22342 Engineering Metrology Viva Questions with Answers
1.
What are measurement standards?
ans. Standards are objects of known size, quantity, roughness, etc. These
standards are used to calibrate and verify measuring instruments. As a result, measured
values are more accurate.
2.
What effect will temperature variation have on precision measurements?
ans. Temperature control during measurement is important because as materials
are heated they expand. Each material expands at a different rate. This leads
to distortion of parts and measuring devices that results in measurement
errors.
3.
How can a vernier scale provide higher accuracy?
ans. A vernier scale uses a second elongated scale to interpolate values on a
major scale.
4.
What are dimensional tolerances, and what are their primary uses?
ans. Dimensional tolerances specify the amount a dimension may vary about a
target value. These are supplied by a designer to ensure the correct function
of a device. If these tolerances are controlled the final product will work as
planned.
5.
Why is an allowance different from a tolerance?
ans. A tolerance is the amount a single dimension can vary. An allowance is an
intentional difference between two dimensions to allow for press fits, running
fits, etc.
6.
What are fits?
ans. There are standard for different types of fits (e.g. press fit, running
clearance). These specify the allowance of two parts, so that they may be made
separately and then joined (mated) in an assembly.
7.
What is the difference between precision and accuracy?
ans. Precision suggests a limit of technology, accuracy is the ability to
achieve a value consistently. These are often interchanged because we are
usually concerned with the accuracy when producing precision parts.
8.
Why are different grades of gauge blocks used?
ans. There are different quality levels for gages blocks. The poorest sets are
workshop grade and are more accurate than most machine tools. The best sets are
very accurate, and must be kept in tightly controlled conditions. The bast sets
are used for calibrating others.
9.
How are a ring gauge and a plug gauge different?
ans. A plug gage goes into a hole, a ring gage surrounds a dimension.
10. Why
is a micrometer used for precise measurement of components in mechanical
engineering?
ans : Digital calipers are pretty accurate, but if you need precision, a
micrometer is the way to go. Some things need to be measured in 1/10000ths of
an inch (e.g. high pressure hydraulic pump pistons) and a digital caliper just
won’t do that. That said, I use calipers all the time and use a mic when I need
to.
11.
How are pressure gauges specified?
ans : There are a number of things to take into account while specifying the
right pressure gauge for your application. This goes from choosing the right
measuring range, choosing the diameter of the dial, to preventing the pressure
gauge from being subject to vibrations and even more of this kind of choices.