Digital height gauges are instrumental tools in the realm of precision measurement. Their primary utility lies in their ability to measure the height of different features on a workpiece. In this comprehensive guide, we delve into the intricacies of digital height gauges, their working principles, components, varieties, and their essential role in manufacturing and quality assurance processes.
Digital Height Gauges: A Brief Introduction
At the heart of many machining operations lies the digital height gauge, an essential tool that ensures exact measurements and quality control. Over centuries, metrology has evolved from rudimentary rulers and callipers to these versatile and precise digital height gauges. These instruments are specifically designed to measure, record, and compare the height of workpiece features, thereby playing a significant role in manufacturing planning and compatibility assessment.
Understanding How Digital Height Gauges Work
Digital height gauges measure the height of workpiece features with the help of a vertical axis beam. This beam comes in various sizes and scales, catering to different industrial needs. Mounted on this axis is a sliding carriage that carries a probe. The operator selects the feature to measure via this reader, which can then be marked or recorded for comparison or analysis. The combination of these core components with various modular attachments enables a broad array of measurement and engineering capabilities.
Essential Components of a Digital Height Gauge
A typical digital height gauge consists of several basic components, each engineered to high standards for producing accurate data.
The Base
Digital height gauges require a solid base, often made of cast iron or granite, to maintain stability and durability. Some digital height gauges, such as Eley Metrology, incorporate air bearings to provide optimal balance. This base is usually placed on a smooth surface plate on a machining desk or worksurface for an ideal foundation.
The Beam
The vertical beam, perpendicular to the base, is a crucial component of all height gauges. These beams, typically made of rigid metal like steel, can span up to 12 inches or 300 millimetres on most digital height gauges. However, some industrial height gauges can extend up to 6 feet, with some featuring dual vertical axis beams for added stability.
The Axis Carriage
The axis carriage carries the probe, scribe, or measuring jaws to the workpiece feature that needs to be measured. This carriage can either be manual or motorised.
Measuring Jaws
Mechanical height gauges usually employ manually operated probes with measuring jaws. These jaws come equipped with two sets of adjustable teeth, similar to a calliper, that can be applied to a workpiece feature with controllable screws.
Scribes
Scribes are used to mark specific points on the workpieces for further machining or calculations. They utilise dyed layout fluid to create dots or lines at precise locations.
Probes
Digital height gauges often employ touch probes. These probes, similar to a fingertip in function, make contact with the workpiece to gather accurate data. They apply a small amount of measurement force to the surface in question, standardising the contact and ensuring the accuracy of each measurement.
Display Screens
The display screens on digital height gauges enable operators to customise features, measure, and extrapolate required data. Depending on the type of digital height gauge, these screens could be LED, LCD, or high-resolution colour displays.
Varieties of Height Gauges
Digital height gauges represent the most recent evolution in a line of three primary types of height gauges. The other two include Vernier and Dial height gauges.
Vernier Height Gauges
Vernier height gauges utilise a Vernier scale on their vertical axis to visually display workpiece height. As these gauges operate without digital calibration, careful transport and set-up are crucial to maintain accuracy.
Dial Height Gauges
Dial height gauges, unlike their Vernier counterparts, use dials to determine height measurements. The dial, connected to measurement jaws, sits on the vertical axis carriage and delivers readings upon manual adjustment.
The Versatility of Height Gauges
Height measurements are invaluable for comparison across a workpiece. Operators can determine properties like width, depth, centre-line measurement, gradient, straightness, and perpendicularity. A well-maintained digital height gauge, therefore, plays a fundamental role in manufacturing and quality control by calculating these critical measurements.
Dive Deeper into Digital Height Gauges
Digital height gauges, along with granite surface plates, are essential tools in metrology, used to measure vertical distances. Like micrometers and calipers, height gauges also come in varieties like Vernier Height Gauges, Dial Height Gages, and more sophisticated Electronic Height Gauges.
Height Gauge Accuracy
The accuracies of height gauges can be as high as up to a thousandth (0.001?) or even a tenth (0.0001?). The primary determinant of a height gauge’s accuracy is how square it is to the reference plane being measured.
Types of Height Gauges
Just like calipers, you can get Vernier Height Gauges and Dial Height Gauges. However, Digital Height Gauges, with their digital display, offer the best user interface. Vernier variants are available in extremely tall formats, but Dial Height Gauges are almost always 12? of full range travel or less.
Dual Post Height Gauges (Dual Beam Height Gauges)
These gauges feature dual vertical axis beams for added stability.
Micrometer Height Gauges
These precision measuring devices offer micrometer accuracy in a height gauge, making them invaluable in precision calibration.
Dial Height Gauge
Dial height gauges typically display only the last few digits on their dial.
Electronic Height Gauges: Motorised and Computerised
These height gauges are a short step away from being full-fledged 3D Coordinate Measurement Machines (CMM). Their motorisation offers greater automation and consistency of measurement, and computerisation allows for calculations to take various measurements.
Height Gauge Accessories
There are several height gauge accessories available, including height gauge scribers for scribing a line on a part at a particular height, and dial indicators to increase accuracy on vertical distances.
General Height Gauge Components and Set-Up
Height gauges comprise a sliding carriage mounted to a vertical axis beam or column that contains a measuring scale. The beam configuration ensures perpendicularity to the base of the height gauge, which is typically made using a rigid material to add stability.
When using a height gauge, a granite surface plate is typically used to measure and scribe part features from a datum plane. A touch probe, scriber, or other measuring probe is employed to locate the desired feature or point on the workpiece being inspected for measurement.
Types of Height Gauges
Height gauges can be broadly divided into four basic types:
- Vernier height gauges
- Dial height gauges
- Digital counter height gauges
- Electronic height gauges
Uses of Height Gauges
Height gauges are used in quality control applications and can perform several types of measurements:
- To measure the distance from a reference surface to a specific feature of a part to verify that it meets specifications and tolerances
- To scribe a part with accurate vertical dimensions or features from a datum plane so that additional machining can be done
- To perform 2D measurements of part features
- To verify centre-to-centre dimensions
- To measure flatness
- To measure angles
- To measure straightness/squareness or perpendicularity of parts