There are many techniques used to perform thickness measurements in manufacturing environments. Traditional thickness measurement options include Isotope, X-Ray, Laser Optical, Piezo Ultrasonic, and Laser Ultrasonic. An effective, yet underutilized technique is EMAT (Electro Magnetic Acoustic Transducer) generated UT. EMAT generates ultrasonic sound waves in the material being inspected and measures the Time-Of-Flight (TOF) of the signal through the part to calculate the thickness.
You may already be using one of the traditional methods to meet your inspection needs, but are those techniques really the best fit for your application? Why should you consider EMAT for thickness measurement?
Unlike traditional Piezo UT sensors, EMAT does not use liquid couplant to perform thickness measurements. It is a 100% dry, non-contact technique. This greatly simplifies automation and integration. EMAT eliminates couplant induced errors, allows inspections at high speeds (up to 60m/s) and is capable of performing inspections at high temperatures and sub-zero temperatures.
EMAT only requires one sensor to perform accurate thickness measurements. Traditional techniques such as Isotope, X-Ray and Laser Optical require multiple sensors and two sided access in order to perform thickness measurements.
Because the EMAT signal is generated in the material being measured and not the sensor, EMAT is not affected by surface conditions. Accurate measurements are easily obtained through coatings, corrosion and contaminates that can confuse or invalidate other techniques.
EMAT is accurate to 12.7µm (0.0005”) with a resolution up to 3mm. Even at high speeds the accuracy and resolution provided using EMAT does not change.
EMAT is free from the dangers and compliancy cost associated with radiation techniques such as X-ray and Isotope. Without the need for liquid couplants, the costs associated with transport, storage, and disposal are eliminated.
There are many benefits to using EMAT over traditional thickness measurement techniques, and these benefits translate into an effective high-speed scanning system for factory integrated thickness measurement inspections.
