Originally Posted by Jim Bailey (Post 600614)

The key is to not "shock" the part by cooling it too quickly, and to not warm it back to room temp too quickly. The program we used for a ring and pinion was 8 hour descend, 8 hour soak, 8 hours back to ambient, follow by a 2 hour "normalizing" where the parts are warmed to +200 degrees for an hour, then allowed to cool to room temp all by them self. Good Cryo machines can do all these steps without ever opening the machine once a run begins. There will be little, if any, effect on the parts heat treatment. Additionally, the Timed Steps of the run are based on the total weight of the parts in the machine... If you really want to "see" cyro in action, treat your Drill Bits, Mills, and Lathe Tooling... Now you know the rest of the story. ...

Originally Posted by Jim Bailey (Post 600614)

That's a pretty broad statement Ralph …. Much better stated as cryo done incorrectly can make your part brittle. You could program your machine to slowly lower the part to Cryo temps ( -300 degrees ) say over 48hrs. Once the part has reached the "soak" cycle say -310 degrees, It can stay there as long as you wanna spend money on Nitrogen to keep it there. Which would be a waste of time and money. The key is to not "shock" the part by cooling it too quickly, and to not warm it back to room temp too quickly. The program we used for a ring and pinion was 8 hour descend, 8 hour soak, 8 hours back to ambient, follow by a 2 hour "normalizing" where the parts are warmed to +200 degrees for an hour, then allowed to cool to room temp all by them self. Good Cryo machines can do all these steps without ever opening the machine once a run begins. There will be little, if any, effect on the parts heat treatment. Additionally, the Timed Steps of the run are based on the total weight of the parts in the machine... If you really want to "see" cyro in action, treat your Drill Bits, Mills, and Lathe Tooling... Now you know the rest of the story. ... Hopefully, you're now armed with enough info to ask the correct questions at your Cryo shop of choice. If they're skipping any of these steps, beware of any BS that will follow in their excuses and explanations of how they do it !