# HYDRAULIC RAM

The hydraulic ram is a pump which raises water without any external power for its operation. When large quantity of water is available at a small height a small quantity of water can be raised to a greater height with the help of hydraulic ram. It works on the principle of water hammer.

# PITOT TUBE

Objective - To measure the velocity of flow at different points in a pipe.

Aim - To find the coefficient of pitot tube. To find the point velocity at the center of a tube for different flow rates . To plot velocity profile across the cross section of pipe.

Introduction - It is a device used for measuring the velocity of flow at any point in a pipe. It is based on the principle that if the velocity of flow at a point becomes zero, there is increase in pressure due to the convection of the kinetic energy into pressure energy. The pitot tube consists of a capillary tube, bent at right angel. The lower end, which is bent through so, is directed in the upstream direction.

# Difference between Centrifugal & Reciprocating pump

Centrifugal Pump
1. It can handle large quantity of water.
2. It is used for low viscous fluid.
3. Efficiency is low.
4. It is less costly.
5. They are lighter than reciprocating pumps.
6. These pumps required less maintenance.

Reciprocating pump
1.  It handle small quantity of water.
2. It is used for high viscous fluid.
3. Efficiency is high.
4. These are costly.
5. These require higher maintenance.

# Difference between Impulse & reaction turbine

Impulse turbine
1. It consists of nozzles and moving blades.
2. It has constant blades channels area.
3. Less floor space is required.
4. Efficiency is less.
5. Required high head and small quantity of water.
6. Draft tube not used in impulse turbine.

Reaction turbine
1. It consists of fixed blades and moving nozzle.
2. It has varying blade channels area.
3. more floor space is required.
4. Efficiency is high.
5. Low head and high rate of flow.
6.Draft tube use in reaction turnine.

# EFFECTS OF SUPERCHARGING

Before supercharging an engine one should understand its effects. The following are the effects of supercharging engine. Some of the point refer to CI engine.

1. Higher power output.
2. Greater induction of charge mass.
3. Better atomization of fuel.
4. Better mixing of fuel and air.
5. Better scavenging of products.
6. Better torque characteristic over the whole speed engine.
7. Quicker acceleration of vehicle.
8. More complete and smoother combustion.
9. Inferior or poor ignition quality fuel usage.
10. Smoother operation and reduction in diesel knock tendency.
11. Increased detonation tendency in SI engine.
12. Improved cold starting.
13. Reduced exhaust smoke.\
14. Reduced specific fuel consumption in turbocharging.
15. Increased mechanical efficiency.
16. Increased thermal stress.
17. Increased heat losses due to increased turbulence.
19. Increased valve overlap period of 60 to 160° of crank angle.
20. Increased cooling requirements of piston and valves.

# Difference between battery ignition, magneto ignition system

Battery ignition system -
1. Source of current is battery,.
2. Difficult to start when battery is not properly charged.
3. The intensity of spark remains almost constant irrespective of the speed of the engine.
4. Wiring involved is complicated.
5. Occupies more space.
6. Requires more maintenance.
7. More expensive.
8. Used in cars and light commercial vehicles.

Magneto ignition system
1. Source of current is magneto.
2. There is no problem of battery discharge.
3. The spark intensity is poor at start and during idling, because the primary and secondary voltages depend upon the speed of the engine.
4. Wiring involved is highly simplified.
5. Occupies less space.
6. Requires less maintenance.
7. Less expensive.
8. Due to light weight preferred for two wheelers and racing cars.

# Shaper Operation

A shaper is a versatile machine tool primarily designed to generate a flat surface by a single point cutting tool. But it may also be used to perform many other operation. The different operation which a shaper can perform are as follow :

1. Machining horizontal surface

2. Machining vertical surface

3. Machining angular surface

4. Cutting slots, grooves, and keyways

5. Machining irregular surface

6. Machining splines or cutting gears

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# Write down needs and importance of energy storage ?

Energy is useful only machine is available at time of use keeping it available until when it is wanted is called storage.

Energy storage system :
1. mechanical energy storage
2. pumped hydro electric storage
3. Compressed air
4. flywheel

Electrical energy storage
1. led acid battery

Thermal energy storage
1. Sensible heat
2. latent heat

# OCTANE NUMBER

The octane number of a fuel may be defined as the percentage by volume of is-octane in a mixture of iso-octane and normal heptane, which shows the same tendency to knock as the fuel, when tested in a specified type of engine under specified operating conditions. Thus an octane rating of 72 means that the fuel has the same knocking tendency as a mixture of 72% iso-octane and 28% normal heptane.

Classification of the mechanical processes

Non-traditional machining processes can be classiffied into various groups according to the type of fundamental machining they employ, namely, mechanical, electrical, chemical, electro-chemical, thermo-electrical, etc. The classification of the machining processes based upon the type of energy used, the mechanism of metal removal in the process, the source of immediate energy required for material removal, and the medium for transfer of those energies, etc.

1. Mechanical

1. Abrasive jet machining

2. Ultrasonic machining

2. Chemical

1. Chemical machining

3. Electro-chemical

1. Electro-chemical machining

2. Electro-chemical grinding

4. Thermo-Electric

1. Ion-Beam machining

2. Plasma arc machining

3. Electrical discharge machining\

4. Electrical-Beam machining

5. Laser-Beam machining

# INTRODUCTION TO MILLING MACHINE?

MILLING MACHINE

The milling machine is a machine tool in which metal is removed by means of a revolving cutter with many teeth, each tooth having a cutting edge which removes metal from a workpiece.

The work is supported by various methods on the work table, and may be fed to the cutter, longitudinally, transversely or vertically.

A great variety of work may be done on a milling machine.

The machine is perhaps next to the late in importance.

Generally there are two type of milling machine

1. Upmilling process - In upmilling process the workpiece is fed opposite to the cutter's tangential velocity.

2. Downmilling process - In downmilling process the workpiece is fed in the same direction as that of the cutter's tangential velocity.

Specification of milling machine

The following are the specification of a column and knee type milling machine:

1. Width and length of the table.

2. Maximum distance the knee can travel.

3. Maximum longitudinal movement and cross feed of the table.

4. Number of spindle speeds.

5. Power of the main drive motor.

Type of milling machines

According to the general design of  the milling machine, the usual classification of the milling machine are:

1. Column and knee type:

(a) Hand milling machine  (b) Plain milling machine (c) Universal milling machine

(d) Omniversal milling machien (e) Vertical machine

2. Manufacturing of fixed bed type:

(a) Simplex milling (b) Duplex milling machine (c) Triplex milling machine

3. Planer type:

4. Special type:

(a) Rotary table milling machine (b) Drum milling machine (c) Planetary milling machine

(d) Pantograph, Profiling and tracer controlled milling machine

Types of milling cutter

Common types of milling cutters are enumerated below:

1. Plain milling cutter      2. Side milling cuttter

3. End milling cutter        4. Face milling cutter

5. Metal slitting cutter      6. Angle milling cutter

7. Formed milling cutter   8. Woodruff-key milling cutter

9. T-slot milling cutter     10. Fly cutter

Milling Operation

The milling operation are classified as follows:

1. Plain or slab milling  2. Face milling    3. Angular milling   4. Form millijng

5. Straddle milling     6. Gang milling  7. End milling   8. T-slot milling

9. Dove-tail milling  10. Saw milling  11. Involute gear cutting

1. Plain or slab milling - Plain milling is used to machine flat and horizontal surfaces .Here plain milling cutter is used, which is held in the arbor and rotated. The table is moved upwards to give the required depth of cut.

2. Face milling -This milling process is used for machining a flat surface which is at right angles to the axis of the rotating cutter. The cutter used in this operation in the face milling cutter.

3. Angular milling - In angular milling an angle milling cutter is used. The cutter used may be a single or double angle cutter, depending upon whether a single surface is to be machined or two mutually inclined surface simultaneously.

4. Form milling - This milling process is used for machining those surface which are of irregular shapes. The form milling cutter used has the shape of its cutting teeth conforming to the profile of the surface to be proved.

5. Straddle milling - Straddle milling is an operation is an which a pair of side milling cutters is used for machining two parallel vertical surfaces of a workpiece simultaneously. The distance between the cutters is adjusted by the spacers. This process is used to mill square and hexagonal surfaces.

6. Gang milling - Gang milling is the name given to a milling operation which involves the use of  a combination of more then two cutters, mounted on a common arbor, for milling a number of flat horizontal and vertical surfaces of a workpiece simultaneously. This method saves  much of machining time and is widely used in repetitive work. The cutting speed of a gang of cutters is calculated from the cutter of the largest diameter.

7.  End milling - It is an operation of producing narrow slots, grooves and key ways using an end mill cutter. The mill tool may be attached to the vertical spindle for milling the slot. Depth of cut is given by raising the machine table.

8. T-slot milling - In the milling machine operation, first a plain slot is cut on the workpiece by  a side and face milling cutter. Then the T-slot cutter is fed from the end of the workpiece.

9. Dove-tail milling - In this milling operation, the end of the cutter is shaped to the required dove-tail angle. The cutter is passed from one end of the workpiece to the other end.

10. Saw milling - It is an operation of production narrow grooves and slots on the workpiece. A slitting saw is used for saw milling.

11. Involute gear cutting - Gear milling operation, often referred as gear cutting, in-volves cutting of different types of gear on a milling machine. For this, either an end mill cutter or a form relieved cutter is used, which carries the profiles on its cutting teeth corresponding to the required profile of the gap between gear teeth.

# DRILLING MACHINE

The drilling machine is one of the most important machine tools in a workshop. As regards its importance it is second only to the lathe, Althrough it was primarily designed to originate a hole, it can perform a number of similar operations. In a drilling machine holes may be drilled quickly and at a low cost. The hole is generated by the rotating edge of a cutting tool known as the drill which exerts large force on the work clamped on the table. As the machine tool exerts vertical pressure to originate a hole it is loosely called  a "drill press".

### TYPES OF DRILLING MACHINE

Drilling machines are made in many different types and sizes, each designed to handle a class of work or specific job to the best advantage.
The different types of drilling machines are:
1. Sensitive drilling machine
2. Portable drilling machine
3. Radial drilling machine
4. Gang drilling machine
5. Multiple spindle drilling machine
6. Automatic drilling machine
7. Deep hole drilling machine

# ELECTRICAL DISCHARGE MACHINE

Electrical discharge machine also known as spark erosion, electro-erosion or spark machining is a process of metal removal based on the principle of erosion of metal by an interrupted electric spark discharge between the electrode tool  (usually cathode) and the work (anode)

Fundamentally, the electric erosion effect is understood by the breakdown. Of electrode material accompanying any from of electric discharge. The discharge is usually through a gas, liquid of in some cases through solids. A necessary condition for producing a discharge is ionization of the dielectric, splitting up of as molecules into ions and electrons.

Illustrates the schematic layout of the electric discharge machining system, The main components are the electric power supply, the electric medium, the work piece and the tool, and a servocontrol.

The workpiece and the tool are electrically connected to a dc electric power. The workpiece is connected to the positive terminal of the electric source, so that it becomes the anode. The tool is the cathode. A gap, known as the “spark gap” in the ranges of 0.05 to 0.05 mm is maintained between the work-piece and the tool, and suitable dielectric slurry, which is non-conductor of electricity is forced through this gap at a pressure of 2 Kgf/cm² or less. When a suitable voltage in the range of 50 to 450 V is applied, the dielectric breaks down and electrons are emitted  form the cathode and the gap is ionized. In fact, a small ionized fluid column is formed owing to formation of an avalanche of electrons in the spark gap where the process of ionizational collision takes place. When more electrons collect in the gap the resistance drops causing electric spark to jump between the workpiece surface and the tool. Each electric discharge or spark causes a focused stream of electrons to move with a very high velocity acceleration from the cathode towards the anode, and ultimately creates compression shock waves on both the electrode surface, particularly at high spots on the workpiece surface, which are closest to the tool. The generation of compression shock waves develops a local rise in temperature. The whole sequence of operation occurs within a few microseconds. However the temperature of spot hit by the electrons is of the order of 10,000 °C. This temperature is sufficient to melt a part of the metals. The forces of electric and magnetic fields caused by the spark produce a tensile force and tear off particles of molten and softened metal from this spot on the workpiece. A port of the metal may vaporize and fill up the gap. The metal is thus removed in this way from the workpiece. The electric and magnetic fields on the heated metal cause a compression force to act on the cathodic tool so that metal  removal from the tool is at a slower rate than that from the workpiece. Hence, the workpiece is connected to the positive terminal and tool to the negative terminal.

Extremely high popularity of the EDM process is due to the following advantage.

1. The process can be applied to all electrically conducting metals and alloys irrespective of their melting points, hardness, roughness or brittleness.

2. Any complicated shape that can be made on the tool can be reproduced on the workpiece.

3. Highly complicated shapes can be made by fabricating the tool with split sectioned shapes, by welding, brazing or by applying quick setting conductive epoxy adhesives.

4. Time of machining is less than conventional machining processes.

5. EDM can be employed for extremely hardened work-piece. Hence the distortion of the work-piece arising out of the heat treatment process can be eliminated.

1. Profile machining of complex contours is not possible at required tolerances.

2. Machining times are too long.

3. Machining heats the work-piece considerably and causes change in surface and metallurgical properties.

4. Excessive tool wear.

5. High specific power consumption.

# MATERIAL AND CONDUCTITY

 Material Conductivity (cal/sec)cm Sliver 1.001 Aluminium 0.485 Iron 0.174 Antinomy 0.004 Cadmium 0.223 Copper 0.927 Lead 0.084 Magnesium 0.270 Molybdenum 0.349 α Nickel 0.157 Platinum 0.166 Tin 0.157 Tungsten 0.382 Zinc 0.270 Titanium alloy 0.021 Glasses 0.0025 Silicon Martices 0.0022 Acrylics 0.0005 Foamed Polystyrene 0.001

# THERMAL RESISTANCE

Observation indicate that in systems flow of fluid, heat and electricity, the flow quantity is directly proportional to the driving potential and inversely proportional to the flow resistance, In hydraulic circuit the pressure along the path is the driving potential and roughness of the pipes is the flow resistance. The current flow in a conductor is governed by the voltage potential and electrical resistance of the material. Likewise, temperature difference constitutes the driving force for heat conduction through a medium.

Obviously there is a one-one correspondence between the flow of electric current and heat.

• Electric current is analogous to thermal heat flow rate.
• Electric voltage correspondence to thermal temperature difference .
• Electric resistance is analogous to quantity dx/KA. This quantity is called thermal resistance.

THIS ARTICLE WAS TAKEN BY HEAT AND MASS TRANSFER BOOK

# Value of Cp     and Cv  for some common gases.

 Name of Gas Cp (KJ/Kg K) Cv (KJ/Kg K) ¥ = Cp / Cv Air 1.000 0.720 1.40 Carbon dioxide (CO2) 0.846 0.657 1.29 Oxygen (O2) 0.913 0.653 1.39 Nitrogen (N2) 1.043 0.745 1.40 Ammonia (NH4) 2.177 1.692 1.29 Carbon monoxide (CO) 1.047 0.749 1.40 Hydrogen (H2) 14.257 10.133 1.40 Argon (A) 0.523 0.314 1.67 Helium (He) 5.234 3.153 1.66 Methane (CH4) 2.169 1.650 1.31