ENGINEERING MECHANICS MCQ-: 2

 Q.1 The ratio of the limiting friction and the normal reaction is known as ___.

A. Sliding friction 

B. Coefficient of friction 

C. Angle of repose

D. Angle of friction 

Ans-: B

Q.2 The angle of projection should be ______ , for maximum range of a projectile. 

A. 30 °

B. 45 °

C. 0 °

D. 60 °

Ans-: B

Q.3 The frictional force encountered after commencement of motion is called _____.

A. Dynamic friction 

B. Limiting friction 

C. Kinematic friction 

D. None of the above 

Ans-: A

Q.4 Which of the following is not the unit of energy?

A. Kg m

B. Kcal

C. Watt hours

D. Watts

Ans -: D

Q.5 The friction force acting when the body is in motion known as ______ .

A. Limiting friction 

B. Dynamic friction 

C. Kinematic friction 

D. Sliding friction 

Ans-: C

Q.6 The centre of gravity of a plane laminar will not be at its geometrical centre in the case of a _______.

A. Rectangular 

B. Circle 

C. Right angled triangle 

D. Square 

Ans-: C

Q.7 The centre of gravity of a right circular solid Cone height h lies at the following  distance from the base ?

A. h/3

B. h/2

C. h/ 6

D. h/4

Ans-: D

Q.8 The friction force acting when the body is just about to move is known as ___. 

A. Limiting friction 

B. Kinematic friction 

C. Sliding friction 

D. None of the above

Ans-: A

Q.9 Coulomb friction is the friction between the bodies having _____  .

A.  relative motion

B. Two dry surface

C. Angular motion

D. All of the above 

Ans-: A

Q.10 Tangent of angle of friction is equal to

A. Angle of repose

B. Friction force 

C. Coefficient of friction 

D. Kinematic friction 

Ans-: C

ENGINEERING MECHANICS MCQ-: 01

 Q.1 work = force × _______ .

 A. Acceleratio                                                      

 B. Distance                                                           

C. Velocity                                                            

 D. Area                                                              

 Ans-: B

Q.2  The change in momentum produced by the action of a force applied on a the body within an infinitely short interval of time is called ?

 A. Force                                                                  

 B. Velocity                                                              

C. Impulse                                                              

D. Frequency                                                          

Ans-: C 

Q.3 The unit of force in S.I. unit is ?

 A. Kilogram                                                            

B. Dyne                                                                    

C. Watt                                                                   

 D. Newton                                                              

And-: D

Q.4 Effect of a force on a body depends upon the ______.

A. Magnitude                                                         

B. Direction                                                           

C. Position or line of action                                 

D. All of the above                                              

Ans-: D

Q.5 Which of the following is not the unit of the power ?

A. Micron                                                               

B. Light year                                                         

C. Millimetre                                                         

D. Milestone.                                                          

Ans-: D

Q.6 Which of the following is applied when trying to turn a key into a lock ?

A. Lever                                                                 

B. Couple                                                               

C. Moment                                                             

D. Coplaner force                                                

Ans -: B

Q.7 The units of moment of inertia of an area are _____.

A. M^4                                                                    .

B. M^3                                                                     

C. Kg/m^2                                                             

D. Kg/m^2                                                               

Ans-: A     

Q.8 The units of moment of inertia of mass are .

A. Kg m^2                                                             

B. Kg/ m^2                                                             

C. M^3                                                                     

D. M^2 / kg                                                              

And-: A

Q.9 Which of the following is not a vector quantity?

A. Velocity                                                             

B. Weight                                                               

C. Moment                                                           

D. Acceleration                                                     

Ans-: B

Q.10 The motion of a particle from one extremity to the other constitutes half an oscillation and is called  ______.

A. Second pendulum                                         

B. Frequency                                                       

C. Beat                                                                   

D. Travel time                                                       

Ans -: C

     

CUTTING FLUID

                       Cutting  fluid  

The Cutting fluids are used to reduce friction , through lubrication, which is a tribological phenomenon characteristic of the machining processes, and occurs at the contact between workpiece and the tool. Also used to remove heat generated from the cutting zone.

Purpose of cutting fluids-: 

• To cool the tool.
• To cool the workpiece. 
• Reduce the friction .
• Protect the finished surface from the corrosion. 
• Reduce the tool wear.

Restrict thermal distortion. 

Types of cutting fluids -: 

1.  Soluble oil
2. Water
3. Mixed oil
4. Chemical additive oil
5. Solid lubricant etc.

ANGLE PLATE

                     Angle plate   

 An angle plate is a work holding device and is used as a fixture in the metal-working.The angle plates are made of  cast iron and is the used in workshop and laboratories. The right angle plates are casted and roughly machin-ed . The holes are provided in vertical plates in order to relive internal stresses. The angle plates are used to check the right angle of the jobs .

This angle plate open and webbed end is the fabricated under strict supervision of highly experienced and professional quality contro-llers. 

Angle plates also may used to hold the work-piece square to the table during marking out the operations. Angle plates are also availab-le adjustable type which can be used for the workpiece that need to be inclined, usually towards a milling cutter.

SIMPLE HARMONIC MOTION

             Simple harmonic motion

If a body moves in a straight line such that it's acceleration is always directed towards a fixed point and is proportional to its distance from the fixed point, it is said to have"simple harmonic motion".                           

Simple harmonic motion is always oscillator . Periodic motion examples are the motion of the hands of a clock, motion of the wheels of a car etc. Simple harmonic motion examples are the motion of pendulum , motion of the spring etc. 

The time taken by the body for one complete oscillation is called time period ' T ' which is equal to 2π/ω ( ω = angular velocity ).                           The acceleration of a particle moving with simple harmonic motion is equal to the  ω^2y ( y = Distance from the mid point ). The velocity of particle moving with the  simple harmoni motion is -:

 V =  ω √ r^2 - y^2   , r = amplitude                     

The time period of simple pendulum is given by ,                                                                                   T = 2π √ l/g                                                         l = length of pendulum 

The motion of particle from one extremity to the other constitutes half an oscillations and called a beat. If a pendulum executes one beat per second or whose time period is the 2 seconds is called " second pendulum ".

For second pendulum,                                                          T = 2π √ l/g   = 2 

SURFACE PLATE

                           Surface plate

The surface plates are extensively used in the workshop and the laboratories as a refe-rence surface testing for flatness of surface. It is a perfectly true surface made of the cast-iron , granite or glass block and set on bench , stand or table with it's flate surface upward . The top face and its adjacent edges are acc-urately machined and scrapped to form a true flate surface. 

     It is used to check the trueness of the flate surface and to copy the master surface on workpiece. It also provide reference datum plan for different measuring instruments as like - V-block, vernier height gauge, dial com-parator etc.

PATTERN MAKING

                       PATTERN MAKING 

The Pattern is the principle tool during the casting process, it may be define as modle of anything, so constructed then it may be used for forming and the impression called mould in the dome shape. When this mould is filled with the molten metal and the metal is allow to solidify , it form a reproduction of pattern is known as casting . The process of making the pattern is known as pattern making.

Foundary engineering deals with the process of making casting in mould prepared by the metal to mould process of producing casting may be classified into five stages -: 

1. Pattern making                                                  2. Moulding                                                            3. Casting and melting                                          4. Fettling                                                                5. Testing and inspection.                   

Pattern material 

1. Wood -: Wood is the most commonly used material for pattern. it is easy to work and is rapidly available , wood can be cut and also fabricated into the numerous form by bend-ing and curling. It may be preserved with the shell.

2. Metal -: Metal is used when large number of casting are desired for a pattern or when conditions are to serves for wooden pattern.

(a) Cast iron  -: Cast iron is used for some of the highly specialised type of the pattern. It is strong give a smooth surface with  Sharp edges and is resistance to the abrasive action of the sand.

(b) White metal -: It is not generally used for the patterns but it is the best material for the making of five shape.

3. Non-Metal -: 

(a) Brass -: The Brass is normally used in the pattern making perticularly when the metal pattern are small.

(b) Aluminium -: It is the best metal because it melts at a relatively low temperature. It is soft and easy to work.

(c) plastic -: Plastic is not finding their place as a the pattern material because, they don't absorb moisture . They are strong resistance to wear have a very smooth surface. 

(d) Rubber -: Originally it is in liquid form and mould over master pattern or into a die and forming a solid shape.

(e) Wax -: Wax pattern are excellent for the investment casting process, the normal prac-tice of forming wax pattern this to inject the liquid or semi-liquid wax into a straight die.

VERNIER CALIPER

                       Vernier caliper

This is a linear measuring instrument and it is used to measure the dimension to second decimal. The vernier caliper is shown in fig. 

 

Main parts of vernier caliper -: 

1. Main scale A  -: It is the fixed beam scale having a fixed jaw at left end and is graduat-ed in millimetre. This is called a metric scale .

2. Vernier scale B -: It consist of sliding jaw and this scale slides over the main scale A . These scale is also graduated in 10 , 20 and 25 divisions. 

3. Jaw C-:These jaw are used to measure the dimensions such as inner radius of inside of the hollow cylinders. 

4. Jaw D  -: These jaw are used to measure the outside diameter of the object like width, thickness etc.

5. Thumb screw E -: It is provided with the vernier scale and used to lock the position of the vernier scale. 

6. Blade F -: The blade is used for measuring depth of the slots.

Least count -:

( 1 ). If there are 10 divisions on the vernier scale, and the smallest division on the main scale is of 1.0 mm.                                          

Then, Least count                                                  =    Smallest division on main scale                         no. of division on vernier scale                    =      1.0            =  0.1 mm.                                              10 

(2). If there are 25 divisions on vernier scale and the smallest division on the main scale is 0.5 mm. Then ,                     

 Least count =   0.5                =  0.02 mm.                                         25

Procedure -: Fix the jaw on the workpiece and then lock the jaw with the help of thumb screw. Then note the reading on main scale angaist zero on vernier scale.  Count the no. of division on vernier scale which co-insides with a division on main scale. Multiply this number by least count and add to the main scale reading. 

Hence ,                                                                    Total reading   = Reading on the main scale   + ( Least count  × no. of division on vernier scale which co-inside with division on main scale ).

DIAL GAUGE

                          DIAL GAUGE 

The dial gauge is graduated in the small units such as 0.01 mm. The gauge carry zero reading at the center with positive and negative readings on either side. It is used to check the size and truness of a finished work to an accuracy of 0.01 mm.TheDial gauge can be used with the various attachments such as inside cali-per and depth gauge, V- block etc which make it situable to check the roundness , flatness, parallelism, ovality, taper and squarness etc. 

         

 

               It is also used to compare to heights           or distances between narrow limits. It             is mostly used for checking diamension           for this purpose the dial gauge is fixed             at a standard dimensions, the needle is           showing showing zero reading.                             Then the parts to be checked are kept           below the pointer.The needle show the           deviation form and the standard size .            The Dial gauge is a sensitive instrument           and it should be handled carefully.

MICROMETER

                        Micrometer

The micrometer is a measuring instrument a which is  used to measure the external  and internal dimensions as well as the depth and heights. It has five main parts frame, anvil, sleeve thimble and spindle . The frame is ' U ' shaped and made of steel. In this the gap of the frame permits the maximum dimension that can be measure on the left end of the frame, the anvil is fixed at a right end, there is a screwed spindle. 

 

The diameter of the anvil and spindle should be equal . A lock nut is provided to lock the spindle to retain the reading. The sleeve has reference line and main scale on it. A tubler cover  fixed with spindle is called thimble . Thimble moves with spindle on main scale . Thimble has 50 equal parts on it's bevelled edges. This is called as circular or vernier scale. Reatchet  screw is provided to tighten the thimble. When correct reading  achieved ratchet slips automatically. 

Least count-: The least distance which can be measured accurately with micrometer is called least count.

Least count = pitch of the spindle screw 

                         No. Of division on thimble 

                     = 0.5 / 50    = 0.01 mm

Reading of micrometer -:  

Reading uncovered on sleeve + ( least count × no of division on thimble with R.F. line )

Reading = 10.5 + ( 0.01 × 15 ) = 10.65 mm

Types of micrometer -: 

1. Outside micrometer 

2. Inside micrometer 

3. Screw thread micrometer 

4. Depth gauge micrometer 

Mechanical MCQ

 Q.1 Which refrigerant is used in central air conditioning?

A. Ammonia

B. R-11

C. R-12

D. Freon 

Ans-: B

Q.2 The radius for which the heat transfer rate is maximum known as ___.

A. Mean radius

B. Radius of heat transfer 

C. Critical radius 

D. None of these 

Ans -: C

Q.3 The rate at which radiation leaves a surface called ?

A. Viscosity 

B. Capacity ratio

C. Reflectivity 

D. Radiosity

Ans-: D

Q.4 Which surface has zero reflectivity?

A. Black body

B. White body

C. Rough surface

D. Finished surface

Ans-: A

Q.5 Cork is a good insulator because it has _______.

A. Black body

B. Porous body

C. Rough body

D. None of these 

Ans-: B

Q.6 Which type of calorific value is measured by bomb calorimeter?

A. Higher calorific value 

B. Lower calorific value 

C. All calorific value 

D. None of the above 

Ans-: A

Q.7 In-viscous fluid is ______.

A. Frictionless fluid

B. Real fluid

C. A+B

D. None of these

Ans-: A

Q.8  The cable attached to the supports and carries its own weight is called?

A. Supporting cable

B. Joining cable

C. Catenary cable

D. Balancing cable

Ans-: C

Q.9 What is the bending moment at hinge of beam? 

A. One

B. Zero

C. Maximum 

D. Minimum 

Ans-: B

Q.10 The beam has more than 2 support below the beam is known as ___?

A. Continuous beam

B. Cantilever beam

C. Simple beam

D. None of the above 

Ans-: A

Q.11 The radius of Mohr circle represents the value of maximum ______.

A. Stress

B. Strain

C. Shear stress 

D. Shear strain

Ans -: C

Q.12 How much is shear stress on the principal planes?

A. Zero

B. One

C. Two

D. 1 / 2

And -: A

Q.13 How many time second pendulum have?

A. 5 seconds 

B. 10 seconds 

C. 2 seconds 

D. 1 second

Ans -: C

Q.14 What is the value of shear force ,where bending moment is maximum?

A. 1.5 

B. 2.5

C. Zero

D. 1.15

Ans -: C

Q.15 The rate of change of bending moment along the length of the beam is known as ___.

A. Shear force 

B. Shear stress

C. Bending force

D. Inertia force 

Ans -: A

SOLAR PHOTOVOLTAIC SYSTEM

                 Solar photovoltaic system                

A photovoltaic power generation is a device which convert the electromagnetic energy directly into electrically. The basic compon-ent in the photovoltaic power generation is the photovoltaic cell. 

The photo-voltaic effect can be described easily for a p-n junction in a semi-conductor material. In a piece of a pure intrinsic semi-conductor such as silicon there are no free electron at absolute zero,since each valance electron of material atom is tied in chemical bond.If this piece of the silicon is doped with phosphorus or arsenic, there will be the ex-cess of electrons leading to a n-type semicon-ductor. Similarly if another piece of the sili-con is doped with boron , there will be a deficiency of electrons leading to a p- type semiconductor. If these two pieces of silicon are connected , a p-n junction is obtained . In tendency will be for the free electron of n-side to flow to the p-side, and the holes of the p-side will tends to flow to the n-region to compensate for their respective deficiencies. Thus a built-in potential barrier is formed.

When light strike on the p-n junction photo-ns with energy above that required to break the covalent bonds will create an electron hole pair. The hole is formed in the valance band,or an electron is added to the conduct-ion band. For a photon in a visible range the diffusion length i.e. average distance which the carrier diffuse before they recombine, has the magnitude of a micron. Those charge carriers that are within a diffusion length of the potential barrier will be trapp-ed by the barriers and caused to flow across it in an attempt to reduce their energy. Therefore a potential energy between the layer is formed and it is used to force the electrons through an external circuit. 

The solar photo-voltaic cells convert incident solar light energy directly to direct current electrical energy. Power delivered depends on intensity of sun light and the load resista-nce. several solar cells can be connected in series on parallel to get desired the voltage, current and power. Solar cells connected in parallel form a module, and the modules are connected in series,parallel ,series-parallel configuration to form a solar PV panel. Solar PV panels are installed outdoors so as to the receive maximum sun light during tha day and thoughtout the year. Solar PV panels are usually fixed type as they à simple ,cheap and maintenance free.

Since solar PV panels deliver DC electrical power only during favourable conditions of  sun light, energy storage batteries as used to supply power during nights and the cloudy weather. For feeding loads t 50 Hz AC supply , DC power supplied by the solar PV panel is converted by means of static inverters to the single phase or three phase. Power conditio-ning unit provided for improving AC wave-form, regulating the voltage, inverting DC to AC and protective control, and monitoring functions. 

Solar energy MCQ-: 01

 Q.1 The diameter of the sun is about ____.

A. 1.2 × 10^4 KM

B. 1.5 × 10^4 KM

C. 2.5 × 10^6 KM

D. 1.39 × 10^6 KM

Ans-: D

Q.2 The mean distance between the sun and the earth is _______.

A. 1.49 × 10 ^8 KM

B. 2.49 × 10 ^6 KM

C. 1.52 × 10 ^5 KM

D. 2.05 × 10 ^4 KM

Ans -: A

Q.3 In the form of electromagnetic radiation from sun, earth receives ______ energy / day.

A. 2.9 × 10 ^13

B. 2.9 × 10 ^11

C. 2.9 × 10 ^15

D. 2.9 × 10^17

Ans-: C

Q.4 A single solar cell has an open circuit voltage of ______.

A. 2.5 to 7.0 V

B. 7.0 to 10.0 V

C. 1.0 to 2.5 V

D. 0.6 to 1.0 V

Ans-: D

Q.5  The solar radiation received per unit area normal to sun rays, in a space outside the earth's atmosphere at earth is called __________.

A. Solar energy 

B. Solar constant

C. Heat energy 

D. Solar collector

Ans-: B

Q.6 Flat-plate collectors are used for _____ temperature applications. 

A. High

B. Constant

C. Low

D. Variable 

Ans-: C

Q.7 Solar power has _____ density.

A. High

B. Low

C. Variable 

D. None of the above 

Ans-: B

Q.8 The solar radiation on a particular location on the earth is affected by _____.

A. Seasonal variation

B. Atmospheric clarity 

C. Daily

D. All of the above 

Ans-: D

Q.9 The solar radiation received outside the earth's atmosphere is called _____.

A. Terrestrial solar radiation 

B. Extra-Terrestrial solar radiation 

C. Outer solar radiation 

D. Non- terrestrial solar radiation 

And-: B

Q.10 The radiation received by the earth is with parallel rays is called ?

A. Beam radiation 

B. Diffuse radiation 

C. Thermal radiation 

D. None of the above 

Ans-: A

SINE BAR

                              SINE BAR 

Sine bar is a accurate instrument for measu-ring angle. Sine bar consist of a rectangular bar made of high quality steel and having steps at the end . A roller is fitted into each step which touch the roller. The Sine bar is specified by the distance between center of two rollers ,i.e. 100 mm , 200 mm , 250 mm and 300 mm . The roller must be of the same diameters. The roller are so fixed that when sine bar is placed on surface plates the sur-face of the bar is exactly parallel to surface plate. 

When component is small size-:

For checking the angle of a component of small size a sine bar is set-up at nominal angle on a surface plates by situable combi-nation of the slip gauge . The component to be checked is pressed over the surface of the sine bar. A dial gauge is carried with surface gauge is move along the upper surface of the component.

When component size is large-:

 The component is placed over a surface plate. The sine bar is placed over the com-ponent. The heights on the rollers are meas-ured by means of vernier height gauge. A dial gauge is used to check the measuring pressure. 

The angle can be found by this formula-:

SINE Ө = H / L

Where, H = Height made by slip gauge.

              L = Distance between roller.

DROP FORGING

 Drop forging-: In drop forging utilizes  a closed impression apply to obtain a desire shape of the component. The shaping is done by the repeated hammering given to the material in the die-cavity. The drop forging sis consist of two-half the lower half of the die is fixed to the anvil of the machine. While the uppr half is fixed to the ramp the heated stock is kept in the die while the ramp 4-5 blows in pick-succession so that a metal spread and completely fill the die-cavity. When the two die half closed the completely cavity form.

The barrier passes used are the following-:

1. Fullering impression 

2. Edging impression 

3. Bending impression 

4. Blocking impression

5. Finishing impression 

1. Fullering impression -: Since drop forging involves only a reduction in cross-section with no up-setting , the very first step is to reduce the stock to the desire size.

2. Edging impression -: This stage is required together the expect amount of material required at each cross-section of the finishing component.

3. Bending impression -: This is required for those parts which have a bend shape. 

4. Blocking impression-: It is very difficult for a material to flow to deep pockets,  Sharp corners etc. Hence before the actual shape obtained the material is allowed to have one or more blocking impressions. Where it requires the shape very near to the final shape.

5. Finishing impression -: This is a final impression there the actual shape required is obtained. 

Cooling tower MCQ -:02

 Q.1 Filling or decking in a cooling tower increases the rate of heat transfer by providing ____.

A. Increase flow of air

B. Increase flow of water

C. A large amount of wetted surface 

D. All of the above 

Ans -: C

Q.2 Which type of fan drive generally cooling towers employ ?

A. Two speed fan drive

B. Multi speed fan drive 

C. Single speed fan drive 

D. Variable speed fan drive 

And-: A

Q.3 The minimum temperature to which water can be cooled in a cooling tower is __.

A. The wet bulb temperature of air

B. The dew point temperature of air 

C. Room temperature 

D. Dry bulb temperature of air

And-: B

Q.4 The performance of an evaporator condenser largely depends on ____.

A. Wet bulb temperature 

B. Dew point temperature 

C. Room temperature 

D. Dry bulb temperature 

Ans-: D

Q.5 In which type of refrigeration system solar energy can be directly used?

A. Vapour absorption 

B. Air refrigeration system 

C. Vapour compression 

D. All of the the above 

Ans -: A

Q.6 What is the means of amount of heat thrown away by the cooling tower in kcal/hr ?

A. Heat load of cooling towers 

B. Drift of cooling towers 

C. Approach of cooling towers 

D. None of the above 

Ans -: A

Q.7 What is mean of cooling range in cooling tower?

A. Amount of heat thrown away by the cooling tower in kcal/hr

B. Difference in temperature of cold water and atmospheric temperature 

C. Difference in temperature of hot water entering and cold water leaving. 

D. None of these

Ans-: C

Q.8 The most commonly used design method for duct size is ?

A. Equal friction method

B. Velocity reduction method

C. Double duct method

D. Static regain method

Ans-: B

Q.9 The process of mixing two or more streams of moist air is called ___.

A. Isothermal 

B. Constant volume 

C. Constant pressure 

D. Adiabatic 

Ans-: D

Q.10 Which type of refrigerating plants not require electricity?

A. Vapour absorption 

B. Vortex tube

C. Air refrigeration 

D. All of the above 

Ans -: A

ROLLING PROCESS

 Rolling process-: The rolling process is a metal forming process in which stock of the material pair of rollers   is passed between one or more pairs of rollers in order to reduce and to maintain the uniform thickness. In other words, it is a process In metal passing through a gap between the rollers rotating in opposite direction. This process is mainly focused on the cross-section of the it not or the metal which is forming.  

 

There are two types of rolling process -:

1. Hot rolling

2. Cold rolling

1. Hot rolling -: Those process working above the recrytalization temperature are termed  as " hot rolling " process.

2. Cold rolling -: Those process working below the recrytalization temperature are termed as cold rolling process. 

Under the action of heat or force when the atom is which a certain higher energy level the new crystal starts forming which is termed as recrytalization. Recrytalization destroy the old grain structure deforming by mechanical working and antaily new crystal which are strain free are formed. In hot working the process may be carried about of the recrytalization temperature with or without actual heating. 

For example-: The recrytalization temperature is below the room temperature and hence working of this metal at room temperature is always hot working. A simple heating is shown in fig. Where the grain start growing after the metal process the recrytalization temperature.  When it is cooled without any hot working the final grain size would be larger then when starts in hot working process.

MACHINE FORGING PROCESS

 Machine forging -: This is also known as up-set forging. Both drop and press forging are also done by machines only up-set forging is reffered as machine forging. Up-set machines are generally horizontal acting. The die-set consist of a die and a corresponding punch. The die consist of two parts one called the stationary greeper die which is fixed to the machine frame and other part is moveable greeper die which moves along with the die slide of the up-setter. The stock help between two greeper die by frition. 

                The two dies when in close position forward the necessary die cavity then the having tool advances against the stock and up-set it to completely fill the die cavity. Having completed the upsetting the heading tools moves back to it's back position. Then the moveable greeper die release the stock by sliding member.

Advantages of machine forging -:

1. High production rate up to 4500 parts per hour.

2. The process can be fully automated.

3. Elimination of the forging draft and flash.

4. High efficiency of material utilization, as the process involves little or no waste

PRESS FORGING

 PRESS FORGING -: In press  forging process die is similar to drop forging die as also the process. In this forging process the metal is shape not by means of a series of load as in drop forging. But by means of a single continuous squeezing action. This squeezing is obtained by means of hydraulic presses. Because of the continuous action of the hydraulic presses the material gets uniformly deformed throughout it's intire gap. More hammer is likely to be transmitted to the machine from in drop forging.

The pressure may have capacites ranging from 5 MN to 50 MN for normal applications. For special applications higher capacities press of the order of 150 MN are required. 

WELDING MCQ-:01

 Q. 1 The point at which the two pieces to be joint known as _____ .

A. Root

B. Weld point

C. Joint

D. Base point

And-: A

Q.2  The portion of the bent joint i.e. melted by the heat of welding is called  ___.

A. Puddle 

B. Melting point

C. Weld point

D. None of the above 

Ans -: A

Q.3 Acetylene also known as _____.

A. C3H4

B. C3H8

C. C2H2

D. C3H3

Ans-: C

Q.4 What is the proportion of the oxygen and acetylene in the natural flame?

A. 1:2

B. Equal 

C. 2:5

D. 1:3

Ans-: B

Q.5 In carburating flame the proportion of oxygen is ____%.

A. 22

B. 35

C. 50

D. 25

Ans-: D

Q.6 In welding process ,the colour of oxygen cylinder is ____.

A.  Black

B. White

C. Green

D. Yellow

And-: A

Q.7 In which type of welding process, the welding torch should be held at an angle of 30 to 40 ° .

A. Forehand welding

B. Backhand welding 

C. Electric arc welding 

D. All of the above 

Ans -: A

Q. 8 Electrods are two types ___.

A. Non-comsumerabl 

B. Non- corrosive 

C. Comsumerabl 

D. A+C

Ans -: D

Q.9 Non-comsumerabl electrod are made up of ___.

A. Copper

B. Carbon

C. Graphide 

D. Tungsten 

E. All of the above 

Ans-: E

Q.10 Which type of electrod is used in the " metal inert gas welding " process?

A. Comsumerabl 

B. Non-comsumerabl 

C. Aluminium electrod 

D. None of the above 

Ans-: A

ELECTRIC ARC WELDING

 Electric arc welding -:                                    In welding generation of heat by an electric arc is one of the most efficient method. Approximately 50 % of the energy is libera-ted in the form of heat produced by the electric arc to fusion matelic peices. This is one of the most widely used method mainly because of the edge of use and high produc-tion rate that can be achieved economically. 

          The main requirement in electric arc welding set-up is the source of the electric power. They are two types-: 

1. A.C. machine-:  

( a ) Transformer   

( b ) Motor or engine drive alternater 

2. D.C. machine -: 

( a ) Transformer with D.C. rectifier 

( b ) Generater 

The transformer does not have any moving part and as a result, oprate with less maintaness cost.

In A.C. welding normally only transformer are used. And in D.C. welding a rectifier or generator can be used to supply the required D.C. power. 

A tipical A.C. arc welding set-up using the transformer is show in fig.  The work peice is kept on a machine table to which the ground lit of the secondary winding of the welding transformer is connected. The other lit of the secondary winding is connected to an elect-rod holder into which electrod is crriped.  When electrod is brought into connecte with the path welding takes place. 

TUNGSTEN - INERT GAS WELDING

 Tungsten-inert gas welding -: It is also known as " gas tungsten arc welding ". It is an inert gas shielded arc welding process using a non- comsumerabl electrod. The electrod may also contain 1 to 2 % of " thorium oxide " mixed along with the core tungsten or tungsten with 0.15 to 0.04 % " zirconium oxide ".

                       

The pure tungsten electrod are less-expansive but will carry less current. The zirconium added in tungsten electrod are better than the pure tungsten. A tipical tungsten inert gas welding set-up in figure. It consist of welding torch at the center of which is the tungsten electrod . The inert gas supply to the welding zone through the annular path surrounding the tungsten electrod to the effectively displayed the atmosphere around the weld puddle. The smaller weld torch may not be provided with any polling devices for the electrod.

             The tungsten inert gas arc welding process can be use for joining of number of material through the most common welding arc aluminium, magnesium and stainless steel.            

S.No.   MATERIAL              ELECTROD

 1.        Stainless steel          De-oxidize Tungsten  

 2.        Aluminium                 All types of tungsten 

 3.       Magnesium                Tungsten 

 4.       De-oxidizing copper  Toriated tungsten 

 5.      High carbon steel       Toriated tungsten 

 6.      Cast iron                       toriated tungsten 

FLUX CORED ARC WELDING

FLUX CORED ARC WELDING -: Flux cored arc welding is the modification of gas metal arc welding.  Where the solid electrod wire is replaced by the tubular electrod containing a flux of the center of electrod through out it's length.  Because of availability of flux in the welding zone the weld metal of any required composition can be slowly controlled and a smooth weld heat can be obtain. Flux cored arc welding are normally used for the welding of structural steel or alloy steel.

                        

METAL INERT GAS WELDING

METAL INERT GAS WELDING -: Metal inert gas welding is also known as " gas metal arc welding " . In this welding utilies a comsumerabl electrod enhance the term metal appear in the title.  There are other gas shielded arc welding process utilising comsumerabl electrods such as flux coat arc welding or of which can be termed under metal inert gas welding. When thicker sheets are to be welded the filler metal requirement the gas metal welding. 

                   

 

 The tipical set-up for MIG show in fig. The comsumerabl electrod is the form of a wire rill,  which is fed at a constant rate . The welding torch is connected to the gas supply cylinder which provide the necessary inert gas . The electrod and workpiece are connected to the welding power supply. The current from the welding machine is change by the rate of feeding of the electrod wire. Normally D.C. arc welding machine are used for metal inert gas welding with electrod positive.

              The shielding gases that can be used for metal inert gas welding are helium, argen , nitrogen, oxygen and carbon dioxide and mixture of the above gases in various propositions. Each of this have that the fact on the formation of heat. The electrod wire comes generally in the form of coils . Various wire composition are available depending on the base metal composition.  The diameter of wire may be of order of 0.5 to 3.2 mm. 

SUBMERGED ARC WELDING

SUBMERGED ARC WELDING-: It is generally used for faster doing welding jobs. It is possible to use larger welding electrod 12 mm as well as very high current 4000 ampier so that very high metal disposition rate of the order of 20 kg/hr or more can be achive with process also very high welding speeds 5 meter/minute are possible in submerged arc welding. Some saw machine are able to well plated of thickness as high as 75 mm in butt joints in a single pass .

                 

 The arc is produced by the comsumerable electrod wire is continuously fed into the wild zone. The welding zone is completely covered by a measure amount of granulated flux which is delivert at a rate of the welding electrod by means suffer welding flux fed tube. The arc offering between electrod and workpiece us completely submerged under the flux and is not visible from outside. The power source are used with submerged arc welding can be either A.C. or D.C. . The electrod wire is normally used are sizes 1.6 to 2.5 , 3.15 , 4 ,5 , 6.3 and 8 mm .

CARBON ARC WELDING

CARBON ARC welding-: Carbon arc welding is the earliest arc welding process. In this process the electrod is made of ideal carbon or graphide. In contrast to graphide electrod , carbon electrod are soft and therefore they can't taken up very high current capasities. The arc with the carbon electrod is more controllable. Lower current act's to the higher electrod life.

                         

  

                       Through the carbon or graphide electrod arc not expected To made as the consumeabl electrod. They do get it to a rate for temperature because of the heat from the arc which causes a slow disintegration of the electrod take as also it's oxidation this means that electrod is slowly consumed.  In the carbon arc welding the required filler material is supply through a sale are filler rod. The arc can be obtain between the carbon electrod and workpiece or between the carbon electrod. 

Cooling tower MCQ

Q.1 Open cooling system is also called as _____ system .  
A. Once through 

B. Air based

C. Reversible 

D. Non-reversible 

Ans-: A

Q.2 What are used in the direct flow system to transverse the pond before uniting at intake?

a) Separators
b) Filters
c) Baffle walls
d) Porous pipes

Ans-: C

Q.3 The type of cooling towers with maximum heat transfer from air to water is ___.

A. Natural draft

B. Mechanical draft

C. A + B

D. None of the above 

Ans -:  B

Q.4 Natural draft cooling towers mostly used in the ______ .

A. Power station

B. Steel industry 

C. Aluminium industries 

D. All of the above 

Ans -: A

Q.5 Normally the guaranteed best approach a cooling tower achived is _____ .

A. 10 ° C

B. 15 ° C

C. 2.8 ° C

D. 8.2 ° C

Ans -: C

Q.6  A cooling tower reduces the water temperature close to _____.

A. Dry bulb temperature 

B. Wet bulb temperature 

C. Atmospheric temperature 

D. Dew point temperature 

Ans -: D

Q.7 The principle of work of the mostly cooling towers is ___.

A. Evaporative cooling 

B. Condensation 

C. Compression 

D. None of the above 

Ans -: A

Q.8  Approximately about _____ of cooling in cooling tower is through the sensible cooling. 

A. 50 %

B. 30 %

C. 20 %

D. 25 %

Ans -: C

Q.9  In cooling towers, higher temperature ______ corrosion potential. 

A. Decrease 

B. Increase 

C. Not affect 

D. Increase at 100 ° C

Q.10 The size of the cooling tower varies ______ with the temperature range .

A. Directly 

B. Inversely 

C. Proportionaly 

D. None of the above 

Ans -: B