Coating Thickness Gauge

What is the Coating Thickness Gauge?

A handheld gauge that measures the thickness of paint, plating or anodizing on metal substrates by magnetic induction or eddy current without damaging the coating. It is the right choice for incoming, in-process and final coating inspection.

Overview

A coating thickness gauge uses a probe that generates a magnetic or eddy current field. On steel and iron, magnetic induction senses the distance between the probe and the ferrous substrate; on aluminum, copper and other non-ferrous metals, eddy current measures the same distance. Combination gauges switch automatically between modes. Typical measuring range is 0 to 1500 micrometers with 0.1 micrometer resolution and an accuracy of about 1 to 3 percent of reading. Two-point calibration using a zero plate and a certified foil corrects for substrate roughness and composition. Readings are taken in seconds and statistics such as mean, maximum and minimum are stored. The method does not work for non-metallic substrates, for which ultrasonic coating gauges are used.

How does it work?

Inspection instruments convert a physical feature of a part into a number or an image that can be compared with a tolerance. Optical instruments magnify and project the silhouette or surface onto a screen or camera and measure distances using calibrated scales or pixel calibration. Eddy current and magnetic induction gauges measure the change in a probe's field caused by a coating over metal. Ultrasonic flaw detectors send high-frequency sound into a material and display echoes from boundaries and discontinuities, locating defects by time of flight. Stylus profilometers drag a fine diamond tip across a surface to record vertical displacement as roughness. Accuracy depends on calibration with traceable standards such as gauge blocks, step standards and foil references, on temperature stability and on operator technique.

What are the key features?

• Automatic ferrous and non-ferrous detection switches between magnetic and eddy current modes.
• Two-point calibration with zero plate and certified foils corrects for substrate effects.
• Statistics for mean, maximum, minimum and standard deviation display on each batch.
• Probes with fine tips measure small or curved surfaces at fast speed.
• Memory and USB export provide traceable records of coating measurements.
• Low and high limit alarms flag out-of-tolerance readings immediately.

What are the technical specifications?

A typical coating thickness gauge configuration offers measuring principle of Magnetic induction and eddy current, measuring range (Fe) of 0–1500 μm, measuring range (NFe) of 0–1500 μm, resolution of 0.1 μm (0–99.9 μm), accuracy of ±(1–3 % of reading + 1 μm) and minimum substrate thickness of 0.2 mm (NFe), 0.5 mm (Fe). Values are indicative of the product class; the exact figures for each configuration are confirmed on the quotation and the calibration documents supplied with the instrument.

Which applications is it used for?

The Coating Thickness Gauge is used in automotive paint thickness, galvanizing and plating inspection, anodized aluminum checks and pipeline and structural steel coating audits. Across the wider Inspection Instruments class, laboratories also deploy it for dimensional inspection of machined parts, paint and plating thickness verification and weld and casting flaw detection.

Which standards and certifications apply?

Relevant standards and methods include ISO 2178, ISO 2808, ISO 4287, ISO 9712, ASTM E114, ISO 10360-1 and ASTM D7091. Certification candidates for this model are CE, RoHS and ISO 9001 manufacturing; each is to be confirmed for the specific configuration before shipment, and certificates are supplied only where they have been issued.

Keep inspection instruments in a temperature-controlled area when tolerances are tight, since thermal expansion affects dimensional results. Calibrate with traceable reference standards appropriate to each instrument, such as gauge blocks, coating foils, calibration blocks for ultrasonic testing and roughness specimens. Verify zero and span before each shift. Protect optics, probes and styli from damage, and store them in cases. Operators of ultrasonic equipment should be qualified to recognized levels such as ISO 9712. Document inspection procedures, acceptance criteria and measurement uncertainty, and keep records for customer audits. Schedule periodic recalibration at intervals defined in the quality system.

How do I select the right Coating Thickness Gauge?

Choose a combined Fe and NFe gauge for mixed metal substrates and an Fe-only gauge for steel structures. Choose an ultrasonic coating gauge for plastic, wood or concrete. In an RFQ specify substrate materials, thickness range, probe type, curvature and surface conditions, statistics needs and any compliance such as ISO 2178 or ISO 2360.

How does it compare with other Inspection Instruments variants?

Choose by the feature to be verified. Use a profile projector or video measuring machine for two-dimensional outlines, holes and small parts. Use a coating thickness gauge for paint, plating or anodizing, selecting magnetic induction for steel substrates and eddy current for non-ferrous metals. Use an ultrasonic flaw detector for internal defects in welds, castings and forgings. Use a roughness tester when surface finish is specified in Ra or Rz. Compare measuring range, resolution, accuracy relative to tolerance, probe or objective options, and software for programs and reports. A good rule is that the instrument accuracy should be one tenth of the tolerance. Consider operator skill, since ultrasonic and manual optical methods depend strongly on technique and training.