300+ REAL TIME Manufacturing Engineering Objective Questions & Answers 2023

250+ TOP MCQs on Foundries Foundry Automation and Answers

Manufacturing Engineering Multiple Choice Questions on “Foundries and Foundry Automation”.

1. Which of the following furnaces, are used extensively in foundries and have such advantages as a high rate of melting?
a) Induction
b) Electric arc
c) Crucible
d) Vacuum arc
Answer: b
Clarification: Electric-arc furnaces, are used extensively in foundries and have such advantages as a high rate of melting (and thus high-production rate), much less pollution than other types of furnaces, and the ability to hold the molten metal for alloying purposes.

2. Which of the following furnaces, are especially useful in smaller foundries?
a) Induction
b) Electric arc
c) Crucible
d) Vacuum arc
Answer: a
Clarification: Induction furnaces, are especially useful in smaller foundries and produce smaller Composition-controlled melts.

3. Which of the following furnace consists of a crucible completely surrounded with a water-cooled copper coil?
a) coreless induction
b) electric arc
c) channel
d) vacuum arc
Answer: a
Clarification: The coreless induction furnace consists of a crucible surrounded with a water-Cooled copper coil through which a high-frequency current pass. Because there is a strong electromagnetic stirring action during induction heating, this type of furnace has excellent mixing characteristics for alloying and adding a new charge of metal.

4. Which of the following furnaces uses a low-frequency current?
a) coreless induction
b) electric arc
c) channel
d) vacuum arc
Answer: c
Clarification: The channel furnace, uses a low-frequency Current (as low as 60 Hz) and has a coil that surrounds only a small portion of the unit.

5. Channel furnaces are used in?
a) superheating
b) holding
c) duplexing
d) all of the mentioned
Answer: d
Clarification: Channel furnace are used in nonferrous foundries and are particularly suitable for (a) superheating (that is, heating above normal Casting temperature to improve fluidity), (b) holding (which makes it suitable for die-casting applications), and (c) duplexing (using two furnaces-for instance, melt the metal in one furnace and transfer it to another).

6. Which of the following furnaces are heated with various fuels, such as commercial gases, fuel oil, and fossil fuel, as well as electricity?
a) Induction
b) Electric arc
c) Crucible
d) Vacuum arc
Answer: c
Clarification: Crucible furnaces, which have been used extensively throughout history, are heated with various fuels, such as commercial gases, fuel oil, and fossil fuel, as well as electricity. Crucible furnaces may be stationary, tilting, or movable.

7. Which of the following furnaces are basically vertical, refractory-lined steel vessels charged with alternating layers of metal, coke, and flux?
a) Cupolas
b) Electric arc
c) Crucible
d) Vacuum arc
Answer: a
Clarification: Cupolas are basically vertical, refractory-lined steel vessels charged with alternating layers of metal, coke, and flux. Although they require major investments and increasingly are being replaced by induction furnaces, cupolas operate continuously, have high melting rates, and produce large amounts of molten metal.

8. Which of the following technique involves magnetic suspension of the molten metal?
a) Cupolas
b) Levitation melting
c) Crucible
d) Induction melting
Answer: b
Clarification: Levitation melting involves magnetic suspension of the molten metal. An induction coil simultaneously heats a solid billet and stirs and confines the melt, thus eliminating the need for a crucible.

9. Which of the following is correct regarding “automation” in industry?
a) reduces the possibility of human error
b) minimizes labour cost
c) increases the production rate
d) all of the mentioned
Answer: d
Clarification: Automation minimizes labor, reduces the possibility of human error, increases the production rate, and attains higher quality levels.

10. Industrial robots are used in foundry operations for ___________
a) cleaning
b) riser cutting
c) mold venting
d) all of the mentioned
Answer: d
Clarification: Industrial robots are now used extensively in foundry operations, such as cleaning, riser cutting, mold venting, mold spraying, pouring, sorting, and inspection.

250+ TOP MCQs on Roll Forming – 3 and Answers

Manufacturing Processes Multiple Choice Questions on “Roll Forming – 3”.

1. During roll forming, a flat strip is passed number of times through the rollers.
a) True
b) False
Answer: a
Clarification: In roll forming, a flat strip is gradually formed to the finished shape. The forming is almost exclusively accomplished by rotating contoured rolls while the material passes through the mill.

2. Which of following is necessary in order to have a good set of rolls?
a) Short horizontal distances
b) Small lead-in flanges
c) A smooth flow of material
d) Less number of forming passes
Answer: c
Clarification: The probability of having a good set of rolls is to follow few rules:
(1) Envision a smooth flow of material,
(2) Do not be skimpy with the number of forming passes,
(3) Avoid too short horizontal distances and too small lead-in flanges.

3. Which of the following is true in case of “too quick” forming (too few passes)?
a) It makes the tooling and the process uneconomical
b) It makes process easier
c) It distorts the product
d) Eliminate the need of a skilled operator
Answer: c
Clarification: “Too quick” forming (too few passes) will distort the product because of the unacceptable level of stresses generated in the metal. On the other hand, too many passes will make the tooling and the process uneconomical.

4. What is “leg length” or “leg ”?
a) The maximum vertical dimension of the profile
b) Total length of the product
c) Excess length of the product
d) Maximum of the section
Answer: a
Clarification: The depth of the section, also called as “leg length” or “leg ”, is the maximum vertical dimension of the profile as it exits from the last pass. Sometimes it called as “depth of corrugation”.

5. In case of “U” channel/ section, the length of travel of the edge of the strip (effective length of the strip) ‘s’, travelling in a helical pattern having initial length ‘l’ is given by_____
a) l² = s² + c²
b) c² = l² + s²
c) s² = l² + c²
d) s = l² + c²
Answer: c
Clarification: As we know, edge of the strip to be bend travels in a helical path, the length of the strip after bending is given by formula:
s² = l² + c², where, s = final length &
l = initial length.

6. What will be the elongation if a 1in high section is formed in four passes in a mill having a horizontal distance (between passes) of 14in?
a) 0.04%
b) 0.16%
c) 0.63%
d) 0.50%
Answer: a
Clarification: Here, h = 1in; number of passes = 4 and each of length = 14in
Therefore, l = 4 * 14 = 56.

Therefore,
Elongation, e = (56.022 – 56)/ 56
= 0.0004 = 0.04%.

7. During roll forming, the strain (elongation) of the outside edge fiber of the strip must remain below the uniform engineering strain (elastic limit).
a) True
b) False
Answer: a
Clarification: If the strain (elongation) exceeds the elastic limit, then the edge of the finished product will become permanently strained. Due to which the finished product will be wavy or the product will have a bow, camber or twist.

8. What is camber in roll forming?
a) Deviation of the strip edge from a straight line in horizontal plane
b) Deviation of the strip edge from a straight line in vertical plane
c) Difference in theoretical and actual elongation of the strip
d) Waviness of the strip
Answer: a
Clarification: Camber is the deviation of the strip edge from a straight line in the horizontal plane. The inside concave edge of the strip is shorter than the outside convex edge. The shorter edge will be under tension and the longer edge will be compressed.

9. When an asymmetrical section is roll formed, the finished product will have _____
a) Camber
b) Cross-bow
c) A twist
d) Waviness
Answer: c
Clarification: When an asymmetrical section is a roll formed, the finished product will have a twist after leaving the last pass, even if the starting material is flat.

10. When forming “Z” sections, the product is twisted in the opposite direction to compensate the machine generated twist.
a) True
b) False
Answer: a
Clarification: A common method used to compensate for the anticipated twist is to twist the product in the opposite direction in the mill, from pass to pass. This principle is used when forming “Z” sections. In other cases, the counter-twisting is accomplished just in the last one or two passes.

250+ TOP MCQs on Electrochemical Etching – 9 and Answers

Manufacturing Processes Multiple Choice Questions on “Electrochemical Etching – 9”.

1. Bending curvature of silicon wafers varies ______ with the specific area of the MpSi structure.
a) linearly
b) inversely
c) cubically
d) it not affected by specific area
Answer: a
Clarification: The structure of MpSi can result broken by oxide-induced stress in the course of this stage. Thinner MpSi layers minimise this problem since the bending curvature of silicon wafers relies linearly on the specific area of the MpSi structure.

2. Silicon oxide layer can be removed using HF solution.
a) True
b) False
Answer: a
Clarification: The silicon oxide layer is selectively removed from the backside of the silicon wafer by a wet chemical etching in a buffer HF solution (BHF). Finally, the remaining silicon is etched away by a wet chemical etching in a solution of TMAH 25 % wt at 85 °C.

3. Length of the silicon dioxide pillars is dependant on the etching time and the pore length.
a) True
b) False
Answer: a
Clarification: Silicon is etched away by a wet chemical etching in a solution of TMAH. After that, a new structure based on silicon dioxide micropillars rises from the backside of the wafer as the silicon dioxide layer covering the pore walls is not etched by TMAH. The length of the resulting silicon dioxide pillars can be established by the etching time and by the pore length in the MpSi structure.

4. Lithographic technique can be used for patterning the Si wafer.
a) True
b) False
Answer: a
Clarification: The backside of the silicon wafer can be patterned by lithographic methods after the oxidation stage, enabling a selective etching on the wafer backside by TMAH.

5. It possible to produce arrays of silicon dioxide pillars inside _____
a) long pipes
b) spherical cavities
c) truncated pyramids
d) thin shells
Answer: c
Clarification: Given that the etching process in TMAH is selectively performed over these areas without protective mask in an anisotropic manner, the approach makes it possible to produce arrays of silicon dioxide pillars inside truncated pyramids.

6. Arrays of cone-like silicon dioxide pillars can be produced using _____
a) truncated MpSi
b) conical MpSi
c) cylindrical MpSi
d) planner MpSi
Answer: b
Clarification: Arrays of cone-like silicon dioxide pillars can be produced when conical MpSi is used as the starting material. The features of these 3D structures can be precisely controlled by the etching parameters and the features of the lithographic patterning.

7. When the doping density in the silicon wafer is increased, then _____
a) electric field strength is increased
b) of depletion region is increased
c) hinderance to charge carries is increased
d) quality of the product is increased
Answer: a
Clarification: When the doping density in the silicon wafer is increased, the electric field strength increases, decreasing the of the depletion region and enabling charge carriers to pass through the space charge region (SCR) by tunnelling.

8. Avalanche breakdown is the dominant mechanism at high doping densities.
a) True
b) False
Answer: b
Clarification: At high doping densities (i.e. ≥1018 cm⁻³) tunneling mechanism dominates the charge transfer while avalanche breakdown is the dominant mechanism at low doping densities.

9. The electric field strength decreases around the depressions present on the silicon wafer surface.
a) True
b) False
Answer: b
Clarification: The electric field strength increases around the depressions and pits present on the silicon wafer surface. This results in a local reduction of the depletion region , which increases the tunneling probability of charge carriers, incrementing the local current density.

10. In the beginning of the electrochemical etching, some of these pits present on the surface of the silicon wafer develop into mesopores.
a) True
b) False
Answer: a
Clarification: In the course of the first seconds of the electrochemical etching, some of these pits present on the surface of the silicon wafer develop into mesopores, the density of which across the surface is established by the doping level and the etching conditions.

250+ TOP MCQs on Abrasive Jet Micromachining – 5 and Answers

Manufacturing Processes Multiple Choice Questions on “Abrasive Jet Micromachining – 5”.

1. Elastomer masks are provided in the form of foils.
a) True
b) False
Answer: a
Clarification: These types of mask usually provided in the form of ready-made foil with self-adhesive properties. Besides, elastomers can show ductile, elastic and brittle behaviour and experiments have to be carried out under relevant practical conditions.

2. Photo-resists are _____ materials.
a) photogenic
b) photosensitive
c) photo-dissociate
d) photo-emissive
Answer: b
Clarification: Photo-resists are photo-sensitive materials. There are two types of photo-resists; positive and negative. The major drawback is that it needs Expensive equipment to prepare the mask.

3. Positive resists are formed when resist is exposed to UV light.
a) True
b) False
Answer: a
Clarification: For positive resists, the resist is exposed with UV light wherever the underlying material is to be removed. In these resists, exposure to the UV light changes the chemical structure of the resist so that it becomes more soluble in the developer.

4. After treatment with UV light, resist is washed away by the developer solution.
a) True
b) False
Answer: a
Clarification: The exposed resist, after UV treatment is washed away by the developer solution, leaving windows of the bare underlying material. In other words, “whatever shows, goes.” The mask, therefore, contains an exact copy of the pattern which is to remain on the wafer.

5. SU-8 is most commonly used negative resist.
a) True
b) False
Answer: a
Clarification: Negative resists behave in just the opposite manner as that of the positive resists. Epoxy-based SU-8 is one of the good negative resists. It is able to provide features with high aspect ratios (>10) with UV-lithography.

6. Structures with high aspect ratios are possible with _____
a) photo-resist material
b) metals
c) elastomers
d) porous silicon
Answer: b
Clarification: Stainless steel masks are very suitable for high particle velocities and fast machining operations. Structures with high aspect ratios are achievable due to the low erosion rate of steel. Attention has been paid to the adhesive layer, which should not only stick the two materials together but also avoid under etching.

7. Feature is the major drawback of metal masks.
a) True
b) False
Answer: a
Clarification: The limiting factors for all metal masks are the feature and the structuring procedure where no free-standing contours are possible. Metal masks should be applied preferably for medium and large sizes.

8. Elastomers are suitable for high air pressures.
a) True
b) False
Answer: a
Clarification: Elastomer foils are easy to pattern and allow a high complexity of the design but the procedure is somewhat time consuming. They are not suitable for high air pressures due to their elastic deformation behaviour.

9. At higher particle velocities, adhesion between the mask and the workpiece material becomes weak.
a) True
b) False
Answer: a
Clarification: The adhesion is significantly weaker for complex patterns and higher particle velocities that may cause a release of the foils from the substrate. Their applicability is limited to single workpieces and feature sizes down to 75μm.

10. High aspect ratios are not possible with SU-8 material.
a) True
b) False
Answer: a
Clarification: A good compromise in terms of feature size and imaging accuracy gives the epoxy based photo-resist SU-8. Since the maximum thickness of an SU-8 layer is about 300μm, no high aspect ratio is achievable and its application is limited to shallow cavities.

250+ TOP MCQs on Friction Welding – 3 and Answers

Manufacturing Processes Multiple Choice Questions on “Friction Welding – 3”.

1. In friction welding process, materials are joined by _____ motion between materials.
a) rectilinear
b) rubbing
c) translatory
d) brownian
Answer: b
Clarification: Friction welding is a solid-state joining process that produces coalescence in materials, using the heat developed between surfaces through a combination of mechanically induced rubbing motion and applied load. The resulting joint is of forged quality.

2. All metallic engineering materials which are _____ can be friction welded.
a) soft
b) weldable
c) forgeable
d) metamaterials
Answer: c
Clarification: As a rule, all metallic engineering materials which are forgeable can be friction welded, including automotive valve alloys, maraging steel, tool steel, alloy steels and tantalum. In addition, many castings, powder metals and metal matrix composites are weldable.

3. Friction welding is _____ process.
a) costly
b) cost saving
c) time consuming
d) highly material selective
Answer: b
Clarification: Since dissimilar materials can be joined, a significant cost savings are possible because engineers can design bimetallic parts that use expensive materials only where needed. Expensive forgings and castings can be replaced with less expensive forgings welded to bar stock, tubes, plates and the like.

4. Friction welding produces quality joints, with a 100% _____ weld.
a) lap joint
b) tee-joint
c) butt joint
d) edge joint
Answer: c
Clarification: Friction welding produces forged quality joints, with a 100% butt joint weld through the contact area. Furthermore, in friction welding heat affected zone is much narrower as compared to other welds, which indeed reduces the cost of post-weld heat treatments (stress relieving processes).

5. Which of the following is not true about friction welding?
a) Dissimilar metals cannot be joined
b) This technique is relatively faster as compared to the other techniques
c) This technique is suitable for any parts of shape or size
d) Sheared surfaces can also be joined by the process
Answer: a
Clarification: Following are the few advantages of friction welding over other techniques:
• Dissimilar metals are joined, even some considered incompatible or unweldable.
• The process is at least twice— and up to 100 times—as fast as other welding techniques.
• Friction welders are versatile enough to join a wide range of part shapes, materials and sizes.
• Joint preparation isn’t critical… machined saw cut, and even sheared surfaces are weldable.

6. Which of the following holds true for friction welding?
a) Hazardous fumes are generated during the process
b) Argon is used as a shielding gas
c) It is a power consuming process
d) There are no solidification defects in the welded parts
Answer: d
Clarification: Following are the few reasons to consider friction welding over other techniques:
• The machine-controlled process eliminates human error, and weld quality is independent of operator skill.
• It’s ecologically clean—no objectionable smoke, fumes, or gases are generated that need to be exhausted.
• No consumables are required— no flux, filler material, or shielding gases.
• Power requirements are as low as 20% of that required of conventional welding processes.
• Since there is no melting, no solidification defects occur, e.g. gas porosity, segregation or slag inclusions.

7. In inertia friction welding ______ energy of welding machine is used.
a) electrical
b) potential
c) rotational
d) frictional
Answer: c
Clarification: Inertia Friction Welding is a variation of friction welding in which the energy required to make the weld is supplied primarily by the stored rotational kinetic energy of the welding machine.

8. In inertia friction welding, one workpiece is connected to _____
a) flywheel
b) the pin tool
c) rotor
d) generator
Answer: a
Clarification: In Inertia Welding, one of the workpieces is connected to a flywheel and the other is restrained from rotating. The flywheel is accelerated to a predetermined rotational speed, storing the required energy. The drive motor is disengaged and workpieces are forced together by the friction welding force.

9. Weld strength in inertia friction welding is more than direct drive friction welding.
a) True
b) False
Answer: a
Clarification: Inertia Friction Welding has the following advantages over the Direct Drive Friction Welding process:
• Helical flow lines and hot working at end of weld cycle can help in weld strength
• Ease of monitoring, given only two variables for welding: energy (RPM) and pressure. Energy can be monitored before a signal is given to weld reducing the variables during welding to one
• Weld torque is measured indirectly by measuring the rate of spindle speed change.

10. In direct drive friction welding, lower weld forces are generated.
a) True
b) False
Answer: a
Clarification: Following are the advantages of direct drive friction welding over inertia friction welding:
• Lower weld force for solid parts. Larger parts can be welded on same tonnage machine
• Lower weld torque if brake is applied at end of weld cycle. Tooling requirements are, therefore, less rigid
• Lower RPM for solid parts
• No flywheel change between setups.

250+ TOP MCQs on Wire-cut EDM – 8 and Answers

Manufacturing Processes Multiple Choice Questions on “Wire-cut EDM – 8”.

1. Submerged machining is extremely useful for applications that generally have_____
a) poor flushing conditions
b) intricate shapes
c) tapered sections
d) good weldability
Answer: a
Clarification: Submerged machining is extremely useful for applications that generally have poor flushing conditions. Applications where poor flushing conditions exist are numerous.

2. Submerged machining is used for ____
a) cutting small taper angles
b) tiny workpieces
c) laminations
d) workpieces with no undercuts
Answer: c
Clarification: Some applications and examples where submerged machining is more practical would be cutting large taper angles, tall workpieces, laminations, tubes, irregular shaped parts, workpieces with undercuts and cutting very close to the edge of the workpiece.

3. There is a greater risk of breaking a wire if ______
a) temperature of the wire is too high
b) larger taper angles are to be cut
c) the flush is not set properly
d) there is an inadequate flow of di-electric fluid
Answer: c
Clarification: There is a greater risk of breaking a wire if the flush is not set properly or if too much power is used. This condition is greatly reduced when cutting the part submerged.

4. How many of the following processes does not need submerged machining capabilities?
– starting a cut from the edge of a workpiece
-slicing a tube
-slicing a bar stock
-starting a cut from a large diameter start hole.
a) 1
b) 2
c) 3
d) 4
Answer: d
Clarification: When starting a cut from the edge of a workpiece, cutting a form tool, slicing a tube or bar stock, or starting a cut from a large diameter start hole, is a slower process without submerged machining capabilities.

5. When parts with existing openings in them must be cut, conventional flushing produces _____
a) air pockets
b) unnecessary tapers
c) undercuts
d) poor flushing
Answer: a
Clarification: When parts with existing openings, slots or cross holes in them must be cut, conventional flushing produces air pockets and results in reduced performance or wire breaks. Submerged machining provides stable cutting of these parts.

6. When it is not possible to have the flushing nozzles close to the top or bottom of the workpiece _____ machines may require constant adjustment of the top and bottom flush.
a) submerged type
b) splash flush
c) rigid flush
d) stock flush
Answer: b
Clarification: When it is not possible to have the flushing nozzles close to the top or bottom of the workpiece, splash flush machines may require constant adjustment of the top and bottom flush. When machining submerged, you can adjust the flush once and forget it.

7. Which of the following is not the benefit of submerged cutting?
a) improved accuracy
b) better surface finish
c) Thermal stability
d) no wire breakage
Answer: d
Clarification: Benefits of submerged cutting are:
• Enhanced thermal stability of the entire set up
• Accurate skim cuts
• Better surface finish
• Improved accuracy.

8. Submerged cutting helps cutting the workpieces without hampering the flush.
a) True
b) False
Answer: a
Clarification: Cutting round stock or tubing presents a combination of adverse effects. Submerged cutting can efficiently cut these jobs without the flush being impaired.

9. Which of the following is not the effect of less maintenance of the wire cut EDM machines?
a) Wire breaks
b) Lines in the part
c) Lowered time to complete the job
d) Rough surfaces
Answer: c
Clarification: the lack of maintenance will lead to slower cutting speeds, size inaccuracy, lines in the part, wire breaks, a rougher surface finish, and (eventually) a service call. Maintenance of Wire EDM machine (or any EDM machine) usually consumes twenty to thirty minutes a week or less.

10. In how many of the following applications, wire cut EDM can be used?
– Manufacturing of progressive, blanking and trim dies
– Extrusion dies
– Cutting difficult to machine materials like hastaloy, inconel and titanium
– Cutting narrow slots and keyways
– Manufacturing of parts where burrs can’t be tolerated.
a) 1
b) 3
c) 4
d) 5
Answer: d
Clarification: Wire cut EDM has a broad range of applications that are continuing to grow. Some of them are listed below:
. Parts with complex geometry’s
. Parts requiring “tenths” tolerances
. Parts where burrs can’t be tolerated
. Thin or delicate parts that are susceptible to tool pressure
. Progressive, blanking and trim dies
. Extrusion dies
Precious metals
. Narrow slots and keyways
. Mold components
. Tooling for forging, or injection molding operations.
. Medical and dental instrumentation
. Cutting hardened materials such as carbide, C.B.N. and P.C.D.
Cutting difficult to machine materials like hastaloy, inconel and titanium
. Aerospace, defense and electronic parts
. Prototypes parts
Production parts
Form tools and inserts
Electrodes (graphite or copper) for vertical EDM.