Question 1 |

The best size wire is fitted in a groove of a metric
screw such that the wire touches the flanks of the
thread on the pitch line as shown in the figure. The
pitch (p) and included angle of the thread are 4 mm
and 60^{\circ} , respectively. The diameter of the best size
wire is ___________ mm (round off to 2 decimal
places).

1.12 | |

2.31 | |

4.25 | |

3.36 |

Question 1 Explanation:

Pitch (p) = 4 mm

Thread angle 2\alpha =60^{\circ}

Semi Thread Angle \alpha =30^{\circ}

Diameter of best size wire

\begin{aligned} d_w&=\frac{p}{2}\sec \alpha \\ d_w&=\frac{4}{2} \sec 30^{\circ}\\ d_w&=2.039 mm=2.31mm \end{aligned}

Thread angle 2\alpha =60^{\circ}

Semi Thread Angle \alpha =30^{\circ}

Diameter of best size wire

\begin{aligned} d_w&=\frac{p}{2}\sec \alpha \\ d_w&=\frac{4}{2} \sec 30^{\circ}\\ d_w&=2.039 mm=2.31mm \end{aligned}

Question 2 |

A shaft of diameter 25^{^{-0.04}}_{-0.07} mm is assembled in a
hole of diameter 25^{^{+0.02}}_{0.00} mm.

Match the allowance and limit parameter in Column I with its corresponding quantitative value in Column II for this shaft-hole assembly.

Allowance and limit parameter (Column I)

P. Allowance

Q. Maximum clearance

R. Maximum material limit for hole

Quantitative value (Column II)

1. 0.09 mm

2. 24.96 mm

3. 0.04 mm

4. 25.0 mm

Match the allowance and limit parameter in Column I with its corresponding quantitative value in Column II for this shaft-hole assembly.

Allowance and limit parameter (Column I)

P. Allowance

Q. Maximum clearance

R. Maximum material limit for hole

Quantitative value (Column II)

1. 0.09 mm

2. 24.96 mm

3. 0.04 mm

4. 25.0 mm

P-3, Q-1, R-4 | |

P-1, Q-3, R-2 | |

P-1, Q-3, R-4 | |

P-3, Q-1, R-2 |

Question 2 Explanation:

(1) Allowance = Lower limit of hole - upper limit of shaft

Allowance = 25.00 - 24.96 = 0.04 mm

(2) Maximum clearance C_{max} = Upper limit of hole - lower limit of shaft

C_{max} = 25.02 - 24.93 = 0.09 mm

(3) Maximum material limit for hole = minimum size of hole = 25.00

Question 3 |

The type of fit between a mating shaft of diameter 25.0^{\begin{matrix}
+0.010\\
-0.010
\end{matrix}}mm and a hole of diameter 25.015^{\begin{matrix}
+0.015\\
-0.015
\end{matrix}}mm is __________.

Clearance | |

Transition | |

Interference | |

Linear |

Question 3 Explanation:

If,

D_{hole} = 25.00 mm,

D_{shaft} = 25.01 mm ( Interference fit.)

D_{hole} = 25.03 mm,

D_{shaft} = 24.99 mm

(Clearance fit)

Some of the assemblies provide clearance fit and some provides interference fit.

Hence, It is transition fit

Question 4 |

A 76.2 mm gauge block is used under one end of a 254 mm sine bar with roll diameter of 25.4 mm. The height of gauge blocks required at the other end of the sine bar to measure an angle of 30^{\circ} is __________mm (round off to two decimal places).

203.2 | |

145.6 | |

214.3 | |

542.6 |

Question 4 Explanation:

\begin{aligned} \sin 30^{\circ} &=\frac{h_{1}}{254} \\ \text{or}\qquad h_{1} &=254 \sin 30^{\circ}=127 \mathrm{~mm} \\ H_{2} &=76.2+127=203.2 \mathrm{~mm} \end{aligned}\\ Case II:

\begin{aligned} \sin 30^{\circ} &=\frac{76.2-h_{1}}{254} \\ \text{or}\qquad h_{1} &=76.2-254 \sin 30^{\circ}\\ &=-50.8 \mathrm{~mm} \end{aligned}

Which is not feasible

Therefore final answer 203.2 mm.

Question 5 |

The allowance provided in between a hole and a shaft is calculated from the difference between

lower limit of the shaft and the upper limit of the hole | |

upper limit of the shaft and the upper limit of the hole | |

upper limit of the shaft and the lower limit of the hole | |

lower limit of the shaft and the lower limit of the hole |

Question 5 Explanation:

It is minimum clearance or maximum interference. It is the intentional difference between the basic dimensions of the mating parts. The allowance may be positive or negative.

Question 6 |

Two smooth identical spheres each of radius 125 mm and weight 100 N rest in a horizontal channel having vertical walls. The distance between vertical walls of the channel is 400 mm.

The reaction at the point of contact between two spheres is _______N (round off to one decimal place).

The reaction at the point of contact between two spheres is _______N (round off to one decimal place).

110 | |

125 | |

258 | |

324 |

Question 6 Explanation:

\begin{aligned} B C &=250^{2}-150^{2} \\ \cos \theta &=\frac{200}{250} \\ \theta &=36.869^{\circ} \end{aligned}

\begin{aligned} R_{2} \cos \theta &=100 \\ R_{2} &=\frac{100 \times 250}{200}=125 \mathrm{~N} \end{aligned}

Question 7 |

Consider the surface roughness profile as shown in the figure.

The center line average roughness (R_a \text{ in }\mu m) of the measured length (L) is

The center line average roughness (R_a \text{ in }\mu m) of the measured length (L) is

0 | |

1 | |

2 | |

4 |

Question 7 Explanation:

R_{G}=\frac{\sum_{i=1}^{n} y}{n}=\frac{4}{4}=1

Question 8 |

Two rollers of diameters D_1 (in mm) and D_2 (in mm) are used to measure the internal
taper angle in the V-groove of a machined component. The heights H_1 (in mm) and H_2
(in mm) are measured by using a height gauge after inserting the rollers into the same
V-groove as shown in the figure.

Which one of the following is the correct relationship to evaluate the angle \alpha as shown in the figure?

Which one of the following is the correct relationship to evaluate the angle \alpha as shown in the figure?

\sin \alpha =\frac{(D_1-D_2)}{2(H_1-H_2)-(D_1-D_2)} | |

\cos \alpha =\frac{(D_1-D_2)}{2(H_1-H_2)-2(D_1-D_2)} | |

cosec\; \alpha =\frac{(H_1-H_2)-(D_1-D_2)}{2(D_1-D_2)} | |

\sin \alpha =\frac{(H_1-H_2)}{(D_1-D_2)} |

Question 8 Explanation:

\begin{aligned} O B &=\left(H_{1}-\frac{D_{1}}{2}\right)-\left(H_{2}-\frac{D_{2}}{2}\right)\\ &=\left(H_{1}-H_{2}\right)-\left(\frac{D_{1}-D_{2}}{2}\right) \\ O A &=\frac{D_{1}-D_{2}}{2} \\ \sin \alpha &=\frac{\frac{\left(D_{1}-D_{2}\right)}{2}}{\left(H_{1}-H_{2}\right)-\frac{\left(D_{1}-D_{2}\right)}{2}} \\ \sin \alpha &=\frac{\left(D_{1}-D_{2}\right)}{2\left(H_{1}-H_{2}\right)-\left(D_{1}-D_{2}\right)} \end{aligned}

Question 9 |

The figure below shows a symbolic representation of the surface texture in a perpendicular
lay orientation with indicative values (I through VI) marking the various specifications
whose definitions are listed below.

P: Maximum Waviness Height (mm);

Q: Maximum Roughness Height (mm);

R: Minimum Roughness Height (mm);

S: Maximum Waviness Width (mm);

T: Maximum Roughness Width (mm);

U: Roughness Width (mm);

The correct match between the specifications and the symbols (I to VI) is:

P: Maximum Waviness Height (mm);

Q: Maximum Roughness Height (mm);

R: Minimum Roughness Height (mm);

S: Maximum Waviness Width (mm);

T: Maximum Roughness Width (mm);

U: Roughness Width (mm);

The correct match between the specifications and the symbols (I to VI) is:

I-R, II-Q, III-P, IV-S, V-U, VI-T | |

I-R, II-P, III-U, IV-S, V-T, VI-Q | |

I-U, II-S, III-Q, IV-T, V-R, VI-P | |

I-Q, II-U, III-R, IV-T, V-S, VI-P |

Question 9 Explanation:

I-R, II-Q, III-P, IV-S, V-U, VI-T

Question 10 |

The most common limit gage used for inspecting the hole diameter is

Snap gage | |

Ring gage | |

Plug gage | |

Master gage |

Question 10 Explanation:

Plug gauges used for hole & Ring gauge used for shaft

There are 10 questions to complete.

Please correct the answer to Q. 29. It’s (a) outside diameter but not roundness.

Thank You Aftaab Alam,

We have updated the answer.