Getting Up Close With The Elcometer PTG


Within ultrasonic testing, there are an infinite number of material thickness measurement applications, from aerospace parts to the thickness of a drinks can. 

Elcometer Precision Thickness Gauges provide operators with the critical capability to non-destructively measure the thickness of a large number of materials and, unlike more traditional low-tech methods, such as callipers, when only one side of the test piece is accessible.

In the Beginning

Following the development of short-time-interval signal processing, required for RADAR during the 1940s, ultrasonic thickness gauges were designed to send out a short pulse of ultrasound into materials and listen out for the return echo caused by the pulse reflecting off of a boundary which, when considering thickness measurement, is typically the back surface of the material.

A simple way to explain how ultrasonic thickness measurement works is to imagine a person shouting into a canyon, and measuring the time it takes to hear the returning whisper amongst all the other echos.When you measure very thin materials, the returning echoes can be heard even before the shout has finished. Due to the extremely short time intervals involved when measuring materials less than 1mm thick, we need some way to extend the travel time of the pulse - or to put it another way, delay the returning echo. This is achieved through the use of a delay line.

What are Delay Lines?

A delay line is a small acrylic or graphite cylinder of known dimensions and material properties that couples and attaches to the face of thetransducer, thereby extending the time between the pulse leaving and returning.The delay line’s thickness is then subtracted from the measured thickness, leaving you with the measurement of the thickness of the test piece.One important consideration with delay lines is the choice of material due to acoustic impedance matching. Acoustic impedance matching is where two materials of a very similar composition don’t produce a strong enough boundary effect to generate an ultrasound response. Graphite, for example, is typically used to measure on plastics.

The Elcometer Precision Thickness Gauge (PTG)

The Elcometer PTG utilises a single 15-20MHz transducer to achieve the maximum precision possible in a direct-contact, handheld gauge.It’s capable of accurately measuring the thickness of materials as thin as 0.15mm/ 6mils (when used in echo-echo mode), and can do this for a variety of materials ranging from titanium and steel to thin composites and plastics. 

Along with its exceptional precision, the Elcometer PTG is packed full of features that make the operator’s job much easier. These include a customisable display that allows the user to identify which statistics are relevant to the current batch of readings, a dynamic stability indicator that quantifies the repeatability of any individual reading and a differential mode to allow the user to compare the variation between the material thickness and a baseline thickness, B-scan and thickness trend graphs, warning limits which indicates when the material is too thin or thick, and much, much more.

Like many of Elcometer's gauges, the Elcometer PTG is fitted with Bluetooth for wireless transfer in batches or real-time to PC or mobile devices - running either our free reporting and data logging software ElcoMaster or third-party software applications, allowing reports to be submitted from the field as well as the office.

The Elcometer PTG is perfect for many industrial applications, including in-line quality checking of difficult-to-measure components - such as 3D printed parts, quality control testing for thin coating application on non-metallic substrates, uniform corrosion monitoring of thin pipes or plates and many others.If you or your customer is looking for an easy-to-use, simple to configure, robust, reliable and accurate precision thickness gauge which is packed full of features to simplify material thickness testing and reporting, the Elcometer PTG is the essential choice.