Practice topic-wise Metrology & Inspection previous year questions for ISRO Mechanical & Aerospace with instant step-by-step solutions and formula breakdowns.
All ISRO Mechanical & Aerospace papers
19 questions.
Year: 2008 | Topic: Metrology
The least count of a metric Vernier caliper having 25 divisions on Vernier scale, matching with 24 divisions of main scale (1 main scale divisions = 0.5mm) is
Answer: C. 0.02 mm
Explanation: Least Count = length of smallest main scale division / Number of divisions on the vernier scale = 0.5 / 25 = 0.02 mm.
Year: 2008 | Topic: Metrology
Standards to be used for reference purposes in laboratories and workshops are termed as
Answer: C. Tertiary standards
Explanation: Tertiary standards are the reference standards employed by NPL and are the first standards to be used for reference in laboratories and workshops.
Year: 2008 | Topic: Metrology
Interchangeability can be achieved by
Answer: A. Standardization
Explanation: Interchangeability in large scale production ensures that each male component fits with a corresponding female component without custom adjustments. This can be achieved by standardization.
Year: 2008 | Topic: Metrology
Plug gauges are used to
Answer: C. Check the diameter of the holes in the workpieces
Explanation: Plug gauges are used to check the diameter of the holes in the workpieces (they check if the hole is within specified tolerance limits, not measure the exact dimension).
Year: 2008 | Topic: Metrology
Basic shaft and basic hole are those whose upper deviations and lower deviations respectively are
Answer: C. Zero, Zero
Explanation: Basic shaft and basic hole are those whose upper deviations and lower deviations respectively are zero, zero.
Year: 2014 | Topic: Metrology and Inspection
Dimension of shaft is $100_{-0.00}^{+0.01}$ and corresponding Hole diameter is $100_{-0.01}^{+0.02}$. The maximum material condition of the fit is
Answer: A. Shaft diameter: 100.01 and hole diameter: 99.99
Explanation: Maximum Material Condition (MMC) refers to the state where the feature contains the maximum amount of material within its tolerance limits. For a shaft, this corresponds to its maximum diameter (upper limit), which is 100 + 0.01 = 100.01. For a hole, it corresponds to the smallest diameter (lower limit), which is 100 - 0.01 = 99.99.
Year: 2015 | Topic: Metrology and Inspection
Plug gauge is used to measure
Answer: B. Cylindrical bores
Explanation: A cylindrical plug gauge is a standard measuring tool specifically designed to check and verify the inside diameter (internal dimensions) of straight cylindrical bores. Conversely, tools like snap gauges or ring gauges are used to measure external dimensions.
Year: 2015 | Topic: Metrology and Inspection
3-2-1 method of location in a jig or fixture would collectively restrict the work piece in 'n' degrees of freedom where the value of 'n' is
Answer: C. 9
Explanation: The 3-2-1 method of location in a jig or fixture is designed to collectively restrict the workpiece in 9 degrees of freedom (out of a total of 12 possible degrees of freedom, consisting of both translational and rotational movements along/about the three axes).
Year: 2015 | Topic: Metrology and Inspection
The figure shows the principle of
Answer: D. Selective assembly
Explanation: Selective assembly is a cost-effective manufacturing approach for reducing overall variation and improving the quality of an assembled product. In this process, components of a mating pair are measured and grouped into several corresponding classes or bins.
Year: 2015 | Topic: Metrology and Inspection
A basic hole is one whose
Answer: A. Lower deviation is zero
Explanation: In a hole-basis system for tolerances and fits, a basic hole is formally defined as a hole whose lower deviation is exactly zero. (Similarly, a basic shaft is one whose upper deviation is zero.)
Year: 2015 | Topic: Metrology and Inspection
As per IT 5, standard tolerance unit (i) is equal to
Answer: C. 0.45 * D^(1/3) + 0.001 D
Explanation: The standard tolerance unit 'i', typically expressed in microns (micrometers), is empirically calculated using the formula i = 0.45 * D^(1/3) + 0.001 * D, where D is the geometric mean diameter in millimeters.
Year: 2015 | Topic: Engineering Drawing
Circular shapes appear in this fashion when viewed at an angle other than 90 degrees
Answer: B. Elliptical
Explanation: When a purely circular shape or feature is viewed from an oblique angle (any angle other than perfectly perpendicular or 90 degrees), its projection mathematically and visually appears as an ellipse.
Year: 2015 | Topic: Engineering Drawing
A drawing which shows the product with its components in their correct physical relationship is called
Answer: C. Assembly drawing
Explanation: Machines and mechanisms are constructed from numerous individual parts. An engineering drawing that portrays the complete final product with all of its components put together in their correct physical relationship is formally known as an assembly drawing.
Year: 2016 | Topic: Metrology and Inspection
A hole is specified as 50(+0.050/-0.000) mm. The mating shaft has a clearance fit with minimum clearance of 0.02 mm. The tolerance on the shaft is 0.03 mm. Maximum clearance between hole and shaft is
Answer: A. 0.100 mm
Explanation: The maximum hole size is $50 + 0.050 = 50.050$ mm and the minimum hole size is $50.000$ mm. For a clearance fit, the minimum clearance is given by (Minimum hole size - Maximum shaft size) $= 0.02$ mm. Thus, Maximum shaft size $= 50.000 - 0.02 = 49.980$ mm. Since the shaft tolerance is $0.03$ mm, the Minimum shaft size $= 49.980 - 0.03 = 49.950$ mm. The maximum clearance is (Maximum hole size - Minimum shaft size) $= 50.050 - 49.950 = 0.100$ mm.
Year: 2016 | Topic: Metrology and Inspection
A wire has a mass (0.3 ± 0.003) g, radius (0.5 ± 0.005) mm and length (6 ± 0.06) cm. The maximum percentage error in the measurement of density is
Answer: D. 4
Explanation: Density $\rho$ is given by the formula $\rho = \frac{m}{V} = \frac{m}{\pi r² L}$. Using error propagation rules, the maximum relative percentage error is given by adding the individual relative errors: $\frac{\Delta \rho}{\rho} \% = \frac{\Delta m}{m} \% + 2\frac{\Delta r}{r} \% + \frac{\Delta L}{L} \%$. Plugging in the values gives: $(0.003/0.3) \times 100 + 2(0.005/0.5) \times 100 + (0.06/6) \times 100 = 1\% + 2(1\%) + 1\% = 4\%$.
Year: 2016 | Topic: Metrology and Inspection
Which of the following pressure gauge is generally used for the calibration of other pressure measuring gauges
Answer: C. Dead weight pressure gauge
Explanation: A dead weight pressure gauge (dead weight tester) serves as a primary standard for pressure measurement. Since it uses known weights subjected to a known area to verify fluid pressure, it is widely utilized for the precise calibration of other pressure measuring gauges.
Year: 2018 | Topic: Metrology
A hole is of dimension phi 60 (+0.015 / +0.000) and the corresponding shaft is of dimension phi 60 (+0.011 / +0.001). When they are assembled they will form a
Answer: C. transition fit
Explanation: Upper size of hole = 60.015 mm. Upper size of shaft = 60.011 mm. The upper size of the shaft is more than the lower size of the hole (60mm) but less than the upper size of the hole. So the assembled parts make a transition fit.
Year: 2018 | Topic: Metrology
Profile of a gear tooth can be checked by
Answer: D. optical projector
Explanation: Profile of a gear tooth can be checked by an optical projector.
Year: 2018 | Topic: Metrology
The reflector combined with auto collimator can be used for checking
Answer: D. alignment
Explanation: Auto-Collimator is an instrument used to measure small angular inclinations. It is also used to check straightness, flatness and alignment.