Закалка распредвала – это предварительная термообработка или окончательная термообработка?

Some are quenched before rough machining (or cold shock). In this case, the blank casting accuracy is high, because rough machining cannot be carried out after quenching and can only be directly ground, and some are quenched after rough machining of the cam. Both processes are exist. But to be precise, they are all pre-heat treatments before finishing.

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