Two readings, two different words. This one is the metal noise, dāng, the reading you also need inside 锒铛入狱, to be thrown in jail in chains. Read chēng, 铛 is a kitchen word meaning a flat shallow pan, as in 电饼铛, an electric griddle.
usage
As a sound word this is usually doubled, 铛铛, for a gong, a bell or an old tram. As vocabulary it survives mainly inside 锒铛, the clank of iron chains.
Left metal radical, the indexing element in its five-stroke side form. It puts 铛 with 钟 (bell), 锣 (gong) and 锅 (pot): the clang it names is metal striking metal.
Right 当 supplies the sound and nothing else, dāng for dāng, an exact match. The same phonetic-only pairing gives 铜 (copper) from 同 and 铬 (chromium) from 各.
