Tweet
I was doing some research and found this excellent article. Maybe it can be added to the tech database.
http://www.fountainheadcryo.com/what_the_heck_is_it.htm
Below is an email correspondence we had with a customer. He asked very good questions and we decided to use it here. It does deal with automotive parts but also gives a good overall view of the process. The name and place has been changed to protect this guy from spam and other nefarious nincumpoops. Our responses are in Italics.
Hello,
My Name is Jerry Stiller, and I own a performance Shop based in Juno, Alaska. I am a member of the internet based International MR2 Owners Club, and your company was mentioned on the list (be prepared for a barrage of E-mails... this is a very vocal group), so I thought I would contact you to answer some questions that I have, and hopefully set up a time to send in a number of parts for treatment. I have long heard of the benefits of cryogenic treatment, and it has been suggested that I use this treatment in building my customer, as well as my own race vehicles, though I have not had the opportunity to do so until now. All information I have heard, has either been in magazines written for the masses (as opposed to seasoned engine builders), or from a friend of a friend who has used the process with good results. From what I have gathered, the process works, and is a tremendous benefit to the strength of the part treated,
This will be a bit of a metallurgical lesson so please bare with me. I feel it is an essential piece of information for you to get the full understanding. (Note: For those engineers and metallurgists out there who read this, take a chill pill. If you have constructive criticism that will be welcome, if you just want to let us know how much you know, we already know your smart.)
The reason a piece of steel is heat treated is to make it wear longer (hardening) and become stronger. Tooling and gears, for example, are hardened because they are made to wear as long as possible. When steel is first made it is in a state called austenite (you may have heard of austenitic stainless). Austenite has a specific arrangement of carbon and iron atoms within its crystalline structure. Austenite is a soft phase and is very easy to wear the carbon and iron atoms away. Because austenite is soft it is very easy to machine using conventional tooling. Gears and other tooling are often rough machined in this state. The tool will then be heat treated. Depending on the chemical composition and the properties needed it will be heated up to 1600 F or higher. At this temperature the atoms that make up the austenitic crystalline structure shift and become what's called martensite. (A good analogy is coal and diamond. They are both made solely of carbon. In coal the carbon atoms are not arranged which makes them readily available to be taken away by wear or some other reaction like heat. In a diamond the carbon atoms have a very different bonding arrangement. Making it the hardest substance known. The way a diamond is formed is through heat and pressure and time, a lot of it.)
Now with the steel at the elevated temp. the tool is quenched. Cooled very quickly in air or water or oil. If we would let the steel cool on its own the martensite would just transform back into austenite, so we have to quench to seal those changes in. When the steel is quenched it obviously cools from the outside in. So it is not all cooling at the same rate. The outside will be mostly martensite and the inside will get progressively more austenitic. Since warping does happen the as quenched tool must be ground to final dimensions taking away the outer most layer which is mostly martensite. Since martensite is very hard and very brittle the tool must be run through a temper cycle (heating up to 300 to 400 F) to add strength to the martensite. If we didn't temper the metal would crack with little applied pressure. Now we get to the cryo. Anytime after the heat treat, days, months, years, the tooling can be cryo treated. The cryo treatment will take the retained austenite (The austenite that did not convert into martensite in the heat treatment) and convert it into martensite. Now almost 100% of your tool structure is martensitic. Cryo treatment also precipitates very fine carbide particles out of the crystalline structure and they migrate into the grain boundaries. This holds the entire matrix together much better and the carbide particles are extremely wear resistant thus helping the martensite resist wear. So the dimensional stability comes from not having two phases of metal existing side by side and the wear resistance comes from the martensite and carbide particles. As you can tell the whole process is very dependent on how the heat treatment was done. If the heat treatment made the part into a piece of crap cryoing it will just make it a cold piece of crap.
incorporated into a build up. Meaning, if I am building a completely balanced and blueprinted engine, at what point should I send in the various parts to be treated? For example, should I send in the crank before, or after I have it verified for straightness,
If it doesn't make any difference to you, sending it to us prior to final grinding or machining would be optimum. The process can be done anytime after the crank is made. We have not had any problems doing them at any stage. But this really depends on the heat treat process. If the heat treatment was not done correctly and we cryo treat after you have it verified; the stresses setup in the improper heat treat will relieve themselves in the cryo process. We warn of this because it would be the cryo that would be blamed for harming the crank when it really was the way it was heat treated. We do have some customers who have their stuff drop shipped to us from the manufacturer. We treat it and send it off to them for finishing. This works well for both. This is the same for engine blocks and heads. With blocks the benefit will be two-fold. The cryo process puts the entire mass of the block through a stress relief. The reason old, old blocks are better than new ones is because they have been through many, many thermal cycles and they obtain a dimensional stability from all of those cycles. The stresses set up in them from the forming process take time to work themselves out. The cryo process does this all at once. So if you cryo- treat a block before machining you will find it will not move from where it was machined. Also, the bores will stay round as they heat up to operating temp. I'm sure I don't have to tell you the benefits of a round bore over an oval bore. Same thing with the heads.
or should I send in the various reciprocating components (bearings, pistons, con rods) before or after the balancing process?
[/i]With these smaller items sending them after balancing is fine. You can decide when it is most convenient for you.[/i]
Here's a unique one... I am having various items ceramic coated, should I have the cryo treatment done before this process?
These items must be done prior to ceramic coating. The metal definitely contracts as it is cooled. The ceramic coating will not contract with cooling. This will create stresses between the metal and the coating, and stress is not good. This is only valid for ceramic coatings, most other coatings, Titanium Nitride, ARVIN, Chrome, will be enhanced if done with the coating on.
I understand that extreme heat or cold will slightly warp metal, so I am completely open to your suggestions.
You are correct. The warping also comes from heating or cooling too quickly. We cool from 1/2 to 2 degrees per minute. This gives the entire mass time to equalize and thus prevents thermal shock.
Could you please suggest which parts benefit from the cryo treatment? I understand the con rods, crank and such, but what else would benefit?
In addition to the items mentioned above, the axels, the brakes, the tranny (which I see you mention below and I'll address it there.) bearings, main caps, transfer case, clutch plate, fly wheel etc. Really the entire engine from the block in. But not an assembled turbo. Anything you get treated should be totally disassembled and clean. Don asked about his turbo that has just been balanced. He didn't want to take it apart. I appreciate that but with the phase changes going on in the metal and the shafts and bearings being very tightly toleranced I cannot take a chance that the turbo be harmed. I told Don that I have no problem doing these things individually but not assembled.
Also, the car and engine/tranny combo that I use and race most is the 3S-GTE found in the 90-95 MR2 Turbo. I have found that the transmission itself becomes the weak link when you reach the 450-500 RWHP limit. Thus my current race car is stuck at this point. The problem is that the actual teeth of the gears begin to break off, thus stripping out a gear sending metal through the case causing a serious failure throughout. It was suggested by JUN USA that cryo treatment of the transmission may give me that extra strength to push me through that Torque limit.
Again go back to the discussion on strength. Here we should know if the teeth are shearing because they have been worn to the point where they break. Or is the metal too weak to be able to take the amount of torque your producing. It could be a heat treat problem in that if the metal was not quenched and tempered correctly the teeth can become brittle and they will shear with any impact applied. With all that said and all things being equal a cryo treated tranny should last three or more times longer than a non-treated one in the area of wear.
I just happen to have a brand new, never been installed Toyota E-153 Tranny in a Toyota crate at my shop. The transmission has only been removed from the crate to remove the viscous coupling LSD, and install a full lock up clutch style LSD. What would be your suggestion for treating the transmission? Should I disassemble it? Should I break it down to each of the hundred or so internal components and send it to you? Should I split the case, and send you the two shafts with all gear sets installed for treatment? Or, my favorite.... Can I send you the full Tranny for a treatment throughout?
Here the best thing may be to send the two shafts with the gear sets installed. This will reduce your weight (and weight is money!!) since the case does not see wear you would be paying me to do that which will not be helped all that much. You have to do the cost/benefit. Will it cost you more of your time to take it down to this point than you will be paying to just treat the whole thing? Since everything gets heated after being cryo'd you should take out any rubber seals.
[ May 07, 2003: Message edited by: camaro_speedemon ]</p>
http://www.fountainheadcryo.com/what_the_heck_is_it.htm
Below is an email correspondence we had with a customer. He asked very good questions and we decided to use it here. It does deal with automotive parts but also gives a good overall view of the process. The name and place has been changed to protect this guy from spam and other nefarious nincumpoops. Our responses are in Italics.
Hello,
My Name is Jerry Stiller, and I own a performance Shop based in Juno, Alaska. I am a member of the internet based International MR2 Owners Club, and your company was mentioned on the list (be prepared for a barrage of E-mails... this is a very vocal group), so I thought I would contact you to answer some questions that I have, and hopefully set up a time to send in a number of parts for treatment. I have long heard of the benefits of cryogenic treatment, and it has been suggested that I use this treatment in building my customer, as well as my own race vehicles, though I have not had the opportunity to do so until now. All information I have heard, has either been in magazines written for the masses (as opposed to seasoned engine builders), or from a friend of a friend who has used the process with good results. From what I have gathered, the process works, and is a tremendous benefit to the strength of the part treated,
This will be a bit of a metallurgical lesson so please bare with me. I feel it is an essential piece of information for you to get the full understanding. (Note: For those engineers and metallurgists out there who read this, take a chill pill. If you have constructive criticism that will be welcome, if you just want to let us know how much you know, we already know your smart.)
The reason a piece of steel is heat treated is to make it wear longer (hardening) and become stronger. Tooling and gears, for example, are hardened because they are made to wear as long as possible. When steel is first made it is in a state called austenite (you may have heard of austenitic stainless). Austenite has a specific arrangement of carbon and iron atoms within its crystalline structure. Austenite is a soft phase and is very easy to wear the carbon and iron atoms away. Because austenite is soft it is very easy to machine using conventional tooling. Gears and other tooling are often rough machined in this state. The tool will then be heat treated. Depending on the chemical composition and the properties needed it will be heated up to 1600 F or higher. At this temperature the atoms that make up the austenitic crystalline structure shift and become what's called martensite. (A good analogy is coal and diamond. They are both made solely of carbon. In coal the carbon atoms are not arranged which makes them readily available to be taken away by wear or some other reaction like heat. In a diamond the carbon atoms have a very different bonding arrangement. Making it the hardest substance known. The way a diamond is formed is through heat and pressure and time, a lot of it.)
Now with the steel at the elevated temp. the tool is quenched. Cooled very quickly in air or water or oil. If we would let the steel cool on its own the martensite would just transform back into austenite, so we have to quench to seal those changes in. When the steel is quenched it obviously cools from the outside in. So it is not all cooling at the same rate. The outside will be mostly martensite and the inside will get progressively more austenitic. Since warping does happen the as quenched tool must be ground to final dimensions taking away the outer most layer which is mostly martensite. Since martensite is very hard and very brittle the tool must be run through a temper cycle (heating up to 300 to 400 F) to add strength to the martensite. If we didn't temper the metal would crack with little applied pressure. Now we get to the cryo. Anytime after the heat treat, days, months, years, the tooling can be cryo treated. The cryo treatment will take the retained austenite (The austenite that did not convert into martensite in the heat treatment) and convert it into martensite. Now almost 100% of your tool structure is martensitic. Cryo treatment also precipitates very fine carbide particles out of the crystalline structure and they migrate into the grain boundaries. This holds the entire matrix together much better and the carbide particles are extremely wear resistant thus helping the martensite resist wear. So the dimensional stability comes from not having two phases of metal existing side by side and the wear resistance comes from the martensite and carbide particles. As you can tell the whole process is very dependent on how the heat treatment was done. If the heat treatment made the part into a piece of crap cryoing it will just make it a cold piece of crap.
incorporated into a build up. Meaning, if I am building a completely balanced and blueprinted engine, at what point should I send in the various parts to be treated? For example, should I send in the crank before, or after I have it verified for straightness,
If it doesn't make any difference to you, sending it to us prior to final grinding or machining would be optimum. The process can be done anytime after the crank is made. We have not had any problems doing them at any stage. But this really depends on the heat treat process. If the heat treatment was not done correctly and we cryo treat after you have it verified; the stresses setup in the improper heat treat will relieve themselves in the cryo process. We warn of this because it would be the cryo that would be blamed for harming the crank when it really was the way it was heat treated. We do have some customers who have their stuff drop shipped to us from the manufacturer. We treat it and send it off to them for finishing. This works well for both. This is the same for engine blocks and heads. With blocks the benefit will be two-fold. The cryo process puts the entire mass of the block through a stress relief. The reason old, old blocks are better than new ones is because they have been through many, many thermal cycles and they obtain a dimensional stability from all of those cycles. The stresses set up in them from the forming process take time to work themselves out. The cryo process does this all at once. So if you cryo- treat a block before machining you will find it will not move from where it was machined. Also, the bores will stay round as they heat up to operating temp. I'm sure I don't have to tell you the benefits of a round bore over an oval bore. Same thing with the heads.
or should I send in the various reciprocating components (bearings, pistons, con rods) before or after the balancing process?
[/i]With these smaller items sending them after balancing is fine. You can decide when it is most convenient for you.[/i]
Here's a unique one... I am having various items ceramic coated, should I have the cryo treatment done before this process?
These items must be done prior to ceramic coating. The metal definitely contracts as it is cooled. The ceramic coating will not contract with cooling. This will create stresses between the metal and the coating, and stress is not good. This is only valid for ceramic coatings, most other coatings, Titanium Nitride, ARVIN, Chrome, will be enhanced if done with the coating on.
I understand that extreme heat or cold will slightly warp metal, so I am completely open to your suggestions.
You are correct. The warping also comes from heating or cooling too quickly. We cool from 1/2 to 2 degrees per minute. This gives the entire mass time to equalize and thus prevents thermal shock.
Could you please suggest which parts benefit from the cryo treatment? I understand the con rods, crank and such, but what else would benefit?
In addition to the items mentioned above, the axels, the brakes, the tranny (which I see you mention below and I'll address it there.) bearings, main caps, transfer case, clutch plate, fly wheel etc. Really the entire engine from the block in. But not an assembled turbo. Anything you get treated should be totally disassembled and clean. Don asked about his turbo that has just been balanced. He didn't want to take it apart. I appreciate that but with the phase changes going on in the metal and the shafts and bearings being very tightly toleranced I cannot take a chance that the turbo be harmed. I told Don that I have no problem doing these things individually but not assembled.
Also, the car and engine/tranny combo that I use and race most is the 3S-GTE found in the 90-95 MR2 Turbo. I have found that the transmission itself becomes the weak link when you reach the 450-500 RWHP limit. Thus my current race car is stuck at this point. The problem is that the actual teeth of the gears begin to break off, thus stripping out a gear sending metal through the case causing a serious failure throughout. It was suggested by JUN USA that cryo treatment of the transmission may give me that extra strength to push me through that Torque limit.
Again go back to the discussion on strength. Here we should know if the teeth are shearing because they have been worn to the point where they break. Or is the metal too weak to be able to take the amount of torque your producing. It could be a heat treat problem in that if the metal was not quenched and tempered correctly the teeth can become brittle and they will shear with any impact applied. With all that said and all things being equal a cryo treated tranny should last three or more times longer than a non-treated one in the area of wear.
I just happen to have a brand new, never been installed Toyota E-153 Tranny in a Toyota crate at my shop. The transmission has only been removed from the crate to remove the viscous coupling LSD, and install a full lock up clutch style LSD. What would be your suggestion for treating the transmission? Should I disassemble it? Should I break it down to each of the hundred or so internal components and send it to you? Should I split the case, and send you the two shafts with all gear sets installed for treatment? Or, my favorite.... Can I send you the full Tranny for a treatment throughout?
Here the best thing may be to send the two shafts with the gear sets installed. This will reduce your weight (and weight is money!!) since the case does not see wear you would be paying me to do that which will not be helped all that much. You have to do the cost/benefit. Will it cost you more of your time to take it down to this point than you will be paying to just treat the whole thing? Since everything gets heated after being cryo'd you should take out any rubber seals.
[ May 07, 2003: Message edited by: camaro_speedemon ]</p>
