SPRX4014 CAM Lab.docx

8/14/2019 SPRX4014 CAM Lab.docx

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SAFETY

GENERAL

Always be ALERT while machining on CNC machine Know / familiarize yourself with the machine be4fore attempting to set or operate First know all the emergency switches location before proceeding with operation Do not press an switch / button / key unless you know fully well about its function Do not poke your head inside the machine when the machine is ON for any

inspection/setting.

Main switch should be OFF during cleaning the machine

Do not use compressed air for cleaning Do not remove/adjust any safety/limit/proximity switches Do not use non-standard tool-holder

SAFETY CHECKS ON THE MACHINE BEFORE START:

Check the Voltage and current Check the lubricant tank

Check the hydraulic tank oil level Check the clamping devices Check and clean the machine Check the position of tail stock

SAFETY CHECK ON THE MACHINE Check the main pressure of the hydraulic/pneumatic system

Check the clamping pressure of the hydraulic /pneumatic system for chuck and fixture. Check the chuck function. Lubricate the clamping device if any manually Move the slides of Ref. Point in the Ref. point return mode. Jog the slides to and fro and check the sliding movements


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Check the centralized lubrication system manually by pressing appropriates switch

manually

Check the coolant supply by pressing appropriate switch Check the settable Zero offset entries Check the program and the appropriate Zero and tool offset Check the feed Override position Check the speed Override position Check for the alarm if any and set it right Check the tool bits Check the tools position with respect to program Check the tool indexing / tool call safety while the machine is in automatic Check the program control levels (single block, dry run, skip, optional stop, etc.,) Be careful Dry run should not be activated unless it is warranted While in Auto if speed feed is missing store OVER STORE mode/direct entry If Coolant is not activated through program, manually activate the coolant switch Open the door at the end of the job, Preferably in jog mode Clean only with brush the tools and the job. Do not use compressed air for cleaning.


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INTRODUCTION TO C.N.C MACHINES

Definition:

NC stands for numerical control. NC is a method of automation where controlling of a machinetool is by means of a prepared program containing series of numbers. These numbers define the

required position of each side, its feed cutting speed etc.

History:

After World War II the US Air Force has the necessary of producing complicated accurate

aircraft parts. It was very difficult to produce such parts using conventional machine tools. As an

effort to develop a suitable machine tool the joint effort of US Air force, the Massachusetts

Institute of Technology (MIT) and the par sons corporation built the first NC machine at the

MIT U.S.A during 1952 this machine makes use of hared wired components as machine control

unit (MCU) and Punched paper tape a the instructional media.

The development in the hardwired components gives the different generation of NC machines as

follows.

Generation vacuum tubes (1952)

Generation Electromechanical relays (1955)

Generation Discrete Semi Conductors (1960)Generation Integrated Circuits (1965)

Generation DNC (1968)

Generation CNC (1970)

Generation Microprocessor and Micro Computers (1975)

CNC CNC Stands for Computer Numerical Control. The NC Machine which controlled by a

dedicated computer is known as CNC Machine.


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CNC Systems available in India

Controller name Producer

1) FANUC FANUC India, Bangalore

2) HINUMERIC HMT Bangalore

3) ANILAM CRUSADER Kirlosker, Mysore

4) ALLEN-BRANDLEY Lakshmi Electric Controls, Coimbatore

5) EIPRO Elpro, Pune

6) ELECTRAMERIC Electronic Pune

APPLICATION OF NC/CNC MACHINES

For materials removal processes like

Milling

Turning

Drilling

Grinding

Boring

Sawing

Palletized Holder :

It is a plate like thing which hold and locate the components in this, while the operator is loading

and setting the work piece on one pallet, Machining of work piece goes on the second pallet.

Numerical Control is the most sophisticated from of automatic control of a machine tool. By

Numerical control of machine tool it is possible to remove errors in production. The cost of

production is lowered High product quality is maintained.

The machine tools like milling machines, boring machines press tools planers and shapers can be

operated by numerical control. All the operations of these machines are controlled in the required

manner by giving instruction to the machine tools. These instructions are in the form of

numerical data.


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Professor John T. parsons applied numerical control to machine tools in 1950s during that

time, the control system was based on vacuum tube technology Computer Numerical Control

(CNC) was introduced in 1970s in this case the control system is built around a minor or

microcomputer and all the logic functions are achieved by a set of software instruction. The

present generation of CNC system is having large control and processing power.

ADVA NTAGES OF CNC TECH NOL OGY

Most of the advantages deprival from CNC technology are because of high level of automation

and high flexibility of CNC machines and their ability to combine multifunction machines

number of workstation and setups signification advantages are.

1. High accuracy and Repeatability

2. Erase of assembly and interchangeability

3. Less scrap and rework

4. Space savings

5. Less materials handling

6. Less paper work

7. Less lead time

8. Less inventory costs

9. High flexibility for design changes

10. Design freedom for complex shapers and contours

11. Reduced tooling

12. Better machine utilization

13. High levels of integration such as

Direct Numerical control (DNC)

Flexible Manufacturing System (FMS)

Adaptive Control (AC)

Computer Aided Design (CAD)


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Computer Aided Manufacturing (CAM)

Computer Integrated Manufacturing (CIM)

TYPES OF CNC MACH I NES

CNC has been applied to all types of machines, some of the popular CNC machines are

1. Vertical Machining Centers (VMC)

2. Horizontal Machining Centers (HMC)

3. Machining centers with indexing heads

4. Multi axis machining centers

5. Head changer machines

6. Milling machines

7. Drilling machines

8. Horizontal axis turning machines

9. Vertical axis turning machines

10. Surface grinders

11. Cylindrical grinders

12. Internal grinders

13. Tool and cutter grinders

14. Thread grinders

15. Special type of grinders

16. Electrical Discharge Machine (EDM)

17. Wire EDM

18. Punching and nibbling machines

19. Forming machines


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Pipe bending machines

Sheet bending machines

Stretch forming machines

Flow forming machines

Gear cutting machine

Gear Hobbing machines

Gear shaping machine

Gear Grinders

Heat treatment equipments

Welding machines

CNC MACHINING CENTRES

Current generation machining centers offer:

High power and wide speed range

High accuracy and repeatability

High productivity

Features like axis calibration, thermal stabilization and measuring probes

Modular construction

Pallet changers with dual pallet or Multiple pallet pools

Facilities required for unmanned operation through at least one shift such as

Work piece recognition

Selection of suitable program

Selection of required set of tools


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Measuring probes for monitoring work piece accuracy fixture offsets, thermal

error and automatic feed back to CNC system for automatics and on line

correction of errors.

Inspection of tools and automatic insertion of tool offset

Tool condition monitoring and recognition of dull/broken tools

Tool life monitoring

Changing of complete tool magazines

Safety guards to protect the operations from flying chips and coolant

Head changer machines with facility for complete automation changing of tool heads

with multi spindles. This facility offers the advantages of higher productivity with multitool operation. While retaining the flexibility of the machining centers.

90 degrees indexing head machines to facilitate switching over from horizontal to vertical

configuration for machining 5 faces of a box type component in a single setup

Servo controlled tilting head or tilting table machines providing the fifth axis for

machining components like twisted blades. Pump impellers etc. which require cutter axis

to be a perpendicular or parallel to the surface being generated.


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CNC TURNI NG M ACHI NES

Turn mil centers have powered tools located on the turret or slide to facilitate off axis milling,

drilling, tapping, reaming boring, slot milling, etc, in the axial or radial direction to enable

complete machining of many components requiring such operations is a single setting. Thisfacility can also be used for machining of radial cams with c axis control

CNC TURNI NG M ACHI NE FEATURE

High powered drives and wide speed range

Simultaneous two tool operation with 4 axis machines

Heavy duty drum type turrets capable of accommodating internal as well as externalturning tools

Automatic tool changer facility

Off axis machining facility

Touch trigger probes for Work piece size monitoring

Tool condition monitoring

Inspection of tools and setting of automatic tool offsets

Compensation for thermal errors

Programmable steady rests and follow rests

Programmable tail stock


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CNC Controllers

There are large numbers of CNC controllers available today. Some of them are listed below.

Acramatic

ENCO-TURN NUM 560 AEG FANUC PHILIPS ASEA GE550 SINUMERIC BOSETI HEIDENHAIN TRAUB DECKED HELLER UNIPRO 80 YASNAC DIXI NC


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List of G-codes

G-code FunctionG00 Positioning rapid transverseG01 Linear Interpolation (feed)

G02 Circular Interpolation CWG03 Circular Interpolation CCWG04 DwellG05 MultibufferG06 Spline InterpolationG07 Cylindrical InterpolationG09 Exact stop checkG10 PMC data settingG11 Data setting mode cancelG12 Polar co-ordinate interpolationG13 Polar co-ordinate interpolation cancel model

G15 Polar co-ordinate interpolation command cancelG16 Polar co-ordinate commandG17 Selection of XY planeG18 Selection of ZX planeG19 Selection of YZ planeG20 Inch unitG21 Metric unitG22 Stored stroke limit function ONG23 Stored stroke limit function OFFG25 Spindle speed fluctuation direction OFFG26 Spindle speed fluctuation direction ONG27 Zero return checkG28 Automatic zero returnG29 Return from zeroG30 2 n reference point returnG31 Skip functionG32/G33 Threading cycleG37 Automatic tool length measurementG40 Tool nose radius compensation cancelG41 Tool nose radius compensation leftG42 Tool nose radius compensation right

G43 Tool length compensation plusG44 Tool length compensation minusG45 Tool offset, extensionG46 Tool offset, reductionG47 Tool offset, double extensionG48 Tool offset, double reductionG49 Tool length compensation cancelG50 Scaling cancel


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G51 ScalingG52 Local co-ordinate systemG54 Selection of work co-ordinate system 1G55 Additional work co-ordinate system 2G56 Additional work co-ordinate system 3

G57 Additional work co-ordinate system 4G58 Additional work co-ordinate system 5G59 Additional work co-ordinate system 6G60 Single direction positioningG61 Exact stop check modeG62 Automatic corner override modeG63 Tapping modeG64 Continuous cutting modeG65 Call of user macroG66 Model call of user macroG67 Model call of user macro, cancelG68 Co-ordinate system rotationG69 Co-ordinate system rotation, cancelG70 Finishing cycleG71 Stock removal in turningG72 Stock removal in facingG73 Peck drilling cycle/Pattern repeatingG74 Peck drilling on Z-axis/ face grooving /

reverse tapping cycle(milling)G75 Peck drilling cycle on X-axis/Int-Ext groovingG76 Multiple threading cycle/ fine boring cycle(M)G80 Canned cycle cancel (milling)G81 Drilling cycle, spot drilling (milling)G82 Drilling cycle, counter(milling)G83 Peck drilling cycle/deep drill(M)G84 Tapping cycle(M)G85/G86 Boring cycle(M)G87 Back boring cycle (M)G88/G89 Boring cycle(M)G90 Absolute programmingG91 Incremental programmingG92 Setting co-ordinate

G93 Inverse time feedG94 Feed rate, mm/minG95/G99 Feed per revolutionG96 Constant surface speed controlG97 Constant surface speed control, cancelG98 Initial level return in fixed cycleG99 R level return in fixed cycle


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List of M-codes

M00 Optional program stop automaticM01 Optional program stop requestM02 Program endM03 Spindle ON clock wise (CW)M04 Spindle ON counter clock wise (CCW)M05 Spindle stopM06 Tool changeM07 Mist coolant ON (coolant 1 ON)M08 Flood coolant ON (coolant 2 ON)M09 Coolant OFFM10 B-axis clampM11 B-axis unclamp

M12 Hyd. Power rotary table onM14 Oil hole drill coolant onM16 Heavy tool changeM17 Tap cycle confirmationM18 Tap cycle cancelM19 Spindle orientationM20 Coolant nozzle upM21 Coolant nozzle middleM22 Coolant nozzle downM23 Direction of contact in XM24 Direction of contact in +XM25 Direction of contact in YM26 Direction of contact in +YM27 Tool breakage directionM28 Automatic gap eliminationM29 M27 & M28 togetherM30 End of program, and rewind, reset to startM50 Air blow onM52 Tool length offset measurementM53 Tool length offset executionM54 Tool length offset cancelM57 Measurement along Z axisM58 Execution along Z axisM59 Cancel along Z axisM60 Measurement along +X axisM61 Measurement along -X axisM62 Execution along X axisM63 Cancel along X axisM64 Measurement along +Y axis


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M65 Measurement along -Y axisM66 Execution along Y axisM67 Cancel along Y axisM70 Return to zero rotary table positionM73 Y axis mirror image off

M74 Y axis mirror image onM75 X axis mirror image offM76 X axis mirror image onM80 Rotary table CW rotationM81 Rotary table CCW rotationM82 Step mode tool removalM83 Step mode tool change cycleM84 Step mode tool jig operationM88 Splash guard openM89 Splash guard closeM90 Pallet changeM92 Pallet unclampM96 Pallet loading and advanceM97 Pallet loading retractM98 Call of sub programM99 End of sub program

M codes vary from machine to machine depending on the functions available on it and themanufacturer of the machine decides them.

There are other M-codes for functions like gear change, tail stock quill in/out, chuckclamp/unclamp, chip conveyor forward/backward, door open /close etc.


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Command DescriptionG18G02G03Xp_

Zp_I_K_

R_F_

specification of arc on zpxp planecircular interpolation clockwise direction (cw)circular interpolation counter clockwise direction (ccw)command values of X axis

command values of Z axisxp axis distance from the start point to the center of an arc with sign, Radiusvaluezp axis distance from the start point to the center of an arc with sign, Radiusvaluearc radius with no signfeed rate along the arc

DWELL G04

A G04 causes the program to wait for a specified amount of time. The time can be specified inseconds with X or U prefixes or in milliseconds with the P prefix. During cutter motion, adeclaration at the end of the motion specified by the statement and an acceleration at the start ofthe motion specified by the next statement are usually applied by the NC controller. A G04 codecan be inserted between the two statements to make a sharp corner .

Format:

G04 X_; or G04 U_; or G04 P_;

INCH/METRIC G20 & G21(G20, G21)

Either inch or metric input can be selected by G code

G20: inch inputG21: mm input

This code must be specified in an independent block before setting the Co-ordinatesystem at the beginning of the program. After the G code for inch/metric conversion is specified,the unit of input data is switched to the least inch or metric input increment of increment systemIS-B. The unit of data input for degrees remains unchanged. The unit system for the followingvalues are changed after inch/metric conversion:

- Feed rate commanded by F code- Positional command- Work piece zero point offset value- Tool compensation value- Unit of scale for manual pulse generator- Movement distance in incremental feed- Some parameters


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REFERANCE POSITION RETURN BACK (G27)

The reference position return check in the function which checks whether the tool has currectlyreturned to the reference position as specified in the program. If the tool has correctly returnedto the reference position along a specified axis, the lamp for the axis goes on.

Format G27 IP_;REFERANCE POSITION RETURN (G28) Tools are automatically moved to the reference position via an intermediate position along aspecified axis. When reference position return is completed, the lamp for indicating thecompletion of return goes on. Positioning to the intermediate positions are performed at therapid traverse rate of each axis.Format G28 IP_;

SECOND REFERANCE POINT RETURN(G30)Up to four references, position can be specified by setting coordinates in the machine coordinatesystem in parameters.Format G30 IP_;

SKIP FUNCTION (G31)Linear interpolation can be commanded by specifying axial move following the G31 commandlike G01. If an external skip is input during the execution of this command, execution of thecommand is interrupted and the next block is executed.

The skip function is used when the end of machining is not programmed is used specified with asignal from the machine, for example, in grinding. It is used also for how to use this function,refer to the manual supplied by the machine tool builder.Format G31 IP_;

G31: one-shot G code (if is effective only in the block in which it is specified).

TOOL NOSE RADIUS COMPENSATIONCompensation functionTools offset:

Standard tool

Offset amount in X axis Actual tool

Offset amount on Z axis


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Tool offset is used to compensate for the difference when the tool actually used differs from theimagined tool used in programming usually, standard tool.

During programming, four digits following the letter is written, the first two digits represent the

tool number and the second two digits represents the tool offset number.Format: T03 05 03 tool number; 05 offset number

TOOL WEAR OFFSET

With the option of tool geometry and wear compensation, it is possible to divide the tool offsetfor compensating the tool shape or mounting position to the geometry offset and tool wear to thewear offset. The total value of the tool geometry offset and compensation option is notequipped. Fig.2 and 3 illustrate the method of differentiation of tool geometry offset from toolwear offset.

Point on the program

Actual tool

Imaginary tool

Z axis wear offset

Z axis geometry offset

FIG.2 Differentiate the tool geometry offset from too wear offset

POINT ON THE PROGRAM

Offset amount on Z axis

FIG 3: Do not differentiate the tool geometry offset from tool wear offset

X a x

i s g e o m e t r y

o f f s e

t v a l u e

O f f s e

t

a m o u n

t o n

X a x

i s


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TOOL NOSE RADIUS COMPENSATION (G40)

In turning operations on lathe, the positions and cutter path for contouring motion cannot be defined directly on the basis of the dimensions specified on a part drawing. The co-ordinatesof the end position is each non touring motion statement of a NC program must be calculated.

This calculation is time consuming and error prone. On modern CNC machines, specialcalculation functions or cutter radius compensation codes are provided to allow a user to utilise part profile coordinates obtainable from the part drawing to program a contouring motion.These are the G41 and G42 codes for tool radius compensation on the left hand and right handsides of a profile respectively. A left or right compensation is based on the fact that the tool is onthe left or right hand side when one goes along the part profile is the direction specified by thecontouring motion statements is the programme. A G-40 code is provided to cancel the cutterradius compensation. The tool nose radius compensation function together with the tool offsetfunction automatically compensates in cutting due to tool nose roundness.

Tool path without compensationTool path with compensation

Tool nose radius

FIG.4: Tool nose radius compensation

The nose of a lathe cutter is only a section of a circle and does not rotate like an end millduring the cutting process. Therefore different types of cutting compensation vectors must beapplied with different types of tools as shown in Fig.5 which illustrates the relationship betweenthe tool and the start point. The end of the arrow is the imaginary tool nose. The direction of theimaginary tool nose viewed from the tool nose centre is determined by the tool motion duringcutting, this is set advance with the offset values. Imaginary tool nose numbers 0 and 9 are usedwhen the tool nose centre coincides with the start point.


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X

Z

Imaginary tool nose Number 1 Imaginary tool nose

Number 2

Imaginary tool nose number 3 imaginary tool nose number 4

Imaginary tool nose number 5Imaginary tool nose radius 6

Imaginary tool nose number 8

Imaginary tool nose number 7

NOTE ON TOOL NOSE RADIUS COMPENSATION

In the linear move before entering the tool nose compensation always add on a value more thanthe radius of the tool.

After the Tool Radius Compensation had been applied and the particular move has beenexecuted (i.e. an arc has been turned) their two linear straight line moves must be made beforecancelling the tool radius compensation with G-40.

The two linear moves must be greater than the tool radius compensation.


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CO-ORDINATE SETTING (G50)G50 enables tool nose radius compensation to the left of the programmed path G50 has 2 uses.Co- ordinate setting block has X, Z, U or W upon it. A maximum spindle speed blockdoes not.

G50 sets the maximum spindle speed for constant surface control. An X, Z, U or W prefix must not be on the block or it will be interpreted as a coordinate setting block.

Example: G50 S20000

G50 creates a new coordinate system is which the tools current position is set to the specifiedcoordinates. The new co-ordinates can be is absolute or incremental form.

Example: G50 X0 Z0G50 U 40

CONSTANT SURFACE SPEED (G96)

The cutting speed during turning is the peripheral speed of the work. The peripheral speed of arotating work reason represents the peripheral path is a given unit time as shown in Fig.6. The

peripheral speed or cutting speed is thus the fully stretched chip length produced is on time. Thecutting speeds vary in direct relation to the diameters, even if the number or revolutions perminute is the same in all cases.

L3 - Length of the stretched chip = D3 X NL2 - Length of the stretched chip = D2 X NL1 - Length of the stretched chip = D1 X N

Fig.6 BASIC CONCEPT OF SURFACE SPINDLE SPEED

The correct selection of the cutting speed for turning is very important.

Cutting speed too low: Time loss and low surface finish. With increasing the cutting speed theSurface speed is improved.

Cutting speed too high: High tool wearThe advantage of the CONSTANT SPEED SURFACE SPEED can be evident through a partingoperation. The diameter of the work where cutting is taking place is steadily decreasing. The cuttingefficiency can only be maintained if the spindle speed is increased at a corresponding rate to the speedwhere the cutting is taking place is constant. This operation however, may not be critical enough towarrant the need for the cutting speed facility. A complex component with turned profiles requiring auniformly right surface finish would demand the use at the C.S.S. facility.

Note: When constant surface speed control us used, the work coordinate system must be set to so thatthe centre of rotation meets the Z-axis (X=0).

Example: G96 S100Set the surface speed to 100 minutes.


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NORMAL SPINDLE SPEED (G97)

G97 cancels constant surface speed. The spindle speed will not change until the next S value isreached.

Example: G97 S1500 MS (or) G97 S1500 M4

FEED PER MINUTE (G98)

Description IllustrationThis command couples with the F word isused to specify feed rate per minute. Thiscan be either mm/min or inch/min. This isthe default.

F

F = Displacement along the Z axis per minute

Example: G98FG0 (METRIC)

Note: The DENFORD FUNIC simulation will default to G98 and this .. and will remainactive until G99 (Feed per revolution) is entered.

G99 FEED PER REVOLUTION

Description Illustration

This command coupled with the F word isused to specify a feed rate per revolution.This can be in mm/rev or inch/rev. The feedrates available are 0.01 200 mm/min.Recommended feed rates are published by


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M-Code (Miscellaneous function)

M00 - Program stop

M01 -Optional stop

M02 - Program end

M03 - Spindle clock wise

M04 - Spindle anti clock wise

M05 -Spindle stop

M06 - Tool change

M07, M08 -Coolant ON

M09 -Coolant OFF

M10 - Chuck open

M11 -Chuck close

M16 -Chuck ID selection

M18 - Chuck OD selection

M30 -Program end & rewind

M98 - Sub program call

M99 -Sub program exit

PROGRAM STOP(M00)

By inserting M)) in a program, the cutting cycle is stopped after the block containingM00 code. The facility is useful if an inspection/check is necessary during an operation. thecycle is the contained by a cycle start.

Example: M00


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OPTIONAL STOP (M01)

Cycle operation is stopped after a block containing M01 is executed. This code is onlyeffective when the optional stop switch on the machine control panel has been pressed.

Example: M01

PROGRAM END(M02)

This code is inserted at the end of the program, when encountered the cycle will be end.To produce another, the system must be rest.

Example: M02

SPINDLE FORWARD(M03)

Description starts the spindle spinning forward

Clock wise or negative direction at the last specified

spindle rate.

Example: M03 S1200

SPINDLE REVERSE (M04)

Description starts the spindle spinning reverse,

Counter clock wise or positive direction at the last

specified spindle rate.

Example: M04 S1000

STOP SPINDLE (M05)

Stop the spindle without changing the spindle speed.


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TOOL CHANGE (M06)

The M06 is conjuction with T word is used to call up the required tool on an automaticindexing turret machines and to activate its tool offsets. The left most digits of the Tignoring zeros selects tool. Tool changes are normally performed with the tool post at a safe

position away from the work piece to the code G28 REFERANCE POINT RETURN would be used in the block prior to M06.

Example: M06 T0200

And T20

And T2 all select tool 2.

COOLANT ON(M07, M08)

Description M08 turns the coolant on

COOLANT OFF(M09)

M09 turns the coolant off

CHUCKS OPEN(M10)

M10 opens pneumatic or similar automatic chuck to allow for bar feed.

CHUCK CLOSE(M11)

M11 closes the chuck

PROGRAM END (M30)

Stop the spindle. Turns the coolant off, terminates and rests the CNC program.

Example: M30


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SUB PROGRAM CALL/ EXIT-M98/M99

MAIN PROGRAM SUB PROGRAMA program is divided into a main

program and subprogram- normally the CNCoperates according to the main program butwhen a command calling a subprogram isencountered in the main program control is

passed to the sub program. When a commandindicating to return to the main program isencountered in the sub program. The first

block of program subroutine must contain a program O

When a program contains certain fixedsequences or frequently repeated patterns,these sequences or patterns may be enteredinto memory subprogram to simplify

programming. A sub program can callanother sub program. When the main

program call a sub program, it is regarded asa one-loop program call.Format: O0001

NOTE ON M98/M99P value specifies the program number and the number of times to execute it. The

rightmost a digit are the program number. The digits to the left are the numbee of repetitions.There can be up to 99 repetitions. If the value is omitted it is caleed oncdeExample: M98 P12

M98 P10012 execute the program number 12 onceWhen a sequence number is specified with address P in the last block of a sub program,

control does not return to the block after in which the sub program was called but rather tothe block with the sequence number specified under address P. However this is effectively ismemory operation.Example: M99 returns to the block following the call

M99 P10 returns to the block with N value 10


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TOOLING

ISO Designation Inserts

A wide variety of tool inserts are used for turing , boring, milling, drilling and other allied

operations. Figure shows some of these inserts. There are several standard systems fordesignating these inserts. The ISO system is discussed in this section.

TNMA TNMG-26 TNMG

SNMA SNMG TCMT

CNMA CNMG CCMT

DNMA DNMG WNMG


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INSERT SELECTION:

Inserts are coded according to the materials which they can be used to cut. The six codescommonly used are listed below:

Code Material DescriptionP Steel Un alloyed and alloyed steelM Stainless steel Austenite stainless steel , cast steelK Cast iron Malleable, grey, S.G

N Non-ferrous Al, other non ferrous, non metallicS Difficult to cut Titanium alloys, Co and steelH Hard Materials Hardened CI and steel

MACHINING CONDITIONS:

These are the factors which affect the application of maximum speed and feed of indexable cutting tools for a given application. They are to be used under highly rigid conditions.

Factor affecting rigidity:

Length or overhang of the tool -The more overhang, the less the rigidity Condition of machine tool - New and well m prone to chatter maintained

Machine tools are less prone to chatter. Rigidity of tool holder - Size of spindle taper - the larger the taper size, the better from rigidity

angle.

Work piece rigidity - Optimum speeds cannot be used with slender orThin work pieces.

Fixture rigidity - Fixture should be rigid. Vibration Isolation - The machine should be free from influence of

Surrounding vibration


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Other factors affecting the selection:

o Type of cut - Continuous, intermittento Use of coolant - There are good and bad effects depending on the insert type.

Machining conditions can be classified into three types:

SlNo.

Conditions Symbol Description

1. Good O Operation at optimal speeds and feeds2. Moderate Operation at less than optimal speeds and feeds3. Critical Operation at significantly less than optimal speeds and

feeds

ISO DESIGNATION OF INSERTS:

Typical ISO designation for the turning and milling inserts are given below:

Turning

Milling

Manufacturing detail

Cutting direction

Cutting edge

Corner radius

Thickness

Length

Special features

Tolerances

Clearance angle

Insert shape

Fig 3.2 ISO designation of inserts

C N M G 12 04 - R PM5

A P H W 20 04 60 T A27


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Detailed Explanation of the ISO designation:

1. Insert shape

Inserts of several shapes are used for different application. In fig 3.3 C, D etc arerhomboidal shapes which are popular. Shape C is particularly used for roughturning. Shape W is now preferred by many users. Shapes D and V are widelyused for finish turning applications. Shape V is useful for contoured parts.

35

V D R

S T W

8582 80


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2. Clearance angle:

The second alphabet represents Clearance angle which from 3degrees to11degrees. Fig3.4 shows the designation of clearance angle.

3 15 30

A D G

5 20

B E N

7 25 11

C F P


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3. Tolerances:The tolerances on the insert are important. The third alphabetical character denotes thetolerances. This shown in fig 3.5.

M

D D S

D M S

A

C

E

G

H

M

0.025

0.025

0.025

0.025

0.0005

0.002

0.005

0.0125

0.025

0.025

0.0005

0.003

0.025

0.025

0.025

0.05

0.001

0.005

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