SUMMER TRAINING REPORT - HAL, LUCKNOW

A REPORT ON INDUSTRIAL TRAINING IN

HINDUSTAN AERONAUTICS LIMITED

LUCKNOW

SUBMITTED TO-

PROF. H. N. GUPTA SIR

SUBMITTED BY-

SALONI RASTOGI- 1105240041

SHAMIMUN NISHA-1105240045

B.Tech (ME 4th year)

IET LUCKNOW

ACKNOWLEDGEMENT

It gives us an immense pleasure to present the report of the Project

undertaken by me during summer training. We owe special debt of gratitude to

Sr. Manager (Training) at Hindustan Aeronautics Limited, Lucknow for his

constant support and guidance throughout the course of my work. His sincerity,

thoroughness and perseverance have been a constant source of inspiration for

us. It is only his cognizant efforts that our endeavours have seen light of the day.

We also take the opportunity to acknowledge the contribution of all the

staff members at HAL for their full support and assistance during the

development of the project.

We are also very thankful to the respected faculty members of IET

Lucknow for their regular guidance which has enabled us to easily grasp practical

aspects in the industry.

CONTENTS

1. INTRODUCTION TO HAL……………………………………..

2. PRODUCTS OF HAL…………………………………………...

3. BASIC FLIGHT THEORY……………………………………...

4. AXES OF MOTION OF AIRPLANE…………………………...

5. MECHANICAL FACTORY……………………………………. Jig Boring Machine Electric Discharge Machine Wire Cut EDM

6. FUEL FACTORY……………………………………………….. Aircraft Fuel System

7. INSTRUMENT FACTORY…………………………………….. Linear Actuator

INTRODUCTION TO HAL

HAL was established as Hindustan Aircraft in Bangalore in 1940 by Seth Walchand Hirachand to produce

military aircraft for the Royal Indian Air Force. The initiative was actively encouraged by the Kingdom of

Mysore, especially by the Diwan, Sir Mirza Ismail and it also had financial help from the Indian Government.

Mysore was favoured because of the availability of cheap electricity. The organisation and equipment for the

factory at Bangalore was set up by William D. Pawley of the Intercontinental Aircraft Corporation of New

York, an exporter of American aircraft to the region. Pawley managed to obtain a large number of machine-

tools and equipment from the United States.

The Indian Government bought a one-third stake in the company and by April 1941 as it believed this to be a

strategic imperative. The decision by the government was primarily motivated to boost British military

hardware supplies in Asia to counter the increasing threat posed by Imperial Japan during Second World War.

The Kingdom of Mysore supplied two directors, Air Marshal John Higgins was resident director. The first

aircraft built was a Harlow PC-5[3] On 2 April 1942, the government announced that the company had been

nationalised when it had bought out the stakes of Seth Walchand Hirachand and other promoters so that it could

act freely. The Mysore Kingdom refused to sell its stake in the company but yielded the management control

over to the Indian Government.

In 1943 the Bangalore factory was handed over to the United States Army Air Forces but still using Hindustan

Aircraft management. The factory expanded rapidly and became the centre for major overhaul and repairs of

American aircraft and was known as the 84th Air Depot. The first aircraft to be overhauled was a Consolidated

PBY Catalina followed by every type of aircraft operated in India and Burma. When returned to Indian control

two-years later the factory had become one of the largest overhaul and repair organisations in the East. In the

post war reorganization the company built railway carriages as an interim activity.

After India gained independence in 1947, the management of the company was passed over to the Government

of India.

Hindustan Aeronautics Limited (HAL) was formed on 1 October 1964 when Hindustan Aircraft Limited joined

the consortium formed in June by the IAF Aircraft Manufacturing Depot, Kanpur (at the time manufacturing

HS.748 under license) and the group recently set up to manufacture Mig-21 under license (with its new

factories planned in Koraput, Nasik and Hyderabad). Though HAL was not used actively for developing newer

models of fighter jets, the company has played a crucial role in modernization of the Indian Air Force. In 1957

company started manufacturing Bristol Siddeley Orpheusjet engines under license at new factory located in

Bangalore.

During the 1980s, HAL's operations saw a rapid increase which resulted in the development of new indigenous

aircraft such as HAL Tejas and HAL Dhruv. HAL also developed an advanced version of the MiG-21, known

as MiG-21 Bison, which increased its life-span by more than 20 years. HAL has also obtained several multi-

million dollar contracts from leading international aerospace firms such as Airbus, Boeing and Honeywell to

manufacture aircraft spare parts and engines.

HAL LUCKNOW (ACCESSORIES DIVISION)

The manufacturing range of this division can be grouped under three categories:

1. Mechanical and hydro-mechanical accessories

2. Engine Accessories.

3. Instrument accessories.

In addition, the division also manufactures the wide variety of ground support equipment like

Ground Power Unit, hydraulic trolley, weapon loading trolley, Test equipment etc. The Aerospace & equipment

research & design Centre is involved in the design and development of hydraulic pumps, actuators, wheels and

brakes etc.

PRODUCTS BY HAL Su 30 MKI - Twin-seater, Multi-role, Long range Fighter / Bomber / Air Superiority Aircraft

MiG-27 M - Single-seater Tactical Fighter / Bomber with variable sweep wings

MiG-21 VARIANTS - Single-seater Front line Tactical Interceptor / Fighter Aircraft

METALLIC DROP TANKS - The Division manufactures different types of metallic drop (Jettisonable) tanks with capacity of 490 and 800 litres

UNDERCARRIAGE - The Division has facilities and expertise in the manufacture and overhaul of Undercarriages of both MiG-27M and MiG-21 variants. The landing gears are of a conventional tricycle type and consist of one steerable Nose wheel leg and two Main wheel legs to roll the aircraft in motion, on the ground, during take-off run and landing run. The Landing Gear legs have Pneumatic shock absorbers.

EJECTION SEAT - The Ejection Seat is installed to provide safe escape to the Pilot from the Aircraft while catapuling is effected with the help of a combined Ejection Gun. The Division has the facilities and expertise in the manufacture and overhaul of ejection seats for both MiG-27M and MiG-21 variants.

CANOPY -The Division manufactures and overhauls canopies of MiG-21 variants and MiG-27M Aircraft.

FLEXIBLE RUBBER FUEL TANKS - The Division manufactures and supplies all types of Rubber Fuel Tanks required for MiG-21 Variants. The Rubber Fuel Tanks are provided with special protection coating against Ozone/heat and adverse climatic conditions.

PRECISION COMPONENTS - The Division also produces precision components like: total gamut of Blades ranging from Compressor Rotors and Stators to Turbine Blades and Nozzle Guide Vanes, intricate Cored Magnesium Alloy Gear Casings, Compressor and Turbine Discs and Shafts, JIS class-l/DlN 5 Spur, Helical Gears and DIN 6 straight and Hypoid / Spiral Bevel Gears ranging from module 1 to 6.

HYDRAULIC SYSTEM AND POWER CONTROL - Hydraulic Pumps, Accumulators, Actuators, Electro-selectors, Bootstrap Reservoirs and  various types of valves

ENVIRONMENTAL CONTROL SYSTEM - Cold Air Unit,  Water Extractors, Non Return Valves and Venturies

ENGINE FUEL CONTROL SYSTEM - Fuel after Burner regulator and distributor, Main Fuel Distributor, Regulator and After Burner Pump, Plunger Pumps, Fuel Metering Device 

INSTRUMENTS - Electrical Indicators, Fuel quantity and flow metering instruments, Flight instruments, Sensors and Switches 

ELECTRICAL POWER GENERATION AND CONTROL   SYSTEM -AC/DC Generator, Control and Protection Units, AC and DC Master Box, Inverters, Transformer Rectifier Unit, Actuators

UNDERCARRIAGE, WHEELS AND BRAKES   -Main and Nose Undercarriage, Main and Nose Wheel, Brake System LRUs 

 TEST RIGS -Dedicated Test Rigs, custom-built Fuel/Hydraulic Test Rigs and Electrical Test Rigs

BASIC AERODYNAMIC FLIGHT THEORY

FORCES OF FLIGHT

The four forces are lift, thrust, drag, and weight .They push a plane up, down, forward, or slow it down.

LIFT

To overcome the weight force, airplanes generate an opposing force called lift. Lift is generated by the motion of the airplane through the air and is an aerodynamic force. "Aero" stands for the air, and "dynamic" denotes motion. Lift is directed perpendicular to the flight direction. The magnitude of the lift depends on several factors including the shape, size, and velocity of the aircraft. As with weight, each part of the aircraft contributes to the aircraft lift force. Most of the lift is generated by the wings. Aircraft lift acts through a single point called the center of pressure. The center of pressure is defined just like the center of gravity, but using the pressure distribution around the body instead of the weight distribution. The distribution of lift around the aircraft is important for solving the control problem.

WEIGHT

Weight is a force that is always directed toward the center of the earth. The magnitude of the weight depends on the mass of all the airplane parts, plus the amount of fuel, plus any payload on board (people, baggage, freight, etc.). The weight is distributed throughout the airplane. But we can often think of it as collected and acting through a single point called the center of gravity. 

DRAG

As the airplane moves through the air, there is another aerodynamic force present. The air resists the motion of the aircraft and the resistance force is called drag. Drag is directed along and opposed to the flight direction. Like lift, there are many factors that affect the magnitude of the drag force including the shape of the aircraft, the "stickiness" of the air, and the velocity of the aircraft. Drag acts through the aircraft center of pressure.

THRUST

To overcome drag, airplanes use a propulsion system to generate a force called thrust. The direction of the thrust force depends on how the engines are attached to the aircraft.  The magnitude of the thrust depends on many factors associated with the propulsion system including the type of engine, the number of engines, and the throttle setting.

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Axes of motion

An aircraft is free to rotate around three axes that are perpendicular to each other and intersect at its center of gravity  (CG). To control position and direction a pilot must be able to control rotation about each of them.

Lateral axis

The lateral axis passes through an aircraft from wingtip to wingtip. Rotation about this axis is called  pitch. Pitch changes the vertical direction that the aircraft's nose is pointing. The  elevators  are the primary control surfaces for pitch.

Longitudinal axis

The longitudinal axis passes through the aircraft from nose to tail. Rotation about this axis is called  roll. Rolling motion changes the orientation of the aircraft's wings with respect to the downward force of gravity. The pilot changes bank angle by increasing the lift on one wing and decreasing it on the other. This differential lift causes bank rotation around the longitudinal axis. The  ailerons  are the primary control of bank. The  rudder  also has a secondary effect on bank.

Vertical axis

The vertical axis passes through an aircraft from top to bottom. Rotation about this axis is called  yaw. Yaw changes the direction the aircraft's nose is pointing, left or right. The primary control of yaw is with the rudder. Ailerons also have a secondary effect on yaw.

It is important to note that these axes move with the aircraft, and change relative to the earth as the aircraft moves. For example, for an aircraft whose left wing is pointing straight down, its "vertical" axis is parallel with the ground, while its "lateral" axis is perpendicular to the ground.

Airplane Wings – How Lift is created

All vertical movement of the aircraft is a consequence of a relative imbalance between the weight of the aircraft and the force of lift produced by the airplane wings. The wings of an aircraft are airfoils designed to create this force of vertical motion. Any surface that alters the airflow to the advantage of a produced force in a particular direction is termed as an airfoil. Airplane wings, designed as airfoils, achieve this by interacting with the remote airflow to produce the desired lift.

Understanding Air at the Molecular Level - Air is composed of molecules moving randomly at high speeds. With respect to airplane wings, these molecules exert a force on the air foil, whenever they come in contact with it. This force or   pressure   is called   static pressure , which entails the total force exerted by the molecules of an air mass. A parcel of air does not remain stationary. Its movement involves the movement of the very molecules within it. When the airplane wings are subjected to an air mass that is stationary, the molecules of air strike the wing at angles that are perpendicular or nearly perpendicular. Perpendicular interaction of molecules against the wing exerts a greater force or a greater static pressure when compared with molecules striking the wing at relatively slanted   angles. Air molecules striking at slanted angles contribute to a relatively lower static pressure. Bernoulli’s principle, which states that “high flow velocity gives a low static pressure” is in line with this concept. The higher the velocity of airflow over airplane wings, the lower would be the static pressure exerted on the wing.

Airplane Wings Creating Lift

Airplane wings are never built in-line with the fuselage of the aircraft. These airfoils are always installed at an angle (generally around 4 degrees). This angle of the wing is termed as the angle of inclination, depicting the particular angle at which the wing is inclined.

• Air molecules strike against a greater portion of the plate.

• Much of the plate is exposed to perpendicular strikes of the air molecules.• The air mass exerts a reactional force that manifests itself in terms of lift anddrag.Whether the speed of the wings itself in the air mass, or the movement of the air mass relative to the wings.

the wings have a relative speed to the air mass.• The air strikes against the inclined wing and speeds up over the wing. This movement of air (upwards and over the wing), is called upwash.• Upwash restricts the random movement of air, causing the molecules to flow in a relatively streamlined manner and, thus speeding it up.• As explained earlier, high speed motion of air causes its static pressure over the airplane wing to decrease.• This creates an area of low pressure over the airplane wings and a relatively higher pressure under them.• This pressure differential exerts an aerodynamic force on the wing which basically has two components; lift and drag.• The lift component acts perpendicular to the direction of the airflow.• Drag is parallel to the airflow.

Aircraft Fuel System

The purpose of an aircraft fuel system is to store and deliver the proper amount of clean fuel at the correct pressure to the engine

Fuel systems should provide positive and reliable fuel flow through all phases of flight including:

– Changes in altitude– Violent maneuvers– Sudden acceleration and deceleration

Requirements of a good fuel system:

Since fuel load can be a significant portion of the aircraft’s weight, a sufficiently strong airframe must be designed.

Varying fuel loads and shifts in weight during manoeuvres must not negatively affect control of the aircraft in flight.

Each system must provide contaminant free fuel regardless of the aircraft’s attitude. Monitor fuel pressure, fuel flow, warning signal and tank quantity.

Types of Fuel systems:

1. GRAVITY FEED SYSTEM –In this system, gravity is used to deliver the fuel to engine fuel control mechanism. The space above the liquid fuel is vented to maintain atmospheric pressure on the fuel as the tank empties. It has no fuel pump and is used for high wing aircrafts.

2. PRESSURE FEED SYSTEM –This system requires the use of a fuel pump to provide required fuel pressure to the engine fuel control component.There are two main reasons these systems are necessary:

– The fuel tanks are too low to provide enough pressure from gravity

– The fuel tanks are a great distance from the engine

Also, most large aircraft with higher powered engines require a pressure system regardless of the fuel tank location because of the large volume of fuel used by the engines.

Fuel System Components

A fuel system consists of storage tanks, pumps, filters, valves, fuel lines, metering devices, and monitoring devices.

Fuel Tanks: Each fuel tank must be able to withstand, without failure, the vibration, inertia, fluid, and structural loads to which it may be subjected in operation. Tanks are constructed of noncorrosive Material. Aircraft fuel tanks contain some sort of baffling to subdue the fuel from shifting rapidly during flight manoeuvres. Use of a scupper constructed around the fuel fill opening to drain away any spilled fuel is also present.

Fuel pump: There are main pumps and emergency pumps. Any pump required for operation is considered a main fuel pump. Emergency pumps are used and must be immediately available to supply fuel to the engine if any main pump fails. Auxiliary pumps are used on many aircraft as well. Sometimes known as booster pumps or boost pumps, auxiliary pumps are used to provide fuel under positive pressure to the engine-driven pump and during starting when the engine-driven pump is not yet up to speed for sufficient fuel delivery. Some aircraft use ejector pumps to help ensure that liquid fuel is always at the inlet of the pump.

Fuel Pipelines: Aircraft fuel lines can be rigid or flexible depending on location and application. Rigid lines are often made of aluminium alloy, stainless steel lines also used. Flexible fuel hose has a synthetic rubber interior with a reinforcing fibre braid wrap covered by a synthetic exterior.Each fuel line must be installed and supported to prevent excessive vibration and to withstand loads due

to fuel pressure and accelerated flight conditions. Lines connected to components of the airplane, between which relative motion could exist, must have provisions for flexibility. Flexible hose assemblies are used when lines may be under pressure and subject to axial loads. Any hose that is used must be shown to be suitable for a particular application. Where high temperatures may exist during engine operation or after shutdown, fuel hoses must be capable of withstanding these temperatures.

Valves: shutoff valve, Check valves, Fuel tank selector valves, etc. They are used to shut off fuel flow or to route the fuel to a desired location. Fuel valves can be manually operated, solenoid operated, or operated by electric motor.

Fuel flow meters : A fuel flowmeter indicates an engine’s fuel use in real time. This can be useful to the pilot for ascertaining engine performance and for flight planning calculations.

Filters, strainers : for draining and cleaning. The fuel strainer should have a sediment trap and drain. Fuel strainers are usually constructed of relatively coarse wire mesh. Fuel filters generally are usually fine mesh.

Quantity indicators : are Fuel Quantity Indicating Systems. Electric fuel quantity indicators are more common than mechanical indicators in modern aircraft. Digital indicators are also available.

Warning device ( Pressure Warning Signal): On aircraft of any size, visual and audible warning devices are used in conjunction with gauge indications to draw the pilot’s attention to certain conditions.

FUEL SUBSYSTEMS:

Some aircraft fuel subsystems allow for fuel:• Jettison• Heating• Cross-Feeding

FUEL JETTISON:• The fuel jettison system comprises a combination of fuel lines, valves, and pumps provided to dump fuel

overboard during an in-flight emergency• This will reduce the weight of the aircraft so an emergency landing is possible

FUEL HEATING:• Fuel heating is necessary for turbine engines to thaw ice particles in the fuel that would otherwise clog

the filters• Fuel is routed through a heat exchanger that uses either engine oil or compressor bleed air to bring the

fuel up to an acceptable temperature

CROSS FEEDING:• Cross feed systems allow the flow of fuel from any of the tanks to any of the engines• Some reasons that this system might be used are:

– Engine failure– Problem with one or more fuel tanks– Redistribute fuel for weight and balance purposes

MECHANICAL FACTORY

JIG BORING MACHINE

• Jig borers are vertical boring machines with high precision bearings. • It was developed primarily for accurately locating and producing holes in precise locations. They are

also called precision co-ordinate measuring machines. It’s used for making numerous holes necessary for jigs, fixtures, gauges and other precision parts.

• The most important tool used in jig borers is: single- point boring bar. Other tools like drills, reamers, and counter borers are also used.

• Very important tool before age of computer-controlled machining centers.

• Jig boring is used to accurately enlarge existing holes and make their diameters highly accurate. Jig boring is used for holes that need to have diameter and total runout controlled to a high degree. Typically, a part has holes machined on regular equipment and then the part is transferred to a dedicated jig boring machine for final operations on the especially accurate holes.

• Jig boring can also maintain high accuracy between multiple holes or holes and surfaces. Tolerances can be held readily within ±.005 mm (±0.0002 inches). Dedicated jig boring machines are designed to machine holes with the tightest tolerances possible with a machine tool.

• When designing a part with holes, it is important to determine what holes must be jig bored. The reason

for this is that jig boring requires extra time and attention. Jig boring can therefore have a big impact on

the lead time of a part. A cross section of a hole being jig bored is shown below.

• Standard boring can be carried out on a mill fitted with a boring head or on a lathe. Boring is accurate on

a lathe since a lathe is dedicated to solids of revolution (axially symmetric parts).

DESCRIPTION:

A jig borer is built lower to the floor & is much more rigid and of highly accurate construction. On the base of it a saddle is supported which move in and out from the operator to the column. A table is

provided to supplement the saddle movement which can move to right or left. Third position adjustment is achieved by the movement of a massive column which support the spindle

housing which is capable of moving up and down the column ways. The spindle moves inside the quill, and the quill moves up-down inside housing, thus giving Telescopic

mechanism. For purpose of high accuracy & precision, the spindle, quill and housing are manufactured under careful

conditions. The spindle and spindle bearing are constructed with very high accuracy. To minimise the errors due to thermal expansion, the housing is made of Invar Cast Iron. Driving mechanism provides speeds ranging from 30 to 1500 r.p.m. so that best cutting speed is there for

each size holes. It is very important for the proper use of jig borer that it is kept in a temperature controlled room. In jig boring only soft material up to a certain hardness can be machined like aluminium, brass and steel.

Single point boring tool consist of a round shaft with one insert pocket designed to reach into a part hole or cavity to remove internal stock in one or several machine passes.

Advantages of boring over reaming: Better finish is obtained. Boring can be done for all sizes while in reamers only standard sizes available. Reamer have a tendency to run away from central axis hence reamers do not give excellent surface finish.

COMPARISON OF BORING ON A BORING MACHINE AND LATHE

LATHE JIG BORERFor a normal boring operation on a lathe, the work revolves mounted in the chuck or on the faceplate, and the single-point boring tool is set to cut and feed.

For the corresponding operation on a jig-borer, the work is stationary on the machine table, while the single-point boring tool revolves and is fed.

On a lathe, however, it would mean loosening and resetting the work, a longer and more difficult job.

The table of the jig-borer can be moved by accurate feed screws in two directions at right angles, the position of a hole can be located on the feed screw micro meter collars. The positions of other holes can be obtained by using end gauges against stops.

ELECTRIC DISCHARGE MACHINE (EDM)

PROCESS EDM is a thermo electrical material removal process, in which the tool electrode shape is formed as

mirror image on work piece surface. The machine tool holds an electrode, which advances into the work material and produces a high

frequency series of electrical spark discharges. The EDM phenomenon can be divided into three stages namely application of adequate electrical

energy, dielectric breakdown, sparking and expulsions (erosion) of work material. The control of erosion of the material is achieved by rapidly recurring spark discharges produced

between the electrode and work piece.

Localised extreme rise in temperature of 10,000oC leads to material removal due to instant vaporization of the material as well as due to melting. However, the heat affected zone is limited to only 2 – 4 μm of the spark crater as there is not enough time for the heat to diffuse towards work piece.

The metal removal rates and surface finish are controlled by the frequency and intensity of the spark. With high sparking frequencies the spark erosion gives substantial metal removal rates. It has been found that high frequency and low amperage settings give the best surface finish.

The higher amount of erosion occurs at the positive electrode, therefore, to have maximum material removal from work piece and have minimum wear on tool, the tool is made cathode and work piece as anode.

Material removal depends on mainly thermal properties of the work material rather than its strength, hardness etc.

Functions of the Dielectric are as follows:

Insulation: One important function of the dielectric is to insulate the work piece from the electrode. The disruptive discharge (a sudden large increase in current through an insulating medium resulting from failure of the medium to withstand an applied electric field) must take place across a spark gap which is as narrow as possible. In this way efficiency and accuracy are improved.

Ionization: After the impulse the spark path must be de-ionized quickly so that the next discharge can be made. The dielectric ought to constrict the spark path as much as possible, so that high energy density is achieved, which increases discharge efficiency at the same time.

Cooling: The spark has a temperature of 8,000-12,000° C when it punctures the work piece and so the dielectric must cool both the electrode and the work piece. Overheating of the electrode must be avoided, so that excessively high electrode wear cannot occur. It must be possible for the metal gases which develop during spark erosion to condense in the liquid.

ADVANTAGES

1. EDM has no contact and no cutting force process, and therefore does not makes direct contact between tool electrode and the work material. This eliminates the chances of mechanical stress, chatter and vibration problems, as is prominent in traditional machining.

2. No complicated fixtures are needed for holding the job.3. Material of any hardness can be cut.4. High accuracy and good surface finish are possible.5. Intricate-shaped cavities can be cut with modest tooling costs.6. Holes completed in one “pass”7. The EDM process is burr-free.8. Thin fragile sections such as webs or fins can be easily machined without deforming the part.

DISADVANTAGES

1. Electrode wear takes place during the EDM operation when the electrode (i.e. the tool) gets eroded due to the sparking action.

2. Limited to electrically conductive materials.3. Slow process, particularly if good surface finish and high accuracy are required4. Dielectric vapour can be dangerous.5. Tool life is limited.6. There is a possibility of taper and overcut in EDM.

CHARACTERISTICS OF EDM:

PARAMETERS VALUESSpark gap 0.005 mm - .125 mmSpark frequency 100-500 KHzPeak voltage across gap

30-250 V

MRR 5000 mm3/min.Dielectric fluid EDM synthetic hydrocarbonTool material Do not know ( maybe copper )

Wire Cut Electric Discharge Machining (WEDM)

The Wire Electric Discharge Machining (WEDM) is a variation of EDM and is commonly known as wire-cut EDM or wire cutting. In this process, a thin metallic wire is fed on-to the work piece, which is submerged in a tank of dielectric fluid such as de-ionized water. This process can also cut plates as thick as 300mm and is used for making punches, tools and dies from hard metals that are difficult to machine with other methods. The wire, which is constantly fed from a spool, is held between upper and lower diamond guides. The guides are usually CNC-controlled and move in the x–y plane. The wire-cut EDM is every useful used for cutting very intricate and delicate shapes.

In the wire-cut EDM process, deionized water is commonly used as the dielectric fluid. Wires made of brass are generally preferred with diameter between 0.02 and 0.30 mm. The deionized water helps in flushing away the debris from the cutting zone. The flushing also helps to

determine the feed rates to be given for different thickness of the materials. The schematic of wire cut EDM is shown in Figure.

The WEDM process requires lower cutting forces in material removal. Hence it is generally used when lower residual stresses in work piece are desired (as in case of aircraft parts).If the energy/power per pulse is relatively low (as in finishing operations), little changes in the mechanical properties of the material are expected due to the low residual stresses. The materials which are not stress-relieved earlier can get distorted in the machining process.

PROCESS OF MATERIAL REMOVAL IN WEDM-

In the WEDM process, the motion of wire is slow. It is fed in the programmed path and material is cut/ removed from the work piece accordingly. Electrically conductive materials are cut by the WEDM process by the electro-thermal mechanisms. Material removal takes place by a series of discrete discharges between the wire electrode and work piece in the presence of a dielectric fluid. The dielectric fluid gets ionized in between the tool-electrode gap thereby creating a path for each discharge. The area wherein discharge takes place gets heated to very high temperatures such that the surface gets melted and removed. The cut particles (debris) get flushed away by the continuously flowing dielectric fluid.WEDM is a non-conventional process and is very widely used in tool steels for pattern and die making industries. The process is also used for cutting intricate shapes in components used for the electric and aerospace industries.

Applications of Wire-Cut EDM

Wire EDM is used for cutting aluminium, brass, copper, carbides, graphite, steels and titanium. The wire material varies with the application requirements. Example: for quicker cutting action, zinc-coated brass wires are used while for more accurate applications, molybdenum wires are used.

In aerospace industry, WEDM is used to manufacture parts including engine, fuel system, and landing- gear components, as well as other high-stress, high-temperature parts.

Virtually all commercial, scientific, and military aeronautical and aerospace hardware has used parts manufactured partially or in whole by WEDM.

The aerospace industry needs the WEDM process to make many of the components used in aircraft because of the intricate shapes, tough alloys, and very tight tolerances involved.

Subsystems of wire EDM –

Power supply. Dielectric system. Wire feeding system. Positioning system.

The power supply and di-electric system used in WEDM is very similar to that of the conventional EDM. The main difference lies only in the type of dielectric used. In wire cut EDM, a moving wire electrode is used to cut complex outlines and fine details in the required work piece. The wire is wound on a spool and is kept in constant tension. The drive system continuously delivers the fresh wire on-to the work area. New wire is continuously exposed to the work piece hence the wear of the wire (tool) is not the major issue in WEDM process. The wire feeding system consists of a large spool of wire and rollers which direct the wire through the machine. The presence of metal contact provides power to the wire and guides it further in-order to keep it straight throughout the cutting process. The other parts are the pinch rollers which provide drive and wire tension.

Process Parameters in WEDM

The process parameters that can affect the quality of machining or cutting or drilling in WEDM process are as follows:

Electrical parameters: Peak current, pulse on time, pulse off time and supply voltage and polarity. Non-electrical parameters: Wire speed; work feed rate, machining time, gain and rate of flushing. Electrode based parameters: Material and size of the wire. Dielectric System: Type, viscosity, and other flow characteristics.

3 Axis Milling3 Axis Milling routines to machine complex, contoured surfaces routinely encountered in mold making and aerospace applications. –

3 Axis Milling modules is built on the core fundamentals of:

Feature-based machining – Reduces programming time by as much as 90% compared to other traditional 3 axis CAM software.    .

Knowledge-based machining – Allows you to capture and reuse the best practices for various operations Full toolpath associativity to solid models – Automatically updates the tools paths and CAM data CAMWorks VoluMill™ – the ultra-high performance toolpath generator for rough milling operations

While CAMWorks 3 Axis cycles are developed for speed, accuracy and efficient memory usage, it also ensures that simple and complex parts can be cut quickly and accurately with a high quality toolpath.

Machining Features

Some of the machining features include:

Adaptive roughing strategy provides the ability to cut using the full depth of the tool and safely run your machine at optimum speed. This can reduce machining time up to 40% over conventional roughing with less wear.

3 Axis finishing operations include parallel slice cut, constant stepover, Z-level, curve project, and others Z Level/Constant stopover combination operation can be used for machining steep and shallower slope

areas in one toolpath. All 3 Axis milling operations support rest or leftover machining. Rest machining is used to reduce air

cutting by restricting toolpaths to areas within the feature that have not been machined previously. The curve project cycle removes material by projecting 2.5 Axis engrave or curve features on the 3 Axis

feature. CAMWorks can calculate a single pass or multiple passes for engraving. Provide the ability to generate toolpaths as separate threads and in separate processes. Multiple toolpaths

will generate simultaneously and at the same time the user can continue working in other areas or on other CAM models.

What is the difference between a 2.5 and 3 axis machine?Response:

An axis is a direction of motion controlled by the CNC machine control. It can be linear (motion along a straight line) or circular (a rotary motion). The number of axes a machine has determines it's machining capabilities. A 2.5 axis machine really has three moving axes, but only two axes can move together (most machines sold today are full three axis machines). For machining centers, a three axis machine will have three linear axes. A four or five axis machine will have three linear axes as well as one or two rotary axes.

Note that 2.5 versus 3 axis has yet another context. 2.5 axis machining requires that the machine have three axes, but only two axes must be moving simultaneously at any one time. (Simple operations, like drilling and most milling, fall into this category).

On the other hand   3-axis machining   requires that all three axes be moving at the same time (More complex operations, like the machining of sculptured surfaces required in molds and air foils, fall into this category.)

INSTRUMENT FACTORY

LINEAR ACTUATOR

A linear actuator is a device that applies force in a linear manner, as opposed to rotationally like an electric motor. There are various methods of achieving this linear motion. Some actually convert rotational motion into linear motion.

Mechanical actuators – Mechanical linear actuators typically operate by conversion of rotary motion into linear motion. Conversion is commonly made via a few simple types of mechanism:

Screw : lead screw, screw jack, ball screw and roller screw actuators all operate on the principle of the simple machine known as the screw. By rotating the actuator's nut, the screw shaft moves in a line.

Wheel and axle : Hoist, winch, rack and pinion, chain drive, belt drive, rigid chain and rigid belt actuators operate on the principle of the wheel and axle. A rotating wheel moves a cable, rack, chain or belt to produce linear motion.[1]

Cam : Cam actuators function on a principle similar to that of the wedge, but provide relatively limited travel. As a wheel-like cam rotates, its eccentric shape provides thrust at the base of a shaft.

Some mechanical linear actuators only pull, such as hoists, chain drive and belt drives. Others only push (such as a cam actuator).

Mechanical actuators typically convert rotary motion of a control knob or handle into linear displacement via

screws and/or gears to which the knob or handle is attached.

Roller screw actuation with traveling screw (rotating nut). A mechanical linear actuator with digital readout(a type of micrometer).

Hydraulic actuators

Hydraulic actuators or hydraulic cylinders typically involve a hollow cylinder having a piston inserted in it.

The two sides of the piston are alternately   pressurized/de-pressurized to achieve controlled precise linear displacement of the piston and in turn the entity connected to the piston.

The physical linear displacement is only along the axis of the piston/cylinder. This design is based on the principles of hydraulics.

A familiar example of a manually operated hydraulic actuator is a hydraulic car jack. Hydraulic actuator is controlled by a hydraulic pump.

Pneumatic actuator

Pneumatic  actuators, or pneumatic cylinders, are similar to hydraulic actuators except they use compressed gas to generate force instead of a liquid. They work similarly to a piston in which air is pumped inside a chamber and pushed out of the other side of the chamber.

Piezoelectric actuators

The piezoelectric effect is a property of certain materials in which application of a voltage to the

material causes it to expand. These actuators are built using multiple thin ceramic strips. When the strips are excited by an electric voltage they cause the actuator to shrink.

Best for applications requiring small range of motion with very high accuracy and speed. Very high voltages correspond to only tiny expansions. As a result, piezoelectric actuators can achieve

extremely fine positioning resolution.

Electro-mechanical actuators

Electro Mechanical Actuator is an equipment which can be used to provide reversible linear motion at a controlled speed.

Electro-mechanical actuators are similar to mechanical actuators except that the control knob or handle is replaced with an electric motor. Rotary motion of the motor is converted to linear displacement of the actuator.

CONCLUSION

CONCLUSION

The joy of flying has fascinated the human race for centuries. Defense avionics major

& Navratana PSU Hindustan Aeronautics Li m ited ( H A L) is in the business of

building a w hole range of aircraft , helicopters and jet trainers .

Besides , the company manufactures aircraft components, overhauls fighter

planes and trains future pilot’s . its success in the design and development of light

combat aircraft Tejas and advanced light helicopter Dhruv has won admiration. HAL

is the backbone of India’s air defense and continues to occupy the strategic importance

reflecting a new pace of growth.

Today the faster growing sector is the aviation sector & is likely to be a

boon for the entire job market . It deals with the manufacture, design &

development of aircrafts.

The project is based on the instruments that are used in the manufacture of the

various aircrafts. A deep knowledge of these instruments is crucial in the perfect

design & manufacture of the air crafts. The project will benefit those who have

interest in the instrument & will provide the reader with the deeper knowledge of the topic.