Myths of Cryogenics
Be Bold. Some of the greatest inventions were stumbled upon. The history of cryogenics is similar in its origin but there have been many advancements in the field. Cryogenics is a disruptive technology.
1. Freezing metal can’t possibly change it.
We hear this a lot, even from metallurgists. The reality is that many things can happen in the crystal structure as the temperature is reduced. In fact, Martensitic transformations have been observed at temperatures as low as 4°K. (Reference: Kulin, S.A. and Cohen, M., Trans, AIME, 188 (1950), p.1139) Basic metallurgy textbooks even give equations that describe some of the things that are happening, but since these things are not generally used in heat-treating most metallurgists and engineers simply do not remember them.
2. That can’t possibly work.
We have independent lab reports, research from major universities such as Illinois Institute of Technology, Louisiana Tech University, University of Trento, Italy and National Heat Treatment Center of Dublin. We have tech papers from NASA, Los Alamos, the US Army Aviation and Missile Command and many others. They all say the process works. Where is the proof of those who say the process can’t work?
3. We’ve never heard of that, so it can’t be any good.
This is neat. We are in a time when technology is bringing forth new wonders in unprecedented volumes. Of course, we hear this a lot from engineers who must assume that they learned all of engineering in their college back in the 1960’s and nothing has changed since then.
4. Your competition calls it Cryogenic Tempering or Deep Cryogenic Tempering
People who use these terms were just looking for things that sound good in marketing the process. First of all, cryo processing is not a tempering process. Cryogenic tempering is a meaningless term. Tempering is defined in ASM’s Metal Handbook as “..reheating hardened steel or hardened cast iron to some temperature below the eutectoid temperature for the purpose of decreasing hardness and increasing toughness.” That is not cryogenic processing. Also, it is not deep. The Cryogenic Society of America defines cryogenics as starting at -244oF. Deep cryogenics is more properly processing near -450oF, which is very close to as low as you can go. We can do deep cryogenic processing.
5. Cryogenics is freezing dead bodies.
We hear this a lot. Freezing bodies with the hope they can be thawed alive is called CRYONICS. Yes, they use cryogenic temperatures, but “cryogenics” is a huge field with applications in food freezing, physics, and even cryogenic treatment of materials.
6. If that were any good, we would have been using it a long time ago.
Refer to the third answer above. Galileo ran into this a lot.
7. Cryogenics is VOODOO Science.
They say this because we can’t totally explain why it works. Studies by the US Army, US national laboratories, and major universities all over the world that say it does work. Science is based on observing things we do not understand, observing that they are repeatable, formulating a theory to explain the observations and then testing the theory by experimentation. There is nothing in scientific method that says that you cannot use something that you don’t understand. If we needed to use only totally understood phenomenon, all progress would be stopped. Science does not flow neatly out of the laboratory into general use. Economics drives what is used in the real world. Cryogenic processing has proven economically desirable.
8. Cryogenic processing makes steel denser.
Interesting: It converts austenite to martensite. The martensite crystal is about 4% bigger than the austenite crystal. In order for the steel to become denser, it will also have to become heavier to make up for the increased volume.
9. Cryogenic processing changes the molecular structure of metals.
Metals get their metallic properties because they are crystalline in structure and not molecular.
10. Your machine is round.
It is round because it is vacuum insulated. It is vacuum insulated because that is the best way to insulate things at -300oF. Rectangular machines have lousy airflow, have heavy structures that pull the cold right out of the chamber, have insulation that breaks down over time and is very hard if not impossible to renew. They have extensive bracing that act as heat bridges. They have problems with door sealing, which lets lots of heat into the chamber. Some square machines actually bend during the cycle so that doors warp open. If square were better, liquid nitrogen would be shipped in square containers
11. If we make our product last twice as long, we won’t sell as many of them.
If you make a better product, your competition will suffer. Their volume will go down; in some cases you may sell fewer widgets, but still make more profit. If you don’t make the best product for the money, someone eventually will. We have a lot of trouble when salesmen get involved in the decision to use cryogenics or not. Their advancement (as well as upper management’s) is based on increasing sales dollars, not increasing profits. .
12. They have a computer controlling their machine! They claim it to be an advantage.
The computer is just doing the same thing that an industrial grade microprocessor based temperature control would do. There is a reason that heat-treaters do not use personal computers on their ovens and it has to do with reliability. .
13. Cryogenics will make the metal brittle.
It has a corollary that cryogenics will make the metal too hard. We usually hear this from people who don’t know about cryogenics. Cryogenic processing rarely makes metal significantly harder. If it does, there was a big heat-treating problem. It rarely makes metal brittle; in fact it often allows the metal to bend more than it would before treatment. If cryogenic processing makes metal brittle, how come we can increase valve spring life up to seven times in racing engines? Metals can be brittle while they are at very cold temperatures, but that does not mean they remain brittle when they warm up. Remember, metals get soft when they get hot, but we use heat to harden them.
14. Cryogenics is only for bad heat treat.
Well, it will convert retained austenite to martensite in a big way. So will cold treating to -140 degrees F. That doesn’t explain why the US Army found that cryogenically treating cold treated gear metal (9310) doubled the life of the metal, or why cryogenic processing increases the life of aluminum, copper, titanium, etc.
15. Our tooling lasts long enough so we see no need to treat it.
It would seem to us that “long enough” is long enough only when the tooling just outlives the market life of the product. Actually, we are looking for tooling costs to be optimized over the product market life. Especially when you know that they are replacing their expensive tool several times a year
16. We can’t spend any more on tooling.
What is really meant is that they cannot spend any more money up front. Success is measured in how little your area spends while producing the same amount.
One very large manufacturer of plastic containers and household goods tried using cryogenic processing on the blades of their scrap grinders. Normally, they would change these blades every three months. They lasted in the machine for two years. The engineer who put them into the machine was bewildered. It would save his division a lot of money. It is his job to save his division money.
18. We don’t have time for that.
Production delays may be a part of someone else’s budget.
19. You Don’t Have Any Research To Support My Application
We may not have research to support the use of cryogenic processing on every widget. If someone has researched your particular situation before you, it is probably your competitor.
20. Cryogenic Processing Will Not Work On (insert material name here) because there is no retained austenite in it.
Metallurgists often say this. It is taught that the only use of cryogenics is to convert austenite to martensite. Following that thought, Cryogenics will not work on austenitic stainless steels, cast iron and non-ferrous metals. It does work on these materials. We have had customers who, while observing huge savings on downtime and part replacement, were ordered by the corporate metallurgist to stop using cryogenics because It can’t work on that metal. One of the biggest uses for cryogenic processing is for brake rotors, which have a pearlitic microstructure. No Austenite, no martensite.
Cryogenics works on brake rotors because it turns the austenite into martensite.
Brake rotors are made from pearlitic cast iron…..no martensite, no austenite. Yet we’ve proven beyond any doubt that brake rotors benefit greatly from our process
21. Cryogenic processing is easy. Just drop the part in liquid nitrogen.
Dropping parts in liquid nitrogen is a good way to create cracks, metal gravel, and such. The research shows that some of the good stuff you get out of cryogenic processing comes from time the part spent going down to -300F, how long it stayed there, and the time it took to come back up. If you do not control these, you are basically wasting your time. Hit the link http://www.youtube.com/watch?v=yg45ILXZ26w.
In this short video made by Jefferson Labs you will see what the stresses created by dipping can do to a piece of rubber. Similar things happen to steel.
22. A fellow walked into our booth at the PRI show and claimed that cryogenics was a hoax because he was a scientist, he had tried it, and there was no increase in fatigue life.
Upon examination, we found that this gentleman, who was a metallurgist for a major spring company, had dropped a spring into liquid nitrogen and claimed that as a cryogenic process.
One of our engine-building customers likes to tell the story about a customer who wanted to have a crankshaft treated (before he met us) and they took it to a heat treater that dunked it in liquid nitrogen. The crankshaft cracked in short order. Actually, it cracked when it hit the liquid nitrogen. Heat treaters typically do not know about cryogenics. Please ask a lot of questions before sending your parts in.
23. We don’t care that it works. We have to know why it works.
This is a sticky point…Many products today such gorilla glass by Dow Corning are used and few others know how and why it works
Knowing why it works is not essential to science.
Here are a few quotes from some scientists:
“The purpose of science is not to obtain a proper solution of the problem discussed by philosophers, namely, what causes objects to behave as they do.” Galileo, Dialogs Concerning Two New Sciences
“To establish the laws of phenomena I have not inquired into the cause one might assign to these forces” Ampere
“In order to predict what is useful to us, it will not be necessary to know the mechanism.” Henri Poincare
Similar views were expressed by Newton & Fourier
24. We want a coating to solve our wear problem.
Some believe that gold or ceramic coating that is .00005 inches thick will armor a piece of metal against anything because it is hard. The fact is that the material under the coating cannot bear the strain. Coatings are fine when you are faced with a problem of reducing friction, inhibiting corrosion, or resisting light abrasion. Coatings are like egg shells.
25. Nobody has ever blown a cryogenically treated engine.
We found this on a competitor’s web site. Racers can break anything, and we have the fragments to prove that. Blowing an engine can be caused by many factors that cryogenics cannot address. i.e. loss of coolant and loss of lubrication.
26. We can’t afford to change the prints.
This came from a manufacturer of large earth moving equipment. We treated some 12.5mm drills for them, which they tested and found far superior to untreated drills. They calculated that it would save them about $75,000/year on this one operation on one part number. This was about 11 years ago. They’ may have spent millions extra on that one operation since then….On that one operation and part.
27. We don’t think it works.
True Story told by both the metallurgist involved and the owners of the company at the time cryogenics was initiated. The company was a major manufacturer of firearms. The metallurgist used Cryogenics and documented savings of over $1,000,000 the first year on tooling. The second year was about $2,500,000. At this point, the company was sold. The Metallurgist was downsized out.
The running of the cryogenic processor was turned over to the maintenance department who promptly shoved it into a corner. When the new management asked about it, maintenance told them they didn’t think that process does anything. About a year later, the accounting department got around to looking at the tooling budget. It had skyrocketed. The company ended up buying a new cryoprocessor. That same Metallurgist is a highly respected “mover and shaker” in ASM. We love telling your story, Fred!
28. We won’t use it until we are being beaten by it.
This came from a highly respected Sprint Cup team owner. He came up with this pronouncement when asked if his team would like to explore the possibilities of using cryogenics. Since over half the cars in Sprint Cup series are using parts we cryogenically processed, and they are winning, I would guess that this fellow is a little late. The trouble is, we have confidentiality agreements with some of the teams we work with, and we can’t tell this guy who we work with.
More to come.