Types of Gauges in Metrology – Complete Overview [with Images]

Types of Gauges: In this article we are going to discuss about the types of gauges in metrology, their uses along with their images. Let’s start with the Definition of Gauge.

Gauges can be mechanical or electro mechanical and the readings can be direct reading from the tool or from a digital screen. Now let us have a brief overview of different types of gauges in mechanical engineering.

1. Plain Plug Gauge

Plain plug gauges are cylindrical types of gauges which are used for checking holes of many different shapes and sizes. They are used to check the inside diameter limit on manufactured parts. There are plug gauges for straight cylindrical holes, tapered, threaded square and splined holes.

These plain plug gauges are made of proper wear-resistant steel, and the handles are made of any suitable steel, such as light metal handles for heavy plain plug gauges or suitable non-metallic handles for smaller plain plug gauges.

The gauging surface of plain plug gauges is hardened to at least 750 H.V. and is suitably stabilized, ground, and lapped.

Plain plug gauges are double-ended for sizes up to 63 mm and single-ended for sizes greater than 63 mm.

The plain plug gauges are designated by ‘GO’ and ‘NOGO’ as applicable.

Types of Plain Plug Gauges 

1. GO and NOGO plain plug gauges for sizes up to 10 mm.

2. GO and NOGO plain plug gauges for size over 10 mm and up to 30 mm (Taper Inserted Type)

3. GO and NOGO plain plug gauges for sizes over 30 mm and up to 63 mm of fastened type.

4. Go and NOGO plain plug gauges for sizes over 63 mm and up to 100 mm of fastened type.

5. GO and NOGO plain plug gauges for sizes over 100 mm and up to 250 mm of flat type. This is a shell form plug gauge. Each plug is relieved to reduced weight.

Figure shows a standard plug gauge used to test the nominal size of a cylindrical hole.

Figure shoes a double ended limit plug gauge used to test the limits of size. At one end it has a plug of minimum limit size the “go” end and ; at the other end a plug of maximum limit, the “no go” end. These ends are detachable from the handle so that they may be renewed seperately when worn.

In a progressive limit plug gauge fig the “go” and “no go” sections of the gauge are on the same end of the handle.

Larger holes are gauged with annular plug gauges, which are shell-constructed for light weight, and flat plug gauges, made in the form of diametrical sections of cylinders.

2. Snap Gauges

Snap gauges are the types of gauges that are used for checking external dimensions. Shafts are mainly checked by snap gauges. They may be solid and progressive or adjustable or double ended. The most usual types illustrated in figure are as follows :

1. Solid or non-adjustable caliper or snap gauge with “go” and “no go” ends is used for large sizes.
2. Adjustable caliper or snap gauge is used for larger sizes.
3. Double ended solid snap gauge with “go” and “no go” ends is used for smaller sizes.

This is made with two fixed anvils and two adjustable anvils, one for the “go ” and the other for the “no go”. The housing of these gauges has two reassess to receive the measuring anvils secured with two screws. The anvils are set for a specified size within an available range of adjustment of 3 to 8 mm. The adjustable gauges can be used for measuring series of shafts of different sizes provided the diameters are within the available range of the gauge.

3. Ring Gauges

Ring gauges are used to test the external diameters. They allow shafts to be checked more accurately since they embrace the whole of their surface. Ring gauges, however, are expensive to manufacture and therefore find limited use. Moreover, ring gauges are are not suitable for measuring journals in the middle sections of shafts.

A common type standard ring gauge shown in the figure. In a limit ring gauge, the “go” and “no go” ends are identified by an annular groove on the periphery. Above about 35mm all gauges are flanged to reduce weight and facilitate handling.

4. Pin Gauges

When the holes to be checked are larger than 75 mm, such as an automobile cylinder, a pin gauge, as shown in the figure, can be used. Pin gauges are such types of gauges.

The gauge is placed lengthwise in the cylinder bore during the measurement, and the measurement is completed. These gauges are particularly useful for measuring grooves or slots.

What do pin gauges measure ?

The PIN GAUGE is the pin shape according to fixed size precisely. The primary purpose of PIN GAUGE is to measure and inspect the diameter of samll holes, it also can be used as a test bar for geometric deviations measurements.

5. Caliper Gauges

A caliper gauge is similar to a snap gauge, but it is used to check the product’s inside and outside dimensions. The inside dimensions (hole diameter) are checked at one end of the caliper gauge, while the outside dimensions are measured at the other (shaft diameter).

6. Feeler Gauges

Feeler gauges are types of gauges used for checking clearances between mating services. They are made in the form of a set of Steel, precision machined blade 0.03 to 1.0 mm thick and 100 mm long. The blades are provided in a holder as shown in the figure. Each blade has indication of its thickness.

The Indian standard establishes 7 sets of feeler gauges : numbers 1, 2, 3, 4, 5, 6, 7, which differ by the number of blades in them and wider range of thickness. Thin blades differ in thickness by 0.01 mm in the 0.03 to 1mm set, and by 0.05 mm in 0.1 to 1.0 mm set.

To find the size of the clearance, one or two blades are inserted and tried for a fit between the contacting surface until blades of suitable thickness are found.

7. Screw Pitch Gauges

Screw pitch gauge serves as an everyday tool used in picking out a required screw and for checking the pitch of a screw threads. They consist of a number of flat blades which are cut out to a given pitch and pivoted in a holder As given in the figure. Each blade is a stamped with the pitch or number of threads per inch and the holder bears and identifying number designating the thread it is intended for. The sets are made for metric threads with an angle of 60 degree, for English threads with angle of 55 degree.

A set for measuring metric threads with 20 blades has pitches form 0.4 to 6 mm and for English threads with 16 blades has 4 to 28 threads per inch.

In checking a thread for its pitch the closest corresponding gauge blade is selected and applied upon the thread to be tested. Several blades may have to be tried until the correct is found.

8. Radius and Fillet Gauges

The functions of these types of gauges is to check the radii of curvature of convex and concave surfaces over a range from 1 to 25 mm. The gauges are made in sets of thin plates curved to different radii at the ends as shown in the figure. Each set consists of 16 convex and 16 concave blades.

9. Plate Gauge and Wire Gauge

The thickness of sheet metal is checked by means of plate gauges, and wire diameters by means of wire gauges. The plate gauge shown in the figure is used to check the thickness of plates from 0.24 to 5.0 mm, and the wire gauge in the figure from 0.1 to 10 mm.

10. Indicating Gauges

Indicating gauges are the types of gauges which employ a means to magnify how much a dimension deviates, plus or minus from a given a standard to which the gauge has been set. They are intended for measuring errors in geometrical form and size, and for testing service for their true position with respect to one another. Besides this indicating gauges can be adapted for checking the run out of two toothed wheels, pulleys, spindles and various other revolving parts of machines.

Indicating gauges can be of a dial or lever type, the former being the most widely used.

11. Air Gauges

Pneumatic or air Gauges are used primarily to determine the inside characteristics of a hole by means of compressed air. There are two types of air Gauges according to operation : a flow- type and a pressure- type gauge

The flow- type operates on the principle of varying air velocities at constant pressure, and the Pressure type operates on the principle of air escaping through an orifice.

Figure illustrates the principle of flow- type gauge which is more widely used at present. Compressed air cleaned and dried through a filter passes through a vertical tapered glass tube containing an indicator float at constant pressure.

The air then passes out through a flexible hose into a gauging head where it escapes through one or more orifices. The amount of flow is controlled by the size of the space between the gauging head and the work and different rates of flow of air in the glass tube covers the indicator float to assume different vertical positions. This is registered in a dial which is calibrated in a fractions of millimetre.

12. Taper Gauges

The most satisfactory method of testing a taper is to use taper gauges. They are also used to get the diameter of taper at some point. Taper gauges are made in both the plug and ring styles and in general, follow the same standard construction as plug and ring gauge. A taper plug and ring gauge is shown in the figure.

When checking a taper hole, the taper plug gauge is inserted into the hole and a slight pressure is exerted against it. If it does not rock in the hole, it indicates that the taper angle is correct. The same procedure is followed in a ring gauge for testing tapered spindle.

The taper diameter is tested for size by noting how far the gauge enters the tapered hole or the tapered spindle enters the gauge. A mark on the gauge shows the correct diameter for the large end of the taper.

To test the correctness of the taper two or three chalk or pencil lines are drawn on the gauge about equidistant along the length or in the hole along a generatrix of the cone. Then the gauge is inserted into the hole and slightly turned. If the lines do not rub off evenly, the taper is incorrect and the setting in the machine must be adjusted until the lines are rubbed equally all along its length. Instead of making lines on the gauge, a thin coat of paint ( red lead, carbon black, Prussian blus, etc. ) Can be applied.

The accuracy of a taper hole is tested by a taper hol is tested by a taper limit gauge illustrated in the figure. This has two check lines “go” and “no go” each at a certain distance from the end face. The “go” portion corresponds to the minimum and the “no go” to the maximum dimension.

13. Thread Gauges

Thread (pitch diameter of thread ) are checked with threads gauges. For checking internal threads (nuts, bushes, etc. ) Plug thread gauges are used, while for checking external threads (screws, bolts ) ring thread gauges or snap gauges are used. Single- piece thread gauges serve for measuring small diameter. For large diameters the gauges are made with removable plug machined with a tang. Standard gauges are made single- piece.

types of thread gauges

Common types of thread gauges are :

1. Plug gauge: A plug gauge is used to check the internal threads of a tapped hole. It has a threaded end that matches the thread pitch and angle of the part being inspected.
2. Ring gauge: A ring gauge is used to check the external threads of a threaded part. It has a smooth bore with threads cut into the inside that match the thread pitch and angle of the part being inspected.
3. Thread pitch gauge: A thread pitch gauge is used to determine the pitch or the distance between the threads of a screw or bolt. It has a set of teeth of different sizes and spacings that are used to match the threads of the part being inspected.
4. Thread angle gauge: A thread angle gauge is used to determine the angle of the thread on a screw or bolt. It has a set of notches or angles cut into the gauge that match the thread angle of the part being inspected.
5. Thread form gauge: A thread form gauge is used to check the shape of the thread, including the crest, root, and flank. It has a series of profiles or outlines that match the thread form of the part being inspected.

14. Form gauges

Form gauges may be used to check the contour of a profile of a workpiece for conformance to certain shape or form specifications.

Template gauge

Form gauges that are made from sheet steel are called profile or template gauge. A profile gauges may contain two outlines that represent the limits within which a profile must lie as shown in the figure.

These were all the types of Gauges. Hope you loved this article. Please leave a comment about your experience reading this post about the Types of gauges.

What are the uses of gauges?

Gauges are widely used in various fields, such as manufacturing, engineering, science, medicine, and everyday life. Here are some common uses of gauges:

• Measurement: A variety of physical quantities, including pressure, temperature, level, thickness, diameter, angle, force, and displacement, can be measured with gauges. They deliver precise measurements that are crucial for research, process monitoring, and quality control.
• Control: Many processes and systems, including fluid flow, pressure, and temperature, can be controlled by using gauges. They could be a part of a feedback loop that modifies the system’s parameters in response to the observed values to guarantee peak effectiveness.
• Safety: The pressure and temperature of boilers, pipelines, and pressure vessels are only a few examples of the conditions that gauges are employed to monitor and manage safely. They can also be used to find flaws, irregularities, or other leaks that could cause dangers or accidents.
• Calibration: Gauges are used in the calibration of various tools and gadgets, including thermometers, pressure transducers, and flow meters. They act as a benchmark to assure the precision and verifiability of the measurements.

What are the three groups of gauges?

While there are several types of gauges, they can be grouped into three main categories based on their purpose or function:

1. Indicating gauges: These gauges are used to indicate a certain value or range of values, such as pressure, temperature, or level. Examples include pressure gauges, temperature gauges, and level gauges.
2. Recording gauges: These gauges are used to continuously record a physical quantity over time, such as temperature or pressure. Examples include chart recorders, data loggers, and strip chart recorders.
3. Control gauges: These gauges are used in control systems to maintain a certain value or range of values for a physical quantity, such as temperature, pressure, or flow rate. Examples include thermostats, pressure switches, and flow controllers.

These categories are not mutually exclusive, and some gauges may belong to more than one category depending on their specific application or function.

How many types of mechanical gauges are there?

There are several types of mechanical gauges used in various applications. Some of the most common types include:

1. Pressure gauges: used to measure fluid pressure in different systems, such as gas and steam pipelines, hydraulic systems, and pneumatic equipment.
2. Temperature gauges: used to measure the temperature of various substances, such as liquids, gases, and solids, in different settings.
3. Flow gauges: used to measure the flow rate of fluids, such as water, oil, and gas, in pipelines and systems.
4. Level gauges: used to measure the level of fluids in tanks or containers, such as water, oil, or chemicals.
5. Force gauges: used to measure the force or tension of objects, such as springs, cables, or wires.
6. Dimensional gauges: used to measure the dimensions of objects, such as length, width, or thickness.
7. Torque gauges: used to measure the torque or rotational force of objects, such as engines or motors.

These are just a few examples of the types of mechanical gauges available, and there may be other specialized gauges used in specific applications or industries.

What are the 4 main types of gauge?

While there are several types of gauges used in different applications, the most common types can be grouped into four main categories:

1. Mechanical gauges: use mechanical elements, such as springs or diaphragms, to measure a physical quantity, such as pressure, temperature, or force.
2. Electrical gauges: use electrical sensors, such as strain gauges or thermocouples, to measure a physical quantity and convert it into an electrical signal that can be displayed or analyzed.
3. Optical gauges: use light or laser beams to measure dimensions, distances, or other physical quantities with high accuracy and precision.
4. Ultrasonic gauges: use sound waves to measure distances, thicknesses, or other physical quantities in solids, liquids, or gases.

These are just a few examples of the types of gauges available, and there may be other specialized gauges used in specific applications or industries.

Frequently Asked Questions: Types of Gauges

Source / Reference :-

1. https://pubmed.ncbi.nlm.nih.gov/10403873/

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