Category: Manufacturing Engineering Objective Questions

250+ TOP MCQs on Metrology-1 and Answers

Manufacturing Engineering Multiple Choice Questions on “Metrology-1”.

1. Maximum deviation in size of shaft or hole is known as
a) Tolerance
b) Fundamental deviation
c) Clearance
d) Interference
Answer: a
Clarification: Tolerance is the maximum deviation in size of shaft or hole.

2. Nearest deviation between hole and shaft from the basic value is known as
a) Tolerance
b) Fundamental deviation
c) Clearance
d) Interference
Answer: b
Clarification: Tolerance is the maximum deviation in size of shaft or hole.

3. When size of the smallest hole is more than size of biggest shaft then it is
a) Clearance fit
b) Interference fit
c) Transition fit
d) None of the mentioned
Answer: a
Clarification: When size of the smallest hole is more than size of biggest shaft then it is clearance fit.

4. Value of minimum clearance is given by
a) Size of smallest hole – size of biggest shaft
b) Size of smallest hole + size of biggest hole
c) Size of smallest shaft – size of biggest shaft
d) None of the mentioned
Answer: a
Clarification: Minimum clearance is the difference between size of smallest hole and size of biggest shaft.

5. Value of maximum clearance is given by
a) Size of smallest hole – size of biggest hole
b) Size of smallest shaft + size of biggest hole
c) Size of smallest shaft – size of biggest shaft
d) None of the mentioned
Answer: b
Clarification: Maximum clearance is given by sum of size of biggest hole and smallest shaft.

6. When size of smallest shaft is more than size of biggest hole then it is
a) Clearance fit
b) Interference fit
c) Transition fit
d) None of the mentioned
Answer: b
Clarification: When size of smallest shaft is more than size of biggest hole then it is interference fit.

7. Value of maximum Interference is given by
a) Size of smallest hole – size of biggest shaft
b) Largest of shaft size hole – smallest hole size
c) Size of smallest shaft – size of biggest shaft
d) None of the mentioned
Answer: b
Clarification: Maximum Interference is the difference between size of largest haft size and smallest hole size.

8. Value of minimum interference is given by
a) Size of smallest hole – size of biggest hole
b) Size of smallest shaft + size of biggest hole
c) Size of smallest shaft – size of biggest hole
d) None of the mentioned
Answer: c
Clarification: Minimum interference is the difference between size of smallest shaft and size of biggest hole.

9. For manufacturing of a certain amount of hole, maximum hole size was found to be 50.14 mm and minimum hole size was found to be 49.98. Tolerance in mm will be
a) 0.12
b) 0.13
c) 0.16
d) 0.20
Answer: c
Clarification: Tolerance is the maximum deviation in size of shaft or hole.

10. In manufacturing of hole and shaft, maximum shaft diameter was 49.88 mm and minimum hole diameter was found to be 49.94 mm. It is a
a) Clearance fit
b) Interference fit
c) Transition fit
d) None of the mentioned
Answer: a
Clarification: When size of smallest hole is more than size of biggest shaft then it is clearance fit.

250+ TOP MCQs on Fundamentals of Casting and Answers

Manufacturing Engineering Multiple Choice Questions on “Fundamentals of Casting”.

1. If we decrease the freezing range, then the fluidity of metal will?
a) Increase
b) Decrease
c) Will not change
d) Initially increase and then decrease
Answer: a
Clarification: Fluidity is inversely proportional to the freezing range. Thus, the shorter the range (as in pure metals and eutectics), the higher the fluidity becomes. Conversely, alloys with long freezing ranges (such as solid-solution alloys) have lower fluidity.

2. According to Chvorinov’s rule the solidification time is a function of volume and surface area and is given by the relationship between volume, area and some exponential power ‘n’. What is the value of n?
a) 1
b) 2
c) 3
d) 4
Answer: b
Clarification: Chvorinov’s rule states that: ts = (B×(frac{V}{A})^n), where ts is the time of solidification, v = volume, A = surface area, n = 1.5 to 2 and B is a constant for metal cast, mold material and casting conditions.

3. Which one of the following expands during solidification?
a) Mild steel
b) Grey cast iron
c) Aluminium
d) Copper
Answer: b
Clarification: Grey cast iron expands upon solidification, as graphite has a relatively high specific volume and it precipitates as graphite flakes during solidification, it causes a net expansion of the metal.

4. Dissolved gases may be removed from molten metal by?
a) Flushing or purging with inert gas
b) Melting and pouring the metal in vacuum
c) Flushing or purging with inert gas or Melting and pouring the metal in vacuum
d) Melting and pouring the metal in nitrogen atmosphere
Answer: c
Clarification: Dissolved gases may be removed from molten metal either by flushing or purging with inert gas or melting and pouring the metal in vacuum.

5. Doubling the time in flat mould will increase the thickness of wall skin by what percentage?
a) 31.6%
b) 41%
c) 73%
d) 22%
Answer: b
Clarification: Thickness is proportional to √ time. When time is doubled in flat mould, thickness of wall skin will increase by 41%.

6. Solidification of casting does not depend upon which factor?
a) Type of metal
b) Thermal properties of metal
c) Geometric relationship between volume and surface area
d) Surface tension
Answer: d
Clarification: Surface tension is a fluid property and solidification time of casting does not depend upon any fluid property.

7. The following characteristic of molten metal influence the fluidity.
i) Mushy zone
ii) Viscosity
iii) Surface tension
iv) Inclusion
Which one of the following is correct?
a) i and ii
b) i only
c) i, ii and iii
d) i, ii, iii and iv
Answer: d
Clarification: All the above mention characteristics influence fluidity. Fluidity in casting is used to designate the casting material ability to fill the mould cavity.

8. What is the function of cores used in casting?
a) To remove dissolved gases
b) To avoid defects
c) To form hollow region
d) To reduce shrinkage porosity
Answer: c
Clarification: Cores form internal cavities inside the structure which will then leads to the final casting shape with hollow structure. Sand inside cores and pattern gives strength and rigidity to the casting structure.

9. Which one of the statements is not correct in metal casting?
a) Rapid cooling produces a solidified skin or shell
b) Those grain that have favourable orientation will grow preferentially
c) Cast iron has wide mushy zones
d) Lack of uniformity in grains size and distribution will cause anisotropic properties
Answer: c
Clarification: Cast iron has low range of mushy zone. Rapid cooling produces a solidified skin or shell and Lack of uniformity in grains size and distribution will cause anisotropic properties.

10. Assertion (A): Chills are used to reduce shrinkage porosity.
Reason (R): the function of chill is to increase the rate of solidification in a critical region.
a) Both A and R is correct, and R is a correct explanation for A
b) Both A and R is correct, and R is an incorrect explanation for A
c) A is wrong but R is correct
d) A is correct but R is wrong
Answer: a
Clarification: Chills are used to reduce shrinkage porosity and the function of chill is to increase the rate of solidification in critical region.

250+ TOP MCQs on Extrusion and Answers

Manufacturing Engineering Multiple Choice Questions on “Extrusion”.

1. In which process the cross section of the metal is reduced by forcing it to flow through a die under high pressure?
a) Forging
b) Forming
c) Extrusion
d) Welding
Answer: c
Clarification: Extrusion is a process that uses a die in order to get a material with a constant cross-sectional cut. The die is what the material is pushed through in order to get the desired shape. Each product has a specific die that will create that shape and characteristic. Extrusion is used with materials such as plastic, aluminum, and dough. These products are either too brittle or too soft to be formed using bending or hammering, so in order to form the desired shapes extrusion is necessary.

2. Which of the following is a type of extrusion process?
a) Direct
b) Indirect
c) Impact
d) All of the mentioned
Answer: d
Clarification: Classification of extrusion processes are shown below.

3. Which of the following is true about the extrusion process?
a) Structure is homogeneous
b) No time is lost in changing the shape
c) Service life of extrusion tool is too high
d) Its leading end is in good shape as compared to rolling
Answer: b
Clarification: No time is lost in changing the shape as the dies may be readily removed in the process of extrusion.

4. In which extrusion process the direction of flow of metal is in same direction as that of ram?
a) Direct
b) Indirect
c) Impact
d) Hydrostatic
Answer: a
Clarification: Direction extrusion is a process in which the metal billet, placed in a container is forced by a ram to pass through a die. In this type, the direction of flow of metals is, in same as that of movement of ram. The punch closely fits the die cavity to prevent the backward flow of the material.

5. In direct extrusion process at higher temperature which of the following is used to avoid friction?
a) Oil
b) Lubricants
c) Molten glasses
d) Wax
Answer: c
Clarification: For steels, stainless steel, and high temperature materials, glass is a good excellent lubrication. The reasons for this are as follows. i. Glass contains its viscosity at elevated temperatures, ii. Has good wetting characteristics, and 3. Glass acts as a thermal barrier between the billet, the container and the die, thus minimizing cooling.

6. Which of the following is not used because of the problem of handling extruded metal coming out through moving ram?
a) Direct
b) Indirect
c) Impact
d) Hydrostatic
Answer: b
Clarification: Indirect extrusion method is not used because of the problem of handling extruded metal coming out through moving ram.

7. Which of the following is not a cold extrusion process?
a) Cold extrusion forging
b) Impact extrusion
c) Hydrostatic extrusion
d) Cold rolling
Answer: c
Clarification: Cold extrusion is done at room temperature or near room temeprature. The processes, impact extrusion, hydrostatic extrusion and cold extrusion forging are the types of cold forging. The advantages of this over hot extrusion are the lack of oxidation, higher strength due to cold working, closer tolerances, and good surface finish.

8. In which of the following process frictional loss is eliminated at the billet container interface?
a) Direct
b) Indirect
c) Impact
d) Hydrostatic
Answer: d
Clarification: In hydrostatic extrusion process frictional loss is eliminated at the billet container interface. This elimination increases the quality of the product.

9. In which of the following process fluid medium is used to apply the load on the billet?
a) Direct
b) Indirect
c) Impact
d) Hydrostatic
Answer: d
Clarification: In hydrostatic extrusion process fluid medium is used to apply the load on the billet. As hydro stands for fluid and static for rest.

10. Extrusion is similar to?
a) Rolling
b) Forming
c) Welding
d) Casting
Answer: a
Clarification: Extrusion is similar rolling in producing constant cross-sectional shape.

11. Which defect arises due to high friction or high speed?
a) Tearing
b) Surface cracking
c) Tearing & Surface cracking
d) Flaking
Answer: c
Clarification: The defects such as, surface cracking and tearing, occurs with high friction or speed. These can also occur with stickling of billet material on die land. Material sticks, pressure increases, product stops and starts to move again. This produces circumferential cracks on surface like a bamboo stem.

12. Which of the following defect is also known as bamboo defect?
a) Blow hole
b) Cold shut
c) Surface cracking
d) Pipe defect
Answer: c
Clarification: Bamboo defects are periodic surface cracks that develop due to the extruded product sticking to the die land.

13. Which of the following defect tends to draw surface oxides and impurities towards the centre of billet?
a) Blow hole
b) Cold shut
c) Surface cracking
d) Pipe defect
Answer: d
Clarification: Pipe defect is the formation of sin hole at the end of the billet. It is associated with direct extrusion. The use of dummy blocks whose diameter is slightly less than that of the billet helps to avoid piping.

14. Which of the following defect is also known as fish tailing?
a) Surface cracking
b) Pipe defect
c) Tearing
d) Internal cracking
Answer: b
Clarification: In extrusion, the pipe defect is also termed as “tail pipe”, and “fish tailing”. It occurs during hot extrusion due to the presence of impurities and oxides.

15. The centre of the extruded product can develop cracks called as?
a) Centre cracking
b) Centre burst
c) Arrow headed fracture
d) All of the mentioned
Answer: d
Clarification: Cracks that are developed in the centre of extruded material is known as internal cracking. These are termed as “centre cracking”, “centre burst”, “chevron cracking”, and as “arrow head cracking”.

250+ TOP MCQs on Broaching and Answers

Manufacturing Processes Multiple Choice Questions on “Broaching”.

1. What is broaching?
a) A machining process used for increasing the size of the existing hole
b) A machining process used for grinding hardened steel
c) A machining process used for making intricate holes accurately
d) A machining process for removal of a layer of material of desired and depth
Answer: d
Clarification: Broaching is a machining process for removal of a layer of material of desired and depth usually in one stroke by a slander rod or bar type cutter called as, having a series of cutting edges with a gradually increased protrusion.

2. What is the main advantage of broaching over shaping process?
a) Use of single point cutting tool which are inexpensive and can be grounded to any shape
b) Thin or fragile jobs can be conveniently machined because of lower cutting forces
c) Surfaces with obstruction can also be machined
d) Removal of the whole material in one stroke
Answer: d
Clarification: In shaping, attaining full depth requires a number of strokes to remove the material in thin layers step-by-step by gradually infeeding the single point tool. Whereas, broaching enables remove the whole material in just a single stroke by gradually rising teeth of the cutter called broach. Some are the advantages of shaping process and surfaces with obstruction cannot be machined by broaching.

3. For which of the following operations, broaching can be used?
a) Threading
b) Grinding
c) Spline cutting
d) Increasing the size of the existing hole for a certain length
Answer: c
Clarification: Machining by broaching is preferably used for making straight through holes of various forms and sizes of section, internal and external through straight or helical slots or grooves, external surfaces of different shapes, teeth of external and internal splines and small spur gears.

4. Why push type broaches are made shorter in length?
a) To reduce machining time
b) To increase the efficiency
c) For easy handling of the tool
d) To avoid buckling
Answer: d
Clarification: Both pull and push type broaches are made in the form of slander rod or bar of varying section having along its length one or more rows of cutting teeth with increasing . Also very high forces are generated during the machining. Therefore, push type broaches are made shorter in length to avoid buckling as they are subjected to compressive load.

5. Why chip breakers are provided on the broach?
a) To reduce machining time.
b) To increase the cutting force by breaking the chips
c) To reduce the friction between tool surface and the workpiece by breaking the chips
d) To break up the wide curling chips
Answer: d
Clarification: Small in-built chip breakers are alternately provided on the roughing teeth of the broaching to break up the wide curling chips and thus preventing them from clogging and increasing force and tool wear. Ductile materials need wider and frequent chip breakers.

6. Why neck section provided in the pull type broaches are made shorter in diameter?
a) To provide better surface finish
b) To remove chips easily
c) To allow failure in case of overloading
d) For holding purpose
Answer: c
Clarification: Neck is one of the essential elements of the broach. Smaller diameter means higher stress concentration. Therefore, in case of overloading neck section will fail first and while keeping the workpiece safe.

7. In broaching, generally the broach remains fixed and the workpiece travels providing cutting velocity.
a) True
b) False
Answer: b
Clarification: In broaching, the workpiece remains stationary throughout the process and the broach travels with the cutting velocity. The broach is also provided with small chip breakers to break up the chips.

8. How many types of broaches are there?
a) 3
b) 5
c) 8
d) 9
Answer: d
Clarification: Various types of broaches have been developed and are used for a wide range of applications. Types of broaches are as follows,
(1) Pull type (2) Push type (3) Ordinary cut type (4) Progressive cut type
(5) Solid type (6) Sectional type (7) Modular type (8) Profile sharpened type
(9) Form relieved type.

9. Which of the following broaches are re-sharpened by grinding at rake faces?
a) Form relieved type
b) Modular type
c) Profile sharpened type
d) Sectional type
Answer: a
Clarification: Form relieved type broaches are sharpened and re-sharpened by grinding at their rake faces. These broaches have more complex cutting edge geometry and varies point-to-point along the cutting edges. Here the product is the replica of the tool form.

10. Which of the following type of broaches are sharpened or re-sharpened by grinding at the flank surfaces?
a) Profile sharpened type
b) Sectional type
c) Segmented type
d) Ordinary cut type
Answer: a
Clarification: Profile sharpened type broaches are sharpened or re-sharpened by grinding at the flank surfaces. These cutters have simple geometry with same rake and clearance angles all over the cutting edge. These broaches are generally designed and used for machining flat surfaces or circular holes.

250+ TOP MCQs on Electrochemical Etching – 5 and Answers

Manufacturing Processes Multiple Choice Questions on “Electrochemical Etching – 5”.

1. Electronic grade silicon wafers are produced by Czochralski growth method.
a) True
b) False
Answer: a
Clarification: Typically, electronic grade silicon wafers (high purity silicon 99.9999999 %—9 N) are produced by Czochralski growth method. In this process, a cylindrical ingot of high purity monocrystalline silicon is formed by pulling a seed crystal from a bath composed of polysilicon.

2. Porous silicon structures are produced by electrochemical etching of silicon wafers in organic solutions of_____
a) acrylonitrile
b) benzene
c) formaldehyde
d) dimethylformamide
Answer: d
Clarification: Typically, porous silicon structures are produced by electrochemical etching of silicon wafers in organic solutions of acetonitrile (CH3CN) or dimethylformamide (C3H7NO) containing hydrofluoric acid (HF).

3. It is mandatory to consider all the safety aspects related to HF handling during etching of Si.
a) True
b) False
Answer: a
Clarification: HF is highly corrosive towards living tissues and its inhalation, ingestion or skin contact are all extremely hazardous and can be lethal. HF should be handled under a hood with proper ventilation, wearing personal HF gas monitor with audible alarm, safety sensor for liquids and proper personal protective equipment such as safety goggles, face shield, chemically resistant butyl rubber gloves and apron.

4. The oxide later formed on commercial Si does not affect the etching of Si.
a) True
b) False
Answer: b
Clarification: The native oxide layer formed on commercial silicon wafers under ambient atmospheric conditions must be removed. The most widespread method to remove this oxide layer is the so-called RCA cleaning process. This process is divided into three steps: namely; (i) removal of organic contaminants, (ii) removal of the native oxide layer and (iii) removal of ionic contaminations.

5. Which of the following can lead to broken porous silicon samples?
a) High current density
b) High concentration of electrolyte
c) Inappropriate design of cell
d) High temperature of the cell
Answer: c
Clarification: An inappropriate design of the cell can lead to broken samples, leaky set-ups and corroded contacts. Note that aspects such as materials, contacts and sealants are critical in the design of the electrochemical cell used to produce porous Si by electrochemical or chemical etching approaches.

6. Cell material must be resistant to HF solution.
a) True
b) False
Answer: a
Clarification: since most common acid electrolytes used to prepare porous Si are HF-based solutions, the materials of choice used to fabricate the body of the etching cells are resistant to HF. The most representative examples of these are polyvinyl chloride (PVC) and polytetrafluoroethylene (PTFE).

7. Which of the following materials is suitable for making sealant while working with HF based solutions?
a) Silicone rubber
b) Polyurethane
c) PVC
d) Acrylonitrile-butadiene copolymer
Answer: d
Clarification: Sealants are standard black O-rings made of acrylonitrile-butadiene copolymer (Perbunan) or vinylidene fluoride-hexafluoropropylene (Viton) are preferred as they are stable in HF at concentrations up to 50 %.

8. Which of the following materials is the better choice for making conductors in cells used to produce pSi by electrochemical etching?
a) Nickel
b) Gold
c) Copper
d) Vanadium
Answer: b
Clarification: It is critical to consider the resistance of the metal used as a contact towards corrosion since a continuous exposure to the etching electrolyte can degrade its integrity with use and thus its performance. Typically, noble metals such as platinum or gold are the best choice as they are inert. Other materials such as stainless steel, brass, tungsten or aluminium can also be used.

9. Hydrogen-terminated silicon surfaces are ____________
a) hydrophobic
b) hydrophilic
c) hydropic
d) deliquescent
Answer: a
Clarification: After the cleaning step and immersion in HF solutions, the silicon wafer surface is terminated with hydrogen atoms (Si–H). Hydrogen-terminated silicon surfaces are hydrophobic, showing a large contact angle for a drop of water [34, 35]. Silicon surfaces dipped in HF or an ammonium fluoride (NH4F) show equivalent hydrophobic character.

10. Roughness of the hydrophobic surfaces formed after dipping silicon in HF solution is dependent on the type of etchant.
a) True
b) False
Answer: a
Clarification: The roughness of these surfaces is highly dependent on the chemical treatment and type of etchant used. While NH4F provides atomically flat surfaces for (111) and (100) oriented silicon surfaces, a treatment with HF creates surfaces with nanometric roughness.

250+ TOP MCQs on Abrasive Jet Micromachining – 1 and Answers

Manufacturing Processes Multiple Choice Questions on “Abrasive Jet Micromachining – 1”.

1. AJMM is widely used for machining of glass and silicon.
a) True
b) False
Answer: a
Clarification: Abrasive Jet Micro Machining (AJMM) is a relatively new approach to the fabrication of microstructures. AJMM is a promising technique to three-dimensional machining of glass and silicon in order to realize economically viable micro-electro-mechanical systems (MEMS).

2. In AJMM, workpiece is exposed to abrasive action of the particles.
a) True
b) False
Answer: a
Clarification: It employs a mixture of a fluid (air or gas) with abrasive particles. In contrast to direct blasting, the surface is exposed completely to the erosive action of the particle beam. Hence, before processing, the substrate material has to be partially shielded by applying an erosion resistant mask.

3. This method is used for _____
a) making finished surfaces
b) thread finishing
c) making grooves
d) cutting
Answer: c
Clarification: This method is used for making accurate shallow holes or grooves, and, with the use of masks, patterns on target material.

4. Resulting abrasive action is dependent on the impact angle of the jet.
a) True
b) False
Answer: a
Clarification: The resulting erosion of the target material can be controlled using masks and by varying parameters such as impact angle and particle flux density, velocity, and particle properties.

5. AJMM is capable of machining anisotropic patterns.
a) True
b) False
Answer: a
Clarification: In contrast to conventional micro-fabrication methods, such as wet and dry etching, AJMM is capable of machining anisotropic patterns and suspended structures with high erosion rate and relatively low cost.

6. Which of the following is true about AJMM?
a) It is a low cost method
b) It is toxic towards the environment
c) It is hazardous to human health
d) It is not capable of anisotropic machining
Answer: a
Clarification: Advantages of AJM:
(1) low capital and operating costs,
(2) environment-friendly process,
(3) no major health hazards, and
(4) ability to machine anisotropic and suspended structures on the same substrate.

7. AJM applications include drilling, engraving of glass, etc. operations.
a) True
b) False
Answer: a
Clarification: Typical AJM applications include drilling, cutting and engraving of glass, ceramics and some hard materials. It can also be used to etch labels in plastics and metals, deburr, deflash and clean materials after conventional machining.

8. In AJMM, abrasive particles are accelerated in a gas stream.
a) True
b) False
Answer: a
Clarification: Fine micro abrasive particles are accelerated in a gas stream (commonly air at a few times atmospheric pressure). The particles are directed towards the focus of machining (less than 1mm from the tip).

9. In AJMM, as the jet fracture off the surface after striking it.
a) True
b) False
Answer: a
Clarification: As the particles impact the surface, they fracture off the surface and create cavities. As the particle impacts the surface, it causes a small fracture, and the gas stream carries both the abrasive particles and the fractured (wear) particles away.

10. The choice of abrasive varies with the type of machining.
a) True
b) False
Answer: a
Clarification: The choice of abrasive particles depends on the type of machining operation. The abrasives should have a sharp and irregular shape for better performance.