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

In this article, we shall learn about the dial indicator its construction, types, working principles, applications, advantages, and disadvantages. We have also shared a Downloadable PDF

Introduction

Dial Indicator is a precision measuring tool. It is commonly used in mechanical applications. It is widely used in manufacturing and maintenance industries. It is a highly versatile instrument and provides accurate results.

Construction of a Dial Indicator

The construction of a Dial indicator changes based on their types. For example, engineers often use two types of dial indicators namely Sector shape and Circular shape. The Sector type dial indicators are not useful for measuring any tool or workpiece. It is often used by engineers to make the measurement more accurate. Also, the Sector type dial indicators are quite limited in range.

Parts of Dial Indicator

• 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.

Types of Dial Indicators

The following are the categories of Dial Indicators:

• 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 is displayed on its face. 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.

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Reversed Balance Dial Indicators

In this indicator, numbers are calibrated in the opposite direction as compared to a Balance Reading Dial Indicator. The numbers on Reversed Balance Dial Indicators run in one direction without stopping.

Continuous Dial Indicators

In a Continuous Dial Indicator figures are calibrated in one direction only. They do not have two sets of numbers featured on balanced reading dial indicators.

Prelinger Dial Indicators

It has a clock-like face, and this tool is used to measure injection molding. It is a precision measuring tool used widely in manufacturing and engineering industries. It provides accurate and reliable measurements of linear distances. It is based on the principle of movement of a spindle attached to a spring-loaded plunger.

Test Dial Indicators

These tools are adjustable. They are generally used to measure the accuracy of other measuring tools such as dial gauge, micrometer, height gauge, etc. The test dial indicator are available in various sizes for different types of applications such as hole depth measuring, flatness detection, runout measurement etc.

Lever Dial Indicators

Lever Dial Indicator is characterized by a scroll and lever mechanism. This type of indicator is more compact and flawless to use. It is used to measure linear distances and small changes in the dimension of components.

Working principle Gear pinion Dial Indicators 

The working principle of a Dial Indicator is that the movement of the spindle is multiplied by the reading of the main scale as per the indication of the needle. The plunger 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.

Working principle of Lever Dial Indicators

A single lever is connected and pivoted at the same point. Although in the case of compound lever dial indicator, multiple levers are concentrated at a single point. Therefore, a fork joint is created. This is the reason why Lever Dial mechanism is difficult to develop.

Application of Dial Indicators 

Following are the applications of a Dial Indicator:

• Dial indicators are used to align a workpiece in a machine. Example : In the case of EDM, grinding machine, lathe machine, and milling machine.
• These tools are also used to check out the runout of the spindle in a machine tool.
• Workpieces can be aligned in the spin fixture with 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.
• Dial indicators are efficient to measure height difference on a surface plate.
• These tools are also very efficient. They can easily 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 used for linear measurements.
• 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.
• Dial Indicators are also used to measure deviations by aligning with some other attachments.
• For a round corner workpiece, the amount of taper can also be measured efficiently by Dial Indicators.

Disadvantages of Dial Indicators 

Following are some disadvantages of dial indicators:

• The precision of Dial Indicators is often lost due to vibration of machinery.
• Space constraints can lead to the installation of the tool at an angle due to which the precision of the measuring device is lost.
• Another crucial disadvantage of the Dial Indicator is the parallax effect.
• In case of journal bearings and sleeve bearing, some amount of axial play seems to be incorporated. Therefore, it has an impact on the accuracy level of Dial Indicators.

Here is a video on How to Measure using a Dial Indicator

FAQ’s

Conclusion

We can conclude by suggesting that dial indicators are valuable for engineering, manufacturing and machining industries. Due to their high precision and versatility they have been the most popular for quality control inspections.