CNC TECHNOLOG

8/4/2019 CNC TECHNOLOG

http://slidepdf.com/reader/full/cnc-technolog 1/115

CNC TECHNOLOGY

CHAPTER - 2

CP 04 02 08

D.JUSTIN BABU



INTRODUCTION TO CNC MACHINES

HISTORY OF NC / CNC / DNC



WHAT IS NUMERICAL CONTOL MACHINES

The machine tool in which the relative movements of the cutting tool and the

work piece and other relevant functions are controlled by the input of numerical

commands and data is called NUMERICAL CONTROL MACHINES




First NC Milling was demonstrated in 1952 at the MASSACHUSETTSInstitute of Technology, USA.

In 1960 the Technology of Direct Numerical Control (DNC) was developed.

The earlier steps were to send the NC data directly to machine control bypassing the TAPE READER.

This way it was possible to control the NC machine tool directly by thecomputer, hence the name DIRECT NUMERICAL CONTROL(DNC).

DNC systems not only eliminated the less reliable TAPE READER but alsorepresented an important step towards total manufacturing automation.





Components of Numerical Control

Machine

Part Program

Machine Control Unit (MCU)



Engineering design of a part

Develop manufacturing plan for the

part

Program numerical control

instructions to allow the part to bemanufactured according to the plan

Process the program to develop

cutter location data set

Post Process for a specific machine

tool

The basic NC

Process

From Bedworth et

al. 1991



TECHNOLOGY OF NC:



TECHNOLOGY OF DNC:

Direct Numerical Control

It is defined as a manufacturing system in whicha number of machines are controlled by acomputer through direct connections



The main parts of a DNC system

CentralComputer

ShopComputer

CNCMachine

CNCMachine

CNCMachine

CNCMachine



CNC-MILLING MACHINE



TWIN CNC MILLING MACHINE



CNC stands for Computer Numerical Control.

Prior to this, it was called NC, for Numerical Control.

In the early 1970's computers were introduced to these controls, hence thename change

What Is CNC?



CNC

In CNC machine tools, a dedicated computer is used

to perform all the basic functions of NC machine.

Additional features available in CNC compared to

NC is Part program can be directly typed using keyboard.

Part program can be edited which is stored in the memory.

Sub programming can be done.

Cutting tool path can be generated.

We can obtain information regarding machine utilization.




The present generations of CNC machines are designed to meet the

requirements of HIGH PRODUCTIVITY, FLEXIBILITY and HIGH RELIABLITY

to produce components of HIGH QUALITY and ACCURACY levels combined

with REDUCTION IN MANUFACTURING COST.



TECHNOLOGY OF CNC:

CNC CONTROLLERNC Programme

Actuating devices(spindle motor,servo motor

and controller)

Machine tool

Feed back transducer(Resolver,Encoder, LinearScale or Tachogenerator)



Basic Elements of a CNC System

COMPUTER

MACHINETOOL

MACHINECONTROL UNIT



ADVANTAGES OF CNC:

Reduced non-productive time:

* Work piece set up time is less.* Tool set up & tool changing time is

less.Elimination of operator errors:

* Machine is controlled by the

computer.* The program is tested before

machining.Improved quality control:

* Greater accuracy.

* Reduced scrap.* Reduced inspection.Reduced floor space:

* one machine can do so manyoperations. Results in reduced floorspace

• Easier to program

• Easy storage of existing

programs

• Easy to change a program

• Avoids human errors

• NC machines are safer to

operate

• Complex geometry is

produced as cheaply as simple

ones

• Usually generates closer

tolerances than manual

machines



• Higher investment cost (CNC machine is more sophisticated and

complex technology).

• Higher maintenance cost (CNC is more complex and moreaccurate).

• Need of trained personnel (Certain aspects of these machineoperations require higher-level skill than a conventional machine).

• Planned support facility:Most of the preparatory work for CNC is done away from the machine.

Hence to reduce machine idle time proper planning is required.

DISADVANTAGES CNC MACHINE



COMPARISON BETWEEN NC AND CNC

NC CNC

1. Hand Wired hence

functions are limited.

1.Software control,

hence function aremany

2.Cannot be use forcomplex contour

machining

2.Can be use forcomplex contour

machining

3.Reliability is poor. 3.Reliability is high.

4.Memory is limited 4.Memory considerablylarge

5.Program editing wasdifficult.

5.Program editing iseasier.

6.Cheaper 6.Comparetively costlier

7.No diagnostic was

available.

7.Diagnostic was available



Any movement under control of NC input is called an

axis. (ie)

2 axis machine: X,Y control (usually lathe)3 axis machine: X,Y,Z control4 axis machine: X,Y,Z, one rotational control

5 axis machine: X,Y,Z, two rotational control*often called machining centers and include toolchanges… Toshiba – 9 axis mill for sub propellers





Typical Programming Procedure



NC SYSTEM

Based on feed back system NC system is classified

Classification of NC system

Open loop system

Closed loop system

Point to point system.

Straight cut or straight line system

Continuous path or conturing system

Based on Motion control system features, the NC system as follows




OPEN LOOP SYSTEM

A control system in which the output value is not checked against the desired

value is known as Open loop control system

Machine tool controls having slide displacements, which do not make any

provision for a feedback signal to be compared with the input, to enable the

feed drive to correct the slide position, are classified as open loop controlled

machines

Less accuracy

A stepper motor is the best example for open loop system



NC SYSTEMClassification of NC system

MCU - AMPLIFIER DRIVE MOTOR

INPUT

MACHINE TOOL SLIDE

DISPLACEMENT GEAR BOX

TAPE READER

OPEN LOOP SYSTEM



Open Loop System

The open loop system are usually of digital type

Example A stepping motor rotated, through a fixed angle in response to an input signal, i.e., digital

electrical signals converts into proportional movement



Applications of Open Loop Control System

• Light duty machines• Less investment

• No need of much accuracy

Disadvantages• Backlash error in lead screw

• Less accurate

Note• SLO-SYN stepper motor used to avoid the drawbacks in open loop

control system



NC SYSTEM


CLOSED LOOP SYSTEM

• A control system in which movement of the machine slide is checked and

corrected with respect to input signals and mainly by the signals from the

feedback device

• The feed back from the monitoring device is then compared with the input

information and the slide position is regulated by the servo system until

it agrees with the desired position

• The use of closed loop control system enable the displacement or

position of a slide to be achieved to a very high degree of accuracy by using

a measuring or monitoring device to determine the slide displacement



ProgramComputer / MCU

Comparator

A MP Servo

motorTechoGen

Gearbox

Machineslide

Data Process in CNC – ClosedLoop Control

PositionalTransducer (or)

Encoder

VFL

Displacement Feed back

Velocity Feed back

NC SYSTEM



NC SYSTEMClassification of NC system

CLOSED LOOP SYSTEM

TAPEREADER

COMPARATORUNIT

PROCESSINGUNIT

CONTROLLING UNITEg: Hydraulic Ram

MACHINE TOOL SLIDEDISPLACEMENT

MESAURINGDEVICE

C o m m a n d S i g n a l

S a y a d i s t a n c e o f 1 0 0

m m Signal

Representing

ActualPositionEg; 99.85 mm

Convertedcommand

ConvertedCommand(100-99.85)

Deviation in

processedFromEg: 0.15Converted intoHydraulic form





NC SYSTEM


Based on Motion control system features, the NC system as follows

• Point-to-Point system

• Straight cut or Straight line system

• Continuous path or Contouring system



NC SYSTEM


POINT-TO-POINT SYSTEM – Positioning System

• Point-to-Point system the machine performs machining operations at

specific positions and does not affect the work piece while moving from one

point to the next.

• In PTP, the importance is given to move the work piece/tool to a predefined

location with respect to other, when the location reached, the operation

performed

• Tool/Table movements are rapid traverse

• Path of movement is irregular

Example: In a drilling machine where co-ordinates are positioned by the system



NC SYSTEM


POINT-TO-POINT SYSTEM



Point to Point (P – type)

P1

P2

P3

P0

Y

X

Point to Point (P – type)

The PTP machines are

best suited for

•Drilling•Tapping

•Punch press

•Boring

•Spot welding•Jig boring machines



NC SYSTEM


STRAIGHT CUT OR STRAIGHT LINE SYSTEM

• In this system, the cutting tool moves parallel to X axis (or) Y axis during

the machining operations at a controlled rate

• This is an extension of Point-to-Point control system when the provision of

straight cut milling capability.

Example

Face Milling.

Pocket milling

Stepped Turning on Lathe

Boring, etc..,



NC SYSTEM


STRAIGHT CUT OR STRAIGHT LINE SYSTEM



Straight Cut (L-type)

P1 P2

P3

P0

Y

XP4



NC SYSTEM


CONTINUOUS PATH OR CONTOURING SYSTEM

• This calls for continuous, simultaneous and co-coordinated or in other

words interrelated motion of the tool and work piece along differentcoordinate axes.

• This enables profiles, contours and curved surfaces to be machined.

• This means that the position of several slides must be controlled on the

machine tool so that their relative position and velocities must be

established at every point and continuously, throughout the entire operation.



CONTINUOUS PATH OR CONTOURING SYSTEM


NC SYSTEM

Contouring System



Contouring or Continuous

P1

P2

P3

P0

Y

X

P4

The contouring systemsare suitable for•Curved paths•Conical shapes•Parabola•Hyperbola

•Fusion welding•Flame cutting



Three types of Interpolatation

Linear Interpolation Circular Interpolation Parabolic Interpolation

X

Y

X

Y

X

Y



APPLICATION OF CNC MACHINES

1. METAL CUTTING MACHINES

CNC Milling

CNC Turning

CNC Drilling / Boring

CNC Gear Cutting

CNC Grinding




2. METAL FORMING MACHINE

• Press Tools

• Injection / Blow Moulding Machines

• Die Casting Machines

• Tube Bending




3. NON CONVENTIONAL MACHINING PROCESS

• EDM Sinking and EDM Wire-cut machines.

• Plasma Arc cutting machines.

• Electron Beam machining.

• Laser Beam machining.

• Ion Beam machining.

• Ultrasonic machining etc.




4. Welding machines (TIG, MIG, Submerged Arc welding etc.)

5. Inspection and Quality Control systems (CMM,LMM).

6. Assembly, Testing and Despatch equipments.

7. Tool and work handling systems

S O CO O S



SERVO CONTROLLERS



The function of a servo can be described as follows.

• A command signal which is issued from the user'sinterface panel comes into servo’s

“POSITIONING CONTROLLER”.

• The positioning controller is the device which storesinformation about various jobs or tasks.

• It has been programmed to activate the motor/load,.Change speed/position.

• The signal then passes into the servo control or“amplifier” section.

The servo control takes this low powerlevel signal and increases, or , amplifies, the power up toappropriate levels to actually result in movements ofservo motor/load.

These low power level signals must be amplified:



• These low power level signals must be amplified:

Higher voltage levels are needed to rotate the servo motor atappropriate higher speeds and high current levels are required toprovide torque to move heavier loads.

• This power is supplied to servo control (amplifier) from the “power supply” which simply converts AC power into the required DC level.

• It also supplies any low level voltage required for operation of integratedcircuits.

• As the power is applied onto the servo motor ,the load begins to

move…Speed and position changes. As the load moves, so does some

other “device” move.

This other “device” is either a

tachometer,resolver or encoder (providing the signal which

is “sent back” to the controller). This “feedback” signal isinforming the positioning controller whether the motor isdoing the proper job.



The positioning controller looks at this feed back signal anddetermines if the load is being moved properly by the servomotor; and, if not , then the controller makes appropriate

corrections.For example

• Assume the command signal has to drive the load of 1000rpm

• For some reason it is actually rotating at 900 rpm.

• The feed back signal will inform the controller that the speed is900 rpm.

• The controller then compares the commanded signal (desired )of 1000rpm and the feed back signals (actual speed) of 900rpmand notes an error.

• The controller then outputs a signal equals the command signal,i.e there is no error.

• Servo system is defined that it consists of several devices whichcontrol or regulate speed/position of a load

Encoder



Encoder• The transducer that is connected directly to the rotor or the lead screw is

the simplest arrangement requiring no additional gearing (manyservomotors come with integral rotary encoders).

Optical Rotary Encoder

• An optical rotary encoder converts the rotary motioninto a sequence of digital pulses.

• The pulses are counted to convert u-absolute or

incremental position measurement.• The encoder generally come in two forms, absolute

encoder and incremental encoder.

• The absolute encoder provides the exact rotational position ofthe shaft whereas the incremental encoder gives the relative position of

the shaft in terms of digital pulses.• The optical encoder consists of a disc (as shown in Fig) with a number of

accurately etched equidistant lines or slots along the periphery.

• The encoder disc is attached to the shaft of the machine whose

rotary position needs to be measured.

Sensor



Position Reference Slot

Sensor

Slotted Hole



• The disc is placed between a light source (generally infrared LED) and a light measuring device (photo diode).

• When the disc rotates the lines are interrupted and thelight measuring device counts the number of times thelight is interrupted.

• By a careful counting and necessary calculations it ispossible to know the position traversed by the shaft.



Retrofitting

Replacing the conventional leadscrews with ball-bearing

screws.

Adding stepper motors ( for open loop control), or dc

servomotors and feedback devices (for closed-lop control); the

drive is added to each controlled axis.

If control is applied three are more axes, the total expense

becomes considerable and the project is not always cost

effective.



SALIENT FEATURES OF CNC MACHINES

• High rigidity.

• High stiffness to weight ratio.

• Thermal stability.

• Good clamping characteristics.

1. MACHINE STRUCTURE



Working Principle of CNC






2.FEED DRIVE

• Slides are actuated by precision pre-loaded re-circulating ball screw and nut

mechanism driven by servomotors and an electronic controller

• Speed motor have a constant Torque• Non-moving slides are held by powerful servo locks and are not

mechanically clamped.



Requirements of CNC Feed drive

• The CNC feed drive should have constant torque to overcomefrictional and working forces

• Should provide variable speed with a speed range of 0.1 rpm to2000 rpm without waviness

• Able to position the tools with the smallest increment of 1-2micrometer

• Low electrical and mechanical time constants

• High torque to weight ratio

• High torque for quick response

• Totally enclosed design-safe & maintenance conditions



Commonly used Feed drives/Drive motors

• DC Silicon Controlled Rectifier (SCR)

• Pulse Width Modulated (PWM) drive

• DC servo motor

– High performance motor

– Start and stop must be made quickly and accurately

– Light weight

– Low inertia armatures of DC servo motor respond quickly to theexcitation voltage changes

• Brush less DC Servo motor

• AC servo motor

• Stepper Motor

• Variable frequency AV drive or Linear motors



Linear Motor

• Most of the CNC Machine tools use linear motor

• It consists of a series of magnets attached to a machine base and aset of electrical coils plotted around a steel laminated core attachedto the moving slide

• A linear motor is an electric motor that has had its stator and rotor"unrolled" so that instead of producing a torque (rotation) it producesa linear force along its length




2. SLIDE WAYS

• In conventional machines, there is direct metal to metal contact between

the slide way and the moving slides which results in very slow movements

and machine utilization.

• The conventional type of arrangement does not meet the requirement of

CNC Machines

• The demand on slide ways is much more in CNC machines because of the

rapid movements and higher machine utilization.

Conventional Slide Way Systems used in Machine Tools





SLIDE WAYS

The design of slide way in a CNC machine should,

Reduce friction.

Reduce wear.

Satisfy the requirements of the movement of the slides.

Improve smoothness of the drive

To meet this requirements CNC machine slide ways, the techniques used

include hydrostatic, linear bearings with balls, rollers or needles and surface

coatings



SLIDE WAYS

In this slide ways air or oil is pumped into small pockets or cavities

machined into the carriage or slides which are in contact with the slide way.

The pressure of the fluid gradually reduces to atmospheric pressure as it seeps

out from the pockets, through the gap between the slide and slide ways.

The hydrostatic slide way provides almost a frictionless condition for the

movement of the slide.

HYDROSTATIC SLIDE WAYS



SLIDE WAYS

For efficient operation it is very important that the fluid and slide ways are kept

clean.

The hydraulic slide ways need a very large surface area to provide adequate

support.




SLIDE WAYS




SLIDE WAYS

LINEAR BEARING WITH BALLS & ROLLERS

The sliding friction due to direct metal contact between the slide and slide

ways is replaced with rolling friction by the use of antifriction ball or roller

bearing.

These are designed to run along precision ground shafts and offer

frictionless movement over varying strock of length with high linear

precision.



SLIDE WAYS


For movement along a flat plane, re-circulating linear roller bearings are used.

The main characteristic of the linear roller bearing is that there is a continuous

roller circulation, which allows unlimited linear movement.

A linear bearing (also called TYCHOWAY), consists of hardened & precision

ground supporting elements and a number of cylindrical rollers



SLIDE WAYS


The rollers are guided between the shoulders of the supporting elements with

very close tolerances.

The guiding element prevents the rollers from falling out and sliding againsteach other.

The guiding elements assist in smooth return of the rollers to the loading zone.



SLIDE WAYS




SLIDE WAYS






Linearslide with Balls

http://www.isotechinc.com/prod21_d.htm



SLIDE WAYS


The rollers are in contact with guide ways machined on the bed of the

machine.

This provides smooth and easy movement.

The machine bed surfaces coming in contact with rollers have to be hardened.

To reduce the problem of accurate machining of bed, hardened steel guides

with special guide forms may be attached to the machine bed and rollers can

move on the rail.







The linear roller bearing can be mounted horizontally for load carryingapplications such as machine tool table.

They can be mounted vertically to provide support, guidance andmotion for vertical elements of the machine tool.

Vee and flat roller arrangement can also be used to provide frictionlesslinear movement.

SURFACE COATINGS



SURFACE COATINGS

The guiding surfaces of the machines are coated with lowfriction materials such as POLYTETRAFLUROETHYLENE

(PTFE), or replaceable strips of low friction material are used.

When the strips wear to such an extent that the alignment is inerror, these can be replaced.

ELEMENTS OF MOTION TRANSMISSION



The rotary motion from the drive motor needs to be converted into linearmotion to move the various axes of the machine.

In conventional machine square thread is used.

The conventional machines use lead screw for motion transmission purpose.

Due to high friction between the lead screw & nut results in poor transmission

efficiency and back lash.

In CNC machines with use of re-circulating ball screw and nut arrangementthese problems have been overcome.

Here again, the approach is to replace sliding friction by rolling friction.

RE CIRCULATING BALL SCREW & NUT

NC MACHINE TOOLS



DRIVE UNITS










The connection between the screw and the nut is through an endless stream

of re-circulating steel balls.

The screw thread is a hardened and ground ball race in which the steel balls,

in the nut, circulate.

The balls rotate between the screw and the nut and at the same point the balls

are returned to start of the thread in the nut.

The rigidity of the drive system & positioning accuracy can be further improved

by pre-loading the nut assembly.





HIGH EFFICIENCY:

As compared to conventional lead screw the efficiency of ball screw & nut

assembly is very high (over 90%).The power requirement is also less due to

reduce friction.

RE CIRCULATING BALL SCREW & NUT ADVANTAGES




REVERSIBILITY:

The ball screw & nut assembly is reversible which makesit possible to back drive the unit .

i.e. by applying axial force to either nut or screw, theunconstrained member can be made to rotate.





WEAR & LIFE:

The re-circulating rollers reduce wear to a minimum and the ball screw. Hence

longer life with out loss of accuracy.






NO STICK SLIP:

Stick slip is a phenomenon, which occurs when small movement between two

lubricated elements are required.

The lubricating medium tries to cause the mating elements to stick to each

other to resist motion and results in a jerky motion as the mating elements try

to stick and then slip during their relative movement.

Since the sliding metal-to-metal contact is substituted by rolling contact, the

stick-up phenomenon is eliminated in the ball screw and nut assembly.


B ll L d S



Ball Lead-Screw




3.FEED-BACK SYSTEM

The accuracy of positioning in CNC is achieved by measuring the position ordisplacement of the slide and comparing it with the command position as per thepart program.

The servo system then actuates the slide such that the error, which is thedifference between actual position and the command position, is brought to zero(is called ERROR DRIVEN SYSTEM).

The position measuring devices could be direct or indirect depending uponwhether the device is directly fitted in the slide or at the end of the ball screw.

Some of the measuring devices are Linear inductosyns, Optical scales withgrating, Rotary encoders, Rotary inductosyns, Brush less synchroresolvers, etc.

FEED BACK DEVICES



FEED BACK DEVICES

FEEDBACK DEVICES

VELOCITY FEEDBACK DEVICE POSITION FEEDBACK DEVICE

FEED BACK DEVICES:Two types of feed back is required



Two types of feed back is required.

1) Velocity feed back

2) Positional feed back

Velocity feed back: It will measure the spindle rpm.

Tachogenerator is used.

It will generate voltage in proportional to the speed.

The tachogenerator is normally built in the servomotor cases

and is directly fitted on the servomotor shaft.

The o/p voltage is compared & monitored the spindle speed.

Rotary encoders are also used to provide feedback for velocity control.





FEED BACK DEVICES



POSITION FEED BACK DEVICE

Measurements from cutting edge are not possible due to the presence of

chips, coolant, holding devices and in some case, due to the component

geometry itself

The positional feed back is provided by measuring the slide movements with

measuring devices

The position measuring devices are either rotary or linear measuring

transducers.





Angular position measuring transducers operates by measuring the angular

speed of a rotating element, normally of a lead screw, from the known value

of the lead screw, movement of the work table or machine slide is calculated

by control system

Angular position measuring transducers operate on the photo electricprinciple

The transducer consists of a disc fitted on the axis of lead screw

The disc is made up of uniform alternate transparent and opaque areas

A light source is fitted on one side of the disc and photocell on the other side

When the disc rotates with rotation of the lead screw, the photocell will sensethe light and dark areas alternatively

As the dark area of the disc is gradually uncovered the light intensity falling

on the photocell goes on increasing until it reaches the maximum when the

transparent part of the disc comes in from the light source

ROTARY OR ANGULAR POSITION MEASURING TRANSDUCERS




As the disc continuous to rotate the dark area starts to reduce the lightintensity falling on the photocell which will gradually reduces to zero when thedark area comes between the photocell and light source

The photocell gives output voltage based on the intensity of light falling on it

and the out put from photocell resembles a sine-wave, which is converted in tosquare shaped pulses to make it useful for control purposes

The number of output pulses is then counted

As the output from the photo cell is related to the rate at which the transparentareas of the disc comes in front of the light source, the speed of the lead

screw is calculated from the known number of lines engraved on the rotatingdisc

The displacement of the slide is then calculated from the lead of the leadscrew




FEED BACK DEVICES





The direction of the rotation of lead screw is sensed by putting a secondphotocell in the circuit

The second photocell is positioned in such a way that the output from the two

photo cell will be out of phase This phase difference is used to determine the direction of rotation of lead

screw

Position measurement by angular position measuring transducer is indirect asthe output of the transducer as to be converted into table displacement





FEED BACK DEVICES


LINEAR POSITION MEASURING TRANSDUCERS

Linear position measuring transducer also operate on the photoelectric

principle.

The linear measuring system measures the displacement of the machine liedfrom a fixed datum.







• A linear measuring system consists of a precision linear scale engraved

with closed space alternate transparent and opaque parallel lines as oneunit and a photocell and light source as the second unit.

• One of the units is fixed on the stationary element of the machine tool and

the other unit is fixed to the moving worktable.

• A pulse is generated by the photocell as it is exposed to light source

through the transparent areas of the linear scale.

FEED BACK DEVICES





• A pulse is generated by the photocell as it is exposed to light source

through the transparent areas of the linear scale.

• From the known number of the engraved lines per unit length on the linear

scale and by counting the pulses, the displacement of the work table can be

established.

FEED BACK DEVICES





• As in the case of rotary transducers, a second photocell is used to detect

the direction of movement.

• The linear system may have either a glass cell in which case light passes

through the transparent area or a ss scale , the light is reflected from thetransparent areas.

FEED BACK DEVICES



.









4.SPINDLE DRIVE

• High spindle power and wide speed range with step less variation ofRPM.

• Full power availability at all speeds.

• DC motors with silicon controlled rectifier (SCR) drive or AC motorswith variable frequency.

• Spindle orientation for Automatic Tool Change and fine boringapplication.

Radial Roller Bearing



Work Holding EndPower from Spindle Motor






5. AUTOMATIC TOOL CHANGER (ATC)

• ATC is an important element of machining centers for increasing the productivity byreducing of idle time during tool change.

• ATC units are capable of performing tool change within 3 to 7 seconds.

• In an ATC unit the tool magazine could be drum type with the capacity up to 40 toolsor chain type with capacity up to 132 tools.

• The tool change arm could be of single gripper or double gripper type.

• The tool selection could be of Sequential type (applicable for less no. of tools andconsuming more time) or of Random type (applicable for no. of tools and consumingless time).

• The latter type is more commonly used.

CHAIN TYPE

TURRET



CHAIN TYPE

DRUM TYPE








6. AUTOMATIC PALLET CHANGER (APC)

• APC aids in increase of productivity by reducing the job set up time.

• Function is to interchange the pallet on the machine that has finishedcomponent and the other pallet with the newly loaded component.

• Setting up of the work piece is done away from the machine tool. Thusimproves machine utilization time.

• The pallet changer gets located on the machine and clamped with heavy

clamping force either hydraulically or mechanically.

• APCs could be of dual pallet type or multiple pallet pool type.





Some other features of CNCs Thermal stabilization of headstock, feed drive elements and machine

structural elements by re-circulated refrigerated oil.

Axial calibration for all fixed mechanical elements.

Lost motion compensation for all fixed mechanical elements.

Usage of Torch trigger probes for post process metrology purposes, Toolcondition monitoring, Tool measurement and setting of tool offsets andthermal error compensation.

Centralized lubrication of slides, etc., controlled by timer or software.

Coolant systems of either flood type or myst type.

Chip conveyors for collection and disposal of chips. Auto diagnostic to aid maintenance and service personnel.

Documents

CNC TECHNOLOG