A thickness gauge is a measurement system that is used to determine the thickness of various materials. They are widely used in manufacturing as well as engineering processes that require a particular material thickness to adhere to industry regulations or customer requirements. The gauge can analyze data regarding the absorption present with energy traveling through the specified sample. The device is simple to operate. Increasing the number of measurement points ensure that the data is accurate.

Choosing the appropriate thickness gauge helps ensure that you achieve the desired outcome during a manufacturing process. Global Gauge Corporation (GGC or Global Gauge) was created in 1999 and purchased Measuray’s intellectual resources and property rights. It launched the inaugural PLC-based instrument called Perfecta X-Ray Thickness Gauges shortly after.

Global Gauge has run up against many of the industry’s top competitors throughout the years such as PDM Technologies and ESC Opportunities. Global Gauge has expanded its equipment portfolio and has supplied many new and upgraded gauges. Global Gauge’s equipment collection is now widely acknowledged as the professional benchmark for non-contact width, and thickness assessment technologies in rolling plants and processing units.

At Global Gauge, thickness gauges for steel and other metals are well manufactured in order to provide the best measurement values along with accuracy and credibility. The users are provided with the best Thickness Gauge design amongst high-quality gauges.

Factors to Consider When Choosing a Thickness Gauge

• Material – The type of material that is being measured has a critical role in determining the model of thickness gauge. For instance, if you want to estimate the thickness of non-metal components, you may need to use thickness gauges that utilize eddy currents; however, if you want to test metals, particularly those with a significant thickness, then maybe a particular radiation-based thickness gauge will be required.

• Precision – The thickness gauge’s accuracy and reliability will always be critical. For top precision, standardization and compensation factors are necessary in metals applications. 

• Range – The gauge’s range is critical based on the application. For instance, if you’re using the gauge to determine the thickness of thin materials then the range must be exact. However, if you want a broad range gauge to evaluate large parts and components then a more precise and accurate range thickness gauge might be required.

It must be considered that when selecting a thickness gauge, there are typically a few specifications in mind that relate to government regulations and customer requirements.

 It is suggested that before selecting the appropriate thickness gauge, you become familiar with the following types:

• Eddy current thickness assessment: This technique helps determine the overall dimensions, such as the thickness of a particular non-conductive deposit on conductive material, but it’s precision is far lower than that of magnetic thickness measurement techniques.

• Ultrasonic thickness measuring system: A device that will determine the thicknesses of the overall coverings as well as the thicknesses of multilayer coating materials.

• Electrolytic Lab thickness measuring system: Another approach that is distinct from the previous three is that it is not a pure nondestructive analysis and requires the destruction of the coating. However, the accuracy is low, and completing the measurement is inconvenient.

• Radiation thickness evaluation: Such type of device can be utilized in the most extreme mill environments where an industrial solution is required.

How to choose the best thickness gauge with respect to the material being tested:

1. If the material being measured is metallic, you can use either a magnetic induction or a specialized eddy current thickness gauge.

• A magnetic induction thickness instrument is used to determine dimensions such as depth and thickness of a magnetic metallic material’s non-magnetic layer.
• An eddy current thickness instrument is used to determine the dimensions of a non-conductive coating on a conductor.
• An x-ray thickness gauge is the best option for flat-rolled metals applications. 

2. If the measuring surface is non-metallic, such as wood, polymer, glass fiber, then an ultrasonic thickness gauge can be used to determine the thickness.

• Based on the observation range, if the universal coating thickness is less than 1000 microns, the spectrum of the standard thickness gauge meets the requirements. If precision is necessary and the covering layer is thin, it is better to choose an established brand with a narrow range.  If the coated layer is thick, it is ideal to select a thickness gauge with an extensive range.

• If the product is somewhat small, it is advised that you use a thickness gauge containing a small probe. The external diameter of the tiny probe’s thickness gauge would be only 5 millimeters, and the measuring portion of the probe is even smaller. It may be used to measure areas having a diameter of at least 2 mm. Others, such as the pipeline’s interior wall, require a small probe.

Different Types of Thickness Gauges

There are numerous thickness gauges available. Acoustic emission devices, air gauges, infrared (IR), beta gauge instruments, and nuclear pieces of equipment are all possibilities. Nondestructive testing (NDT) uses acoustic emission instruments to assess appropriate acoustic or vibrational characteristics. Air gauges are ideal for determining the thickness of metallic sheets/strips, polymer webs & coatings, and certain other thin substances or component sections.

The absorption of electromagnetic radiation by infrared, nuclear, as well as beta gauge equipment is used to determine the thickness or elemental mass of webs, sheet elements, or coverings. The proportion of radiation directed back or transmitted via non-metallic substances such as paper as well as plastic sheets or webs is evaluated to establish absorption capabilities.

Eddy current or other electromagnetic approaches and methodologies including electromagnetic acoustic resonance (EMAR), might very well be used to determine the thickness. Along with thickness measurement, eddy current plus penetrating radar approaches are utilized to detect faults, the integrity of the connection or weld, including electrical conductivity. The eddy current methodology is the most extensively used electromagnetic nondestructive testing approach.

EMAR technologies transmit signals enabling resonant acoustic investigation via non-contact electromagnetic transducers. Every signal generated by the non-contact EMAR causes a clean resonant response. Additionally, electronic and mechanical thickness gauges are available.

Laser micrometers, magnetic systems (using the processes of Hall effect and induction techniques), optical-based instrumentation, X-ray gear, snap gauges, and even ultrasonic inspection (UT) procedures are all examples of where thickness gauges are used. Micrometers are tools used to perform precise measurements.

They are composed of a specialized ground spindle as well as an anvil that is installed in a steel framework. Along with conventional micrometers, calipers and laser micrometers are used to determine the thickness of materials. Laser shearography method, magneto-optical technologies, along with holographic interferometry are all approaches used by optical equipment.

Snap gauges are also referred to as functional or attribute gauges. Pulse-echo thickness gauges are frequently used with UT thickness gauges. These gauges may be used to measure the dimensions such as the thickness dimensions of sculpted plastic onto industrial cutting machines, drilling, including grinding and crushing tool handles, along with medical devices used in surgeries and dentistry.

Applications of Thickness Measurement Gauges

Digital thickness gauges are incredibly versatile instruments that might be used for a wide variety of tasks:

• Vehicle/Automotive Market – The majority of thickness measurement gauges have been used by steel feeding the automobile industry. They are used to determine the thickness measurements of sheets of metal and identify flaws in automobile bodywork and also to assess the thickness of panes of glass being used in automobile windscreens. The specified Ultrasonic thickness testing instruments are frequently required to identify production faults, while professional coating paint thickness meters are used in automobile auto-repair as well as bodywork garages to deposit metallic coatings to the proper thickness.

• Engineering/Manufacturing – Similar to the automotive sector, significant factories, along with the engineering companies that manufacture everything from parts for large systems to vehicles typically use a thickness measurement gauge to assure the reliability and consistency parameters of items produced on the assembly line. In aviation parts, it is critical to inspect for defects and irregularities thoroughly.

• Jewelers – Jewelers can always use specialized gold testing gauges to determine the thickness dimensions of gold as well as other precious materials. Jewelers can determine whether a particular gold article comprises a deep-rooted core of a foreign substance by using an ultrasonic thickness investigational setup.

• Construction and Building – Thickness gauges have been frequently used to determine the thickness measurements of structures and other structural components. Homebuilders and architects may guarantee that concrete walls are free of flaws that could contribute to the building’s instability by doing thickness testing. Similarly, copper pipes and commercial pipelines can be examined routinely for corrosion.

• Highway and Local Administrations – Thickness gauges may be used to check the thickness depth and values of metallic substances and concrete bridge pillars to make sure that they meet regulatory requirements and do not degrade prematurely. These instruments are frequently used to locate air pockets within the cementitious materials and rusting on steel frames as well as supports.

• Fuel Tanks and Chemicals – Ultrasonic testing measuring devices can detect high corrosion in fuel and chemical storage containers.

• Archaeology – Students and scientists can investigate the thickness dimensions of unearthed pots and delicate materials using nondestructive ultrasonic diagnostic procedures. Ultrasonic thickness measurement gauges have been used in the glass manufacturing industry to record the thickness measurements of glass dimensions in furniture reflectors, housing glass windows, and car windscreens and reflecting materials.

• Healthcare – Coating thickness meters are being used to determine whether the molded plastic layers on medical instruments and tools as well as utensils provide adequate protection.

• Industrial equipment – Industrial-grade instruments such as x-ray thickness gauges and isotope thickness gauges are both durable and safe when it comes to operation.

Calibration of the Thickness Measurement Gauge

The calibration procedure for thickness measurement gauges varies according to the gauge class as well as industry regulations and specifications.  Calibration methods for coating thickness measurement gauges include one-point or single-point calibration, including the foil calibration, as well as the two-foil calibration process. Ultrasonic thickness measurement gauges demand calibration blocks that have been authorized.

Calibration at a Single Spot

One-point or single-point process calibration is a common approach that does not utilize foils. It is performed on an uncoated test piece by bringing the measurement gauge probe relatively close to the selected measuring position as possible. This calibration technique uses a single reference point, which is the zero number value hence the term “one-point calibration.”

Standardization of Foils (The Two-Point or Two Foil Calibration)

Such a calibration process makes use of a very well known thickness calibration foil. To start, a single-point calibration technique is performed, followed by the placement of a foil on an uncoated test piece. After positioning the probe within the very same selected measuring area, the device’s markers are utilized to adjust the exhibited thickness value till it matches the thickness of such foil. 

When consumers demand greater accuracy, this approach is frequently preferred over single-point calibration. To do this result, a foil must be somewhat thicker than the film thickness dimensions of the experimental material.

This two-foil calibration process, which is frequently used for more challenging thickness measuring procedures, involves two specific foils of varying thicknesses and dimensions (these are generally graduated, provided that the foil one is approximately 0.5 times the test sample’s thickness, whereas the second coil around 1.0 times the object’s thickness). The above calibration method makes use of two reference locations concerning the probe, one for the thicker amount and one for the thinner one. This method is most frequently used with coarse or uneven materials.

Calibration by Ultrasonic Inspection

The typical approach for calibrating any ultrasonic thickness measurement gauge typically consists of examining the gauge’s linearity using authorized calibration frames (also regarded as the ultrasonic calibration benchmarks). The blocks span between 1.5 millimeters to 50 millimeters. A typical approach might entail 4 or 5 separate tests using different millimeter blocks to establish uniformity. A probe is positioned at a specific position upon the calibration piece by which acoustic waves are released and detected once they reach the back face of the said block.

Important note: Certain ultrasonic thickness measurement gauges involve the utilization of a special coupling gel to ensure that no gaseous gaps or voids exist between the measuring surface as well as the transducer.

Consider the following when purchasing a thickness measurement gauge:

The specimen material can have an effect on the kind of thickness measurement gauge required. While a thickness measurement gauge is adequate for the majority of metals, polymers, and ceramics, materials like rubber may demand more sophisticated gauges with greater depths.

Thickness – When purchasing a thickness measurement gauge, it is critical to ensure that the thickness measurement spectrum is sufficient for the specimen being measured. Thicker materials demand lower frequencies for measurement, whereas thinner specimens demand higher frequencies.

Contour/Geometry of surface – The material’s surface may impair the gauge’s capability to the couple as well as to produce an accurate and precise thickness reading. For observations on convex materials, non-contacting dip gauges may be required to ensure proper sound couplings.

Resolution/Precision – Some thickness gauges are often more precise than basic units. When working with fine specimens such as glasses, plastic, as well as paints, greater precision may be necessary.

Cost – Today’s marketplace offers a wide variety of thickness measurement gauge variants, ranging from very scientifically advanced ultrasonic devices to reduced-cost thickness measurement gauge versions. When purchasing a thickness measurement gauge, it has been critical to evaluate the characteristics you require on a periodic schedule. For example, in the case you are required to adhere to industry regulations, you will need a verified thickness measurement gauge, which is often more costly than an average thickness gauge.

Different Thickness Measurement Gauges

The thickness gauges have been used to determine the depth of the covering of materials that covers the base. Another use is the thickness assessment of components and workpieces.

Device classifications:

• Electromagnetic Steel – Capable of displaying magnetic flux density.
• Magnetic –  They are designed explicitly for bodies made of aluminum that have been magnetized. Ultrasonic technology is compatible with both metals as well as plastic.
• The eddy current –  They have been used in conjunction with aluminum to evaluate the strength of induced current constituents in the body.

Consolidated –  The advantage of this type is that it allows for the use of both an eddy current as well as an electromagnetic sensor. Devices are incredibly accurate in determining performance.