed back and servo motors

Types of NC control systems reversible feature, errors can be corrected, by comparing with target position.

• Thus formed a closed loop.• Higher accuracy than open loop systems because of feed

back.• Applications:

• Larger NC machines because of higher loads.• For greater accuracy, any kind of load.

• Expensive and complex.

What the Programmer has to do to make Part Programming

1. Study the relevant component drawing thoroughly.2. Identify the type of material to be machined.3. Determine the specifications & function of M/C to be used.4. Decide the dimension and mode: -metric or inch.5. Decide the coordinate system: -Absolute or Incremental.6. Identify the plane of cutting.7. Determine the cutting parameters for the job/tool combination.8. Decide the feed rate programming: -MM/MIN or M/Rev.9. Check the tooling required.10.Establish the sequence of machining operations.11.Identify whether use of special features like Subroutines, Mirror, Imaging

etc. is required or not.12.Decide the mode of storing the part program once it is completed.

Central Processing Unit CPU

Console Interface

Operator Paned

Taper Redder

CRT Key Board

Punch Tape

X Axis

Servo Amplifier

Servo Motor

Encoder

Y Axis

Servo Amplifier

Servo Motor

Encoder

Z Axis

Servo Amplifier

Servo Motor

Encoder

Detail Drawing

Producing Planning

Component SizeType of

Machining Required

Machining type

(Machine Setting)Process

Operation

schedule and time estimatio

n

Work holding

and location

Speeds and feeds

CNC Machining program

Program Proving

Component production

Tooling type

Form in which stock material is

supplied

Coordinates SystemAbsolute Coordinate SystemIncremental Coordinate System

Absolute and Incremental co-ordinates In the absolute programming, the end point of a motion is

programmed with reference to the program zero point. In incremental programming, the end point is specified with

reference to the current tool position.

Absolute traverse to N1, then to N2 X20.0 Z50.0 X50.0 Z30.0

Absolute traverse to N1, incremental to N2 X20.0 Z50.0 U30.0 W-20.0

A X2.000 Y2.000B X1.000 Y-2.000

G90 ABSOLUTE POSITION COMMANDWhen using a G90 absolute position command, each

dimension or move is referenced from a fixed point, known as ABSOLUTE ZERO (part zero). Absolute zero is usually set at the corner edge of a part, or at the center of a square or round part, or an existing bore.

ABSOLUTE ZERO is where the dimensions of a part program are defined from. Absolute dimensions are referenced from a known point on the part, and can be any point the operator chooses, such as the upper-left corner, center of a round part, or an existing bore.

G91 INCREMENTAL POSITION COMMANDThis code is modal and changes the way axis motion

commands are interpreted. G91 makes all subsequent commands incremental.

What is the value in X and Y for each hole in absolute G90 positioning when each moveis defined from a single fixed part zero point of an X0 Y0 origin point.PT1 = X______ Y______PT2 = X______ Y______PT3 = X______ Y______PT4 = X______ Y______PT5 = X______ Y______PT6 = X______ Y______PT7 = X______ Y______PT8 = X______ Y______

From PT8 to PT9 = X______ Y______From PT9 to PT10 = X______ Y______

From PT10 to PT11 = X______ Y______From PT11 to PT12 = X______ Y______From PT12 to PT13 = X______ Y______From PT13 to PT14 = X______ Y______

What is the value for each hole in INCREMENTAL G91 positioning when each move is defined from the previous position and the zero point shifts with the new position.

Fixed zero V/S Floting zero

Fixed zero: -Origin is always located at some position on M/C table (usually at south west corner/Lower left-hand) of the tables & all tool location are defined W.R.T. this zero

Floting Zero: -• Very common with CNC M/C used now a days.• Operator gas lobeity to set zero point at any

convenient position on M/C table• The Coordinate system is knows as work

coordinate system (WCS)

Part ProgrammeThe coded instructions or commands listed in a logical sequence to have a

machine tool perform a specific tasks or a series of tasks in order to produce a finished product in the minimum amount of time.

Programming Format% Programme Number.N Sequence Number (Block Identification Number).G Preparatory functions (G00 to G99). This prepares the M/C for next operation.X,Y,Z Primary motion Dimension in the X,Y,Z direction respectively.U,V,W Secondary motion Dimension in the X,Y,Z direction respectively.P,Q,R Tertiary motion Dimension in the X,Y,Z direction respectively.I,J,K Distance to the are center or thread leads parallel to X,Y,Z respectively.A,B,C Angular Dimension around in the X,Y,Z direction respectively.R Parameters.F Feedrate.S Spindle Speed/Cutting Speed.T/D Tool number.M Miscellaneous function (Machine Codes)EOB End of Block.

PART PROGRAMMING FOR CNC

The transfer of an engineering blueprint of a product to a part program can be performed manually using a calculator or with the assistance of a computer language. A part programmer must have an extensive knowledge of the machining processes and the capabilities of the machine tools . In this section, we describe how the part programmers execute manually the part programs.

First, the machining parameters are determined . Second, the optimal sequence of operations is evaluated . Third, the tool path is calculated . Fourth, a program is written. Each line of the program, referred to as a block, contains the required data for transfer from one point to the next.

A typical line for a program is given below.N100 G91 X -5.0 Y7 .0 F100 S200 T01 M03 (EOB)

DEFINITIONS WITHIN THE FORMAT

1. CHARACTER : A single alphanumeric character value or the "+" and "-" sign.

2. WORD : A series of characters defining a single function such as a, "X" displacement, an "F" feedrate, or G and M codes. A letter is the first character of a word for each of the different commands. There may be a distance and direction defined for a word in a program. The distance and direction in a word is made up of a value, with a plus (+) or minus (-) sign. A plus (+) value is recognized if no sign is given in a word.

3. BLOCK : Series of words defining a single instruction. An instruction may consist of a single linear motion, a circular motion or canned cycle, plus additional information such as a feedrate or miscellaneous command (M-codes).

4. POSITIVE SIGNS : If the value following an address letter command such as A, B, C, I, J, K, R, U, V, W, X, Y, Z, is positive, the plus sign need not be programmed in. If it has a minus value it must be programmed in with a minus (-) sign.

5. LEADING ZERO'S : If the digits proceeding a number are zero, they need not be programmed in. The control will automatically enter in the leading zero's.

EXAMPLE: G0 for G00 and M1 for M01, Trailing zeros must be programmed: M30 not M3, G70 not G7.

6. MODAL COMMANDS : Codes that are active for more than the line in which they are issued are called MODAL commands. Rapid traverse, feedrate moves, and canned cycles are all examples of modal commands. A NON-MODAL command which once called, are effective only in the calling block, and are then immediately forgotten by the control.

7. PREPARATORY FUNCTIONS : "G" codes use the information contained on the lineto make the machine tool do specific operations, such as :1.) Move the tool at rapid traverse.2.) Move the tool at a feedrate along a straight line.3.) Move the tool along an arc at a feedrate in a clockwise direction.4.) Move the tool along an arc at a feedrate in a counterclockwise direction.5.) Move the tool through a series of repetitive operations controlled by "fixed cycles" such as, spot drilling, drilling, boring, and tapping.

8. MISCELLANEOUS FUNCTIONS : "M" codes are effective or cause an action to occur at the end of the block, and only one M code is allowed in each block of a program.

9. SEQUENCE NUMBERS : N1 thru N99999 in a program are only used to locate andidentify a line or block and its relative position within a CNC program. A program can be with or without SEQUENCE NUMBERS. The only function of SEQUENCE NUMBERS is to locate a certain block or line within a CNC program.

Programming Key Letters• O - Program number (Used for program identification) • N - Sequence number (Used for line identification) • G - Preparatory function • X - X axis designation • Y - Y axis designation • Z - Z axis designation • R - Radius designation • F – Feed rate designation • S - Spindle speed designation • H - Tool length offset designation • D - Tool radius offset designation • T - Tool Designation • M - Miscellaneous function

List of G-codesG-code Function G00 Positioning rapid traverse G01 Linear interpolation (feed) G02 Circular interpolation CW G03 Circular interpolation CCW G04 Dwell G20 Inch unit G21 Metric unit G28 Automatic zero return G40 Tool nose radius compensation cancel G41 Tool nose radius compensation left G42 Tool nose radius compensation right G43 Tool length compensation G54 Work co-ordinate system 1 selection G55 Work co-ordinate system 2 selection G56 Work co-ordinate system 3 selection G57 Work co-ordinate system 4 selection G58 Work co-ordinate system 5 selection G59 Work co-ordinate system 6 selection

G80 Canned cycle cancel G81 Drilling cycle G82 Drilling cycle with dwell G83 Peck drilling cycle / deep drill G84 Tapping cycle G85 Boring / Reaming cycle G86 Boring cycle G87 Back boring cycle G90 Absolute command G91 Incremental command G94 Feed per minute G95 Feed per revolution G98 Return to initial point in canned cycle G99 Return to R point in canned cycle

List of M codes

M codes vary from machine to machine depending on the functions available on it. They are decided by the manufacturer of the machine. The M codes listed below are the common ones.

M-codes Function M00 Optional program stop automatic M01 Optional program stop request M02 Program end M03 Spindle ON clock wise (CW) M04 Spindle ON counter clock wise (CCW) M05 Spindle stop M06 Tool change M07 Mist coolant ON (coolant 1 ON) M08 Flood coolant ON (coolant 2 ON) M09 Coolant OFF M30 End of program, Reset to start M98 Sub program call M99 Sub program end

History of CNC

The word address format

Each line of program == 1 block

Each block is composed of several instructions, or (words)

Sequence and format of words:

N3 G2 X+1.4 Y+1.4 Z+1.4 I1.4 J1.4 K1.4 F3.2 S4 T4 M2

sequence no

preparatory function

destination coordinates dist to center of circle

feed rate spindle speed

tool

miscellaneous function

ABSOLUTE PRESET G92

USED TO SHOW CURRENT TOOL POSTION W.R.T. ZERO AT THE TIME OF STARTING M/C.

ONCE THE CUTTER POSITION IS DEFINED USING G92 M/C WILL DRAW ITS CO-ORDINET SYSTEM

ONCE G92 IS DEFINED THEN THERE IS NO NEED TO DEFINE G90

IT IS MODELFORMATG92 X__ Y__ Z__ (CURRENT TOOL POSITION W.R.T ZERO OF JOB)

REFERENCE POINT AND RETURN

G28 Return To Reference Point, set optional intermediate pointThe G28 code is used to return to the machine zero position on all axes. If an X, Y, Z, or A axis is on the same block and specifies a location, only those axes will move and return to the machines’ zero reference point and the movement to the machines‘ zero reference point will be through that specified location.

Format: -G91 G28 X0 Y0 Z0;

Setting work co-ordinate system (G54 - G59) G54 Work co-ordinate system 1 selection G55 Work co-ordinate system 2 selection G56 Work co-ordinate system 3 selection G57 Work co-ordinate system 4 selection G58 Work co-ordinate system 5 selection G59 Work co-ordinate system 6 selection

G54 X_ Y_ Z_ ；

G00 Rapid traverse When the tool being positioned at a point preparatory to a cutting motion, to save time it is moved along a straight line at Rapid traverse, at a fixed traverse rate which is pre-programmed into the machine's control system. Typical rapid traverse rates are 10 to 25 m /min., but can be as high as 80 m/min. Format N_ G00 X__ Y__Z__

G01 Linear interpolation (feed traverse) The tool moves along a straight line in one or two axis simultaneously at a programmed linear speed, the feed rate. Format N__ G01 X__ Y__Z__ F__

G02/03 Circular interpolation

Format N__ G02/03 X__ Y__Z__ I__ J__K__ F__ using the arc center OR N__ G02/03 X__ Y__Z__ R__ F__ using the arc radius G02 moves along a CW arc G03 moves along a CCW arc

Arc center The arc center is specified by addresses I, J and K. I, J and K are the X, Y and Z co-ordinates of the arc center with reference to the arc start point.

I = X coord. of center - X coord. of start point J = Y coord. of center - Y coord. of start point K = Z coord. of center - Z coord. of start point I, J and K must be written with their signs.

Arc radius

The radius is specified with address R.

Block format N__ G02 X__Y__ Z__ R__ F__ N__ G03 X__Y__ Z__ R__ F__

DWELL COMMAND

G04 Dwell Format ： G04X_; or G04F_; or G04P_; X: Specified time(decimal point is permitted) F: Specified time(decimal point is permitted) P: Specified time(decimal point is unpermitted) Explanation ： G04 command dwell. The execution of the next block is delayed by the specified time, specify dwell for each rotation in feed per rotation mode. Dwell is use to stop feed for specified period of time.

G04 X15 ,G04 F15, G04 P15000Here M/C will Dwell for 15 second. The function Not modal. It can be used in Boring, Making CAM Profile, at these point dwell is required.

G15/G16 Commands of polar coordinate The value can be inputted in the form of the polar coordinates (radius and angle ) The angle is position when the first axis of the selected plane is anticlockwise, and negative when it is clockwise.

G16 ； Start the command of polar coordinates (polar coordinates mode)

G15 ； Cancel the order of polar coordinate.

G17/G18/G19 Selection of planes

Use the parameters to appoint the circumrotate axis is X Y or Z ,or the axis that parallel to these axis , specify the G code to select the plane , to this plane , the circumrotate axis is the appointed line axis. For example, when the circumrotate axis is the axis that parallel to the X axis ,G17 should specify the plane of X and –Y, and only circumrotate axis one can be set.

When we omit the address of the axis of X Y and Z , we consider the third axis’s address is omitted

In the program, which are not appointed by the order of G17 G18 G19,the plane stay the same.

Inch/metric command change; G20, G21

G20/G21;

G20 : Inch command G21 : Metric command

G20 and G21 selection is meaningful only for linear axes and it is meaningless for rotary axes. The input unit for G20 and G21 will not change just by changing the command unit.

In other words, if the machining program command unit changes to an inch unit at G20 when the initial inch is OFF, the setting unit of the tool offset amount will remain metric. Thus, take note to the setting value.

Cutter radius compensation (CRC)

G40 Tool nose radius compensation Cancel G41 Tool nose radius compensation Left G42 Tool nose radius compensation Right

Format: -G41 X_ Y_D_ ； G42 X_ Y_D_ ；

SUBROUTINE

A subprogram is a separate program called up by another program. The use of subprograms can significantly reduce the amount of programming on some parts. Subroutines allow the CNC programmer to define a series of commands which might be repeated several times in a program and, instead of repeating them many times, they can be “called up” when needed. A subroutine call is done with M98 and a Pnnnn. The P code command identifies the O program number being used when executed with M98

M99: -An M99 ends a sub-program and returns back to the next line in the main program after the M98 sub-program call.

Tool length compensation (G43) Different tools of different lengths are used in machining any part. The lengths of the tools are not considered in the part program. They are entered in the machine’s memory, and are considered automatically for each motion in the program depending on the tool that is being used. The tool lengths in the Z direction are called the Tool length offsets. Codes Function G43 Make the value of the cutter’s offset add to the value of Z coordinates of the program G44 Make the value of the cutter’s offset subtract the value of Z coordinates of the Program G49 Cancel the offset of the length of the cutter Format: - G43 Z_ H_ ； G44 Z_ H_ ； G49 Z_ ；

Canned cycles Canned or fixed cycles are programming aids that simplify programming. Canned cycles combine many programming operations and are designed to shorten the program length, minimize mathematical calculations, and use minimal tool motions. Examples : drilling, peck drilling, tapping, boring, back spot facing. G81 Drilling cycle G82 Drilling cycle with dwell (Counter bore cycle) G83 Peck drilling cycle / deep drill G84 Right hand tapping cycle G85 Boring / Reaming cycle G86 Boring cycle G87 Back boring cycle G74 Left hand tapping cycle G76 Fine boring cycle

G98/G99 plane of return point When the tool gets to the bottom of the hole, it can return back to the plane of R point and the initialized plane initialized by G98/G99. Generally speaking, G99 is used in the first drilling plane while G98 is used in the last drilling, even though we use G99 to drill, the plane of the initialized position would keep the same.

G81 X_Y_Z_R_F_K_ ；X_ Y_: Data of hole site Z_: Depth of the bottom of hole(absolute coordinate ） R_: Starting point or raising point per time （ absolute coordinate ） F_: Feeding rate of cutting K_: Number of replication (if necessary)

G82 X_Y_Z_R_P_F_K_ ；X_ Y_: Data of hole site Z_: Depth of the bottom of hole(absolute coordinate ） R_: Starting point or raising point per time (absolute coordinate ） P_: Pause time (unit ： ms) F_: Feeding rate of cutting K_: Number of replication (if necessary)

G83 X_Y_Z_R_Q_F_K_ ；Z_: Depth of the bottom of hole(absolute coordinate ） R_: Starting point or raising point per time (absolute coordinate ） Q_: Offset of hole bottom F_: Feeding rate of cutting K_: Number of replication (if necessary)

G84 X_Y_Z_R_P_F_K_ ； operation manual FANUC milling programming X_ Y_: Data of hole site Z_: Depth of the bottom of hole(absolute coordinate ） R_: Starting point or raising point per time （ absolute coordinate ） P_: Pause time (unit ： ms) F_: Feeding rate of cutting K_: Number of replication (if necessary)

G85 X_Y_Z_R_F_K_ ；X_ Y_: Depth of the bottom of hole(absolute coordinate ） R_: Starting point or raising point per time （ absolute coordinate ） F_: Feeding rate of cutting K_: Number of replication (if necessary)

G86 X_Y_Z_R_F_K_ ；X_ Y_: Data of hole site Z_: Depth of the bottom of hole(absolute coordinate ） R_: Starting point or raising point per time （ absolute coordinate ） F_: Feeding rate of cutting K_: Number of replication (if necessary)

G87 X_Y_Z_R_Q_P_F_K_ ；X_ Y: Data of hole site Z_: Depth of the bottom of hole(absolute coordinate ） R_: Starting point or raising point per time （ absolute coordinate ） Q_: Offset of hole bottom P_: Pause time (unit ： ms) F_: Feeding rate of cutting K_: Number of replication (if necessary)

G88 Fixed point dring cycle (G88) Format G88 X_Y_Z_R_P_F_K_;

X_ Y_: Data of hole site Z_: Depth of the bottom of hole(absolute coordinate ） R_: Starting point or raising point per time （ absolute coordinate ） P_: Pause time (unit ： ms) F_: Feeding rate of cutting K_: Number of replication (if necessary)

G88 Pause when feeding to bottom and spindle stops then withdraw quickly

G89 Boring cycle(G89)

Format G89 X_Y_Z_R_P_F_K_ ；X_ Y_: Data of hole site Z_: Depth of the bottom of hole(absolute coordinate ） R_: Starting point or raising point per time （ absolute coordinate ） P_: Pause time (unit ： ms) F_: Feeding rate of cutting K_: Number of replication (if necessary)

G89 Pause when feeding to bottom and spindle stops then withdraw quickly Example N005 G80 G90 G0 X0 Y0 M06 T1 ； change the boring cutter of Ø20 N010 G55 ； call workpiece coordinate of G55 N020 M03 S1000 N030 G43 H1 Z50 ； call length compensation N040 G89 Z-30 R1 P2000 F200 ； boring cycle N050 G80 G0 Z50 ； cancel fixed circle N060 M05 N070 M30

G73 Rapid depth drill circle(G73) Format G73 X__Y__Z__R__Q__ F__K__

X_ Y_: Data of hole site Z_: Depth of the bottom of hole(absolute coordinate ） R_: Starting point or raising point per time （ absolute coordinate ） Q_: Depth of cutting per time （ no symbol, increment ） F_: Feeding rate of cutting K_: Number of replication (if necessary)

G74 X__Y__Z__R__ P__F__K__

X_ Y_: Data of hole site Z_: Depth of the bottom of hole(absolute coordinate ） R_: Starting point or raising point per time （ absolute coordinate ） P_: Depth of cutting per time （ no symbol, increment ） F_: Feeding rate of cutting K_: Number of replication (if necessary)

Fine boring cycle (G76)

G76 X__Y__Z__R__Q__P__F__K__

Z_: Depth of the bottom of hole(absolute coordinate ） R_: Starting point or raising point per time （ absolute coordinate ） Q_: Offset of hole bottom P_: Pause time (unit ： ms) F_: Feeding rate of cutting K_: Number of replication (if necessary)

CIRCULAR POCKET MILLINGThere are two G codes, G12 and G13 that will provide for pocket milling of a circularshape. They're different only in which direction of rotation is used. G12 and G13 arenon-modal.

G12 Circular Pocket Milling ClockwiseX Position in X axis to center of circular pocketY Position in Y axis to center of circular pocketZ Z depth of cut, or it's the increment depth of cuts when used with G91I Radius Of First Circle (Or it's the finish radius if K is not used)K Radius Of Finished Circle (If specified)Q Radius cut increment step-over of the spiral out (Q is used with K only)L Loop count for repeating incremental depth of cuts (L is used with G91)D* Cutter Comp. Offset Number (Enter cutter size in offset display register)F Feed Rate in inches (mm) per minuteThis G12 code implies the use of G42 cutter compensation right

G13 Circular Pocket Milling Counterclockwise

This G13 code implies the use of G41 cutter compensation left and will bemachining in a counterclockwise direction, but is otherwise the same as G12.G13 is usually preffered instead of G12, since G13 will be climb cutting when usedwith a standard right handed tool.