Thickness Gauge or Flaw Detector: Which Is Best for Your Application?

1. Thickness Gauge or Flaw Detector: Which Is Best for Your Application? What's the difference between ultrasonic thickness gauges and flaw detectors? This is a commonly asked question when determining the right nondestructive testing (NDT) tool for an application, as the two devices are similar in a few ways. The Similarities Between Ultrasonic Thickness Gauges and Flaw Detectors Ultrasonic thickness gauges and flaw detectors use the same basic concepts. They both use transducers that generate sound waves and both measure the time it takes for that sound to leave a transducer, travel through a material, bounce off a reflector, and return to the transducer. A sound pulse generated by a transducer travels through a test piece and reflects back from the inside surface or far wall And both use the basic equation of: Distance = Velocity * Time/2 This equation divides by two since the one-way time measurement to the reflector is all that’s required. The reflection and transmission of high-frequency sound waves—known as ultrasound—has long been an important tool for evaluating the integrity of welds, as well as testing structural metals, pipes and tanks, boiler tubes, railroad rails and axles, aerospace composites, and many other industrial applications. Industrial ultrasonic testing equipment continues to be popular since it:  Is cost effective, quick, and reliable  Usually requires no test piece preparation other than wetting with couplant  Has no specific safety hazards or regulatory licensing requirements associated with its use Selecting an ultrasonic thickness gauge or flaw detector for an application largely depends on the main goal of the measurement. Before we get into the key differences between these instruments, let’s take a brief look at their use throughout the years. History of Ultrasonic Equipment Ultrasonic test instruments have been used in industrial applications for more than 60 years. Early ultrasonic instruments were released in the 1940s, the majority of which were primarily focused on flaw detection. The first digital thickness gauges (also known as “D Meters”) were released in the 1960s. However, using a flaw detector to measure thickness was the more popular, preferred method up until the 1980s— when digital thickness gauges offered the capability to display an onboard waveform (e.g., an A-scan).

2. The visual display of the waveform on the thickness gauge device gave users more confidence as they could see what a digital reading corresponded to in real-time. Today, these small, powerful instruments either come standard with waveform or provide it as a software option. What Is an Ultrasonic Thickness Gauge? An ultrasonic thickness gauge can accurately measure the thickness of a material and locate surface corrosion or erosion from one side of a part. It can measure just about any common engineering material of metals, plastics, composites, fiberglass, ceramics, and glass. Ultrasonic thickness gauges can measure the thickness of a wide variety of products for manufacturing quality control, such as plastic tubing and parts used in the medical industry. Inspectors also use them to test the structural integrity of critical parts and infrastructure, such as aircraft turbine blades for wear or pipes and tanks for in-service corrosion. Advantages of an Ultrasonic Thickness Gauge Here are some advantages of an ultrasonic thickness gauge:  More consistent and accurate time-of-flight (ToF) measurement. Straight beam inspection measures the ToF to a material’s back surface, which corresponds to the total thickness of that material.  Compact size and lower cost.  Easy to calibrate and operate.  Measurement advantages include: oAuto zero compensation: enables a more precise zero offset measurement, which contributes to a more accurate ToF measurement. oV-path correction: compensates for the angular sound path of corrosion measurements using a dual element transducer, providing the highest degree of accuracy and repeatability over a large thickness range. Most flaw detectors do not compensate for this angular sound path. What Is an Ultrasonic Flaw Detector? An ultrasonic flaw detector is designed to locate and size discontinuities such as cracks, voids, porosity, and disbonds in various materials and welded joints. Flaw detection can potentially be applied to any standard engineering material. Most tests involve steel and other structural metals; however flaw detectors can also be used on plastics, composites, fiberglass, and ceramics.

3. A flaw detector also has the ability to reasonably measure material thickness accurately but isn’t designed for precision thickness. Advantages of an Ultrasonic Flaw Detector Here are some advantages of an ultrasonic flaw detector:  Highly versatile: oStraight beam inspection measures to a defect or a void to locate the distance to the flaw from the material’s surface. oAngle beam inspection to check the integrity of welds. oIdeal for scanning applications (due to a faster update rate of 60 Hz compared to a 25– 30 Hz update rate of a thickness gauge) Visit https://thebombaytools.com/product_ctg/inspection_gauges/ for Height Gauge, Dial Gauge,Surface Roughness Tester, Oil Dip Tape, Cross Hatch Cutter, Wet Film Thickness Gauge WFT, IR Thermometer, Alcohol Tester Breath Analyzer, Torque Wrench, Britool, Tohnichi, Torque Multiplier, Gedore, Straight Edge Ready Stock, Surface Plates, Lutron Electrical Testing Instruments, MItutoyo Japan, Insize Meausring Instruments.