Dial Indicator: Construction, Types, Working Principle, Applications, Advantages, and Disadvantages [PDF]

Written By Saswata Baksi

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The Dial Indicator is a mechanical device that consists of pinions, gears or levers. By the means of a dial indicator precision of a workpiece can be measured by an engineer. Although it is working as a comparator also (Baxterand Meijer, 2017).

Construction of a Dial Indicator:

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Construction of a Dial indicator changes regarding their categories. As an example, engineers often use two types of dial indicators such as Sector shape and Circular shape. But the Sector type dial indicators are not useful for measuring any tool or workpiece. It is often used by engineers to make the most accurate measurement. Also, the Sector type dial indicators are quite limited in range.

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Some of the major parts of a Dial Indicator are as follows:

  • A dial with the incorporation of the main scale.
  • The plunger (spindle).
  • Indicator (Needle).
  • Locking screw or Locknut.
  • Mini dial that represents the number the revolutions.
  • Magnification mechanism.
parts of an dial indicator image
Outer parts of a dial indicator
Inner parts of a dial indicator
Inner parts of a dial indicator

Types of Dial Indicators: 

Enormous categories of Dial Indicators have existed in the market, which is very effective to measure the precision of a workpiece. The categories of Dial Indicators are as follows:

  • Balance reading Dial Indicators
  • Reversed Balance Dial Indicators
  • Continuous Dial Indicators
  • Reverse continuous Dial Indicators
  • Prelinger Dial Indicators
  • Test Dial Indicators
  • Lever Dial Indicators

Balance reading Dial Indicators:

In this type of dial indicator, all the information on this indicator is arranged upon its face.

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The numbers are printed in two directions.

Positive numbers are calibrated to the right-hand side of zero and negative numbers are featured on the left-hand side of zero.

Reversed Balance Dial Indicators:

In this indicator, numbers are calibrated in the opposite direction as compared to the aforementioned dial indicator.

Continuous Dial Indicators:

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Figures are calibrated in one direction only without any sort of separation.

Reverse continuous Dial Indicators:

It is the opposite of continuous Dial indicators.

Prelinger Dial Indicators:

It has a clock-like face, and this tool is used to measure injection molding.

Test Dial Indicators:

These tools are adjustable.

Lever Dial Indicators:

This tool is characterized by a scroll and lever mechanism.

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This type of indicator is more compact and flawless to use.

Dial Indicators are also categorized based on their connection. Such as dial indicator connect with a C-Clamp or Swivel plate.

Working principle Gear pinion Dial Indicators: 

The working principle of the Dial Indicators is that the movement of the spindle multiplied with the reading of the main scale due to the indication of the needle. In addition to this, at the main scale rotation of pinions and gears is indicated.

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The plunger which meshes with P1 and G1. G1 will mesh with gears and pinions to enhance accuracy. P3 will be connected with the needle and thus it will show the deflection.

gear pinion type dial indicator
Gear pinion type dial indicator

Working principle of Lever Dial Indicators:

 It is a simple type of Dial Indicators. A single lever is connected and pivoted at the point. Although in the case of compound level dial indicator multiple levers are concentrated in a single point. Therefore, a fork joint is created. That is why this type of mechanism is difficult to develop.

Single lever type dial indicator
Single lever-type dial indicator
compound lever type dial indicator
Compound lever-type dial indicator

Application of Dial Indicators: 

Dial indicators are used in enormous ways by engineers, some of them are given below briefly:

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  • Dial indicators are used to align a workpiece in a machine. Such as, in the case of EDM, grinding machine, lathe machine, and milling machine.
  • The tools are also used to check out the runout of the spindle in a machine tool.
  • Workpieces can be aligned in the spin fixture by the help of Dial Indicators.
  • It is also used to measure surface roughness.
  • Dial indicators are used to measure parting lines in injection molding.
  • It is useful to measure pit depth in EDM (Moldmakingresource, 2020).
  • Dial indicators are efficient to measure height difference on a surface plate.
  • Along with that, the tools are also very efficient to align a fixture in 5 axes milling machines.
  • Dial indicators are used by engineers to inspect the precision of a workpiece in a grinding machine.

Advantages of Dial Indicators: 

Some of the most effective advantages of Dial Indicators are given below:

  • Dial indicator is the most flawless tool in taking linear measurements.
  • The tool is very efficient to assure the quality of a workpiece (Luo et al. 2018).
  • Due to small tolerances, the size of the tool is very compact and thus, it can be used seamlessly in mass production.
  • Dial indicator is also useful in dimension control.
  • Moreover, Dial Indicators are also be used to measure several deviations by aligning with some other attachments.
  • Out of roundness, the amount of tapper can also be measured efficiently by Dial Indicators.

Disadvantages of Dial Indicators: 

Here are some disadvantages of dial indicators:

  • The precision of Dial Indicators often lost due to the vibration of machinery.
  • Space constraints can lead to installing the tool at an angle due to which precision of the measuring device lost.
  • Another crucial disadvantage of the tool is the parallax effect.
  • End float can act as a devil for Dial Indicators. In the case of journal bearings and sleeve bearing, some amount of axial play seems to be incorporated. Therefore, its impact on the accuracy level of Dial Indicators.

Here is a video on How to Measure by a Dial Indicator:

You May Interested to Read Other Types of Comparators:

Sigma Comparator
Johansson Mikrokator

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References:


Media Credits:

  • Image 1: Actual image by Lucasbosch – Own work, CC BY-SA 3.0, https://commons.wikimedia.org/w/index.php?curid=34769961 – Modified by Author
  • Image 2: Metrology, Prof. Dr. Kanakuppi Sadashivappa, Department of Industrial and Production Engineering, Bapuji Institute of Engineering and Technology-Davangere, Find the source here.
  • Image 3, 4, 5: Engineering Metrology by M. Mahajan
  • Feature Image: Modified by Author
  • Video By: SuburbanTool Inc
About the Author

Saswata Baksi

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Saswata Baksi is an Excutive Editor and Lead Content Writer of Learn Mechanical, with a background degree in Mechanical Engineering from KIIT- An Institute of Eminence. Apart from that, he is also a certified SEO expert.

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