Why does single layer grinding wheel show progressive rise of force during grinding of high speed steel?

—The geometry of grit undergoes irreversible change in the form of rounding or flattening due to wear caused by rubbing action of hard carbides present in high speed steel.

Why is aluminium oxide preferred to silicon carbide in grinding steel?

Al2O3 is tougher than SiC. Therefore it is preferred to grind material having high tensile strength like steel. Moreover, Al2O3 shows higher chemical inertness than SiC towards steel leading to much improved wear resistance during grinding.

TYPES OF DRILL PRESSES

—Vertical or pillar type

—Radial Arm type

—Gang drill

—Multi Spindle drill

—Numerical Control drill

DRILLING Helix Angle (ψ)

—Helix angle is the angle between the leading edge of the land and the axis of the drill. Sometimes it is also called as spiral angle.

—The helix results in a positive cutting rake

—This angle is equivalent to back rake angle of a single point cutting tool.

—  Usual – 20° to 35° – most common

—  Large helix : 45° to 60° suitable for deep holes and softer work materials

—  Small helix : for harder / stronger materials

—  Zero helix : spade drills for high production drilling micro-drilling and hard work materials

DRILLING Point Angle (2β)

—The point angle is selected to suit the hardness and brittleness of the material being drilled.
—

Harder materials have higher point angles, soft materials have lower point angles.—

An increase in the drill point angle leads to an increase in the thrust force and a decrease in the torque due to increase of the orthogonal rake angle.

—This angle (half) refers to side cutting edge angle of a single point tool.—

     Standard Point Angle is 118°

   It is 116° to 118° for medium hard steel and cast iron

— It is 125° for hardened steel
    It is 130° to 140° for brass and bronze
—It is only 60° for wood and plastics

Current Affair

SUNWAY taihuliht (CHINA)-WORLD'S FASTED SUPER COMPUTER

Questions On HARDNESS TESTING.

Herbert cloudburst Hardness test is conducted to know

Uniformity of hardness over a surface

Softness of non-metallic components

Hardness of non-metallic components

Hardness at specified depth inside the surface

Which of the following would you prefer for checking the hardness of very thin sections?

Knoop hardness test

Hebert cloud burst test

Shore's Scleroscope

Vickers hardness tes

A measure of Rockwell hardness is the

Depth of penetration of indenter

Surface area of indentation

Projected area of indentation

Height of rebound

A carbon steel having Brinell Hardness number 100 should ultimate tensile strength closer it

350 N/mm2

100 N/mm2

200 N/mm2

1000 N/mm2

The hardness of lathe bed material should be measured by

Brinell hardness tester

Rockwell tester

Shore Scleroscope

Vickers hardness teste

Questions on Material Testing Objectives Usefull for PSUs

Impact Test is used to measure

Toughness

Hardness

Permeability

Fluidity

Spiral test used to measure

Fluidity

Micro hardness

Toughness

Permeability

With the increase of percentage of carbon in the steel, which one of the following properties does increase?

Ductility

Hardness

Modulus of elasticity

Toughness

Cupping test is used to measure

Formability

Fluidity

Toughness

Micro hardness

Questions on SPECIAL CASTING objectives

Which one of the following casting processes is best suited to make bigger size hollow symmetrical pipes?

Centrifugal casting

Die casting

Investment casting

Shell moulding

In a centrifugal casting method

No core is used

Core may be made of any metal

Core is made of sand

Core is made of ferrous metal

Poor machinability of centrifugally cast iron pipe is due to

Dense structure

Chilling

Segregation

High mould rotation speed

Which of the following are the most likely characteristics in centrifugal casting?

Fine grain size and high density

Fine grain size and high porosity

Coarse grain size and high porosity

Coarse grain size and high density

Which of the following are produced by slush casting?

Hollow castings with thin walls

Hollow castings with thick walls

Thin castings

Thick castings

The method of casting for producing ornamental pieces are:

Pressed and slush casting

Slush and gravity casting

Gravity and semi permanent mould casting

Semi permanent mould and pressed casting

The process of making hollow castings of non-circular shape and desired thickness by permanent mould without the use of cores is known as

Slush casting

Die casting

Pressed casting

Centrifugal casting

Tricky one

Gold is
1-para magnetic
2-dia magnetic
3-ferro magnetic
4-ferro electric

Devices&Measurements Very usefull in PSUs EXAMS

Venturimeter	Rate of flow (Discharge)
Flow Nozzle	-do-
Orifice Meter	-do-
Bend meter	-do-
Rotameter	-do-
Pitot Tube	Velocity
Pitot Static Tube	Static & stagnation Pressure head
Hot wire anemometer	Air & gas velocity
Current Meter	Velocity in open channels
Barometer	Atmospheric Pressure
Piezometer	Small & +ve pressure measurement
Simple U tube manometer	Both +ve and –ve pressure
Aneroid/Mercury barometer	Local atmospheric pressure
Pyrometer	High temp. from a distance
Thermo couple	Surface Temperature
Tachometer	Angular Velocity
Prony brake dynamometer	Engine brake power
Kentometer	Vacuum pressure in a condenser
Bolometer	Thermal Radiation
Orsat Apparatus	Volumetric analysis of dry flue gases
Sling  psycometer	Moisture in air
Mcleod Gauge	Vacuum pressure
Durometer	Hardness of Rubber
Ph meter	Acidity/ alkanity of a solution
Microphone	Convert sound signal to analog electrical signal
Odometer	Distance covered by an automobile
V –notch	Discharge
Mechanical strain gauge	Quasi static strain
Hydrometer	Specific gravity of liquids
Hygrometer	Relative Humidity(water vapour in air)
Turbine meter	Average velocity

International org & their Heads Sure shot in Every PSUs Questions

Mr. Ban Ki Moon Secretary General, United Nation Organization
Mr. Jan Eliasson First Day Secretary general UNO
Dr. Jim YOng Kim President World Bank (International Bank For Reconstruction & Development)
Ms. Christine Lagarde Managing Director, International Monetary Fund
Ms. Irina Bokova Director General , UNESCO
Mr. Mukhira Kituyi Secretary General UNCTAD
Mr. Peter Tomka President , International Court of Justice (Latest update)
Mr. Mr. Takehiko Nakao President, Asian Development Bank
Ms. Baroness Patricia Secretary General, Commonwealth
Mr. Roberto Azevedo Director General , WTO
Mr. Zaheer Abbas President International Cricket Council
Mr. Shashank Manohar Chairman of ICC Cricket Council
Mr. Yukia Amano Director General, International Atomic Energy Agency (IAEA)
Mr. Hassan Malik Chairman , SAARC
Ms. Phumzile Mlambo Nqcuka - Head of UN Women
Mr. Arjun Bahadur Thapa Secretary General, SAARC
Mr. Salil Shetty Sec, Gen, Amensty International
Ms. Helen Clerk Director General of UNDP
Mr. Klaus Schweb Chairman, WEF (World Economic Forum)
Mr. David Richardson CEO of Int. Cricket Council
Mr. Hassan Rouhani Chairperson/ Secretary Gen. of NAM
Mr. Thomas Bach President International Olympic Committee
Mr.N.Ramachandran President of Indian Olympic Association
Prince Zeid Hussein UN High Commissioner for Human Rights

Question asked in ESE

Addition of which of the following improves machining of copper?
(a) Sulphur
(b) Vanadium
(c) Tin
(d) Zinc

Engineering Materials Questions

1-Aluminium Bronze is also known as :
(a) Muntz metal
(b) White metal
(c) Duraluminium
(d) Imitation gold

2-In case of power screws, what is the combination of materials used for the screw and the nut?
(a) Cast iron screw and mild steel nut
(b) Carbon steel screw and phosphor bronze nut
(c) Cast iron screw and cast iron nut
(d) Aluminium screw and alloy steel nut

3-The percentage of phosphorous in phosphor bronze is
(a) 0.1                (b) 1
(c) 11.1               (d) 98

4-Gunmetal, which is used in journal bearings, contains
(a) 88% Cu, 10% Sn, 2% Zn
(b) 80% Cu, 10% Zn, 10% Al
(c) 85% Cu, 5% Mg, 10% Al
(d) 85% Cu, 5% Sn, 10% Pb

5-Admirality Brass is used for
(a) Condenser Tubes
(b) Rivets
(c) Piston rods
(d) Utensils

6-Monel metal is an alloy of
(a) Iron and carbon
(b) Copper and zinc
(c) Aluminium and copper
(d) Copper and nickel

7-Babbit is an alloy of
(a) Sn, Cu, Sb and Pb
(b) Sn and Cu
(c) Sn, Cu and Pb
(d) Sn, Cu and Sb

8-Babbit lining is used on brass/bronze bearings to
(a) Increase bearing resistance
(b) Increase compressive strength
(c) Provide anti-friction properties
(d) Increase wear resistance
.
9-Why are babbit alloys used for bearing material?
(a) They have excellent embeddability
(b) They are relatively stronger than other bearing materials
(c) They do not lose strength with increase in temperature
(d) They have high fatigue strength

10-Babbitt are used for
(a) Gears          (b) Bearings
(c) Bolts            (d) Clutch liners

11-Tin base white metals are used where the bearings are subjected to
(a) Large surface wear
(b) Elevated temperatures.
(c) Light load and pressure
(d) High pressure and load
.
12-Columbium is a :
(a) Nuclear material
(b) Automobile material
(c) Film material
(d) Foam material

13-Duralumin Alloy contains aluminium and copper in the ratio of
%Al %Cu
(a) 94 4
(b) 90 8
(c) 88 10
(d) 86 12

Some important Questions on Alloying elements & Their applications asked in SAIL

1-18/8 stainless steel contains
(a) 18% stainless, 8% chromium.
(b) 18% chromium, 8% nickel.
(c) 18% tungsten, 8% nickel.
(d) 18% tungsten, 8% chromium
.
2-The alloy steel designated as 40 Cr18 Ni 2 by Bureau of Indian Standards contains
(a) 0.4% C, 18% Cr and 2% Ni
(b) 4.0% C, 1.8% Cr and 0.2% Ni
(c) 0.4% C, 1.8% Cr and 2% Ni
(d) 0.4% C, 1.8% Cr and 0.2% Ni

3-Which one of the following elements is a ferritic stabilizer?
(a) Nickel
(b) Manganese
(c) Copper
(d) Chromium

4- Which one of the following elements is an austenitic stabilizer?
(a) Chromium
(b) Tungsten
(c) Nickel
(d) Molybdenum

5-Small percentage of boron is added to steel to
(a) Increases hardenability
(b) Reduce machinability
(c) Increases wear resistance
(d) Increase endurance strength

6-Some high speed steels have cobalt (Co) added to them in amounts ranging from 2% to 15%, since this element improves the
(a)Cutting efficiency, especially at high temperature
(b) Depth hardening ability of the HSS tool
(c) Red hardness of the HSS tool
(d) Grain structure of the HSS tool

7-Silicon steel is widely used in [ISRO-2K15]
Cutting Tools
Dies and Punches
Electrical Industry
Chemical Industry

8-Addition of vanadium to steel results in improvement of
(a) Heat-treatability by quenching
(b) Hardenability
(c) Fatigue strength
(d) Resistance to oxidation at elevated temperature

9-For improving the strength of steel at elevated temperatures, which one of the following alloying element is used?
(a) Copper
(b) Tungsten
(c) Aluminium
(d) Zinc

10-Which one of the following is the major alloying element in Invar?
(a) Aluminium
(b) Nickel
(c) Vanadium
(d) Copper

11- Coefficient of Expansion is practically nil in a particular alloy. What is this alloy?
(a) Hadfield Manganese Steel
(b) Invar
(c) Vitallium
(d) Stellite

12-Invar is used or measuring tapes primarily the to its
(a) Non-magnetic properties
(b) High nickel content
(c) Low coefficient of thermal expansion
(d) Hardenability

Questions on Auto collimator

Q1-Auto collimator is used to check
(a) Roughness 
(b) Flatness
(c) Angle
(d) Automobile balance
.
Q2-An autocollimator is used to
(a) measure small angular displacements on flat surface
(b) compare known and unknown dimensions
(c) measure the flatness error
(d) measure roundness error between centers

Few Important Questions on Welding asked in PSUs

Q1-In atomic hydrogen welding, hydrogen acts as
(a) A heating agent
(b) One of the gases to generate the flame
(c) An effective shielding gas protecting the weld
(d) A lubricant to increase the flow characteristics of weld metal

Q2-The welding process which uses a blanket of fusible granular flux is
(a) Tungsten inert gas welding
(b) Submerged arc welding
(c) Electroslag welding
(d) Thermit welding

Q3-In which of the following welding processes, flux is used in the form of granules?
(a) AC arc welding
(b) Submerged arc welding
(c) Argon arc welding
(d) DC arc welding

Q4- The welding process in which bare wire is used as electrode, granular flux is used and the process is characterized by its high speed welding, is known as:
(a) Shielded arc welding
(b) Plasma arc welding
(c) Submerged arc welding
(d) Gas metal arc welding

Q5-In MIG welding, the metal is transferred into the form of which one of the following?
(a) A fine spray of metal
(b) Molten drops
(c) Weld pool
(d) Molecules

Q6-Which one of the following welding processes uses non- consumable electrodes?
(a) TIG welding
(b) MIG welding
(c) Manual arc welding
(d) Submerged arc welding.

Q7-Which of the following arc welding processes does not use consumable electrodes?
(a) GMAW
(b) GTAW
(c) Submerged Arc Welding
(d) None of these

Q8-Following gases are used in tungsten inert gas welding [ISRO-09]
(a) CO2 and H2
(b) Argon and neon
(c) Argon and helium
(d) Helium and neon

Q9-Too high welding current in arc welding would result in
(a) Excessive spatter, under cutting along edges, irregular deposits, wasted electrodes
(b) Excessive piling up of weld metal, poor penetration, wasted electrodes
(c) Too small bead, weak weld and wasted electrodes
(d) Excessive piling up of weld metal, overlapping without penetration of edges, wasted electrodes

Q10-Pinch effect in welding is the result of
(a) Expansion of gases in the arc
(b) Electromagnetic forces
(c) Electric force
(d) Surface tension of the molten metal

Q11-Arc blow is more common in
(a) A.C. welding
(b) D.C. welding with straight polarity
(c) D.C. welding with bare electrodes
(d) A.C. welding with bare electrodes

Q12-In a linear arc welding process, the heat input per unit length is inversely proportional to
(a)Welding current
(b)Welding voltage
(c)Welding speed
(d)Duty cycle of the power source

Q13-In arc welding, d.c. reverse polarity is used to bear greater advantage in
(a) Overhead welding
(b) Flat welding of lap joints
(c) Edge welding
(d) Flat welding of butt joints

Q14-In manual arc welding, the equipment should have drooping characteristics in order to maintain
(a) Voltage constant when arc length changes
(b) Current constant when arc length changes
(c) Temperature in the are constant
(d) Weld pool red-hot

Q15-In arc welding, the arc length should be equal to
(a) 4.5 times the rod diameter
(b) 3 times the rod diameter
(c) 1.5 times the rod diameter
(d) Rod diameter

Q16-In arc welding, penetration is minimum for
(a) DCSP
(b) DCRP
(c) AC
(d) DCEN

Q17-Thick steel plate cut with oxygen normally shows signs of cracking. This tendency for cracking can be minimised by
(a) Slow speed cutting
(b) Cutting in two or more stages
(c) Preheating the plate
(d) Using oxy-acetylene flame

Q18-Oxyacetylene reducing flame is used while carrying out the welding on
(a) Mild steel                      (b) High carbon steel
(c) Grey cast iron               (d) Alloy steels

Q19-The edge of a steel plate cut by oxygen cutting will get hardened when the carbon content is
(a) Less than 0.1 percent
(b) Less than 0.3 percent
(c) More than 0.3 percent
(d) Anywhere between 0.1 to 1.0 percent

Q20-In oxy-acetylene gas welding, for complete combustion, the volume of oxygen required per unit of acetylene is
(a) 1
(b) 1.5
(c) 2
(d) 2.5

Q21-By which one of the following methods gray cast iron is usually welded?
(a) TIG welding                  (b) MIG welding
(c) Gas welding                  (d) Arc welding

Q22-The temperature of a carburising flame in gas welding is that of a neutral or an oxidising flame.
(a) Lower than
(b) Higher than
(c) Equal to
(d) Unrelated to

Q23-In Oxyacetylene gas welding, temperature at the inner cone of the flame is around
(a) 3500°C
(b) 3200°C
(c) 2900°C
(d) 2550°C

Q24-The ratio of acetylene to oxygen is approximately………. for a neutral flames used in gas welding.
(a) 1 : 1
(b) 1 : 2
(c) 1 : 3
(d) 1.5 : 1

Q25-The correct sequence of the given materials in ascending order of their weldability is
(a) MS, copper, cast iron, aluminium
(b) Cast iron, MS, aluminium copper
(c) Copper, cast iron, MS, aluminium
(d) Aluminium, copper, cast iron, MS

Q26- The major difficulty during welding of aluminium is due to its
(a) high tendency of oxidation
(b) high thermal conductivity
(c) low melting point
(d) low density

Few Important Questions on Milling:

Q1 Climb milling is chosen while machining because
(a) The chip thickness increases gradually 
(b) It enables the cutter to dig in and depth of cut
(c) The specific power consumption is reduced 
(d) Better surface finish can be obtained

Q2 The cutting speed of a milling cutter while cutting brass is:
(a) 45 to 60 m/min       (b) 30 to 40 m/min
(c) 25 to 35 m/min        (d) 15 to 20 m/min

Q3- Which one of the following operations is carried out at the minimum cutting velocity if the machines are equally rigid and the tool work materials are the same?
(a) Turning
(b) Grinding
(c) Boring
(d) Milling

Q4- The arbor of a milling machine is used to hold which one of the following?
(a) Spindle                 (b) Over-arm
(c) Cutting tool           (d) Mandrel

Q5- In milling machine, the cutting tool is held in position by
(a) Chuck                   (b) Spindle
(c) Arbor                     (d) Tool holder

Q6- For machining, which one of the following gang milling operations is employed?
(a) Threads
(b) Bores
(c) Grooves
(d) Steps on prismatic parts

Q7- Gang milling is a
(a) Milling process for generating hexagonal surfaces
(b) Process of cutting gears
(c) Process in which two or more cutters are used simultaneously
(d) Milling operation combined with turning

Q8- In a milling operation two side milling cutters are mounted with a desired distance between them so that both sides of a work piece can be milled simultaneously. This set up is called.
(a) Gang milling                   (b) Straddle milling
(c) String milling                   (d) Side milling.

Q9- What is the process of removing metal by a milling cutter which is rotated against the direction of travel of the work piece, called?
(a) Down milling  (b) Up milling
(c) End milling     (d) Face milling

Few Important Questions on TOM :

Q1-Klein's construction can be used when
(a) crank has a uniform angular velocity
(b) crank has non uniform velocity
(c) crank has uniform angular acceleration
(d) crank has uniform angular velocity and angular acceleration

Q2-The sense of Corioli's component is such that it
(a) leads the sliding velocity vector by 90°
(b) lags the sliding velocity vector by 90°
(c) is along the sliding velocity vector
(d) leads the sliding velocity vector by 180°

Q3-The number of links and instantaneous centers in a reciprocating engine mechanism are
(a) 4, 4
(b) 4, 5
(c) 5, 4
(d) 6, 4
(e) 4, 6

Q4-A kinematic chain requires at least
(a) 2 links and 3 turning pairs
(b) 3 links and 4 turning pairs
(c) 4 links and 4 turning pairs
(d) 5 links and 4 turning pairs

Q5-A slider crank chain consists of following numbers of turning and sliding pairs
(a) I, 3
(b) 2, 2
(c) 3, 1
(d) 4, 0

Q6-Whitworth quick return mechanism is obtained by inversion of
(a) slider crank mechanism
(b) kinematic chain
(c) five link mechanism
(d) roller cam mechanism

Q7-A chain comprises of 5 links having 5 joints. Is it kinematic chain ?
(a) yes
(b) no
(c) it is a marginal case
(d) data are insufficient to determine it

Q8-Peaucellier mechanism has
(a) eight links
(b) six links
(c) four links
(d) twelve links

Q9-Higher pairs are those which have
(a) point or line contact between the two elements when in motion
(b) surface contact between the two ele¬ments when in motion
(c) elements of pairs not held together mechanically
(d) two elements that permit relative motion

Q10-A pantograph is a mechanism with
(a) lower pairs
(b) higher pairs
(c) rolling pairs
(d) turning pairs

Q11-A point on a link connecting double slider crank chain traces a
(a) straight line
(b) circle
(c) parabola
(d) hyperbola
(e) ellipse.

Q12-Typewriter constitutes
(a) machine
(b) structure
(c) mechanism
(d) inversion

Q13-To transmit power from one rotating shaft to another whose axes are neither parallel nor intersecting, use
(a) spur gear
(b) spiral gear
(c) bevel gear
(d) worm gear

Q14-The number of links in pantograph mechanism is equal to
(a) 2
(b) 3
(c) 4
(d) 5

Q15-Ackermann steering gear consists of
(a) sliding pairs
(b) turning pairs
(c) rolling pairs
(d) higher pairs

Q16-Davis steering gear consists of
(a) sliding pairs
(b) turning pairs
(c) rolling pairs
(d) higher pairs

Q17-Which of the following would constitute a link
(a) piston, piston rings and gudgeon pin
(b) piston, and piston rod
(c) piston rod and cross head
(d) piston, crank pin and crank shaft
(e) piston, piston rod and cross head
.
Q18-If there are L number of links in a mechanism then number of possible inversions is equal to
(a) L + 1
(b) L- 1
(c) L
(d) L + 2

Q19-The maximum value of the pressure angle in case of cam is kept as
(a) 10°
(b) 14°
(c) 20°
(d) 30°

Few Important Questions on Gear Manufacturing :

Q1- Gear lapping
(a) An operation after heat treatment 
(b) An operation prior to heat treatment
(c) An independent operation for gear reconditioning
(d) None of the above

Q2- Gear cutting on a milling machine using an involute profile cutter is a
(a) Gear forming process
(b) Gear generating process.
(c) Gear shaping process

(d) Highly accurate gear producing process.
Q3- Which one of the following processes of gear manufacture results in best accuracy of the involute gear tooth profile?
(a) Milling
(b) Hobbing
(c) Rotary gear shaper

(d) Rack type gear shaper
Q4- By which one of the following machines the teeth of an internal spur gear can be cut accurately?
(a) Milling machine
(b) Slotting machine
(c) Hobbing machine
(d) Gear-shaping machine

Q5- In gear hobbing
(a) Only hob rotates
(b) Only gear blank rotates
(c) Both hob and gear blank rotate
(d) Neither hob nor gear blank rotates

Q6- Internal gear cutting operation can be performed by
(a) Milling
(b) Shaping with rack cutter
(c) Shaping with pinion cutter
(d) Hobbing

Q7- Which of the following cannot be cut by hobbing process?
(a) Helical gears (b) Bevel gears
(c) Worm gears (d) Spur gears

Q8- Gear burnishing process for
(a) Removing residual stresses from teeth roots
(b) Surface finishing
(c) Under-cut gears
(d) Cycloidal gears

Q9- Which one of the following is not a feature of gear hobbing process?
(a) High rate of production
(b) Generation of helical gears
(c) Very accurate tooth profile
(d) Generation of internal gears