Category: Manufacturing Engineering Objective Questions

Manufacturing Engineering Multiple Choice Questions on “Milling Operations-1”.

1. Which of the following milling operation can be used for machining a flat surface, parallel to the axis of cutter?
a) Slab milling
b) Face milling
c) Angular milling
d) Form milling
Answer: a
Clarification: Slab milling operation can be used for machining a flat surface, parallel to the axis of cutter. It uses face cutters.

2. Which of the following milling operation can be used for machining of flat surface which is the right angle to the axis of cutter?
a) Slab milling
b) Face milling
c) Angular milling
d) Form milling
Answer: b
Clarification: Face milling operation can be used for machining a flat surface, perpendicular to the axis of cutter. It may use periphery cutters or face cutters.

3. Which of the following milling operation can be used for machining of flat surface which is at some angle to the axis of cutter?
a) Slab milling
b) Face milling
c) Angular milling
d) Form milling
Answer: c
Clarification: Angular milling operation can be used for machining a flat surface, which is at some angle to the axis of cutter.

4. Which of the following milling process is used for machining of irregular shapes?
a) Slab milling
b) Face milling
c) Angular milling
d) Form milling
Answer: d
Clarification: Form milling operation can be used for machining Irregular surface. It uses special form cutters.

5. Which of the following milling process is used for machining of two parallel vertical surface of a job simultaneously?
a) Key way milling
b) Groove milling
c) Gang milling
d) Straddle milling
Answer: d
Clarification: Straddle milling operation can be used for machining of two parallel vertical surface of a job simultaneously.

6. Which of the following milling process is used for machining of a number of flat horizontal and vertical surfaces simultaneously using more than two cutters at the same time mounted on common arbor?
a) Key way milling
b) Groove milling
c) Gang milling
d) Straddle milling
Answer: c
Clarification: Gang milling uses multiple cutters. All the cutter works simultaneously during the milling operation.

7. Which of the following milling operation can be used for producing grooves in work piece?
a) Key way milling
b) Groove milling
c) Gang milling
d) Straddle milling
Answer: b
Clarification: Groove milling can be used for producing grooves in work piece.

8. Which of the following operation can be used for parting of work piece in two pieces?
a) Key way milling
b) Groove milling
c) Saw milling
d) Straddle milling
Answer: c
Clarification: Saw milling can be used for parting off operations. It uses special milling cutters.

9. In which of the following milling cutters, power requirement will increase slightly?
a) Negative rake angle tool
b) Positive rake angle tool
c) Both positive and negative rake angle tool
d) None of the mentioned
Answer: b
Clarification: Power requirement for positive rake angle tool is generally more than negative rake angle tool.

10. Which of the following cutter can be used for finishing off previously milled slot?
a) Key way milling cutter
b) Dovetail milling cutter
c) Saw milling cutter
d) Slitting milling cutter
Answer: b
Clarification: Dovetail milling cutters are used for finishing previously milled slots.

Manufacturing Engineering Multiple Choice Questions on “Electric Discharge Machining”.

1. Which of the following machine uses non conventional machining technique for metal removal?
a) Grinding machine
b) Milling machine
c) Electric discharge machine
d) None of the mentioned
Answer: c
Clarification: Electronic discharge machine is a non conventional machining technique for metal removal.

2. Which of the following material cannot be machined using electronic discharge machine?
a) Iron
b) Aluminum
c) Copper
d) Wood
Answer: d
Clarification: Wood is a bad conductor of electricity and hence cannot be machined using electronic discharge machine.

3. Which of the following material can be machined using electronic discharge machine?
a) Iron
b) Rubber
c) Plastic
d) Wood
Answer: a
Clarification: Iron is a good conductor of electricity and hence can be machined using electronic discharge machine.

4. Which of the following EDM machine is used for cutting shapes cut out of a flat sheet or plate of metal?
a) Wire EDM
b) Sinker EDM
c) Wire and Sinker EDM both
d) None of the mentioned
Answer: a
Clarification: Wire EDM used for cutting shapes cut out of flat sheet or plate of metal. It is an unconventional process of machining.

5. Which of the following EDM machine is used for die cast tooling?
a) Wire EDM
b) Sinker EDM
c) Wire and Sinker EDM both
d) None of the mentioned
Answer: b
Clarification: Sinker EDM is used for die cast tooling. It is an unconventional process of machining.

6. Dielectric medium in EDM is used for
a) Flushing away the debris
b) To make the medium conducting
c) To decrease the material removal rate
d) None of the mentioned
Answer: a
Clarification: Dielectric in EDM is used for flushing away the debris generated during the process of machining, which may slow down the material removal rate if not removed instantly.

7. Material removal rate in EDM increases with
a) Increase in melting point of work piece
b) Increase in Current
c) Decrease in current
d) None of the mentioned
Answer: b
Clarification: MRR is directly proportional to the current.

8. Material removal rate in EDM increases with
a) Increase in melting point of work piece
b) Decrease in Current
c) Decrease in melting point of work piece
d) None of the mentioned
Answer: c
Clarification: MRR is inversely proportional to a melting point of work piece.

9. For maximum power delivery using resistance capacitance relaxation circuit in EDM, discharge voltage should ___ % of the supply voltage?
a) 80
b) 23
c) 65
d) 72
Answer: d
Clarification: Find optimum value using L-C circuits.

10. In an EDM machine, metal removal rate is 1.937 cubic mm / min. If total amount of material to removed is 600 cubic mm. Time required in min will be
a) 100
b) 200
c) 309
d) 402
Answer: c
Clarification: Time required= (Total material to be removed/material removal rate).

Manufacturing Engineering Puzzles on “Fusion Welding Processes-2”.

1. Which of the following is used to generate Acetylene gas?
a) Calcium
b) Carbon
c) Calcium carbonate
d) Calcium carbide
Answer: d
Clarification: Acetylene is a hydrocarbon consisting of two carbon atoms and two hydrogen atoms. The simplest process reacts calcium carbide with water to produce acetylene gas and a calcium carbonate slurry, called hydrated lime. The chemical reaction may be written as CaC₂ + 2H₂O → C₂H₂ + Ca (OH)₂.

2. Striking voltage as compared to a voltage during arc welding is?
a) less
b) same
c) more
d) can’t say
Answer: c
Clarification: The minimum voltage enough to arc across a given gap is called as the striking voltage. It is more than the arc voltage in arc welding.

3. How many zones are there in a carburising flame?
a) one
b) two
c) three
d) four
Answer: c
Clarification: If the oxygen is insufficient for full combustion, the flame is known as a reducing, or carburizing, flame. The temperature of a reducing flame is lower; hence, such a flame is suitable for applications requiring low heat, such as brazing, soldering, and flame-hardening operations.

4. Due to which of the following reasons distortion in welding occurs?
a) Oxidation of weld pool
b) Use of high voltage
c) Improper clamping
d) Use of high current
Answer: c
Clarification: As if the clamping is improper the weld will not be at the right place.

5. In reverse polarity welding _____________
a) work piece is connected as negative, and holder is earthed
b) electrode holder is connected to negative and work piece to positive
c) electrode holder is connected to positive and work piece to negative
d) both electrode holder and work piece are connected to negative
Answer: c
Clarification: In direct current reverse polarity (DCRP) or direct current electrode positive (DCEP), when base metals relate to the negative terminal of the power source and electrode relates to the positive terminal.

6. Where does maximum flame temperature occur?
a) Next to inner cone
b) At the inner cone
c) At the tip of the flame
d) At the outer cone
Answer: b
Clarification: Maximum flame temperature occur at inner cone. As flame moves from inner to outer temperature drop takes places.

7. In which of the following welding processes, electrode gets consumed?
a) TIG welding
b) Resistance welding
c) Thermit welding
d) Arc welding
Answer: d
Clarification: As in arc welding, welding is totally dependent on electrode, so it will be consumed.

8. Which of the following statements about welding is incorrect?
a) Increased corrosion resistance
b) Even materials like stainless steel and aluminium can be welded
c) No flux required
d) High welding speed
Answer: c
Clarification: Flux is mainly used for the following purposes: (a) It prevents the oxidation o the surface of the weld which can contaminate the welded potion, (b) It helps in forming alloy at the welded portion which improves the strength, (c) In arc welding the flux coating helps in directing the spark that’s why the electrode is kept concave in shape so that spark can be precisely directed towards the cavity where welding has to be performed.

9. Where is half corner weld used?
a) where efficiency of the joint should be 50 percent
b) where longitudinal shear is present
c) where severe loading is encountered, and the upper surfaces of both pieces must be in the same plane
d) For welding materials heavier than 12 gauge
Answer: d
Clarification: The half-open corner joint is used for welding materials heavier than 12 gauge.

10. Which of the following percentage of carbon in steel is most weldable?
a) 0.15
b) 0.25
c) 0.35
d) 0.8
Answer: a
Clarification: Low carbon steel is typically the most readily welded steel in a room temperature environment.

11. In which of the following metals does the phenomenon of ‘weld decay’ occurs?
a) stainless steel
b) cast iron
c) carbon steel
d) bronze
Answer: a
Clarification: Weld decay is a form of intergranular corrosion, usually of stainless steels or certain nickel-base alloys, that occurs as the result of sensitization in the heat-affected zone during the welding operation.

12. On which of the following principles does the ‘positive pressure type torch’ work?
a) equal volume
b) positive pressure
c) equal pressure
d) equal flow
Answer: c
Clarification: There are two types of welding and cutting torches commonly used. They are the positive-pressure type (also known as an equal pressure type or medium type pressure type torch), and the injector type.

13. Why is post cleaning necessary at brazed joint?
a) to avoid corrosion
b) to avoid slagging
c) to avoid oxidation
d) to avoid scaling
Answer: a
Clarification: Depending on the brazing process, we may need to perform post-braze joint cleaning to remove residual flux. This step is crucial for several reasons; including the corrosive nature of most fluxes and the possibility that excess flux could contribute to joint failure. The most common cleaning methods involve water-specifically soaking/wetting and quenching.

14. While welding, which of the following material welding, neutral flame is not used?
a) cast iron
b) steel
c) copper
d) zinc
Answer: d
Clarification: The neutral flame has a one-to-one ratio of acetylene and oxygen. A neutral flame is named neutral since in most cases will have no chemical effect on the metal being welded. Neutral welding flames are commonly used to weld: mild steel, stainless steel, cast iron, copper, aluminium, etc.

15. Which of the following statements about “projection welding” is correct?
a) It is multi spot welding process
b) It is an arc welding process
c) It is a continuous spot-welding process
d) It is a process used for joining round bars
Answer: a
Clarification: Projection welding is a modification of spot welding in which the weld is localized by means of raised sections, or projections, on one or both workpieces to be joined. This is high-production process, and multiple projection welds can be arranged by suitable designing and jigging.

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Manufacturing Engineering Multiple Choice Questions on “Casting Techniques For Single Crystal Components”.

1. In which of the following casting process, the metal being poured into the mold begins to solidify at ceramic walls?
a) conventional casting
b) directional solidification
c) single crystal
d) induction melting
Answer: a
Clarification: The conventional-casting process uses a ceramic mold. The molten metal is poured into the mold and begins to solidify at the ceramic walls. The grain structure developed is poly crystalline.

2. In which of the following casting process, preheating of ceramic mold is done by radiation?
a) conventional casting
b) directional solidification
c) single crystal
d) induction melting
Answer: b
Clarification: The directional-solidification process was first developed in 1960. The ceramic mold is preheated by radiant heating, and the mold is supported by a water-cooled chill plate.

3. In which of the casting process, the mold has either corkscrew or helical shape construction?
a) conventional casting
b) directional solidification
c) single crystal
d) induction melting
Answer: c
Clarification: In crystal growing, developed in 1967, the mold has a constriction in the shape of a corkscrew or helix. The cross section is so small that it allows only one crystal to fit through.

4. Which of the following casting technique has a greater impact in semiconductor industry?
a) conventional casting
b) directional solidification
c) single crystal
d) induction melting
Answer: c
Clarification: Single-crystal growing is a major activity in the semiconductor industry in the manufacture of the silicon wafers in microelectronic devices.

5. Which of the following parameter is used to determine the nature of cast components by sealing the opening in casting?
a) Surface defects
b) Pressure tightness
c) Ductility
d) Brittleness
Answer: b
Clarification: Pressure tightness of cast components (valves, pumps, and pipes) usually is determined by sealing the openings in the casting and pressurizing it with Water, oil, or air.

6. Which of the following test allows us to remove specimens form various casting sections?
a) surface defects
b) pressure tightness
c) destructive
d) non-destructive
Answer: b
Clarification: In destructive testing, specimens are removed from various sections of a casting and tested for strength, ductility, and other mechanical properties and to determine the presence, location, and distribution of porosity and any other defects.

7. In which of the following casting method, alloy is melted by induction in a ceramic crucible?
a) conventional casting
b) melt spinning
c) pressure die casting
d) vacuum arc melting
Answer: b
Clarification: In a common method called melt spinning, the alloy is melted by induction in a ceramic crucible. It is then propelled under high gas pressure against a rotating copper disk (chill block), which chills the alloy rapidly.

8. Which of the following casting technique, a seed crystal is dipped into the molten metal and then pulled out slowly?
a) crystal pulling method
b) melt spinning
c) single crystal
d) Sankaranarayanan Ramasamy method
Answer: a
Clarification: In the crystal-pulling method, a seed crystal is dipped into the molten metal and then pulled out slowly (at a rate of about 10 /, tm/s) while being rotated.

9. The zone at which a rod of polycrystalline silicon rests on a single crystal and an induction coil heats these two pieces is called as?
a) crystal pulling method
b) melt spinning
c) floating zone
d) vacuum arc melting
Answer: c
Clarification: The second technique for crystal growing is the floating-zone method. Starting with a rod of polycrystalline silicon resting on a single crystal, an induction coil heats these two pieces while the coil moves slowly upward. The single crystal grows upward while maintaining its orientation.

10. In which of the following method, dopants are added?
a) crystal pulling method
b) melt spinning
c) floating zone
d) vacuum arc melting
Answer: a
Clarification: In the crystal-pulling method, dopants may be added to the liquid metal to impart special electrical properties. Single crystals of silicon, germanium, and various other elements are grown with this process.

Manufacturing Engineering Multiple Choice Questions & Answers (MCQs) on “Quality Assurance”.

1. The basic difference between MRP and MRP-II is:
a) inventory
b) bom
c) finance
d) capacity planning
Answer: c
Clarification: MRP-II is related to finance.

2. Inventory record file gives the following information
a) lot size
b) machine details
c) customer name
d) none of the mentioned
Answer: a
Clarification: Only lot size is considered in inventory record file.

3. Bill of material structure is used to
a) calculate net requirements
b) calculate due dates
c) calculate man power requirements
d) all of the mentioned
Answer: a
Clarification: None.

4. Just in time manufacturing philosophy emphasizes on
a) man power
b) manufacturing
c) profit
d) inventory
Answer: d
Clarification: None.

5. Forecasting is used for
a) dependent demand items
b) independent demand items
c) all of the mentioned
d) none of the mentioned
Answer: b
Clarification: None.

6. CRP takes material requirements from MRP and converts to
a) standard hours of man power
b) standard hours of machine
c) standard hours of load
d) all of the mentioned
Answer: d
Clarification: None.

7. Capacity planning is concerned with
a) how many machines required
b) how much labour required
c) all of the mentioned
d) none of the mentioned
Answer: c
Clarification: None.

8. MRP-II system is called a closed loop system because it considers
a) inventory
b) finance
c) man power
d) none of the mentioned
Answer: b
Clarification: Only MRP-II system contains finance.

9. P.M.T.S( Predetermined Motion Time System) include
a) M.T.M (Method Time Measurement)
b) W.F.S (Work Factor Systems)
c) B.M.T.S (Basic Motion Time Study)
d) All of the mentioned
Answer: d
Clarification: None.

10. M.T.M is used to
a) improve existing methods
b) establish time standards
c) develop effective methods in advance of the beginning of production
d) all of the mentioned
Answer: d
Clarification: None.

11. For a small scale industry, the fixed cost per month is Rs. 5000. The variable cost per product is Rs. 20 and sales price is Rs. 30 per piece. The break even production per month will be
a) 300
b) 40
c) 500
d) 1000
Answer: c
Clarification: If x is the break even production per month, then
5000 + 20x = 30x
or, x = 500.

12. Two alternatives can produce a product. First has a fixed cost of Rs. 2000 and a variable cost of Rs. 20 per piece. The second method has a fixed cost of Rs. 1500 and a variable cost of Rs.30. The break even quantity between the two alternatives is
a) 25
b) 50
c) 75
d) 100
Answer: b
Clarification: If x is the break even quantity, then
2000 + 20x = 1500 + 30x
or, x = 50.

Manufacturing Processes Interview Questions and Answers for freshers on “Electro-Chemical Machining – 3”.

1. In ECM, one needs to understand fluid flow while designing the tool for machining complex shapes.
a) True
b) False
Answer: a
Clarification: Because of the interaction of working-tip shape and dimensions, location of insulation, current density and feed rate, the design of tools for machining complex shapes requires understanding of fluid flow, electrical and electrochemical principles as well as experience and ingenuity.

2. Which of the following does not hold true about ECM?
a) ECM cell must avoid flutter and arcing
b) Part and the cathode must have adequate current-carrying capacity
c) Tool must have shape exactly same as that of the mirror image of the part
d) It gives burr free surface
Answer: c
Clarification: Tool dimensions must be slightly different from the nominal mirror dimensions of the completed part to allow for ECM overcut. ECM cell must have strength and rigidity to avoid flutter and arcing.

3. For which of the following ECM cannot be used?
a) Tapering a predrilled hole in iron block
b) To make stepped hole is a nickel alloy
c) To generate ribs on metal surface
d) To machine Al₂O₃
Answer: d
Clarification: Open-flow cathode (tool) is used to generate the outside diameter wall and leave an embossment. Stepped tool is used for sinking a stepped through-hole. Cone shaped tool is to generate taper in a predrilled hole. Al₂O₃ cannot be machined by ECM as it is ceramic.

4. Electrolyte should carry away the heat generated and products of the reaction.
a) True
b) False
Answer: a
Clarification: Electrolyte used in ECM should-
• Complete the electrical circuit between the tool and the workpiece
• Allow the desirable machining reactions to take place
• Carry away the heat generated during the operation
• Carry away products of reaction from the zone of machining.

5. Which of the following is not a desirable electrolyte property?
a) Low viscosity
b) High specific heat
c) Lower resistance to film formation on the workpiece
d) Non-corrosiveness
Answer: c
Clarification: Desirable electrolyte properties are as follows-
• High electrical conductivity – ease in ionisation
• Low viscosity – for easy flow
• High specific heat – to carry more heat
• Chemical stability – to be chemically neutral or does not disintegrate during the reaction
• High resistance to formation of passivating film on the workpiece surface
• Non corrosiveness and non-toxicity
• Inexpensiveness and easy availability.

6. Electrolyte flow plays an important role in ECM.
a) True
b) False
Answer: a
Clarification: Need for sufficient electrolyte flow between the tool and the workpiece-
• To carry away the heat and the products of machining
• To assist the machining process at the required feed rate, producing a satisfactory surface finish, cavitation, stagnation and vortex formation should be avoided since these lead to bad surface finish
• There should be no sharp corners in the flow path. All corners in the flow path should have a radius.

7. Which of the following is a sludging type electrolyte?
a) NaOH solution
b) KOH solution
c) NaCl solution
d) CuSO₄ solution
Answer: c
Clarification: There are two types of electrolytes-
(1) Sludging type: These are solutions of salts which forms precipitate (sludge) after reaction with metals. For example: solutions of typical salts like NaCl.
(2) Non-sludging type: These are solutions of salts which do not form heavy precipitate or form soluble compounds after reacting with metals. For example: strong alkali solutions.
CuSO₄ does not form any solution.

8. Tool with an electrolyte supply slot leaves small ridge on the work.
a) True
b) False
Answer: a
Clarification: Tool with an electrolyte supply slot is simple to manufacture, but such a slot leaves small ridges on the work. However, the ridges can be made very small by making the slot sufficiently narrow. The flow from a slot takes place in a direction perpendicular to the slot and the flow at the end is poor – therefore the slot is terminated near the corners of the workpiece surface.

9. The insulation in ECM should have_____
a) adhesion to the tool
b) roughness
c) high water absorption tendency
d) chemically active
Answer: a
Clarification: Desirable qualities of insulation are as follows-
• Adhesion to the tool: preformed insulation can be held to the tool by shrink fitting, adhesives or fasteners
• Sealing without pores or leaks that could cause stray machining by current leakage
• Adequate thickness
• Smoothness to avoid disturbing the flow of electrolyte
• Resistance to heat for continuous service at 200°C without breakdown
• Durability to resist wear in guides and fixtures
• Chemical resistance to the electrolyte
• High electrical resistivity
• Uniform application to minimize disturbance of the flow of electrolyte and to prevent interference
• Low water absorption.

10. Spraying or dipping method is used for applying insulation.
a) True
b) False
Answer: a
Clarification: Generally the simplest method of applying insulation is by spraying or dipping. Teflon, urethane, phenolic, epoxy, powder coating and other materials are commonly used for insulation. Sprayed or dipped coatings of epoxy resins are among the most effective insulating materials. For optimum effectiveness, these coatings should be used with a protective lip on the tool to protect the edge of the insulation from the flow force of the electrolyte.

11. Which of the following does not hold true about ECM?
a) Lower current density leads to poor surface finish
b) Small gap between tool and the workpiece can cause short circuit
c) Gap between the tool and the workpiece doesn’t affect the process parameters
d) MRR is dependent on feed rate and electrolyte composition
Answer: c
Clarification: Current density is not only controlled by the amount of current that the power supply is delivering, but also by the size of the gap. A small gap results in the highest current density. However, when it’s very small, there is a danger of sludge particles bridging the gap and causing a short circuit. When the gap is too large, current density is reduced, resulting in a poor surface finish and decreased MRR.

12. Pick the incorrect one from the following options.
a) Voltage across the cutting gap influences the current and the MRR
b) Higher voltage decreases the equilibrium machining gap
c) Increased current leads to electrolyte heating
d) ECM can be used for facing and turning complex 3D surfaces
Answer: b
Clarification: Low voltage decreases the equilibrium machining gap and results in a better surface finish and finer tolerance control. Voltage across the cutting gap influences the current and the MRR and is controlled in most ECM operations. Increased current leads to electrolyte heating – low temperature of the electrolyte is conducive for a better surface finish and tolerances.

13. Which of the following largely affects the MRR?
a) ECM cell size
b) Tool shape
c) Feed rate
d) Complexity of the product
Answer: c
Clarification: Feed rate determines the current passed between the tool and the work. High feed rate results in higher MRR. High feed rates also decrease the equilibrium machining gap resulting in improvements of the surface finish and tolerance control. At slower feed rates, the MRR decreases as the gap increases resulting in the rise of resistance and drop in the current.

14. Conductivity of the solution can be increased by_____
a) increasing the gap between the tool and the workpiece
b) increasing the temperature of the solution
c) increasing the concentration of the solution
d) using conductive workpiece
Answer: c
Clarification: Electrolyte conductivity can be increased in following ways-
• Increasing the concentration will cause conductivity to rise
• Temperature increases of the electrolyte also increases conductivity
Low concentration and low temperature will results in lower MRR. Electrolyte conductivity affects the resistance across the gap, but the gap doesn’t affect the conductivity of the electrolyte.

15. The velocity and the electrolyte flow through the gap is also an important parameter affecting the surface finish and MRR.
a) True
b) False
Answer: a
Clarification: If the velocity is too low, the heat and by-products of the reaction build in the gap causing non-uniform material removal. A velocity that is too high will cause cavitation, also uneven material removal.

Processes for Interviews,