Dial Gauge

What is a Dial Gauge?

A dial gauge is an essential tool for precision measurement, especially in machining and quality control. It ensures the dimensional accuracy of manufactured components and parts. There are various types of dial indicators to meet diverse measurement needs, including mechanical, digital, and lever-type dial indicators.

Types of Dial Gauge

Mechanical Dial Gauge:

This type uses a needle and gear system to convert linear movement into rotary motion, which is displayed on the dial.
Comes with an analog display that shows the measured value.
Offers high accuracy and reliability and does not require batteries.

Digital Dial Gauge:

Uses electronic components to display results.
Can be equipped with additional features, such as data output and memory.
Offers an easier-to-read display, but requires a battery.

Lever Dial Gauge(Test Gauge):

The measuring arm moves laterally in relation to the dial.
Especially suited for measurements in tight spaces and for precisely measuring different parts of a workpiece.

Construction of a Dial Gauge

A dial indicator consists of several components:

• Dial: Displays the measurement result, either with a needle (mechanical) or a digital display.
• Needle: In a mechanical dial indicator, indicates the measured value.
• Measuring Arm: Makes contact with the surface being measured and transmits the movement to the measuring mechanism.
• Interchangeable Contact Points: Ball, cone, flat, etc. tips allow for different types of measurements.
• Body and Base Attachment: Allows the dial indicator to be mounted on measurement stands.
• Zeroing Mechanism: Allows the dial indicator to be zeroed before starting measurements.

Magnetic Stand for Dial Gauge Indicator Attachment

Dial indicators are often attached to a magnetic stand, which allows for quick and easy mounting to the measuring surface. The magnetic stand provides the necessary stability and accuracy required for measurements.

Applications

Dial indicators are widely used in various applications:

• Calibration of Measurements: Precision measurements and equipment calibration require a dial indicator for accurate values.
• Geometric Tolerances: For example, checking straightness, flatness, and parallelism.
• Part Inspection: Used as a tool for checking parts during the manufacturing process.
• Runout Measurement: Determining runout related to rotation, such as concentricity and axial runout.

Dial Indicator Accuracy and Measuring Range

• Accuracy: Typically 0.01 mm, but there are dial gauge indicators on the market with 0.001 mm accuracy.
• Measuring Arm Stroke: Varies by model, from a few millimeters to several tens of millimeters.

How to Use a Dial Gauge

Selecting a Dial Gauge:

• Select a dial indicator according to your measurement needs, considering accuracy and measuring range.
• Ensure that the dial gauge is calibrated and in good condition.

Setup:

• Secure the dial gauge firmly to the measuring stand, using a magnetic base if needed.
• Adjust the measuring arm to contact the surface to be measured.

Calibration and Zeroing:

• Before starting measurement, calibrate and zero the dial indicator properly.
• Make sure the dial gauge does not move or vibrate during measurement.

Measuring:

• Read the measurement result from the dial: from the needle in mechanical dial indicators and from the display in digital ones.
• Ensure the measuring arm follows the measured surface evenly during continuous measurements.

Maintenance and Calibration

To ensure the accuracy and longevity of a dial indicator, it’s important to maintain and calibrate the device regularly:

• Cleaning: Keep the dial gauge clean and free of dust.
• Lubrication: Lubricate mechanical parts according to recommended maintenance intervals.
• Protection: Store the dial gauge in a protective case when not in use.
• Calibration: Regular calibration ensures the accuracy of the dial indicator.

Dial Gauge Indicator Cosine Error

During measurements, it's important to minimize the angle between the direction of movement and the intended measuring direction. If the measuring direction is skewed (cosine error), the measurement error can increase significantly. The dial indicator reading should be compensated with a correction factor based on the angle, as shown in the table below.

Summary

A dial gauge is a versatile and precise measuring instrument essential for technical measurement and quality assurance. Different types of dial gauges — such as mechanical, digital, and lever dial gauges — can be used for various measurement needs. With interchangeable tips and a magnetic stand, dial indicators offer flexible and accurate measurement solutions. Regular maintenance and calibration are crucial to ensure the instrument’s accuracy and reliability. A dial gauge enables precise and repeatable measurement results, which are vital for manufacturing high-quality products and components.