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GATE Past Year Questions: Machining Processes | Manufacturing Engineering - Mechanical Engineering PDF Download

Q1: A flat surface of a C60 steel having dimensions of 100 mm (length) × 200 mm (width) is produced by a HSS slab mill cutter. The 8-toothed cutter has 100 mm diameter and 200 mm width. The feed per tooth is 0.1 mm, cutting velocity is 20 m/min and depth of cut is 2 mm. The machining time required to remove the entire stock is ______ minutes (rounded off to 2 decimal places). [GATE ME 2024 ]Ans: 2.2 to 2.65
Data given:
Z = 8, D = 100 mm, w = 200 mm 
V = 20 m/min, d = 2 mm, ft = 0.1 mm/ tooth
N = ?
GATE Past Year Questions: Machining ProcessesGATE Past Year Questions: Machining Processes
Le = effective length of approach = QR + L = 14 + 100 = 114 mm
= For removal of entire length
GATE Past Year Questions: Machining Processes
So, feed = ft × NZ = 0.1 × 63.662 × 8 = 50.93 mm/min
tm/c = Le/F = 114/50.93 = 2.24 min

Q2: A cutting tool provides a tool life of 60 minutes while machining with the cutting speed of 60 m/min. When the same tool is used for machining the same material, it provides a tool life of 10 minutes for a cutting speed of  100 m/min. If the cutting speed is changed to 80 m/min for the same tool and work material combination, the tool life computed using Taylor's tool life model is _____ minutes (rounded off to 2 decimal places).  [GATE ME 2024]
Ans: 
21 to 22.5
Taylor Tool Life Equation
VTn = Constant
GATE Past Year Questions: Machining Processes

Given : V1 = 60(m/min)⁡, T1 = 60 min
V2 = 100(m/min)⁡, T2 = 10 min
So, to find out GATE Past Year Questions: Machining Processes

InV1 + n nnT1 = lnV+ nlnT2
lnV1 - InV2 = n[lnT- InT1]

GATE Past Year Questions: Machining Processes

Now, V3 = 80 m/min, T= ?

GATE Past Year Questions: Machining Processes

So, GATE Past Year Questions: Machining Processes=100 × 100.285
⇒ T3 = 21.87 min

Q3: The grinding wheel used to provide the best surface finish is  [GATE ME 2024]
(a) A36L5V
(b) A54L5V
(c) A60L5V
(d) A80L5V
Ans: (d)
Grinding Wheel Components :
Abrasive Type A60-M5-V
Abrasive size A60-M5-V
Grade/Hardness A60-M5-V
Structure A60-M5-V
Bond A60-M5-V

GATE Past Year Questions: Machining Processes

Fig. Specification of grinding wheel
Fine and superfine grain size give best surface finish.

Q1: A solid part (see figure) of polymer material is to be fabricated by additive manufacturing (AM) in square-shaped layers starting from the bottom of the part working upwards. The nozzle diameter of the AM machine is a/10 mm and the nozzle follows a linear serpentine path parallel to the sides of the square layers with a feed rate of a/5 mm/min.
Ignore any tool path motions other than those involved in adding material, and any other delays between lay
ers or the serpentine scan lines.
The time taken to fabricate this part is _______ minutes. (Answer in integer)  [GATE ME 2023]
GATE Past Year Questions: Machining ProcessesAns:
9000 to 9000
V = (3a)2 × 1.5a + (2a)2 × a + (a)2 × 0.5a
= 18a3

GATE Past Year Questions: Machining Processes

= (18a3/a3) x 100 x 5 = 9000 min

Q2: In an ideal orthogonal cutting experiment (see figure), the cutting speed V is 1 m/s, the rake angle of the tool α = 5º, and the shear angle, ϕ, is known to be 45º.
Applying the ideal orthogonal cutting model, consider two shear planes PQ and RS close to each other. As they approach the thin shear zone (shown as a thick line in the figure), plane RS gets sheared with respect to PQ (point Rshears to R2, and S1 shears to S2).
Assuming that the perpendicular distance between PQ and RS is δ = 25 μm, what is the value of shear strain rate (in s-1) that the material undergoes at the shear zone? [GATE ME 2023]
GATE Past Year Questions: Machining Processes(a) 1.84 × 104
(b) 5.20 × 104
(c) 0.71 × 104
(d) 1.30 × 104
Ans: 
(b)
Data given α = 5º
ϕ = 45º
ΔH = 25 μm
V =  1 m/sec

GATE Past Year Questions: Machining Processes

Shear strain rate = GATE Past Year Questions: Machining Processes = 5.20 x 104s-1

Q3: A cuboidal part has to be accurately positioned first, arresting six degrees of freedom and then clamped in a fixture, to be used for machining. Locating pins in the form of cylinders with hemi-spherical tips are to be placed on the fixture for positioning. Four different configurations of locating pins are proposed as shown. Which one of the options given is correct?  [GATE ME 2023]GATE Past Year Questions: Machining Processes(a) Configuration P1 arrests 6 degrees of freedom, while Configurations P2 and P4 are over-constrained and Configuration P3 is under-constrained.
(b) Configuration P2 arrests 6 degrees of freedom, while Configurations P1 and P3 are over-constrained and Configuration P4 is under-constrained.
(c) Configuration P3 arrests 6 degrees of freedom, while Configurations P2 and P4 are over-constrained and Configuration P1 is under-constrained.
(d) Configuration P4 arrests 6 degrees of freedom, while Configurations P1 and P3 are over-constrained and Configuration P2 is under-constrained.

Ans: (a) 
3-2-1 principle of location
The 3-2-1 principle of location (six point location principle) is used to constrain the movement of workpiece along the three axes XX, YY and ZZ.
This is achieved by providing six locating points, 3-pins in base plate, 2-pins in vertical plane and 1-pin in a plane which is perpendicular to first two planes.

Q1: In an orthogonal machining operation, the cutting and thrust forces are equal in magnitude. The uncut chip thickness is 0.5 mm and the shear angle is 15º. The orthogonal rake angle of the tool is 0º and the width of cut is 2 mm. The workpiece material is perfectly plastic and its yield shear strength is 500 MPa. The cutting force is _________ N (round off to the nearest integer).  [GATE ME 2022 SET-2]
Ans:
2700 to 2750
Given, FC = FT
Uncut chip thickness (t1) = 0.5mm 
Shear angle (ϕ) = 15º
Orthogonal rake angle α = 0º
Width of cut w = 2mm 
Shear strength (τS) = 500MPa
Cutting force fc = ____ N
FS = Fcosϕ - FT sinϕ
= FC cosϕ - FC sinϕ
= FC (cosϕ - sinϕ)

GATE Past Year Questions: Machining Processes

GATE Past Year Questions: Machining Processes

= 2732 N.

Q2: A straight-teeth horizontal slab milling cutter is shown in the figure. It has 4 teeth and diameter (D) of 200 mm. The rotational speed of the cutter is 100 rpm and the linear feed given to the workpiece is 1000 mm/minute. The width of the workpiece (w) is 100 mm, and the entire width is milled in a single pass of the cutter. The cutting force/tooth is given by F = Ktcw, where specific cutting force K = 10N/mm2, w is the width of cut, and tc is the uncut chip thickness.
The depth of cut (dd) is D/2, and hence the assumption of d/D << 1 is invalid. The maximum cutting force required is __________ kN (round off to one decimal place).  [GATE ME 2022 SET-2]
GATE Past Year Questions: Machining ProcessesAns:
2.4 to 2.6
Given data, No. of teeth (n) = 4 
Diameter of cutter (D) = 200mm
Rotational speed (N) = 100rpm 
Linear feed to work piece = 1000 mm/min
Width of work piece (w) = 100mm
Cutting force/tooth = F = Ktcw
Specific cutting force = K = 10N/mm2
Depth of cut (d) = D/2 
Feed (f) = 1000/100 = 10mm/rev
Uncut chip thickness = t
Maximum uncut chip thickness (tc)max

GATE Past Year Questions: Machining Processes
Maximum force
(F)max = K(tc)max·ω
= 10 x 2.5 x 100
= 2500 N = 2.5 kN

Q3: Which of these processes involve(s) melting in metallic workpieces?  [GATE ME 2022 SET-2]
(a) Electrochemical machining
(b) Electric discharge machining
(c) Laser beam machining
(d) Electron beam machining
Ans:
(b, c, d)
GATE Past Year Questions: Machining ProcessesNon traditional thermal energy process includes electrical discharge machining (EDM), electron beam machining (EBM), and laser beam machining (LBM). EDM removes metal by a series of discrete electrical discharge (sparks) that cause localized temperatures high enough to melt or vaporize the metal in the immediate vicinity of the discharge. EBM adopts a high velocity stream of electrons focused on the workpiece surface to remove material by melting and vaporization. LBM employs the light energy from a laser to remove material by vaporization and ablation.

Q4: A 1 mm thick cylindrical tube, 100 mm in diameter, is orthogonally turned such that the entire wall thickness of the tube is cut in a single pass. The axial feed of the tool is 1 m/minute and the specific cutting energy (u) of the tube material is 6 J/mm3. Neglect contribution of feed force towards power. The power required to carry out this operation is _________ kW (round off to one decimal place). [GATE ME 2022 SET-1]
Ans: 
30 to 32
Given data, cylindrical tube thickness (t) = 1 mm
Diameter (D) = 100 mm
Orthogonal cutting such that entire wall thickness of tube is cut in single pass.
Therefore, Tube thickness = depth of cut = d = 1mm
Axial feed of the tool = 1m/min = f.N
Specific cutting Energy (U) = 6J/mm3
Power _________ kW
Specific cutting energy(U) = 6J/mm= Power/MRR
Power = 6 x MRR
= 6 x f.d.v
= 6 x f.d.π.D.N
= 6 × d × π × D × f.N
= 6 x 1 × π ×100 x 1 x (1000/60)
= 31415.9 J/sec or Watt
= 31.4 kW

Q5: Under orthogonal cutting condition, a turning operation is carried out on a metallic workpiece at a cutting speed of 4 m/s. The orthogonal rake angle of the cutting tool is 5º. The uncut chip thickness and width of cut are 0.2 mm and 3 mm, respectively. In this turning operation, the resulting friction angle and shear angle are 45º and 25º, respectively. If the dynamic yield shear strength of the workpiece material under this cutting condition is 1000 MPa, then the cutting force is ______________ N (round off to one decimal place).  [GATE ME 2022 SET-1]
Ans:
2570 to 2576
Cutting speed (V) = 4m/sec
Orthogonal rake angle α = 5º
Uncut chip thickness (t1) = 0.2 mm
Width of cut (w) = 3mm
Friction angle β = 45º
Shear angle (ϕ) = 25º
Shear strength (τ0) = 1000MPa
Cutting force (Fc) =____N
FS = Rcos(ϕ + β - α)
GATE Past Year Questions: Machining Processes
GATE Past Year Questions: Machining Processes
= 2573.4 N

Q6: Electrochemical machining operations are performed with tungsten as the tool, and copper and aluminum as two different workpiece materials. Properties of copper and aluminum are given in the table below.
GATE Past Year Questions: Machining ProcessesIgnore overpotentials, and assume that current efficiency is 100% for both the workpiece materials. Under identical conditions, if the material removal rate (MRR) of copper is 100 mg/s, the MRR of aluminum will be ________________ mg/s (roundoff to two decimal places). [GATE ME 2022 SET-1]
Ans:
27 to 30
Copper At. Wt = 63, Valency = 2
GATE Past Year Questions: Machining Processes
Aluminium At. Wt = 27, Valency = 3
e =27/3 = 9
Material Removal Rate in g/s is given by
MRR = e.I/F
e = Chemical equivalent
I = Current
F = Faraday constant
At Constant current & Faraday's constant
MRR ∝ e
GATE Past Year Questions: Machining Processes
MRRAl = 28.57 mg/s

Q7: Which of the following additive manufacturing technique(s) can use a wire as a feedstock material?  [GATE ME 2022 SET-1]
(a) Stereolithography
(b) Fused deposition modeling
(c) Selective laser sintering
(d) Directed energy deposition processes
Ans: (b, d)
Fused-deposition modeling consists of a computercontrolled extruder, through which a polymer filament is deposited to produce a part slice by slice.
Selective laser sintering uses a high-powered laser beam to sinter powders or coatings on the powders in a desired pattern. Selective laser sintering has been applied to polymers, sand, ceramics, and metals.
Stereolithography involves a computer-controlled laser-focusing system, that cures a liquid thermosetting polymer containing a photosensitive curing agent.
Directed energy deposition (DED) processes enable the creation of parts by melting material as it is being deposited. Although this basic approach can work for polymers, ceramics, and metal matrix composites, it is predominantly used for metal powders. Thus, this technology is often referred to as "metal deposition" technology.

Q8: A CNC worktable is driven in a linear direction by a lead screw connected directly to a stepper motor. The pitch of the lead screw is 5 mm. The stepper motor completes one full revolution upon receiving 600 pulses. If the worktable speed is 5 m/minute and there is no missed pulse, then the pulse rate being received by the stepper motor is  [GATE ME 2022 SET-1]
(a) 20 KHz
(b) 10 kHz
(c) 3 kHz
(d) 15 kHz
Ans:
(b)
No. of steps required for one full revolution of stepper motor shaft or lead screws n= 600
Pitch (p) = 5mm
Linear table speed Vtable = 5m/min = 5000mm/min
RPM of lead Screw (NS) = Vtable/p = 1000 rpm
We have equation of frequency of pulse generator
fp = Ns x nS
fp = 1000 × 600 = 600,000 pulses/min
fp = 600000/60 pulses/sec
fp = 10000 pulses/sec or Hz
fp = 10 kHz

Q1: In a pure orthogonal turning by a zero rake angle single point carbide cutting tool, the shear force has been computed to be 400 N. The cutting velocity, V= 100m/min, depth of cut, t = 2.0 mm, feed, s= 0.1mm/revolution and chip velocity, V= 20m/min, the shear strength, τs of the material will be _______MPa (round off to two decimal places). [GATE ME 2021 SET-2]
Ans:
388 to 400
α = 0º
Fs = 400 N
Cutting velocity (V) = 100 m/min (Vc)
d = 2.0 mm(t)
f = 0.1 mm/rev (So)
Chip velocity (Vc) = 20 m/min (Vf)
GATE Past Year Questions: Machining Processes (V= chip velocity; V = cutting velocity)
= 20/100 = 0.2
GATE Past Year Questions: Machining Processes
ϕ = 11.31º
GATE Past Year Questions: Machining Processes
t = f sin 90º
b = d sin 90º
bt = fd
GATE Past Year Questions: Machining Processes
= 392.23 MPa

Q2: A surface grinding operation has been performed on a Cast Iron plate having dimensions 300 mm (length) x 10 mm (width) x 50 mm (height). The grinding was performed using an alumina wheel having a wheel diameter of 150 mm and wheel width of 12 mm. The grinding velocity used is 40 m/s, table speed is 5 m/min, depth of cut per pass is 50 μm and the number of grinding passes is 20. The average tangential and average normal force for each pass is found to be 40 N and 60 N respectively. The value of the specific grinding energy under the aforesaid grinding conditions is __________J/mm3 (round off to one decimal place). [GATE ME 2021 SET-2]
Ans: 
38 to 39
Power = Fc·V
= 40 N × 40 m/s = 1600 W
MRR = 10 x 0.050 x (5000/60) mm3/s
= 41.667 mm3/s
GATE Past Year Questions: Machining ProcessesGATE Past Year Questions: Machining Processes

Q3: The machining process that involves ablation is  [GATE ME 2021 SET-2]
(a) Abrasive Jet Machining
(b) Chemical Machining
(c) Electrochemical Machining
(d) Laser Beam Machining
Ans: (d) 
Laser beam machining (LBM) is a nonconventional machining process, which broadly refers to the process of material removal, accomplished through the interactions between the laser and target materials. The processes can include laser drilling, cutting, grooving, writing, scribing, ablation, welding, cladding, milling, and so on. LBM is a thermal process, and unlike conventional mechanical processes, LBM removes material without mechanical engagement. In general, the workpiece is heated to melting or boiling point and removed by melt ejection, vaporization, or ablation.

Q4: In a grinding operation of a metal, specific energy consumption is 15 J/mm3. If a grinding wheel with a diameter of 200 mm is rotating at 3000 rpm to obtain a material removal rate of 6000 mm3/min, then the tangential force on the wheel is _______N (round off to two decimal places). [GATE ME 2021 SET-1]
Ans:
45 to 50
Esp = 15 J/mm3
MRR = 6000 mm3/min
N = 3000 rpm
D = 200 mm
GATE Past Year Questions: Machining Processes

GATE Past Year Questions: Machining Processes

Q5: An orthogonal cutting operation is performed using a single point cutting tool with a rake angle of 12º on a lathe. During turning, the cutting force and the friction force are 1000 N and 600 N, respectively. If the chip thickness and the uncut chip thickness during turning are 1.5 mm and 0.75 mm, respectively, then the shear force is _______N (round off to two decimal places).  [GATE ME 2021 SET-1]
Ans: 
625 to 750
Fc = 1000 N, F = 600 N, t = 0.75 mm, tc = 1.5 mm, α = 12º
This is orthogonal turning operation
GATE Past Year Questions: Machining Processes

⇒ ϕ = 28.63º
Method - 1: Using force relations
F = Fc sin α + Ft cos α
600 = 1000 sin 12º + ft cos12º
or Ft = 400.85 N
∴ Fs = Fcosϕ - Fsinϕ
= 1000 cos 28.63º - 400.85 sin28.63º
= 685.66 N
Method - 2 : Using Merchant circle
Fc = Rcos(β - α)
F = R sinβ
or GATE Past Year Questions: Machining Processes

GATE Past Year Questions: Machining Processes

GATE Past Year Questions: Machining Processes
0.6 cos β cos12º + 0.6 sin β sin12º = sinβ
0.586888 cos β = (1 - 0.6 sin 12º) sinβ = 0.875253 sin β
GATE Past Year Questions: Machining Processes
⇒ β = 33.84º
∴ F = R sin β
600 = R sin 33.84º
⇒ R = 1077.44 N
∴ Fs = R cos (ϕ + β - α)
= 1077.44 cos (28.63º + 33.84º - 12º)
= 685.77 N

Q6: The correct sequence of machining operations to be performed to finish a large diameter through hole is  [GATE ME 2021 SET-1]
(a) drilling, boring, reaming
(b) boring, drilling, reaming
(c) drilling, reaming, boring
(d) boring, reaming, drilling
Ans: (a) 
Drilling: to produce a hole, which then may be followed by boring it to improve its dimensional accuracy and surface finish.
Boring: to enlarge a hole or cylindrical cavity made by a previous process or to produce circular internal grooves.
Reaming: is an operation used to (a) make an existing hole dimensionally more accurate than can br achived by drilling alone and (b) improve its surface finish. The most accurate holes in workpieces generally are produced by the following sequence of operation.
Centering -> Drilling -> Boring -> Reaming.

Q7: In a machining operation, if a cutting tool traces the workpiece such that the directrix is perpendicular to the plane of the generatrix as shown in figure, the surface generated is  [GATE ME 2021 SET-1]
GATE Past Year Questions: Machining Processes(a) plane
(b) cylindrical
(c) spherical
(d) a surface of revolutio
Ans:
(b)
GATE Past Year Questions: Machining Processes
Q1: Bars of 250 mm length and 25 mm diameter are to be turned on a lathe with a feed of 0.2 mm/rev. Each regrinding of the tool costs Rs. 20. The time required for each tool change is 1 min. Tool life equation is given as VT0.2 = 24 (where cutting speed V is in m/min and tool life T is in min). The optimum tool cost per piece for maximum production rate is Rs. ________ (round off to 2 decimal places).  [GATE ME 2020 SET-2]
Ans: 26 to 28
Optimum tool life GATE Past Year Questions: Machining Processes
GATE Past Year Questions: Machining Processes
GATE Past Year Questions: Machining Processes
= 24/40.2 = 18.19 m/min
V = πDN
⇒ 18.19 = π x 0.025 x N
⇒ N = 231.6 rpm
Maching time per piece
GATE Past Year Questions: Machining Processes
Number of tool needed per piece work = 5.397/4 piece
∴ The optimum tool cost per piece = (5.397/4) x 20 = 26.985

Q2: A cylindrical bar with 200 mm diameter is being turned with a tool having geometry 0°-9°-7°-8°-15°-30°-0.05 inch (Coordinate system, ASA) resulting in a cutting force Fc1. If the tool geometry is changed to 0°-9°-7°-8°-15°-0°-0.05  inch (Coordinate system. ASA) and all other parameters remain unchanged, the cutting force changes to Fc2. Specific cutting energy (in J/mm3) is U= U0(t1) - 0.4, where U0  is the specific energy coefficient, and t1 is the uncut thickness in mm. The value of percentage change in cutting force Fc2, i.e. GATE Past Year Questions: Machining Processesis _______ (round off to one decimal place). [GATE ME 2020 SET-2]
Ans:
-5.8 to -5.5
Cs1 = 30°
∴ λ1 = 90 - 30 = 60°
Cs2 = 0°
∴ λ2 =90 - 0 = 90°
We know that specific energy consumption
GATE Past Year Questions: Machining Processes
GATE Past Year Questions: Machining Processes


Q3: The process, that uses a tapered horn to amplify and focus the mechanical energy for machining of glass, is  [GATE ME 2020 SET-2]
(a) electrochemical machining
(b) electrical discharge machining
(c) ultrasonic machining
(d) abrasive jet machining
Ans: (c)
In Ultrasonic machining, the function of horn (also called concentrator, it is a tapered metal bar) is to amplify and focus vibration of the transducer to an adequate intensity for driving the tool to fulfll the cutting operation.

Q4: In a turning process using orthogonal tool geometry, a chip length of 100 mm is obtained for an uncut chip length of 250 mm.
The cutting conditions are cutting speed = 30 m/min. rake angle = 20º.
The shear plane angle is _________ degrees (round off to one decimal place).  [GATE ME 2020 SET-1]
Ans:
22 to 25
GATE Past Year Questions: Machining Processes
GATE Past Year Questions: Machining Processes

ϕ = tan-1(0.4354) = 23.5º.

Q5: The following data applies to basic shaft system:
tolerance for hole = 0.002 mm,
tolerance for shaft = 0.001 mm,
allowance = 0.003 mm,
basic size = 50 mm.
The maximum hole size is ______ mm (round off to 3 decimal places).  [GATE ME 2020 SET-1]
Ans:
50.005 to 50.005
Using diagram method
GATE Past Year Questions: Machining ProcessesUL of hole = BS + 0.003 + 0.002 mm = 50.005 mm

Q6: The base of a brass bracket needs rough grinding. For this purpose, the most suitable grinding wheel grade specification is  [GATE ME 2020 SET-1]
(a) C30Q12V
(b) A50G8V
(c) C90J4B
(d) A30D12V
Ans:
(a)
Base of brass bracket need rough grinding, for this purpose the most suitable grinding wheel grade specifcation is C30Q12V.
Because 30 is a grain number.

MULTIPLE CHOICE QUESTION

Try yourself: Grinding ratio is defined as Volume of wheel wear

A

GATE Past Year Questions: Machining Processes

B

GATE Past Year Questions: Machining Processes

C

GATE Past Year Questions: Machining Processes

D

GATE Past Year Questions: Machining Processes

MULTIPLE CHOICE QUESTION

Try yourself: The binding material used in cemented carbide cutting tools is

[PI 2011]

A

Graphite

B

Tungsten

C

Nickel

D

Cobalt

MULTIPLE CHOICE QUESTION

Try yourself: During turning of a low carbon steel bar with TiN coated carbide insert, one needs to improve surface finish without sacrificing material removal rate. The achieve improved surface finish one should

[PI 2010]

A

Decrease nose radius of the cutting tool and increase depth of cut

B

Increase nose radius of the cutting tool

C

Increase feed and reduce nose radius of the cutting tool

D

Increase depth of cut and increase feed

MULTIPLE CHOICE QUESTION

Try yourself: A side and face cutter 125 mm diameter has 10 teeth. If operates at a cutting speed of 14 m/ min with a table traverse 100 mm/min the feed per tooth of the cutter is

[PI 2002]

A

10 mm

B

2.86 mm

C

0.286 mm

D

0.8 mm

MULTIPLE CHOICE QUESTION

Try yourself: A grinding wheel is said to be glazed if

[PI 1995]

A

grains have become blunt, but do not fall out

B

gap between the grains is filled by swarf

C

it becomes black due to burning

D

part of the wheel is chipped off

MULTIPLE CHOICE QUESTION

Try yourself: If the index crank of a dividing head is turned through one complete revolution and 10 holes in a 30 hole Circle plate, the workpiece turns through (in degrees)

[PI 1992]

A

6

B

12

C

240

D

480

MULTIPLE CHOICE QUESTION

Try yourself: Find the speed range ratio for the drilling machine spindle if the minimum and maximum diameters of drills used are 5 mm and 25 mm respectively and if the machinability indices for the work materials are 120 (brass) and 40 (alloy steel)

[PI 1992]

A

3/5

B

5/3

C

5

D

15

MULTIPLE CHOICE QUESTION

Try yourself: In a grinding wheel marked with AA-48-L-7-V25, L refers to

[PI 1992]

A

abrasive type

B

wheel structure

C

wheel hardness

D

manufactures code

MULTIPLE CHOICE QUESTION

Try yourself: A drilling machine has to be designed with 8 spindle speeds ranging approximately between 120 to 1200 rpm. The 5th spindle speed is

[PI 1991]

A

445

B

480

C

620

D

865

MULTIPLE CHOICE QUESTION

Try yourself: Assertion (A): Single start threads are used for fastening purposes.
Reason (R): Single start threads are easier to produce in a lathe.

[PI 1990]

A

Both A and R are true and R is the correct explanation of A

B

Both A and R are true but R is not a correct explanation of A

C

A is true but R is false

D

A is false but R is true

MULTIPLE CHOICE QUESTION

Try yourself: The length, width and thickness of a steel sample are 400 mm, 410 mm, 40 mm and 20 mm, respectively. Its thickness needs to be uniformly reduced by 2 mm in a single pass by using horizontal slab miling. The miling cutter (diameter : 100 mm, width ; 50 mm) has 20 teeth and rotates at 1200 rpm. The feed per tooth is 0.05 mm. The feed direction is along the length of the sample. If the over-travel distance is the same as the approach distance, the approach distance and time taken to complete the required machining task are :

[ME 2019,Set-1]

A

21 mm, 39.4 s

B

14 mm,18.4 s

C

14 mm, 21.4 s

D

21 mm, 28.9 s

MULTIPLE CHOICE QUESTION

Try yourself: Better surface finish is obtained with a large rake angle because

[ME 2014,Set-4]

A

the area of shear plane decreases resulting in the decrease in shear force and cutting force

B

the tool becomes thinner and the cutting force is reduced

C

less heat is accumulated in the cutting zone

D

the friction between the chip and the tool is less

MULTIPLE CHOICE QUESTION

Try yourself: Cutting tool is much harder than the workpiece.Yet the tool wears out during the tool-work interaction, because

[ME 2014,Set-3]

A

extra hardness is imparted to the workpiece due to coolant used

B

oxide layers on the workpiece surface impart extra hardness to it

C

extra hardness is imparted to the workpiece due to severe rate of strain

D

vibration of induced in the machine tool

MULTIPLE CHOICE QUESTION

Try yourself: The time taken to drill a hole through a 25 mm thick plate with the drill rotating at 300 rpm and moving at a feed rate of 0.25 mm/rev is

[ME 2002]

A

10 sec

B

20 sec

C

60 sec

D

100 sec

MULTIPLE CHOICE QUESTION

Try yourself: The hardness of a grinding wheel is determined by the

[ME 2002]

A

hardness of abrasive grains

B

ability of the bond to retain abrasives

C

hardness of the bond

D

ability of the grinding wheel to penetrate the workpiece

MULTIPLE CHOICE QUESTION

Try yourself: A conventional lathe and a CNC lathe are under consideration for machining a given part. The relevant data are shown below:
GATE Past Year Questions: Machining Processes
The machine preferred for producing 100 pieces is

[ME 2000]

A

conventional lathe

B

CNC lathe

C

any of the above

D

None of these

MULTIPLE CHOICE QUESTION

Try yourself: Abrasive material used in grinding wheel selected for grinding ferrous alloys is

[ME 2000]

A

SiC

B

Diamond

C

Al203

D

Boron carbide

MULTIPLE CHOICE QUESTION

Try yourself: Plain milling of mild steel plates produces

[ME 1995]

A

irregular shaped discontinuous chips

B

regular shaped discontinuous chips

C

continuous chips without BUE

D

jointed chips

MULTIPLE CHOICE QUESTION

Try yourself: Among the conventional machining processes, maximum specific energy is consumed in

[ME 1995]

A

Turning

B

Drilling

C

Planning

D

Grinding

MULTIPLE CHOICE QUESTION

Try yourself: Cutting power consumption in turning can be significantly reduced by

[ME 1995]

A

Increasing rake angle of the tool

B

Increasing cutting angle of the tool

C

Widening the nose radius of the tool

D

Increasing the clearance angle

MULTIPLE CHOICE QUESTION

Try yourself: A grinding wheel A 27 K 7 V is specified for finish grinding of a HSS cutting tool. What do you understand about the wheel from the above code.
Is this an appropriate choice?

[ME 1994]

A

yes

B

no, because abrasive is not correct

C

no, grain size is not correct

D

no, because grade is not correct choice

MULTIPLE CHOICE QUESTION

Try yourself: A milling cutter having 8 teeth is rotating at 150 rpm. If the feed per tooth is 0.1 mm, the speed in mm per minute is

[ME 1993]

A

120

B

187

C

125

D

70

MULTIPLE CHOICE QUESTION

Try yourself: A milling cutter having 10 teeth is rotating at 100 rpm. The table feed is set at 50-mm per minute. The feed per tooth in mm is

[ME 1991]

A

5

B

0.5

C

0.2

D

0.05

MULTIPLE CHOICE QUESTION

Try yourself: For cutting double start screw threads of pitch 1.0 mm on a lathe, the thread cutting tool should have a feed rate of

[ME 1991]

A

0.5 mm/rev

B

1.0 mm/rev

C

2.0 mm/rev

D

4.0 mm/rev

MULTIPLE CHOICE QUESTION

Try yourself: If the longitudinal feed in centreless grinding is expressed by Vf = πDN sinα, D stands for

[ME 1990]

A

Diameter of blank

B

Diameter of finished workpiece

C

Diameter of control wheel

D

Diameter of grinding wheel

MULTIPLE CHOICE QUESTION

Try yourself: Pure metal pose machinability problem in turning operations. The reason is the

[ME 1988]

A

Increased length of contact due to the production of continuous chip

B

Susceptibility to Chemical reactions

C

Tendency to from intense adhesion Joint with the tool face

D

Ab senc e of in clusion s wh ich aid s ch ip formation

MULTIPLE CHOICE QUESTION

Try yourself: Cutting speed in grinding is set to a high value to

[ME 1988]

A

Reduce the cutting time

B

Increase the bond strength

C

Improve cooling of job and wheel

D

Reduce the wheel wear

MULTIPLE CHOICE QUESTION

Try yourself: The ideal cutting fluid for low speed machining of metals should be one which

[ME 1988]

A

removes the heat faster from the cutting zone

B

forms a coating on the cutting tools by Chemical reaction

C

forms a low shear strength film of work material at the tool chip interface

D

serves as a dielectric, minimizing thereby reactions due to EMF at the interface

MULTIPLE CHOICE QUESTION

Try yourself: If in a turning operation both the feed rate and the nose radius are doubled the surface finish value will be

[ME 1987]

A

Decreases by 50%

B

Increases by 300%

C

Increases by 100%

D

Remains unaffected

MULTIPLE CHOICE QUESTION

Try yourself: The standard specification of a grinding wheel is A-46-M-6-V-21. It means a wheel of

[ME 1987]

A

Aluminum oxide of mesh size 6

B

Boron carbide of mesh size 46

C

Aluminum oxide of mesh size 46

D

Silicon carbide of mesh size 6

The document GATE Past Year Questions: Machining Processes is a part of the Mechanical Engineering Course Manufacturing Engineering.
All you need of Mechanical Engineering at this link: Mechanical Engineering

FAQs on GATE Past Year Questions: Machining Processes

1. What are the most common machining processes covered in GATE Mechanical Engineering?
Ans. The most common machining processes covered in GATE Mechanical Engineering include turning, milling, drilling, grinding, and electrical discharge machining (EDM). Each of these processes has distinct characteristics and applications, making them essential for various manufacturing scenarios.
2. How can I prepare for the machining processes section in the GATE exam?
Ans. To prepare for the machining processes section in the GATE exam, candidates should study the fundamentals of different machining operations, their parameters, and applications. Practicing previous years' GATE questions, solving numerical problems, and understanding the latest manufacturing technologies can also enhance preparation.
3. What is the significance of cutting tool materials in machining processes?
Ans. Cutting tool materials play a crucial role in machining processes as they determine the efficiency, wear resistance, and overall performance of the machining operation. Common materials include high-speed steel (HSS), carbide, and ceramic, each suited for specific machining conditions and materials being machined.
4. What role do machining parameters play in the machining process?
Ans. Machining parameters, such as cutting speed, feed rate, and depth of cut, significantly influence the quality of the finished product, tool life, and machining efficiency. Optimizing these parameters is essential for achieving desired surface finishes and dimensional accuracy in machined components.
5. How is the concept of surface finish relevant in machining processes?
Ans. Surface finish is a critical aspect of machining processes as it affects the aesthetic appearance, performance, and durability of the machined part. A better surface finish can reduce friction, wear, and fatigue, making it an important consideration during the design and manufacturing stages.
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