1. Which type of tolerance provided in drilling mostly?
a) Bilateral
b) Unilateral
c) Trilateral
d) Compound
Explanation: Mostly unilateral tolerance is provided in drilling as dimension is allowed to vary in one direction only. Hole is always oversize, not undersize.
2. What is mean clearance?
a) Maximum size of hole minus maximum size of shaft
b) Minimum size of hole minus minimum size of shaft
c) Mean size of hole minus mean size of shaft
d) Average of both size of shaft and hole
Explanation: Statistical approach allows wider tolerances compared to complete interchangeability approach. Methods used by statistical approach are usually permits cheaper production. Mean clearance is equal to (mean size of hole – mean size of shaft).
3. Which of the following is incorrect about tolerances?
a) Too loose tolerance results in less cost
b) Tolerance is a compromise between accuracy and ability
c) Too tight tolerance may result in excessive cost
d) Fit between mating components is decided by functional requirements
Explanation: Loose tolerance results in increase in cost, assembly problems and poor performance of the product. Tight tolerance results in unnecessary machining and inspection time.
4. Quality control charts doesn’t depend on which factor?
a) Normal distribution
b) Random sampling
c) Independence between samples
d) Binomial distribution
Explanation: In establishing of realistic specifications, control charts are considered as a good guide for the design office. Quality control charts are based on the assumptions of random sampling and normal distribution.
5. Which of the following option is true for given statements?
Statement 1: Bilateral tolerances are used in mass production techniques.
Statement 2: The basic size should be equal to upper and lower limits.
a) T, T
b) F, F
c) T, F
d) F, T
Explanation: Bilateral tolerances are preferred in mass production techniques where setting of a machine is done for the basic size. If unilateral tolerances are specified in place of bilateral, then basic size should be changed to make it bilateral. Basic size is in half way between lower and upper limits.
6. If a clearance fit is present between shaft and hole, what is the tolerance on shaft or hole for a complete interchangeable approach?
a) ½ of maximum clearance – ½ of minimum clearance
b) ¼ of maximum clearance – ¼ of minimum clearance
c) Maximum clearance – minimum clearance
d) ¾ of maximum clearance – ¾ of minimum clearance
Explanation: There are two approaches for deciding of tolerances and shafts i.e. statistical and complete interchangeable approach. There is no risk is taken about a single non-conforming assembly in complete interchangeable approach.
7. Which of the following option is incorrect about interchangeability?
a) Increase output
b) Increase cost of production
c) Useful in mass production
d) Assembly time increases
Explanation: An interchangeable part is one that can be replaced with a similar part manufactured to the same drawing. It can be used in mass production with an economic oriented approach. Assembly time decreases as mating parts are interchangeable.
8. What are the main considerations for deciding the limits of a particular part?
a) Functional requirement
b) Economics and interchangeability
c) Interchangeability and functional requirement
d) Interchangeability, functional requirement and economics
Explanation: Functional requirements are related to the function of a component that is what is required to do. Interchangeability is for ease of replacement of part. Economics is related to the minimum cost and time.
9. For full interchangeability, what is the relation between the process capability of a machine and manufacturing tolerance of the part?
a) Process capability = Manufacturing tolerance
b) Process capability ≥ Manufacturing tolerance
c) Process capability > Manufacturing tolerance
d) Process capability ≤ Manufacturing tolerance
Explanation: For full interchangeability, only such machines are selected for manufacturing whose process capability ≤ manufacturing tolerance. If this condition is satisfied, then the component will meet the desired tolerance and capable of mating with other.
10. Which of the following option is correct in given statements about interchangeability?
Statement 1: Standardisation is not so much of importance for interchangeability.
Statement 2: Interchangeability follows ‘normal distribution’.
a) F, T
b) T, T
c) F, F
d) T, F
Explanation: Standardisation is important in interchangeability. It is essential to follow a common standard by all, only then interchangeability is possible. All standards used by the manufacturing unit are traceable to international standards.