PMTF

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Pakistan Machine Tool Factory (Pvt) Ltd. (PMTF)

is aprecision engineering goods manufacturing enterprise inPakistan, established in technical

collaboration with M/s.Oerlikon Buhrle & Co. of Switzerland who are the world'srenowned

manufacturers of Machine Tools. The factory cameinto regular production in 1971.It is located Off

National Highway, about 35 Km from KarachiCity near Landhi Industrial Estate and spread over an area

of 226 acres out of which 17 acres are occupied by works. Thefactory employs about 1900 engineers,

technician, workersand other service staff. The layout of the factory is accordingto the best European

standards. This factory is a unit of StateEngineering Corporation of Pakistan and is engaged in

theproduction of Machine Tools, Automotive Transmissions andAxles Components, Gears for

Locomotives, Pressure Die Castparts and other products.

PMTF

has rich experience in Designing and Manufacturing of precision engineering goods and its facilities

includeDesigning, Machining, Forging, Heat Treatment, Assembly, DieCasting etc.

PMTF

is certified to ISO 9001.Quality Assurance System andhas excellent Quality Control and Testing facilities

to meet theinternational quality requirement.

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Departments Introduction:

Design Centre

Machining

Tool Room

Material Testing

Heat Treating

Forging

Machine Tool Rebuilding

Design Centre:

Computer Aided Design & Manufacturing (CAD/CAM) facilitiesare installed for Product Design and

Tools/Jigs/Fixtures Designand CNC Shop in 1990. Engineering software from Computervision (USA) and

Autodesk namely:- CADDS 5- Design View- Personal Designer- Personal Designer/Personal Machinist-

Micro draft- Personal Data Extract- Mechanical Desktop power pack (with Auto Cad)are used for design

of products, tools, jigs, fixtures, cutters,forging & die casting dies, gears, equipments,

mechanicaldevices.

Machining:

The works facility consists of variety of conventional and CNCmachine tools capable of performing

various machiningoperations such as turning, planning, milling, drilling, jigboring, thread grinding, deep

hole drilling, gear hobbling

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shaping and shaving, gear grinding, spiral bevel gear cutting,broaching to the close tolerances specified

in the design. Themaximum machining capabilities are as follows:

Turning

: Max. 1000 mm dia x 4000 mm length x 800 kgwt.

Shaping/Planning

: Max. 6000 mm length x 1500 mm width x 2000kg wt.

Boring/Drilling

: Max. 600 mm dia/50 mm dia max.

Gear Cutting

: 10 module x 700 mm dia max.

Grinding

: Max. 400 mm dia x 2500 mm length x 500 kg wt.

Pressure DieCasting

: Max 650 ton locking force x 12 kg wt.

Besides above facilities special purpose machines areavailable for die-sinking, spark erosion, thread

grinding, jigboring, spine rolling, vertical turning, copy milling for intricateprecision components.

Tool Room:

The factory has a fully equipped Tool Room facility capable of manufacturing jigs & fixtures,

special tools like drills, gauges,cutters and holding devices, special high precision machinetools like jig

boring, thread grinding, die sinking, relievinglathes, vertical copying lathes, precision milling machines

andspecial purpose tool grinding of Swiss and German originsupplements the facility and ensures that all

specificationsand tolerances essential for tool room accuracy is met. The Tool Room is linked with Tool

Design Section fully equippedwith computer Aided Design facilities and supported byMetrology section

located in same area for precise calibrationand control of tool room products. All

recommendedinternational standards are followed for toolings.

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Material Testing:

a. Metallographic:

Complete Evaluation of :Macro and Micro StructureNon - Metallic Inclusion & segregationCase

Hardening and Case DepthPhoto Micrograph of StructureFailure Analysis

b. Mechanical Testing:

Facilities to determine:Mechanical PropertiesStress - Strain Tensile and Compressive StrengthShear and

Impact Test

c. Chemical Testing:

Complete Analysis of:Metals and AlloysFerrous and Non Ferrous ElementsPaints, Chemicals, Ores, Oils

Greases etc

d. Non-Destructive Testing:

Determination of:Internal Cracks by Ultrasonic TestingSurface Cracks by Magnaflux and Dye-

Penetration

Heat Treatment:

The Heat Treatment shop is the largest and the most wellequipped in the country. The equipment is of

French, Germanand Italian origin. The Facilities has

- For Carburizing and Case Hardening :Five Sealed Quench Furnaces Three Gas Fired Pit-type Muffle

Furnaces Two Rotary Hearth Furnaces with Quenching PressElectrically Heated Tempering FurnaceFor

Induction Hardening:Three High Frequency and Medium Frequency InductionHardening MachinesFor

Surface Hardening:Flame Hardening MachineFor Hardening High Speed Steel:Salt Bath

FurnacesHydraulic Presses, Shot Blasting Machines, Sand BlastingPlant are available for post-heat

treatment process.

Forging:

The Forging shop is equipped with two drop hammers of 3000kg and 1500 kg Pneumatic hammers of

600 kg and 300 kg, Trimming press of 320 tons and 1000 tons, Friction ScrewPress of 480 tons, Heating

of stock for forging is done in rotaryhearth furnace. Furnace car-bottom type is installed fornormalizing

the forged components. Removal of scales is donein Tumbler & Table type shot blasting machines. The

forgeshop is capable of production of forgings up to 20 kg and 200mm in diameter.

Machine Rebuilding:

Machine Rebuilding is a comparatively new technology in theindustrially developed countries. It should

not be mixed withmachine tool repair and maintenance and overhaul. The main

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characteristic of Machine Rebuilding are:

- The rebuilt machine has same performance andaccuracy as a new machine.- The warranty period is

same as for a new one.- Cost of Rebuilding is one-third of the price of newequivalent machine.PMTF

has

established this machine rebuilding facility in1994 with the assistance of UNIDO experts from UK and

sincethen has undertaken the rebuilding activity with targetedoutput set for 10 to 12 machines per

annum.

Quality Control:

Inspection and Testing is carried out according to proceduresestablished for ISO 9001 Quality Assurance

System. Theinspection activities are backed up with the facility forcalibration of measuring and testing

devices.

PMTF Products range includes:

MACHINE TOOLS:

1- Heavy duty & light duty Milling Machines(Horizontal,Universal & Vertical)2- Vertical Copying Milling &

Boring Machines3- Turret Milling Machine4- Precision Centre Lathes5- Universal Radial Drilling Machine

(Portable)6- Pantograph Engraving Machine7- Special Purpose Machine Tools8- Manual Arbor Press

TRANSMISSION:

1- Gear and Shafts for Agriculture Tractors like MasseyFerguson (MF 240, MF 375),and Fiat

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(Fiat 480, Fiat 640).2- Traction Gears and Pinions for Locomotives3- Gears for various Industrial

applications4- Components for Bedford Trucks & Buses etc.

DIE CAST COMPONENTS:

1- Aluminum Pressure Die Cast components for HondaMotorcycle Model CD 70 & CG 125, and Suzuki

Motorcycle;Model A80.2- Aluminum Pressure Die Cast components for DomesticAppliances3- Aluminum

Pressure Die Cast components of Gas Meter forGas distribution industries.4- Aluminum Pressure Die

Cast components for Suzuki CarModel SB 308

TEXTILE MACHINERY:

1- Ring Spinning Frame Model FA 506

MISCELLANEOUS:

1- Gears for various Industrial Applications.2- Spares for various plants/machinery.3- Machines /

Equipments as per customer's design /requirement.

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Topics Covered:

N C & CNC

Numerical control

(

NC

) refers to the automation of machinetoolsthat are operated by abstractly programmed

commandsencoded on a storage medium, as opposed to manuallycontrolled via hand wheels or levers

or mechanicallyautomated via cams alone. The first NC machines were builtin the 1940s and 50s, based

on existing tools that weremodified with motors that moved the controls to follow pointsfed into the

system on paper tape. These earlyservomechanisms were rapidly augmented with analog anddigital

computers, creating the modern

ComputerNumerical Controlled

(

CNC

) machine tools that haverevolutionized the design process.In modern CNC systems, end-to-end

component design ishighly automated usingCAD/CAMprograms. The programsproduce a computer file

that is interpreted to extract thecommands needed to operate a particular machine, and thenloaded

into the CNC machines for production. Since anyparticular component might require the use of

a number of different tools - drills, saws, etc. - modern machines oftencombine multiple tools into a

single "cell". In other cases, anumber of different machines are used with an externalcontroller and

human or robotic operators that move thecomponent from machine to machine. In either

case thecomplex series of steps needed to produce any part is highlyautomated and produces a part

that closely matches theoriginal CAD design

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Earlier forms of automation:

Cams

The automation of machine tool control began in the 1800swithcamsthat "played" a machine tool in

the way that camshad long been playingmusical boxesor operating elaboratecuckoo clocks. Thomas

Blanchardbuilt his gun-stock-copyinglathes (1820s-30s), and the work of people such asChristopher

Miner Spencerdeveloped theturret latheinto thescrew machine(1870s). Cam-based automation had

alreadyreached a highly advanced state byWorld War I(1910s).However, automation via cams is

fundamentally different fromnumerical control because it cannot be abstractlyprogrammed. There is no

direct connection between thedesign being produced and the machining steps needed tocreate it. Cams

can encode information, but getting theinformation from the abstract level of anengineering

drawing into the cam is a manual process that requires sculptingand/ormachiningandfiling. At least two

forms of abstractlyprogrammable control had existed during the 1800s: those of the Jacquard loomand

of mechanical computerspioneered byCharles Babbageand others. These developments had

thepotential forconvergencewith the automation of machine toolcontrol starting in that century, but the

convergence did nothappen until many decades later.

Tracer control:

The application of hydraulicsto cam-based automationresulted in tracing machines that used a stylus

to trace atemplate, such as the enormousPratt & Whitney "KellerMachine", which could copy templates

several feet across.

[1]

Another approach was "record and playback", pioneered atGeneral Motors(GM) in the 1950s, which

used a storagesystem to record the movements of a human machinist, andthen play them back on

demand. Analogous systems arecommon even today, notably the "teaching lathe" which gives

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new machinists a hands-on feel for the process. None of thesewere numerically programmable,

however, and required amaster machinist at some point in the process, because the"programming" was

physical rather than numerical.

Servos and selsyns:

One barrier to complete automation was the requiredtolerances of the machining process, which are

routinely onthe order of thousandths of an inch. Although it would berelatively easy to connect some

sort of control to a storagedevice like punch cards, ensuring that the controls weremoved to the correct

position with the required accuracy wasanother issue. The movement of the tool resulted in

varyingforces on the controls that would mean a linear output wouldnot result in linear motion of the

tool. The key development inthis area was the introduction of theservo, which producedhighly

accurate measurement information. Attaching twoservos together produced a selsyns, where a remote

servo'smotions was accurately matched by another. Using a varietyof mechanical or electrical systems,

the output of the selsynscould be read to ensure proper movement had occurred. The first serious

suggestion that selsyns could be used formachining control was made by Ernst F. W. Alexanderson,

aSwedish immigrant to the U.S. working atGeneral Electric (GE). Alexanderson had worked on the

problem of torqueamplification that allowed the small output of amechanicalcomputerto drive very

large motors, which GE used as part of a largergun layingsystem forUS Navyships. Like machining,gun

lying requires very high accuracies, less than a degree,and the motion of the gun turrets was non-linear.

In November1931 Alexanderson suggested to the Industrial EngineeringDepartment that the same

systems could be used to drive theinputs of machine tools, allowing it to follow the outline of atemplate

without the strong physical contact needed byexisting tools like the Keller Machine. He stated that it

was a

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"matter of straight engineering development." However, theconcept was ahead of its time from a

business developmentperspective, and GE did not take the matter seriously untilyears later, when

others had pioneered the field.

Parsons and the invention of NC:

The birth of NC is generally credited to John T. Parsons,

amachinist and salesman at his father's machining company,Parsons Corp. In 1942 he was told

thathelicopterswere goingto be the "next big thing" by the former head of Ford Trimotor production,

Bill Stout. He calledSikorsky Aircraftto inquireabout possible work, and soon got a contract to build

thewooden stringers in the rotor blades. After setting upproduction at a disused furniture factory and

ramping upproduction, one of the blades failed and it was traced to thespar. As at least some of the

problem appeared to stem fromspot welding a metal collar on the stringer to the metal spar,so Parsons

suggested a new method of attaching the stringersto the spar using adhesives, never before tried on an

aircraftdesign.But that development led to Parsons to wondering about thepossibility of using stamped

metal stringers instead of wood,which would be much easier to make and stronger too. Thestringers for

the rotors were built to a design provided bySikorsky, which was sent to them as a series of 17

pointsdefining the outline. Parsons then had to "fill in" the dots withaFrench curveto generate an

outline they could use as atemplate to build the jigs for the wooden versions. But how tomake a tool

able to cut metal with that shape was a muchharder problem. Parsons went to visit Wright Field to see

FrankStulen, who was the head of the Rotary Ring Branch at the

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Propeller lab. Stulen concluded that Parsons didn't really knowwhat he was talking about, and realizing

this, Parsons hiredhim on the spot. Stulen started work on 1 April 1946 and hiredthree new engineers to

join him.Stulen's brother worked at Curtis Wright Propeller, andmentioned that they were usingpunch

cardcalculators forengineering calculations. Stulen decided to adopt the idea torun stress calculations on

the rotors, the first detailedautomated calculations on helicopter rotors. When Parsonssaw what Stulen

was doing with the punch card machines, heasked him if they could be used to generate an outline

with200 points instead of the 17 they were given, and offset eachpoint by the radius of the cutting tool

on a mill. If you cut ateach of those points, it would produce a relatively accuratecutout of the stringer

even in hard steel, and it could easily befiled down to a smooth shape. The resulting tool would beuseful

as a template for stamping metal stringers. Stulen hadno problem doing this, and used the points to

make largetables of numbers that would be taken onto the machine floor.Here, one operator read the

numbers off the charts to twoother operators, one each on the X and Y axis, and they wouldmove the

cutting head to that point and make a cut. This wascalled the "by-the-numbers method".At that point

Parsons conceived of a fully automated tool. Withenough points no manual working would be needed at

all, butwith manual operation the time saved by having the partmore closely match the outline

was offset by the time neededto move the controls. If the machine's inputs were attacheddirectly to the

card reader this delay, and any associatedmanual errors, would be removed and the number of

pointscould be dramatically increased. Such a machine couldrepeatedly punch out perfectly accurate

templates oncommand. But at the time he had no funds to develop theseideas.When one of Parsons

Salesmen was on a visit to Wright Field,he was told of the problems the newly-formedUS Air Force

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was having with new jet designs. He asked if Parsons hadanything to help to them. Parsons

showedLockheedtheir ideaof an automated mill, but they were uninterested. They hadalready decided

to use 5-axis template copiers to produce thestringers, cutting from a metal template, and had ordered

theexpensive cutting machine already. But as Parsons noted:Now just picture the situation for a minute.

Lockheed hadcontracted to design a machine to make these wings. Thismachine had five axes of cutter

movement, and each of thesewas tracer controlled using a template. Nobody was using mymethod of

making templates, so just imagine what chancethey were going to have of making an accurate airfoil

shapewith inaccurate templates. Parsons worries soon came true, and in 1949 the Air Forcearranged

funding for Parsons to build his machines on hisown. Early work with Snyder Machine & Tool Corp

proved thatthe system of directly driving the controls from motors failedto have the accuracy needed to

set the machine for aperfectly smooth cut. Since the mechanical controls did notrespond in a linear

fashion, you couldn't simply drive it with acertain amount of power, because the differing forces

wouldmean the same amount of power would not always producethe same amount of motion in the

controls. No matter howmany points you included, the outline would still be rough.

Enter MIT:

This was not an impossible problem to solve, but wouldrequire some sort of feedback system, like a

selsyn, to directlymeasure how far the controls had actually turned. Faced withthe daunting task of

building such a system, in the spring of 1949 Parsons turned to theMIT Servomechanisms Laboratory,a

world leader in mechanical computing and feedback

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systems. During the war the Lab had built a number of complex motor-driven devices like the motorized

gun turretsystems for theB-29and the automatic tracking system fortheSCR-584radar. They were

naturally suited to building aprototype of Parsons' automated "by-the-numbers" machine. The MIT team

was led by William Pease assisted by JamesMcDonough. They quickly concluded that Parsons'

designcould be greatly improved; if the machine did not simply cut

at

points A and B, but instead moved smoothly

between

thepoints, then not only would it make a perfectly smooth cut,but could do so with many fewer points -

the mill could cutlines directly instead of having to define a large number of cutting points to "simulate"

it. A three-way agreement wasarranged between Parsons', MIT and the Air Force, and theproject

officially ran from July 1949 to June 1950. The contractcalled for the construction of two "Card-a-matic

MillingMachine’s, a prototype and a production system. Both to behanded to Parsons for attachment to

one of their mills in orderto develop a deliverable system for cutting stringers.Instead, in 1950 MIT

bought a surplusCincinnati MillingMachine Company"Hydro-Tel" mill of their own and arrangeda new

contract directly with the Air Force that froze Parsonsout of further development. Parsons would later

comment thathe " never dreamed that anybody as reputable as MIT woulddeliberately go ahead and

take over my project." In spite of the development being handed to MIT, Parsons filed for apatent on

"Motor Controlled Apparatus for Positioning Machine Tool" on 5 May 1952, sparking a filing by MIT for a

"NumericalControl Servo-System" on 14 August 1952. Parsons' receivedUS Patent 2,820,187on 14

January 1958, and the companysold an exclusive license toBendix.IBM,FujitsuandGeneralElectricall took

sub-licenses after having already starteddevelopment of their own devices.

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MIT's machine:

MIT fit gears to the various hand wheel inputs and drove themwithroller chainsconnected to motors,

one for each of themachine's three axes (X, Y and depth). The associatedcontroller consisted of five

refrigerator-sized cabinets that,together, were almost as large as the mill they wereconnected to. Three

of the cabinets contained the motorcontrollers, one controller for each motor, the other two thedigital

reading system. Unlike Parsons' original punch card design, the MIT designused standard 7-trackpunch

tapefor input. Three of thetracks were used to control the different axes of the machine,while the

other four encoded various control information. Thetape was read in a cabinet that also housed sixrelay-

basedhardware registers, two for each axis. With every readoperation the previously read point was

copied into the"starting point" register, and the newly read one into the"ending point". The tape was

read continually and the numberin the register increased until a "stop" instruction, four holesin a line,

was encountered. The final cabinet held a clock that sent pulses through theregisters, compared them,

and generated output pulses thatinterpolated between the points. For instance, if the pointswere far

apart the output would have pulses with every clockcycle, whereas closely spaced points would only

generatepulses after multiple clock cycles. The pulses are sent into asumming register in the motor

controllers, counting up by thenumber of pulses every time they were received. Thesumming registers

were connected to adigital to analog

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convertorthat output increasing power to the motors as thecount in the registers increased. The

registers were decremented by encoders attached to themotors and the mill itself, which would reduce

the count byone for every one degree of rotation. Once the second pointwas reached the pulses from

the clock would stop, and themotors would eventually drive the mill to the encodedposition. Each 1

degree rotation of the controls produced a0.0005 inch movement of the cutting head.. The

programmercould control the speed of the cut by selecting points thatwere closer together for slow

movements, or further apart forrapid ones. The system was publicly demonstrated in September

1952,appearing in that month's

Scientific American

. MIT's systemwas an outstanding success by any technical measure, quicklymaking any complex cut

with extremely high accuracy thatcould not easily be duplicated by hand. However, the systemwas

terribly complex, including 250vacuum tubes, 175 relaysand numerous moving parts, reducing its

reliability in aproduction setting. It was also very expensive, the total billpresented to the Air Force was

$360,000.14, $2,641,727.63 in2005 dollars. Between 1952 and 1956 the system was used tomill a

number of one-off designs for various aviation firms, inorder to study their potential economic impact.

Proliferation of NC:

The Air Force funding for the project ran out in 1953, butdevelopment was picked up by the Giddings

and LewisMachine Tool Co. In 1955 many of the MIT team left to formConcord Controls, a commercial

NC company with Giddings'backing, producing theNumericordcontroller. Numericord wassimilar to the

MIT design, but replaced the punch tape with amagnetic tapereader thatGeneral Electricwas working

on. The tape contained a number of signals of different phases,

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which directly encoded the angle of the various controls. Thetape was played at a constant speed in the

controller, whichset its half of the selsyns to the encoded angles while theremote side was attached to

the machine controls. Designswere still encoded on paper tape, but the tapes weretransferred to a

reader/writer that converted them intomagnetic form. The magtapes could then be used on any of the

machines on the floor, where the controllers were greatlyreduced in complexity. Developed to produce

highly accuratedies for an aircraft skinning press, the Numericord "NC5" wentinto operation at G&L's

plant atFond du Lac, WIin 1955.Monarch Machine Tool also developed an NC-controlled lathe,starting in

1952. They demonstrated their machine at the1955 Chicago Machine Tool Show, along with a number

of other vendors with punch card or paper tape machines thatwere either fully developed or in

prototype form. Theseincluded Kearney & Trekker’s Milwaukee-Matic II that couldchange its cutting tool

under NC control. A Boeing report noted that "numerical control has proved itcan reduce costs, reduce

lead times, improve quality, reducetooling and increase productivity.” In spite of thesedevelopments,

and glowing reviews from the few users,uptake of NC was relatively slow. As Parsons later noted: The

NC concept was so strange to manufacturers, and so slowto catch on, that the US Army itself finally had

to build 120 NCmachines and lease them to various manufacturers to beginpopularizing its use. In 1958

the MIT published its report on the economics of NC. They concluded that the tools were competitive

with humanoperators, but simply moved the time from the machining tothe creation of the tapes. In

Forces of production

Noble claimsthat this was the whole point as far as the Air Force wasconcerned; moving the process off

of the highly unionized

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factory floor and into the un-unionizedwhite collardesignoffice.

CNC arrives:

Many of the commands for the experimental parts wereprogrammed "by hand" to produce thepunch

tapesthat wereused as input. While the system was being experimentedwith, John Runyon made a

number of subroutines on thefamousWhirlwindto produce these tapes under computercontrol. Users

could input a list of points and speeds, and theprogram would generate the punch tape. In one instance,

thisprocess reduced the time required to produce the instructionlist and mill the part from 8 hours to 15

minutes. This led to aproposal to the Air Force to produce a generalized"programming" language for

numerical control, which wasaccepted in June 1956.Starting in September Ross and Pople outlined a

language formachine control that was based on points and lines,developing this over several years into

theAPT programminglanguage. In 1957 theAircraft Industries Association(AIA) andAir Material

Commandat theWright-Patterson Air Force Base joined with MIT to standardize this work and produce

a fullycomputer-controlled NC system. On 25 February 1959 thecombined team held a press conference

showing the results,including a 3D machined aluminum ash tray that was handedout in thepress

kit.Meanwhile,Patrick Han rattywas making similardevelopments at GE as part of their partnership

with G&L onthe Numericord. His language, PRONTO, beat APT intocommercial use when it was

"released" in 1958. Han rattythen went on to developMICRmagnetic ink characters thatwere used in

cherub processing, before moving toGeneralMotorsto work on the groundbreakingDAC-1CAD system.

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APT was soon extended to include "real" curves in 2D-APT-II.With its release, MIT reduced its focus on

CNC as it moved intoCAD experiments. APT development was picked up with theAIA in San Diego, and

in 1962, to Illinois Institute of Technology Research. Work on making APT an internationalstandard

started in 1963 under USASI X3.4.7, but manymanufacturers of CNC machines had their own one-

off additions (like PRONTO), so standardization was notcompleted until 1968, when there were 25

optional add-ins tothe basic system. Just as APT was being released in the early 1960s, a

secondgeneration of lower-cost transistorized computers was hittingthe market that were able to

process much larger volumes of information in production settings. This so lowered the cost

of implementing a NC system that by the mid 1960s, APT runsaccounted for a third of all computer time

at large aviationfirms.

CAD meets CNC:

While the Servomechanisms Lab was in the process of developing their first mill, in 1953 MIT's

MechanicalEngineering Department dropped the requirement thatundergraduates take courses

in drawing. The instructorsformerly teaching these programs were merged into theDesign Division,

where an informal discussion of computerizeddesign started. Meanwhile the Electronic Systems

Laboratory,the newly rechristened Servomechanisms Laboratory, hadbeen discussing whether or not

design would ever start withpaper diagrams in the future.In January 1959, an informal meeting was

held involvingindividuals from both the Electronic Systems Laboratory andthe Mechanical Engineering

Department's Design Division.Formal meetings followed in April and and May, which resultedin the

"Computer-Aided Design Project". In December 1959,

Proliferation of CNC

The price of computer cycles fell drastically during the 1960swith the widespread introduction of

usefulminicomputers.Eventually it became less expensive to handle the motorcontrol and feedback with

a computer program than it waswith dedicated servo systems. Small computers werededicated to a

single mill, placing the entire process in a smallbox.PDP-8's andData General Novacomputers were

commonin these roles. The introduction of themicroprocessorin the1970s further reduced the cost of

implementation, and todayalmost all CNC machines use some form of microprocessor tohandle all

operations. The introduction of lower-cost CNC machines radicallychanged the manufacturing industry.

Curves are as easy tocut as straight lines, complex 3-D structures are relativelyeasy to produce, and the

number of machining steps thatrequired human action have been dramatically reduced. Withthe

increased automation of manufacturing processes withCNC machining, considerable improvements

in consistencyand quality have been achieved with no strain on theoperator. CNC automation reduced

the frequency of errors andprovided CNC operators with time to perform additional tasks.CNC

automation also allows for more flexibility in the wayparts are held in the manufacturing process and

the timerequired to change the machine to produce differentcomponents

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During the early 1970s the Western economies were mired inslow economic growth and rising

employment costs, and NCmachines started to become more attractive. The major U.S.vendors were

slow to respond to the demand for machinessuitable for lower-cost NC systems, and into this void

steppedthe Germans. In 1979, sales of German machines surpassedthe U.S. designs for the first time.

This cycle quickly repeateditself, and by 1980 Japan had taken a leadership position, U.S.sales dropping

all the time. Once sitting in the #1 position interms of sales on a top-ten chart consisting entirely of

U.S.companies in 1971, by 1987 Cincinnati Milacron was in 8thplace on a chart heavily dominated

by Japanese firms.Many researchers have commented that the U.S. focus onhigh-end applications left

them in an uncompetitive situationwhen the economic downturn in the early 1970s led to

greatlyincreased demand for low-cost NC systems. Unlike the U.S.companies, who had focused on

the highly profitableaerospace market, German and Japanese manufacturerstargeted lower-profit

segments from the start and were ableto enter the low-cost markets much more easily.

Today

Although modern data storage techniques have moved onfrom punch tape in almost every other role,

tapes are stillrelatively common in CNC systems. This is because it wasoften easier to add a punch tape

reader to a microprocessorcontroller than it was to re-write large libraries of tapes into anew format.

One change that was implemented fairly widelywas the switch from paper tomylartapes, which are

muchmore mechanically robust.Floppy disks,USB flash drivesandlocal area networkinghave replaced the

tapes to somedegree, especially in larger environments that are highlyintegrated

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The proliferation of CNC led to the need for new CNCstandards that were not encumbered by licensing

or particulardesign concepts, like APT. A number of different "standards"proliferated for a time, often

based aroundvector graphicsmarkup languagessupported byplotters. One such standardhas since

become very common, the "G-code" that wasoriginally used onGerber Scientificplotters and then

adaptedfor CNC use. The file format became so widely used that it hasbeen embodied in anEIAstandard.

In turn, G-code wassupplanted bySTEP-NC, a system that was deliberatelydesigned for CNC, rather than

grown from an existing plotterstandard.A more recent advancement in CNC interpreters is support

of logical commands, known as parametric programming.Parametric programs include both device

commands as wellas a control language similar toBASIC. The programmer canmake if/then/else

statements, loops, subprogram calls,perform various arithmetic, and manipulate variables tocreate a

large degree of freedom within one program. Anentire product line of different sizes can be

programmed usinglogic and simple math to create and scale an entire range of parts, or create a stock

part that can be scaled to any size acustomer demands.As digital electronics has spread, CNC has fallen

in price to thepoint where hobbyists can purchase any number of small CNCsystems for home use. It is

even possible tobuild your own.

Description:

Modern CNC mills differ little in concept from the originalmodel built at MIT in 1952. Mills typically

consist of a tablethat moves in the Y axis, and a tool chuck that moves in X andZ (depth). The position of

the tool is driven by motors througha series of step-down gears in order to provide highly accurate

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movements, or in modern designs, direct-drivesteppermotors.As the controller hardware evolved, the

mills themselves alsoevolved. One change has been to enclose the entiremechanism in a large box as a

safety measure, often withadditional safety interlocks to ensure the operator is farenough from the

working piece for safe operation. Mechanicalmanual controls disappeared long ago.CNC-like systems

are now used for any process that can bedescribed as a series of movements and operations.

Theseincludelaser cutting,welding, friction stir welding,ultrasonicwelding, flame andplasma cutting,

bending, spinning,pinning, gluing, fabric cutting, sewing, tape and fiberplacement, routing, picking

and placing (PnP), and sawing.

Programmable logic controller

A programmable logic controller (PLC) or programmablecontroller is adigital computerused

forautomationof electromechanicalprocesses, such as control of machinery onfactoryassembly lines,

amusement rides, or lighting fixtures.PLCs are used in many industries and machines, such aspackaging

and semiconductor machines. Unlike general-purpose computers, the PLC is designed for multiple

inputsand output arrangements, extended temperature ranges,immunity to electrical noise,

and resistance to vibration andimpact. Programs to control machine operation are typicallystored in

battery-backed ornon-volatile memory. A PLC is anexample of areal timesystem since output results

must beproduced in response to input conditions within a boundedtime, otherwise unintended

operation will result

4

Features:

The main difference from other computers is that PLCs arearmored for severe conditions (such as dust,

moisture, heat,cold) and have the facility for extensiveinput/output(I/O)arrangements. These connect

the PLC tosensorsandactuators. PLCs read limitswitches, analog process variables(such as temperature

and pressure), and the positions of complex positioning systems. Some usemachine vision. Onthe

actuator side, PLCs operateelectric motors,pneumaticorhydrauliccylinders, magneticrelays,solenoids, or

analogoutputs. The input/output arrangements may be built into asimple PLC, or the PLC may have

external I/O modulesattached to a computer network that plugs into the PLC.

System scale:

A small PLC will have a fixed number of connections built infor inputs and outputs. Typically, expansions

are available if the base model has insufficient I/O.Modular PLCs have a chassis (also called a rack) into

whichare placed modules with different functions. The processorand selection of I/O modules is

customized for the particularapplication. Several racks can be administered by a singleprocessor, and

may have thousands of inputs and outputs. Aspecial high speed serial I/O link is used so that racks can

bedistributed away from the processor, reducing the wiring costsfor large plants.

User interface:

4

PLCs may need to interact with people for the purpose of configuration, alarm reporting or everyday

control.AHuman-Machine Interface(HMI) is employed for thispurpose. HMIs are also referred to as

MMIs (Man MachineInterface) and GUI (Graphical User Interface).A simple system may use buttons and

lights to interact withthe user. Text displays are available as well as graphical touchscreens. More

complex systems use a programming andmonitoring software installed on a computer, with the

PLCconnected via a communication interface.

Communications:

PLCs have built in communications ports usually 9-PinRS232,and optionally

forRS485andEthernet.ModbusorDF1isusually included as one of thecommunications protocols.Others'

options include variousfieldbusessuch asDeviceNet orProfibus. Other communications protocols that

may be usedare listed in theList of automation protocols.Most modern PLCs can communicate over a

network to someother system, such as a computer running aSCADA (Supervisory Control And Data

Acquisition) system or webbrowser.PLCs used in larger I/O systems may have peer-to-peer

(P2P)communication between processors. This allows separateparts of a complex process to have

individual control whileallowing the subsystems to co-ordinate over thecommunication link. These

communication links are also oftenused forHMIdevices such as keypads orPC-typeworkstations. Some of

today's PLCs can communicate over awide range of media including RS-485, Coaxial, and

evenEthernetfor I/O control at network speeds up to 100 Mbit/s

4

PLC compared with other control systems:

PLCs are well-adapted to a range of automationtasks. Theseare typically industrial processes in

manufacturing where thecost of developing and maintaining the automation system ishigh relative to

the total cost of the automation, and wherechanges to the system would be expected during

itsoperational life. PLCs contain input and output devicescompatible with industrial pilot devices and

controls; littleelectrical design is required, and the design problem centerson expressing the desired

sequence of operations inladderlogic(orfunction chart) notation. PLC applications aretypically highly

customized systems so the cost of a packagedPLC is low compared to the cost of a specific custom-

builtcontroller design. On the other hand, in the case of mass-produced goods, customized control

systems are economicdue to the lower cost of the components, which can beoptimally chosen instead

of a "generic" solution, and wherethe non-recurring engineering charges are spread overthousands or

millions of units.For high volume or very simple fixed automation tasks,different techniques are used.

For example, a consumerdishwasherwould be controlled by an electromechanicalcamtimercosting only

a few dollars in production quantities.Amicrocontroller-based design would be appropriate

wherehundreds or thousands of units will be produced and so thedevelopment cost (design of power

supplies and input/outputhardware) can be spread over many sales, and where the end-user would not

need to alter the control. Automotiveapplications are an example; millions of units are built eachyear,

and very few end-users alter the programming of thesecontrollers. However, some specialty vehicles

such as transitbusses economically use PLCs instead of custom-designedcontrols, because the volumes

are low and the developmentcost would be uneconomic.

4

Very complex process control, such as used in the chemicalindustry, may require algorithms and

performance beyond thecapability of even high-performance PLCs. Very high-speed orprecision controls

may also require customized solutions; forexample, aircraft flight controls.Programmable controllers are

widely used in motion control,positioning control and torque control. Some manufacturersproduce

motion control units to be integrated with PLC so thatG-code(involving aCNCmachine) can be used to

instructmachine movements.PLCs may include logic for single-variable feedback analogcontrol loop, a

"proportional, integral, derivative" or "PIDcontroller." A PID loop could be used to control

thetemperature of a manufacturing process, for example.Historically PLCs were usually configured with

only a fewanalog control loops; where processes required hundreds orthousands of loops, adistributed

control system(DCS) wouldinstead be used. As PLCs have become more powerful, theboundary between

DCS and PLC applications has become lessdistinct.PLCs have similar functionality asRemote Terminal

Units. AnRTU, however, usually does not support control algorithms orcontrol loops. As hardware

rapidly becomes more powerfuland cheaper,RTUs, PLCs andDCSsare increasingly beginningto overlap in

responsibilities, and many vendors sell RTUs withPLC-like features and vice versa. The industry

hasstandardized on the IEC 61131-3 functional block language forcreating programs to run on RTUs and

PLCs, although nearlyall vendors also offer proprietary alternatives and associateddevelopment

environments

Digital and analog signals:

Digital or discrete signals behave as binary switches, yieldingsimply an On or Off signal (1 or 0, True or

False, respectively).Push buttons, limit switches, andphotoelectric sensorsare

4

examples of devices providing a discrete signal. Discretesignals are sent using eithervoltageorcurrent,

where aspecific range is designated as

On

and another as

Off

. Forexample, a PLC might use 24 V DC I/O, with values above 22 VDC representing

On

, values below 2VDC representing

Off

, andintermediate values undefined. Initially, PLCs had onlydiscrete I/O.Analog signals are like volume

controls, with a range of valuesbetween zero and full-scale. These are typically interpreted asinteger

values (counts) by the PLC, with various ranges of accuracy depending on the device and the number of

bitsavailable to store the data. As PLCs typically use 16-bit signedbinary processors, the integer values

are limited between-32,768 and +32,767. Pressure, temperature, flow, and weightare often represented

by analog signals. Analog signals canusevoltageorcurrentwith a magnitude proportional to thevalue of

the process signal. For example, an analog4-20 mA or 0 - 10 V input would beconvertedinto an integer

value of 0- 32767.Current inputsare less sensitive to electrical noise (i.e. fromwelders or electric motor

starts) thExample:

As an example, say a facility needs to store water in a tank. The wateris drawn from the tank by another

system, as needed, and ourexample system must manage the water level in the tank.Using only digital

signals, the PLC has two digital inputs fromfloatswitches(Low Level and High Level). When the water

level is above theswitch it closes a contact and passes a signal to an input. The PLC usesa digital output

to open and close the inletvalveinto the tank.When the water level drops enough so that the Low Level

float switchis off (down), the PLC will open the valve to let more water in. Once thewater level rises

enough so that the High Level switch is on (up), thePLC will shut the inlet to stop the water from

overflowing. This rung isan example of seal in logic. The output is sealed in until some conditionbreaks

the circuit.

an voltage inputs

4

| Low Level High Level Fill Valve ||------[/]------|------[/]----------------------(OUT)---------

|| | || | || | || Fill Valve | ||------[ ]------| || || |

An analog system might use a waterpressure sensoror aloadcell, and an adjustable (throttling) dripping

out of the tank,the valve adjusts to slowly drip water back into the tank.In this system, to avoid 'flutter'

adjustments that can wear outthe valve, many PLCs incorporate "hysteresis" whichessentially creates a

"deadband" of activity. A technicianadjusts this deadband so the valve moves only for asignificant

change in rate. This will in turn minimize themotion of the valve, and reduce its wear.A real system

might combine both approaches, using floatswitches and simple valves to prevent spills, and a rate

sensorand rate valve to optimize refill rates and preventwaterhammer. Backup and maintenance

methods can make a realsystem very complicated.

Programming:

PLC programs are typically written in a special application ona personal computer, then downloaded

by a direct-connectioncable or over a network to the PLC. The program is stored inthe PLC either

in battery-backed-upRAMor some other non-volatileflash memory. Often, a single PLC can be

programmedto replace thousands of relays.Under theIEC 61131-3standard, PLCs can be

programmedusing standards-based programming languages. A graphicalprogramming notation

calledSequential Function Chartsisavailable on certain programmable controllers.Recently, the

International standardIEC 61131-3has becomepopular. IEC 61131-3 currently defines five

programminglanguages for programmable control systems: FBD (Function

4

block diagram), LD (Ladder diagram), ST (Structured text,similar to thePascal programming language), IL

(Instructionlist, similar toassembly language) and SFC (Sequentialfunction chart). These techniques

emphasize logicalorganization of operations.While the fundamental concepts of PLC programming

arecommon to all manufacturers, differences in I/O addressing,memory organization and instruction

sets mean that PLCprograms are never perfectly interchangeable betweendifferent makers. Even within

the same product line of a singlemanufacturer, different models may not be directly

History

Origin:

The PLC was invented in response to the needs of theAmerican automotive manufacturing industry.

Programmablecontrollers were initially adopted by the automotive industrywhere software revision

replaced the re-wiring of hard-wiredcontrol panels when production models changed.Before the PLC,

control, sequencing, and safety interlock logicfor manufacturing automobiles was accomplished

usinghundreds or thousands of relays,cam timers, anddrumsequencersand dedicated closed-loop

controllers. Theprocess for updating such facilities for the yearly modelchange-overwas very time

consuming and expensive, as therelay systems needed to be rewired by skilled electricians.In 1968 GM

Hydramatic (the automatic transmission divisionof General Motors) issued a request for proposal for

anelectronic replacement for hard-wired relay systems. The winning proposal came from Bedford

Associates of Bedford, Massachusetts. The first PLC, designated the 084because it was Bedford

Associates' eighty-fourth project, wasthe result. Bedford Associates started a new company

4

dedicated to developing, manufacturing, selling, and servicingthis new product: Modicum, which

stood for Modular DigitalController. One of the people who worked on that project wasDick Morley,

who is considered to be the "father" of the PLC. The Modicum brand was sold in 1977 toGould

Electronics,and later acquired by German CompanyAEGand then byFrenchSchneider Electric, the current

owner.One of the very first 084 models built is now on display atModicum’s headquarters inNorth

Andover, Massachusetts. Itwas presented to Modicum byGM, when the unit was retiredafter nearly

twenty years of uninterrupted service. Modicumused the 84 moniker at the end of its product range

until the984 made its appearance. The automotive industry is still one of the largest users of PLCs.

Development:

Early PLCs were designed to replace relay logic systems. These PLCs were programmed in "ladder logic",

whichstrongly resembles a schematic diagram of relay logic.Modern PLCs can be programmed in a

variety of ways, fromladder logic to more traditional programming languages suchas BASIC and C.

Another method isState Logic, aVery HighLevel Programming Languagedesigned to program PLCsbased

onState Transition Diagrams.Many of the earliest PLCs expressed all decision making logicin

simpleladder logicwhich appeared similar to electricalschematic diagrams. This program notation was

chosen toreduce training demands for the existing technicians. Otherearly PLCs used a form

of instruction listprogramming, basedon a stack-based logic solver.

Programming:

rive system

or

hydraulicpower transmission

is a drive or transmission system thatuses hydraulic fluid under pressure to drive machinery. Theterm

hydrostatic refers to the transfer of energy from flow andpressure, not from thekineticenergy of the

flow. Such asystem basically consists of three parts. The generator (e.g. a

4

hydraulic pump, driven by anelectric motor, a combustionengineor awindmill); valves, filters, piping etc.

(to guide andcontrol the system); the motor (e.g. ahydraulic motororhydraulic cylinder) to drive the

machinery.

Principle of a hydraulic drive:

Pascal's law is the basis of hydraulicdrive systems. As the pressure in thesystem is the same, the force

that thefluid gives to the surroundings istherefore equal to pressure x area. Insuch a way, a small piston

feels asmall force and a large piston feels alarge force. The same counts for a hydraulic pumpwith a

small swept volume, that asksfor a smalltorque, combined with ahydraulic motor with a large

sweptvolume, that gives a large torque.In such a way a transmission with a certain ratio can be

built.Most hydraulic drive systems make use of hydraulic cylinders.Here the same principle is used- a

small torque can betransmitted in to a large force.By throttling the fluid between generator part and

motor part,or by using hydraulic pumps and/or motors with adjustableswept volume, the ratio of the

transmission can be changedeasily. In case throttling is used, the efficiency of thetransmission is limited;

in case adjustable pumps and motorsare used, the efficiency however is verylarge. In fact, up to around

1980, ahydraulic drive system had hardly anycompetition from other adjustable(electric) drive

systems.Nowadays electric drive systems usingelectric servo-motors can be controlled

4

in an excellent way and can easily compete with rotatinghydraulic drive systems. Hydraulic cylinders are

in factwithout competition for linear (high) forces. For thesecylinders anyway hydraulic systems will

remain of interestand if such a system is available, it is easy and logical to usethis system also for the

rotating drives of the cooling systems

Hydraulic cylinder:

Hydraulic cylinders(also called linear hydraulic motors) aremechanical actuators that are used to give a

linear forcethrough a linear stroke. A hydraulic cylinder is without doubtthe best known hydraulic

component. Hydraulic cylinders areable to give pushing and pulling forces of millions of metrictons, with

only a simple hydraulic system. Very simplehydraulic cylinders are used in presses; here the

cylinderconsists out of a volume in a piece of iron with a plungerpushed in it and sealed with a cover. By

pumping hydraulicfluid in the volume, the plunger is pushed out with a force of plunger-area *

pressure.More sophisticated cylinders have a body with end cover, apiston-rod with piston and a

cylinder-head. At one side thebottom is for instance connected to a single clevis, whereas atthe other

side, the piston rod also is foreseen with a singleclevis. The cylinder shell normally has hydraulic

connectionsat both sides. A connection at bottom side and one at cylinderhead side. If oil is pushed

under the piston, the piston-rod ispushed out and oil that was between the piston and thecylinder head

is pushed back to the oil-tank again. The pushing or pulling force of a hydraulic cylinder is:F = Ab * pb -

Ah * phF = Pushing Force in NAb = (π/4) * (Bottom-diameter)^2 [in m2]Ah = (π/4) * ((Bottom-

diameter)^2-(Piston-rod-diameter)^2))[in m2]pb = pressure at bottom side in [N/m2]

4

ph = pressure at cylinder head side in [N/m2]Apart from miniature cylinders, in general, the

smallestcylinder diameter is 32 mm and the smallest piston roddiameter is 16 mm.Simple hydraulic

cylinders have a maximum working pressureof about 70 bar, the next step is 140 bar, 210 bar,

320/350bar and further, the cylinders are in general custom build. Thestroke of a hydraulic cylinder

is limited by the manufacturingprocess. The majority of hydraulic cylinders have a strokebetween 0,3

and 5 metres, whereas 12-15 metre stroke is alsopossible, but for this length only a limited number of

suppliersare on the market.In case the retracted length of the cylinder is too long for thecylinder to be

build in the structure. In this casetelescopiccylinderscan be used. One has to realize that for

simplepushing applications telescopic cylinders might be availableeasily; for higher forces and/or double

acting cylinders, theymust be designed especially and are very expensive. If hydraulic cylinders are only

used for pushing and the pistonrod is brought in again by other means, one can also useplunger

cylinders. Plunger cylinders have no sealing over thepiston, or the piston does not exist. This means

that only oneoil connection is necessary. In general the diameter of theplunger is rather large compared

with a normal pistoncylinder, because this large area is needed.Whereas a hydraulic motor will always

leak oil, a hydrauliccylinder does not have a leakage over the piston nor over thecylinder head sealing,

so that there is no need for amechanical brake.

Hydraulic motor:

4

The hydraulic motor is the rotary counterpart of thehydrauliccylinder.Conceptually, a hydraulic

motor should be interchangeablewithhydraulic pump, because it performs the oppositefunction -- much

as the conceptual DCelectric motorisinterchangeable with a DCelectrical generator. However,most

hydraulic pumps cannot be used as hydraulic motorsbecause they cannot beback driven. Also, a

hydraulic motoris usually designed for the working pressure at both sides of the motor.

Hydraulic valves:

These valves are usually very heavy duty to stand up to highpressures. Some special valves can control

the direction of theflow of fluid and act as a control unit for a system.

Pneumatics

Pneumatics

is the use of pressurized gasto affectmechanical motion.Pneumatic power is used inindustry, where

factory machinesare commonly plumbed forcompressed air; other compressedinert gasescan also be

used. Pneumatics also hasapplications indentistry,construction,mining, and otherareas.

Examples of pneumatic systems:

4

•

Pneumatic drill(jackhammer) used by road workers

•

Pneumatic nail gun

•

Electro-pneumatic action

•

Pneumatic switches

•

Air compressors

•

Vacuum pump

•

Barostatsystems used inNeuro gastroenterologyand forresearching electricity

•

Cable jetting, a way to install cables in ducts

Gases used in pneumatic systems:

Pneumatic systems in fixed installations such as factories usecompressed air because a sustainable

supply can be made bycompressing atmospheric air. The air usually has moistureremoved and a small

quantity of oil added at the compressor,to avoid corrosion of mechanical components and to

lubricatethem.Factory-plumbed, pneumatic-power users need not worryabout poisonous leakages as

the gas is commonly just air.Smaller or stand-alone systems can use other compressedgases which are

anasphyxiationhazard, such asnitrogen-often referred to asOFN (oxygen-free nitrogen), whensupplied in

cylinders.Any compressed gas other than air is anasphyxiationhazard -including nitrogen, which makes

up approximately 80% of air.Compressedoxygen(approx. 20% of air) would notasphyxiate, but it would

be an extreme fire hazard, so is neverused in pneumatically powered devices.Portable pneumatic tools

and small vehicles such asRobotWarsmachines and other hobbyist applications are oftenpowered by

compressedcarbon dioxidebecause containersdesigned to hold it such assoda streamcanisters and

fireextinguishers are readily available, and thephase change

4

between liquid and gas makes it possible to obtain a largervolume of compressed gas from a lighter

container thancompressed air would allow.Carbon dioxideis both anasphyxiant and poisonous, and

can also be a freezing hazardwhen vented.

Comparison to hydraulics:

Both pneumatics and hydraulics are applications of fluidpower. Pneumatics uses an easily compressible

gas such asair or a suitable pure gas, whilehydraulicsuses relativelyincompressible liquid media such as

oil. Most industrialpneumatic applications use pressures of about 80 to 100pounds per square inch (psi)

(500 to 700kilopascals).Hydraulics applications commonly use from 1,000 to 5,000 psi(7 to 35 MPa), but

specialized applications may exceed 10,000psi (70 MPa).

Advantages of pneumatics:

Simplicity of Design And Control

Machines are easily designed using standard cylinders & othercomponents. Control is as easy as it is

simple ON - OFF typecontrol.

Reliability

Pneumatic systems tend to have long operating lives andrequire very little maintenance.Because gas is

compressible, the equipment is less likely tobe damaged by shock. The gas in pneumatics

absorbsexcessive force, whereas the fluid of hydraulics directlytransfers force.

Storage

4

Compressed Gas can be stored, allowing the use of machineswhen electrical power is lost.

Safety

Very small fire hazards (compared to hydraulic oil).Machines can be designed to be overload safe.

Advantages of hydraulics:

•

Fluid does not absorb any of the supplied energy.

•

Capable of moving much higher loads and providingmuch higher forces due to the incompressibility.

•

The hydraulic working fluid is basically incompressible,leading to a minimum of springaction. When

hydraulicfluid flow is stopped, the slightest motion of the loadreleases the pressure on the load; there is

no need to"bleed off" pressurized air to release the pressure on theload.

Pneumatic Logic:

Pneumatic logic systems are often used to control industrialprocesses, consisting of primary logic units

such as:

•

AndUnits

•

OrUnits

•

'Relay or Booster' Units

•

Latching Units

•

'Timer' UnitsPneumatic logic is a reliable and functional control method forindustrial processes.

In recent years, these systems havelargely been replaced by electrical control systems, due to

thesmaller size and lower cost of electrical components.Pneumatic devices are still used in processes

wherecompressed air is the only energy source available or upgradecost, safety, and other

considerations outweigh the advantageof modern digital control.

Abstracts

Successes and Short ComingsSuccesses

4

There were many successes, both on our side and on thecompany side. Personally the following is what

we succeededon:

•

First, to us it was a success having been given a chanceto handle work on various machines that we

believe willnever see like these.

•

Through the work that we used to do; our knowledgerelated to the machines was largely broadened.

We canclearly understand how one can effectively study issuesconcerning.

•

We weren’t familiar practically with CNC, PLC, controlsand Pneumatic Hydraulic Systems, but now

we canconfidently use it with ease. The Pakistan Machine Tool Factory largely succeeded a lotthrough

our skills, competence and the overall output of mywork because;

•

We used our skills, studies and hands too in workshopsand departments. Therefore enabling to

meet deadlines

Short Comings

There weren’t many short comings since as an intern we weregiven a lot of support by our supervisors

and other fellowstaff. Therefore the major short comings that I did face were:

•

Time was limited and therefore I had to leave pre-maturely before the complete products of my effort

werefinalized.

•

In terms of cultural differences I must say that nobodyshould expect it as easy to integrate in a different

culture.

4

But the difficulty was not based on the way, we werewelcomed here, it was that we needed some time

to feelcomfortable with our new environmentSS