Dial Indicator is a very important comparator used in mechanical industrial measurement applications. in this article we will see how dial indicator works, parts, working principle, Construction of dial indicator, advantages, and disadvantages of dial indication.

Table of Contents

Dial Indicator:

Working Of Dial Indicator

It operates on the principle, that a very slight upward pressure on the spindle at the contact point is multiplied through a system of gears and levers. It is indicated on the face of the dial by a dial finger. Dial indicators consists of a body with a round graduated dial and a contact point connected with a spiral or gear train so that hand on the dial face indicates the amount of movement of the contact point. They are designed for use on a wide range of standard measuring devices such as dial box gauges, portal dial, hand gauges, dial depth gauges, diameter gauges and dial indicator snap gauge.

Corresponds to a spindle movement of 1 mm. The movement mechanism of the instrument is housed in a metal case for its protection. The large dial scale is graduated into 100 divisions. The indicator is set to zero by the use of slip gauges representing the basic size of the part.

Dial indicator Parts and Diagram :

MAIN COMPONENTS OF DIAL GAUGE

Circular dial body
Round graduated dial
Pointer
Gear train
Lever
Plunger

Types Of Dial indicators :

Types of dial indicators Several different types of dial indicators exist, differentiated by factors such as their size, connection method and the type of information featured on their face

Balanced reading dial indicators
Continuous Dial Indicators
Reversed Balanced Dial Indicators
Reversed Continuous Dial Indicators
Test Dial Indicators
Plunger Dial Indicator
Lever Dial Indicator

Balanced reading dial indicators – Balanced reading dial indicators are so named for the way that information is arranged upon the dial’s face. Figures are printed upon the face of this dial running in two directions, starting from a zero in the center. Often, positive numbers are featured to the right of the zero and negative numbers to the left.

Continuous Dial Indicators – Continuously numbered dial indicators do not have the two sets of numbers featured on balanced reading dial indicators. The figures on this type of dial indicators run in one direction without stopping and without any type of a separation.

Reversed Balanced Dial Indicators – Reversed Balanced Dial Indicators are named because they have the same basic positive and negative scales to each side of a zero, but the positive numbers are to the left and the negative are to the right.

Reversed Continuous Dial Indicators – Reversed continuous, or counter-clockwise, dial indicators are the same as continuous dial indicators except that the numbers run in the opposite direction.

Plunger Dial Indicator – Plunger Dial Indicator also have a clock-like face but are characterized by the plungers mounted on one of their sides. One common use for plunger dial indicators is to measure the work of injection molding machines. The mechanism which allows this type of dial indicator to work is a rack and pinion, which changes the linear thrust of the plunger into rotary motion for the dial.

Lever Dial Indicator – Lever Dial Indicator are characterized by their lever and scroll mechanisms, which cause the stylus to move. This type of dial indicators are more compact and easier to use than plunger-type dial indicators and are therefore quite often used.

Requirements of Good Dial Indicator:

1. It should give trouble-free and dependable readings over a long period.
2. The pressure required on measuring head to obtain zero reading must remain constant over the whole range.
3. The pointer should indicate the direction of the movement of the measuring plunger.
4. The accuracy of the readings should be within close limits of the various sizes and ranges
5. The movement of the measuring plunger should be in either direction without affecting the accuracy.
6. The pointer movement should be damped, so that it will not oscillate when the readings are being taken.

Applications:

1. Comparing two heights or distances between narrow limits.
2. To determine the errors in the geometrical form such as ovality, roundness, and taper.
3. For taking accurate measurements of deformation such as intension and compression.
4. To determine positional errors of surfaces such as parallelism, squareness, and alignment.
5. To Check the alignment of lathe centers by using a suitable accurate bar between the centers.
6. To check the trueness of milling machine arbors and to check the parallelism of shaper arm with table surface or vice.