The 'run it wet' advice from my shift lead at Mueller Metalworks was dead wrong

Back in March at the Mueller plant in Cleveland, my shift lead Pete kept telling me to run the big squeeze castings wet, said it kept the die cool and stopped sticking. I followed his advice for two days straight, and I got nothing but porosity and a batch of 40 scrapped housings. Turns out the alloy we were using hates moisture at that temp, and the old timer who taught Pete was working with a different mix 20 years ago. I finally checked the spec sheet myself and found the dry cycle recommendation, but the damage was done and we lost a full shift. Has anyone else gotten handed down advice that just doesnt match what the metal actually does anymore?

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paige_craig12d ago

I read a metallurgy forum thread a few months back that said the whole "run it wet" trick comes from old die casters who were using zinc alloys, not aluminum. The moisture actually reacts with the aluminum at high temps and creates hydrogen gas pockets, which is exactly the porosity you saw. Pete probably learned it from someone who never ran a spectrometer on their scrap. I've seen that same thing happen with guys insisting on certain release agents that just coat the die but never let the casting vent right. You did the right thing checking the spec sheet yourself, but that lost shift is on the system that lets 20 year old folklore override the actual process sheet.