A Computer Numerical Control (CNC) system is a Numerical Control system

wherein a dedicated stored program computer is used to perform some or all the basic NC

functions in accordance with control programs stored in the read write memory of the

computer. The CNC machines are mainly utilized for batch production. The advantages

of CNC are: (1) High accuracy and repeatability (2) Less material handling (3) High

flexibility for design changes (4) Reduced toolings (5) Better machine utilization (6) Less

scrap and rework. The accuracy of CNC machines depend upon the (1) Quality of the

drive motors (2) Quality of the ball screws.

The equipment for each axis of CNC machines consist of a mechanical device that

performs the motion, a drive motor that supplies the power for the axis and a ball screw

that transfers the power from the drive motor to the mechanical device. Rotation of the

ball screw makes motion of the mechanical device possible. The drive motor is the link

between the ball screw and the CNC control. Also called a servomotor, it allows

extremely precise rotation.

The machines, which are available in CNC Shop, are the following:

(1) DECKEL FP2A (VERTICAL SPINDLE MILLING MACHINE)

(2) DECKEL FP4AT (VERTICAL SPINDLE MILLING MACHINE)

(3) DECKEL MAHO MH600C (HORIZONTAL SPINDLE MILLING

MACHINE)

(4) HARDINGE CONQUEST T42 CNC LATHE

(5) HARDINGE SUPERSLANT CNC LATHE

(6) HMT KTM 1000 CNC HORIZONTAL MACHINING CENTRE

(7) MIKRON UCP 710 5 – AXIS MACHINE

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DECKEL FP2A

Technical Data

Working Range

X – axis (Longitudinal) - 300 mm

Y – axis (Transverse) - 300 mm

Z – axis (Vertical) - 350 mm

Quill stroke (Vertical) - 60 mm

Control System

Fagor CNC 8025GP Control

Main Drive

Pole changing 3-phase brake motor for clockwise/counterclockwise rotation

Power rating - 1.6 / 2 KW

No. of spindle speeds - 21

Range of spindle speeds - 31.5 to 3150 rpm

Speed progression factor - 1.25

Spindle taper - ST ISO 40 (M16)

Tools clamped mechanically and unclamped by hydraulic force.

Table Slide

Max load on table slide - Appr. 600 kg

Universal Table

FP2A is supplied with a universal table. The table top of the universal table can be

rotated through 360 manually. The table can be tilted about the A and B axes (only by

40) by means of a ratchet tool.

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DECKEL FP4AT

Technical Data

X – axis (Longitudinal) - 560 mm

Y – axis (Transverse) - 500 mm

Z – axis (Vertical) - 450 mm

Control System

Dialogue 11 Control

Main Drive

Pole changing 3-phase brake motor for clockwise/counterclockwise rotation

Power rating - 2.0 / 4.0 KW

Change Speed Transmission

No. of spindle speeds - 21

Range of spindle speeds - 40 to 4000 rpm

Speed progression factor - 1.25

Tool Changer for Vertical Spindle

Tool dia max, with all stations occupied - 80 mm

Both adjacent locations free - 100 mm

Max tool length from spindle nose - 300 mm

No of tools - 20

Spindle taper - ST ISO No 40 (M16) [Std

Taper No 40 with metric

draw–in thread, 16 mm dia]

Table Slide

Max load on table slide - 800 kg

The applications of the machine include machining of workpiece of high weight.

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DECKEL MAHO MH600 C

(Horizontal Spindle Milling Machine with Vertical Spindle Attachment)

Technical Data

Traversing Range

X – axis - 600 mm

Y – axis - 450 mm

Z – axis - 450 mm

Control System

Philips CNC 532 Control

Work Spindle

Tool mounting - ISO 40

Spindle Speeds and Feed Rates

Work spindle speeds, directly programmable - 20 to 6300 rpm

Feed rates, directly programmable along X, Y, Z axes - 1 to 6000 mm/min

Tool Change and Tool Magazine

Magazine stations - 30

Tool shank - ISO 40

Tool dia max, with all stations occupied - 130 mm

Both adjacent locations free - 80 mm

Max tool length (from spindle nose) - 250 mm

Max tool weight - 10 kg

Electrical

Voltage - 380 V for 3 phase

Frequency - 50 Hz

The NC rotary table can be used for program controlled table rotation.

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HARDINGE CONQUEST T42 CNC LATHE

Specifications

Control system - GE Fanuc 18T

Spindle run out - 1 micron

Max capacity - Dia 220 mm

Distance between centres - 400 mm

No of turret - 1

No of tools on turret - 12

Live tools - 6

Spindle indexing - 2 1/2

Controllable axes - 2 (X and Z axes)

Machine cost - 54 lakhs

The standard Conquest machines have a 12 station turret top plate. The special feature

of this machine is Live Tooling. It is designed to perform machining such as milling,

drilling and tapping on work piece locations not parallel or not in line with the spindle

centerline. Programming the live tooling is accomplished by means of five special M

Codes used for standard machining.

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HARDINGE SUPERSLANT CNC LATHE

Specifications

Control system - GE Fanuc 6T

Spindle run out - 0.5 micron

Max capacity - Dia 220 mm

Distance between centres - 400 mm

No. of turrets - 2

No. of tools on each turret - 8

Live tools - 4 (in top turret)

Controllable axes - 4 (X and Z axes in 2 turrets)

Additional features - Part catcher conveyor for

chip removal (scrap type)

Machine cost - 36 lakhs

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MIKRON UCP 710 5 – AXIS MACHINE

Technical Data

Distance of Traverse

X – axis - 800 mm

Y – axis - 650 mm

Z – axis - 500 mm

Control

Heidenhain iTNC 530

Spindle Version 12000 rpm

Spindle speed - 50 to 12000 rpm

Power - 16 KW at 44% CD,

12 KW at 100% CD

Lubrication - Grease

Max tool projection

Upto 1000 rpm - 350 mm

Upto 4000 rpm - 250 mm

Upto 10000 rpm - 200 mm

Tool Changer TC 30

Magazine positions - 30 with firm position coding

Tool retention - ISO 40

Tool diameter - 90 mm if completely

occupied and 140 mm if

partially occupied

Max tool length - 300 mm without taper

Max tool weight - 8 kg

Max weight of all tools - 180 kg in the drum magazine

Tool change time - Appr. 9 seconds

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The machine is designed as a travelling slide machine. All three linear movements are

executed with the tool. The three axes unit consists of a cross – slide for the X movement,

transverse slide for Y movement and the spindle slide for Z movement. The three basic

axes X, Y, Z are driven by maintenance free AC servomotors via ballscrews, which

provide an outstanding feed performance.

The machine is equipped with an NC rotary tilt table with digitally controlled drives

in the shape of the fourth and fifth axes. The axes can be traversed individually or

simultaneously. In addition, both axes can be clamped hydraulically in any position and

independently of each other. Clamping takes place by means of the hydraulic unit of the

machine. Both axes are driven by AC motor. In the tool magazine, the tools are kept in

position by means of spring loaded jaws.

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HMT – KTM 1000 CNC HORIZONTAL MACHINING CENTRE

Specifications

Range of Axes Travel

Longitudinal – X axis (Table) - 1750 mm

Vertical – Y axis (Spindle) - 1300 mm

Depth – Z axis (Column) - 1000 mm

B – axis - 360 (continuous)

Control System

Siemens 840D

Feed Rates

Linear axes – X, Y, Z axes - 1 to 7000 mm/min

Rotary axis - 1440 / min

Spindle

Drive - 15 KW (20 HP) AC motor

Speeds - 10 to 3600 rpm

Tapping speed range - 20 to 1000 rpm

Nose - ISO 45 taper

Draw bolt - Spring clamped, hydraulically

unclamped

Automatic Tool Changer and Magazine

Capacity - 60 tool storage

Tool weight - 15 kg max

Tool length - 400 mm

Tool size - 90 mm dia max (160 mm dia

max with adjacent pockets

empty)

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Table

Overall table work surface - 1000 x 1000 mm square

rounded to 1250 mm dia

Max overall table load - 1800 kg

Accuracy

Positioning of linear axes - 0.009 over full travel

Repeatability of all linear axes - 0.005

Rotary axes positioning - 4 seconds of arc accuracy

Rotary axes repeatability - 5 seconds

Weight of machine - 19 tonnes appr

HMT KTM 1000 CNC machining center is a CNC controlled horizontal

spindle machining centre, which consists basically of the following units –

1. Machine

2. Control Unit

3. Hydraulic Power Supply

The machine offers three perpendicular axes motions together with a rotary

fourth axis, pallet shuttle, automatic tool selection for 60 tool magazine and an automatic

tool changer. The X axis motion is provided by the motion of the table. The Y axis

motion is provided by the vertical motion of the spindle head perpendicular to the spindle

axis. The Z axis motion is provided by the horizontal motion of the column parallel to the

spindle axis. The machine control unit is a specially designed Siemens 840D CNC

equipped with a feedback capable of controlling the four axes motions of the machine.

The table rotating in both directions and having its axis of rotation parallel to Y axis

constitutes the B axis.

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CNC PROGRAMMING

A part program is an ordered set of instructions, which define slide and spindle

motion as well as auxiliary functions. These functions are written in a part language

consisting of a series of data blocks. Each data block contains adequate in formations for

the machine tool to perform one or more machine functions. The basic unit for part

program is the Block. Normally one line or block information represents one describable

operation or several describable operations that are independent of each other.

The block and the program have the following configuration:

N0000 G00 X00.0 Y000.0 M00 S00 T00 ;

Sequence Preparatory Dimension Misc. Spindle Tool End of

Number: Function word function Function Function Block

G Codes for GE FANUC 18 – T Control System

G00 – Positioning - This command generates linear motion on one or axes (X, Y or Z

axes) from current position to programmed end points at a rate determined by the %

Rapid Override switch.

G01 – Linear Interpolation - This command generates linear motion on one or more axes

(X, Y or Z axes) from the current position to the programmed end points at a rate

specified by a feedrate command in the same block or by an active feedrate from a

preceding block.

G02 – Clockwise Arc Interpolation - This command is used with I and K words (arc

centre offset) or R word (radius) to provide the necessary qualifying dimensions of the

arc. The path is traced by the tool for clockwise arc.

G03 – Counterclockwise Arc Interpolation - This command is used with I and K words

(arc centre offset) or R word (radius) to provide the necessary qualifying dimensions of

the arc. The path is traced by the tool for counterclockwise arc.

G04 – Dwell - The dwell command must be programmed with X, U or P word to specify

the duration of the dwell in seconds. It does not generate axis motion. E.g. :- G04 X2.5,

G04 U2.5, G04 P2500 (P word gives dwell duration in milliseconds, since decimal point

programming cannot be used with P word).

G20 – Inch Data Input - Inch mode allows the programmer to program in inch units.

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G21 – Metric Data Input - Metric mode allows the programmer to program in metric

units.

G40 – Cancel TNRC – The TNRC cancel command, when programmed in a block by

itself, cancels tool compensation.

Other G codes that are most commonly used are:

G41 – TNRC – Workpiece right of tool

G42 – TNRC – Workpiece left of tool

G65 – Macro call

G70 – Automatic finishing cycle

G71 – Automatic rough turning cycle

G72 – Automatic rough facing cycle

G73 – Automatic rough pattern repeat cycle

G74 – Automatic drilling cycle

G76 – Automatic threading cycle

G80 – Cancel face machining cycle

G81 – Single pass face drilling cycle

G84 – Face tapping cycle

G98 – Inches / Millimeters per minute feedrate

G99 – Inches / Millimeters per revolution feed rate

M Codes

M00 – Program Stop - The program stop function stops the program, stops the spindle

and turns the coolant off. This function can be used for gauging and end – for – ending

the workpiece.

M01 – Optional Stop - This function performs the same function as M00, if the optional

stop push button on the control panel has been activated before the block containing the

M01 is read by the control. This function is useful when it is necessary to gauge the

workpiece during setup.

M02 – End of Program - The end of program function indicates the end of program and

is usually found in the last block programmed

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M03 – Main Spindle Forward - The main spindle forward command causes the spindle

to run in the forward direction at the programmed spindle speed (S word).

M04 – Main Spindle Reverse - The main spindle reverse command causes the spindle to

run in the reverse direction at the programmed spindle speed (S word).

M08 – Coolant On - The coolant on command turns the coolant pump on.

M09 – Coolant Off - The coolant off command turns the coolant pump off.

M30 – End of Program - The end of program command indicates the end of a program

and is usually found in the last block programmed. It stops the spindle, turns the coolant

off and rewinds the program to its beginning.

M98 – Subprogram Call - The subprogram call must be in the main part program block,

which activates a subprogram. It is programmed with a P word, which specifies a

subprogram number.

G Codes (FAGOR AUTOMATION)

G00 – Positioning (M)

G01 – Linear interpolation

G02 – Clockwise circular helical interpolation (M)

G03 - Counterclockwise circular helical interpolation (M)

G04 – Dwell, duration programmed by means of K word

G05 – Round corner (M)

G06 – Circular interpolation with absolute centre coordinates

G40 – Cancellation of radius compensation (M)

G41 – Left hand radius compensation (M)

G42 – Right hand radius compensation (M)

G43 – Length compensation (M)

G44 – Cancellation of length compensation (M)

G70 – Programming in inches (M)

G71 – Programming in millimeters (M)

G81 – Drilling canned cycle (M)

G82 – Drilling canned cycle with dwell (M)

G83 – Deep drilling canned cycle (M)

G90 – Programming with absolute coordinates (M)

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G91 – Programming with incremental coordinates (M)

G94 – Feedrate F in mm/min (inches/min) (M)

G95 – Feedrate F in mm/rev (inches/rev) (M)

(M) – Modal

Modal means that once the G functions have been programmed, they remain active

until cancelled by another G function, which is incompatible.

General Program Format

Beginning of Program% Stop code (EOR)O------- Letter ‘O’ and the program numberG20 or G21 Inch or metric mode

Beginning of OperationN----- (-----) Sequence search number and

messageG97 S1000 M13 or M14 1000 rpm and spindle directionT-------- Index to tool station and call offsetX----- Z------ Move tool to activate tool offset

If using CSSG50 S----- Max rpm limitG96 S----- Surface feet (meters)/ Mt speed

If using TNRCG01 G41 or G42 X---- Z---- F100 TNRC, Non–cutting move reqd

RPM feedrate-----------------------------------------------------------------------------------------------G01 G99 X---- Z---- F----- Machine part, inches (mm) / rev

feed---------------------------------------------------------------------------------------------X----- (and / or) Z----- Clear part by 3 times the tool tip diaM98 P1 or M98 P2 Call safe OD or ID, end subprogramM01 Operation stop

Program EndingM30 Rewind program – stop machine% Stop code

Bar JobUse the repeat mode push button on the operator’s panel.

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