Printable Version of Topic

Posted by: lmcchesney Apr 14 2004, 09:56 AM

I'v brought up this topic before, shoptalkforums, PP and I think here, but have never gotten a finished result/direction. I know that the topic is filled with proprietary beliefs, but there must be some good experience here or a source of reference to expand our knowledge.
Thanks,
L. McChesney

Posted by: synthesisdv Apr 14 2004, 10:13 AM

I know jake treats alot of parts using cryo. I think he has measured benefits in terms of wear, etc.

dr

Posted by: Dave_Darling Apr 14 2004, 10:23 AM

Jake is a believer, I am not. At least, not yet. Last I heard, he was going to be setting up a test fixture to test different treatments on cams and lifters. That has the potential to make me a believer.

I know people who have strong opinions each way on the subject. For instance, some 944 club racers I know have tried the "frozen rotors" thing and found precisely zero difference in brake effectiveness or longevity. Other people swear that their brakes last twice as long, don't heat up as much, and so on.

--DD

Posted by: ArtechnikA Apr 14 2004, 10:34 AM

the research continues.

some people believe it's The Ultimate Solution.
some people believe it's The Ultimate Con.

some of each will never change their opinions in the face of any evidence.

the broad feeling is that for parts that are never heated to a major fraction of their interesting metalurgical-change temperature, it can do some good. (i.e. - any possible marginal benefit in brake rotors for track service is not worth the cost.)

especially for stressed parts that undergo flexure - springs - it seems to have quantifiable benefit. it may improve hardness and toughness without the usual increase in brittleness - which is the traditional non-cryo tradeoff in the search for high-Rockwell-number hardness.

mind you, this is all for steel. probably carbon (i.e. not 'stainless') steel, although that's a less-well documented area. some people claim great results with nonferrous materials such as aluminum alloy; i can understand how it works with ferrous materials - i have yet to see a plausible chemical explanation for how it can possibly work in aluminum. (not to say it doesn't, or it can't - but if it -does- it would involve some mechanism i simply don't know of. but i am not a metalurgist...)

Posted by: lapuwali Apr 14 2004, 10:59 AM

Years ago, when this subject first came up, I just happened to know some metallurgists working at Lawerence Livermore. I asked their opinion, and they felt it was snake oil. Since then, a number of people have claimed measurable benefits, at least for things like brake rotors. However, I have yet to see the results of a properly scientific test. Some of the benefits I've heard of on brake rotors can be explained in other ways.

At worst, the process doesn't seem to hurt.

Posted by: Eric_Shea Apr 14 2004, 03:02 PM

I would not be a believer...

...until I saw it with my own two eyes.

A friend of mine owns AirPower Racing here in Utah. He was running a track event at Pueblo with his 993. He heard his rear brakes grinding and decided "WTF, I'm just gonna stay out here. I'll need to replace them anyway and I only have another lap to go..." (or something like that)

Turns out he was running metal on the rear rotors. Big-time. I saw what was left of the pads (pad mount I should say, there was no pad left at all and 1/2 the mount ground off)

He's still using the rotors. I felt them, they're fine. They were cryo'd.

Posted by: cnavarro Apr 14 2004, 07:11 PM

First hand experience- when we were making birals, we ended up having to machine a set of ductile iron liners after they had been cryo'ed. We ended up destroying every single liner and some of our tooling. It's made me a believer. Any 105mm Nickies receive cyro'ing before plating!

Charles Navarro
LN Engineering
http://www.LNengineering.com
Aircooled Precision Performance

Posted by: ArtechnikA Apr 14 2004, 07:17 PM

so you're using your experience with iron liners to conclude it's effective on aluminum ?
how is that even close ?

cryo works in ferrous materials due to the whole Martensite/Austenite/Pearlite carbide thing - what's the mechanism in aluminum alloy that makes it work ? and what kind of similar A/B tests did you try on aluminum ?

ductile iron and aluminum alloy are just about as close to apples and oranges as i can imagine ...

Posted by: jridder Apr 14 2004, 07:48 PM

I've starting cryo'ing all my dead parts in hopes that some day I'll find a way to bring them back to life.

Posted by: cnavarro Apr 14 2004, 08:41 PM

I was just trying to make a point that it works. It's affect on aluminum is much less than on iron, but we have seen the difference in how the aluminum machines after it's been cyro'ed. The affect on cast AL is greater than on extruded, fyi, since the grain structure is already aligned in the extrusion due to the high pressures during forming. That is why Nickies are made out of an extruded tube, rather than solid billet. Not to mention it adds a wee bit of time to machining to have to hog out a solid tube....and talk about scrap!

Charles Navarro
LN Engineering
http://www.LNengineering.com
Aircooled Precision Performance

Posted by: ArtechnikA Apr 16 2004, 03:40 AM

cool, thanks.

i'd love to know what's going on inside the metal, but i do know there are heat-treat ranges (the 'T' numbers) for aluminum alloy so i guess there's a theoretical basis, and you've done the comparisons, so -something- must be happening...