Mechanical metrollgy and measurements

1. Gauges and
comparators
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2. Gauges:
• A gauge is an important measuring device in the field of design
engineering. It is a device used to provide certain dimensional
information, according to a specified standard or system. Some
gauges are meant to measure the size of the object.

3. Types of Gauges:
Gauges are classified into eight types, they are:
• Plug gauge.
• Ring gauge.
• Taper gauge.
• Snap gauge.
• Feeler gauge.
• Thread gauge.
• Form gauge.

4. Ring Gauge
Ring Gauge
• A ring gauge is a fixed gauge that is used for measuring the external
diameters of cylindrical objects. They are made of thermally resistant steel
for greater strength and stability. Ring gauge incorporates the tolerance
principle, with “go” and “not go” sections.

5. Taper Gauge:
Taper Gauge
They are the measuring devices used to measure the width of gaps, grooves,
hole diameter, and the inner diameter of the pipe. A taper gauge is made of
both plug and ring styles.

6. Plug Gauge:
Plug Gauge:
• A plug gauge is a fixed gauge that is used for measuring the shape and size
of a hole. A plug gauge comes with different diameters. They are helpful to
measure the inside diameters of drilled holes or holes that are machined into
a manufactured part, component, or assembly.

7. Comparator:
• COMPARATORS: A comparator is a precision instrument employed to
compare the dimension of a given component with a working standard
(usuallyslip gauges). It thus does not measure the actual dimension but indicate
howmuch it differs from the basic dimension.In mass production identical
component parts are produced on avery large scale.⚫ Micrometer and Vernier
caliper are not more feasible because skill involve and time required to measure
the dimension. In such case comparator is more suitable for the measurement.

8. Classification of Comparators:
Classification:
1. Mechanical Comparator: It works on gears pinions, linkages,levers, springs etc.
2. Pneumatic Comparator: Pneumatic comparator works by using high pressure air, valves, back
pressure etc.
3. Optical Comparator: Optical comparator works by using lens,mirrors, light source etc.
4. Electrical Comparator: Works by using step up, step downtransformers.
5. Electronic Comparator: It works by using amplifier, digital signaletc.
6. Combined Comparator: The combination of any two of the abovetypes can give the best
result.

9. Importance of Comparators:
• Comparators can give precision measurements, with consistent accuracy by
eliminating human error. They are employed to find out, by how much the
dimensions of the given component differ from that of a known datum.

10. Advantages of Mechanical Comparators:
Advantages of mechanical comparators:
•Cheaper than all the other type of comparators,Does not require any
external source of power or air supply.
•These comparators use a linear scale that can be easily understood.
•Usually these comparators are robust and compact but are very easy to
handle.

11. Advantages of Optical Comparators
• Just the versatile measuring capabilities of the optical comparator are a huge
advantage of this precision measurement device. Additionally, optical
comparators offer more than just dimensions by providing length and width
measurements as well as revealing possible imperfections along the surface
of a part.

12. Advantages of Comparators
It is very accurate and precise. High magnification up to 30000: 1 is possible in
a pneumatic comparator. Since indicating device and measuring head are placed
at different places, there is no interference. They are self-cleaning because a jet
of air helps in cleaning the workpiece.