Dr. Freeze
New Member
- Joined
- Jun 18, 2003
I recieved quite a few email after my post regarding cryogenic processing of TB crankshafts in the topic; "What material are TR cranks made of." Every email wanted to know more about the process so instead of answering dozens of emails seperately about it I though I would post an article I wrote on the process that will be published in "Fastest Street Car" magazine in the near future...
I want to emphasize that though I own a cryogenic processing business that specializes in motorsports components; this is NOT a solicitation for my business but an informational article aimed at answering questions regarding the process. Thanks.
-Jeb
Cryogenics and Motorsports:
Improving Racing Through Technology
Have you ever noticed the “trickle down” effect that motorsports receives from the aerospace industry? A/N plumbing, exotic materials, new machining techniques, and high tech processes all find their way into our racecars… A perfect example of this is deep cryogenic processing; aerospace industries have used this treatment for over thirty years on critical components to increase their durability, relieve residual stresses, stabilize critical dimensions, and increase overall lifespan. Through the research and development of aeronautics, cryogenic processing progressed into the industrial and manufacturing segment as a means of improving tooling life; then it made its way into the firearms industry in the form of stress relieving high grade target rifle barrels. It also found its way into other sporting goods such as aluminum softball bats and golf clubs; many major manufacturers use the process to provide greater striking distance for their customers. Finally it has made its way to our sport. Today it is embraced by professional racers in many different sanctioning bodies, NASCAR, Formula One, Trans-Am, and the NHRA are but a few of the organizations whose racers use the cryogenic process to ensure their components never let them down at a critical moment. But, like many racers, you may not be familiar with the process and why it is something that you should look into.
What is Cryogenics and What Are Its Results and Benefits?
Cryogenics typically draws images of bodies frozen in suspended animation awaiting the day a cure for disease is found and they can be reanimated; in our case though it is much more mundane. Cryogenic processing was discovered accidentally by NASA engineers who found that some components on satellites were markedly stronger after they returned from the cold vacuum of space. But in more common terms it can actually be viewed as an extension of the heating/quenching/tempering cycle. We will examine Deep Freeze Cryogenics’ Vari-Cold™ process to shed some light on both the process itself and the physical attributes that are found after processing.
The Vari-Cold process is based on a predetermined thermal cycle that involves cooling of the material in a computer controlled cryogenic chamber. Vari-Cold utilizes the ramping benefits of ultra-cold nitrogen gas in conjunction with the deep cryogenic “soak” benefits provided by the use of liquid nitrogen. Materials are initially cooled to cryogenic temperatures with nitrogen gas utilizing precisely controlled temperature profiles, then slowly introduced to liquid nitrogen for the duration of the “soak” period (approximately 20 hours). The liquid phase provides the most efficient and uniform deep cryogenic soak at a constant temperature of –320 degrees Fahrenheit (impossible to achieve with gas alone). Materials are then slowly brought back to ambient temperatures. At that time, those materials requiring a post-cryo tempering are moved to a specially designed oven to complete this critical procedure.
The use of precisely controlled temperature profiles avoids any possibility of thermal stress that is experienced when a material or part is subjected to abrupt or extreme temperature changes. Though liquid nitrogen is used as a refrigerant, no material is introduced to the liquid until it has been slowly cooled and stabilized at cryogenic temperatures by the gaseous phase of the process.
Cryogenically treated materials show a marked increase in wear resistance without any discernable change in dimensional or volumetric integrity. The treated material becomes less brittle, without a significant change in overall hardness. The most significant and consistent change is the increased toughness, dimensional stability, and the ability to withstand increased abuse. The process is also used extensively to relieve residual and tensile stresses produced by forging, casting, machining, or welding of the subject material.
Two main changes in the microstructure of the material occur as a result of cryogenic processing. These changes are the principal reasons for the dramatic improvement in wear resistance.
First the retained austenitic grain structure (a loose knit, weak grain structure always present after heat treatment) is transformed into the harder, more durable martensitic grain structure. The range of retained austenite in a material after tempering may be as high as 50 percent or as low as five percent dependant upon the tempering equipment and the accuracy of the operator. Cryogenic treatment simply continues the conversion initiated by heat treatment, whereby 100 percent of the retained austenite is converted to martensite. As greater amounts of this retained austenitic structure is transformed and the wear resistant martensitic grain is increased, the material obtains a more uniform hardening. It can be viewed as a “through hardening” that goes above and beyond what is found in the heat treating cycle.
Second, fine eta carbide particles or precipitates are formed during the long cryogenic “soak” depending upon the alloying elements of the material. These are in addition to the larger carbide particles present before the cryogenic processing. The fine particles or “fillers,” along with the larger particles, form a dense, more coherent, and much tougher matrix in the material.
The surface energy of the martensitic structure is higher than the surface energy of the austenitic structure due to differences in their atomic structures. In potential adhesive-wear situations (like those found in the reciprocating assemblies of engines and driveline components), the martensitic grain is less likely to tear out than is the austenitic structure. The adhesive-wear coefficient is decreased, and the wear rate is decreased. In abrasive-wear situations (like piston to cylinder bore wear and clutch wear), both the martensitic formation and the fine eta carbide formation work together to reduce wear. The additional fine carbide particles help support the martensite matrix. This makes it more difficult to dig out lumps of the material. When a hard particle is squeezed onto the surface, the carbide matrix resists plowing and wear is reduced.
Almost any kind of ferrous and non-ferrous material, for whatever application, will exhibit a lifespan increase. As fewer parts are needed there is a substantial savings for the racer. Additionally decreased instances of component failure and wear will allow you to go more rounds and win more races with less time involved in maintenance and part replacement.
Motorsports Applications and Benefits
As recounted from above, just about any component that is subject to wear can be improved through cryogenic processing. It doesn’t matter whether it’s nodular iron, forged steel, aluminum, titanium, and even some composites (like nylon, delrin, and Teflon); they all exhibit increased durability and lifespans. Anywhere there is a possibility of wear, whether it is friction related, rolling, abrasive, adhesive, or impact; cryogenically treated components will keep the racer on the track. During the course of DFC’s research and development some components simply stood out after processing; the following are some examples.
Engine blocks and reciprocating assemblies are among the most significant of all components that show remarkable improvements after cryogenic treatment. Cast iron blocks that have been processed show decreased wear on the cylinder wall and have a reduced coefficient of friction resulting in better cylinder sealing. The further benefits of dimensional stabilization and stress relief are evident when you tear your engine down after the season; you will no doubt notice that your cylinders are no longer round but have become oval. Why? Whenever you bore, hone, or perform any other machining they become stressed. Pistons become oval when heated and wear against the cylinder wall forcing a similar shape on them; then you have poor sealing and increased leakdown resulting in decreased power. The cryogenic treatment removes these stresses on both the block and the pistons so now when they become hot there is no stress to cause these distortions. The pistons and cylinders still grow but they do so uniformly and the cylinder seal remains constant. When the engine block is cryogenically treated and the stresses are removed the dimensions stay constant and the reciprocating assembly will remain in proper alignment. Crankshafts and their bearings will resist the adhesive wear common in their usage and it is often found that bearings can be reused after an entire season because there is no wear evidenced. Typically a racer will see a four to eight percent increase in power production over an identical untreated engine.
Among the most highly stressed components in an engine are the valvetrain components. Valve springs themselves are the number one producer of heat in an engine due to their vibratory nature. Through cryogenic processing they stabilize at their rated pressure much more quickly and remain within spec for a longer length of time. Pushrods are less likely to bend or break after treatment, as are rocker arm assemblies. Camshafts and lifters are among the most significant of increases found after cryogenic treatment. The flat tappet camshafts and lifters common in many classes due to camshaft rules exhibit durability increases sometimes in excess of 400 percent. A few of DFC’s clients even report that the typical break-in procedure for flat tappet cams is no longer required! Roller camshafts and lifters in the racing environment typically have very aggressive ramp profiles that require extreme spring pressures in order to maintain lifter contact. These pressures are extremely hard on the needle bearings in the lifters as well as on the cam lobe itself. Cryogenically treated roller cams and lifters will live a longer and more productive life ensuring consistent valve timing.
Driveline components such as ring and pinions, axles, transmissions, clutch assemblies, and braking assemblies are subjected to some of the harshest punishment in the motorsports environment. The impact wear on differentials and axles in drag racing can be significantly reduced through cryogenic treatment. A torque converter manufacturer unwilling to convert to spragless configuration increased their torque carrying capability by over 250 lb/ft. on their inner and outer sprags through DFC’s Vari-Cold process. Brake rotors in a road-racing environment have shown lifespan increases of 500 percent. The process allows for more aggressive pads to be used without a detrimental affect on rotor life. Input and output shafts in transmissions, even those built out of the ultra-tough Vasco 300m material, show marked increases in torque handling capacity after cryogenic treatment.
Unfortunately the process does have a downfall; that downfall is that those unfamiliar with it will persist in their present thinking that it’s all a good marketing ploy. Afterall, cryogenic processing shows no outwardly visual change and if you can’t see it, it doesn’t exist, right? It doesn’t feel different either. So many racers dismiss a product or process because the physical benefits cannot be seen or felt; but the results at the end of the season speak for themselves. Perhaps some day it will be common knowledge that cryogenically treated components last longer and produce more consistent results. If you’re experiencing breakage or want that last little edge what do you have to lose? The guy in front of you knows…
I want to emphasize that though I own a cryogenic processing business that specializes in motorsports components; this is NOT a solicitation for my business but an informational article aimed at answering questions regarding the process. Thanks.
-Jeb
Cryogenics and Motorsports:
Improving Racing Through Technology
Have you ever noticed the “trickle down” effect that motorsports receives from the aerospace industry? A/N plumbing, exotic materials, new machining techniques, and high tech processes all find their way into our racecars… A perfect example of this is deep cryogenic processing; aerospace industries have used this treatment for over thirty years on critical components to increase their durability, relieve residual stresses, stabilize critical dimensions, and increase overall lifespan. Through the research and development of aeronautics, cryogenic processing progressed into the industrial and manufacturing segment as a means of improving tooling life; then it made its way into the firearms industry in the form of stress relieving high grade target rifle barrels. It also found its way into other sporting goods such as aluminum softball bats and golf clubs; many major manufacturers use the process to provide greater striking distance for their customers. Finally it has made its way to our sport. Today it is embraced by professional racers in many different sanctioning bodies, NASCAR, Formula One, Trans-Am, and the NHRA are but a few of the organizations whose racers use the cryogenic process to ensure their components never let them down at a critical moment. But, like many racers, you may not be familiar with the process and why it is something that you should look into.
What is Cryogenics and What Are Its Results and Benefits?
Cryogenics typically draws images of bodies frozen in suspended animation awaiting the day a cure for disease is found and they can be reanimated; in our case though it is much more mundane. Cryogenic processing was discovered accidentally by NASA engineers who found that some components on satellites were markedly stronger after they returned from the cold vacuum of space. But in more common terms it can actually be viewed as an extension of the heating/quenching/tempering cycle. We will examine Deep Freeze Cryogenics’ Vari-Cold™ process to shed some light on both the process itself and the physical attributes that are found after processing.
The Vari-Cold process is based on a predetermined thermal cycle that involves cooling of the material in a computer controlled cryogenic chamber. Vari-Cold utilizes the ramping benefits of ultra-cold nitrogen gas in conjunction with the deep cryogenic “soak” benefits provided by the use of liquid nitrogen. Materials are initially cooled to cryogenic temperatures with nitrogen gas utilizing precisely controlled temperature profiles, then slowly introduced to liquid nitrogen for the duration of the “soak” period (approximately 20 hours). The liquid phase provides the most efficient and uniform deep cryogenic soak at a constant temperature of –320 degrees Fahrenheit (impossible to achieve with gas alone). Materials are then slowly brought back to ambient temperatures. At that time, those materials requiring a post-cryo tempering are moved to a specially designed oven to complete this critical procedure.
The use of precisely controlled temperature profiles avoids any possibility of thermal stress that is experienced when a material or part is subjected to abrupt or extreme temperature changes. Though liquid nitrogen is used as a refrigerant, no material is introduced to the liquid until it has been slowly cooled and stabilized at cryogenic temperatures by the gaseous phase of the process.
Cryogenically treated materials show a marked increase in wear resistance without any discernable change in dimensional or volumetric integrity. The treated material becomes less brittle, without a significant change in overall hardness. The most significant and consistent change is the increased toughness, dimensional stability, and the ability to withstand increased abuse. The process is also used extensively to relieve residual and tensile stresses produced by forging, casting, machining, or welding of the subject material.
Two main changes in the microstructure of the material occur as a result of cryogenic processing. These changes are the principal reasons for the dramatic improvement in wear resistance.
First the retained austenitic grain structure (a loose knit, weak grain structure always present after heat treatment) is transformed into the harder, more durable martensitic grain structure. The range of retained austenite in a material after tempering may be as high as 50 percent or as low as five percent dependant upon the tempering equipment and the accuracy of the operator. Cryogenic treatment simply continues the conversion initiated by heat treatment, whereby 100 percent of the retained austenite is converted to martensite. As greater amounts of this retained austenitic structure is transformed and the wear resistant martensitic grain is increased, the material obtains a more uniform hardening. It can be viewed as a “through hardening” that goes above and beyond what is found in the heat treating cycle.
Second, fine eta carbide particles or precipitates are formed during the long cryogenic “soak” depending upon the alloying elements of the material. These are in addition to the larger carbide particles present before the cryogenic processing. The fine particles or “fillers,” along with the larger particles, form a dense, more coherent, and much tougher matrix in the material.
The surface energy of the martensitic structure is higher than the surface energy of the austenitic structure due to differences in their atomic structures. In potential adhesive-wear situations (like those found in the reciprocating assemblies of engines and driveline components), the martensitic grain is less likely to tear out than is the austenitic structure. The adhesive-wear coefficient is decreased, and the wear rate is decreased. In abrasive-wear situations (like piston to cylinder bore wear and clutch wear), both the martensitic formation and the fine eta carbide formation work together to reduce wear. The additional fine carbide particles help support the martensite matrix. This makes it more difficult to dig out lumps of the material. When a hard particle is squeezed onto the surface, the carbide matrix resists plowing and wear is reduced.
Almost any kind of ferrous and non-ferrous material, for whatever application, will exhibit a lifespan increase. As fewer parts are needed there is a substantial savings for the racer. Additionally decreased instances of component failure and wear will allow you to go more rounds and win more races with less time involved in maintenance and part replacement.
Motorsports Applications and Benefits
As recounted from above, just about any component that is subject to wear can be improved through cryogenic processing. It doesn’t matter whether it’s nodular iron, forged steel, aluminum, titanium, and even some composites (like nylon, delrin, and Teflon); they all exhibit increased durability and lifespans. Anywhere there is a possibility of wear, whether it is friction related, rolling, abrasive, adhesive, or impact; cryogenically treated components will keep the racer on the track. During the course of DFC’s research and development some components simply stood out after processing; the following are some examples.
Engine blocks and reciprocating assemblies are among the most significant of all components that show remarkable improvements after cryogenic treatment. Cast iron blocks that have been processed show decreased wear on the cylinder wall and have a reduced coefficient of friction resulting in better cylinder sealing. The further benefits of dimensional stabilization and stress relief are evident when you tear your engine down after the season; you will no doubt notice that your cylinders are no longer round but have become oval. Why? Whenever you bore, hone, or perform any other machining they become stressed. Pistons become oval when heated and wear against the cylinder wall forcing a similar shape on them; then you have poor sealing and increased leakdown resulting in decreased power. The cryogenic treatment removes these stresses on both the block and the pistons so now when they become hot there is no stress to cause these distortions. The pistons and cylinders still grow but they do so uniformly and the cylinder seal remains constant. When the engine block is cryogenically treated and the stresses are removed the dimensions stay constant and the reciprocating assembly will remain in proper alignment. Crankshafts and their bearings will resist the adhesive wear common in their usage and it is often found that bearings can be reused after an entire season because there is no wear evidenced. Typically a racer will see a four to eight percent increase in power production over an identical untreated engine.
Among the most highly stressed components in an engine are the valvetrain components. Valve springs themselves are the number one producer of heat in an engine due to their vibratory nature. Through cryogenic processing they stabilize at their rated pressure much more quickly and remain within spec for a longer length of time. Pushrods are less likely to bend or break after treatment, as are rocker arm assemblies. Camshafts and lifters are among the most significant of increases found after cryogenic treatment. The flat tappet camshafts and lifters common in many classes due to camshaft rules exhibit durability increases sometimes in excess of 400 percent. A few of DFC’s clients even report that the typical break-in procedure for flat tappet cams is no longer required! Roller camshafts and lifters in the racing environment typically have very aggressive ramp profiles that require extreme spring pressures in order to maintain lifter contact. These pressures are extremely hard on the needle bearings in the lifters as well as on the cam lobe itself. Cryogenically treated roller cams and lifters will live a longer and more productive life ensuring consistent valve timing.
Driveline components such as ring and pinions, axles, transmissions, clutch assemblies, and braking assemblies are subjected to some of the harshest punishment in the motorsports environment. The impact wear on differentials and axles in drag racing can be significantly reduced through cryogenic treatment. A torque converter manufacturer unwilling to convert to spragless configuration increased their torque carrying capability by over 250 lb/ft. on their inner and outer sprags through DFC’s Vari-Cold process. Brake rotors in a road-racing environment have shown lifespan increases of 500 percent. The process allows for more aggressive pads to be used without a detrimental affect on rotor life. Input and output shafts in transmissions, even those built out of the ultra-tough Vasco 300m material, show marked increases in torque handling capacity after cryogenic treatment.
Unfortunately the process does have a downfall; that downfall is that those unfamiliar with it will persist in their present thinking that it’s all a good marketing ploy. Afterall, cryogenic processing shows no outwardly visual change and if you can’t see it, it doesn’t exist, right? It doesn’t feel different either. So many racers dismiss a product or process because the physical benefits cannot be seen or felt; but the results at the end of the season speak for themselves. Perhaps some day it will be common knowledge that cryogenically treated components last longer and produce more consistent results. If you’re experiencing breakage or want that last little edge what do you have to lose? The guy in front of you knows…
