Acoustic Resonance Testing on Castings
Acoustic resonance testing generates sound waves in the casting and measures their frequencies. These are compared with a reference spectrum to detect internal defects or structural problems. It is a quick method for quality control.
Physical-Chemical Mechanism of Action
Acoustic resonance testing uses the natural natural frequencies of a casting. By mechanical impact, sound waves are generated that propagate in the material and reflect at interfaces. These reflections form resonance peaks whose frequencies are measured.
Metallurgical Relevance & Risks in Welding
Internal casting defects such as pores or irregularities change the natural frequencies of the material. These deviations can be detected by acoustic resonance testing before the casting is put into operation. A missing or inaccurately measured reference spectrum can lead to false alarms and thus misinterpretation of results.
Workshop Practice & Action Instructions
The test should be performed on a cool casting to ensure that thermal deformations do not affect the frequency measurement. The impact frequencies should be in the range of 20 Hz to 1 kHz to capture most relevant natural frequencies. The reference spectrum should be created based on the specific casting and its materials. If deviations are detected, further test methods such as X-ray examination or ultrasonic testing should be performed.