Traditional destructive testing of Spot Welds, such as those detailed in ISO 10447 https://www.iso.org/standard/61276.html are common in automobile manufacturing, and include peel and chisel tests for routine quality. However, the amount of time, effort, and scrap associated with destructive testing makes non-destructive test (NDT) methods attractive.
Ultrasonic testing of spot welds in automotive applications is becoming more common and has been proven to be a good indicator of the quality of spot welds. A well-designed ultrasonic inspection system intended for testing spot welds will look at the multiple reflections of the ultrasonic signals that travel through the spot weld and calculate the thickness and diameter of the spot weld as well as identify flaws that may be present.
Traditionally, ultrasonic systems required a substantial amount of operator training and practice to be able to interpret the signals to determine the integrity of the weld. Newer, sophisticated systems with advanced algorithms will do the evaluation for the operator and provide a Pass/Fail analysis along with detailed information about the weld, which speeds up the testing process and removes the potential for differences in human interpretation. With the right ultrasonic inspection system, an operator can quickly become proficient at using the system to accurately test between 4 and 8 spot welds per minute.
To learn about the operational principles and additional information on ultrasonic spot weld testing systems, see: https://www.progeneroproducts.com/wp-content/uploads/2022/08/Ultrasonic-Spot-Weld-test-system-operational-principles.pdf
The right ultrasonic NDT system implemented properly will save much time and money while reducing the potential waste that can occur while waiting for the results from traditional destructive testing. In addition to providing quick and accurate information about a spot weld, a good NDT system will record the results of the test for further evaluation and provide valuable feedback to weld engineers so they can make adjustments, repairs, and improvements to the weld systems.