Cryogenically treated axle shafts 1

[ChetSzy]

Posted in the cryogenic forum but have had no replies - maybe some info here?

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Fellas, I have been searching high and low and I cannot seem to find conclusive data regarding testing of cryogenically treated axle shafts. I understand that a number of professional race teams may benefit from cryogenic treatment but that is privileged information.

The data I am looking for would be the typical non-cryo versus cryo numbers regarding tortional load capacity.

Thanks in advance.

 

[balu1]

ChetSzy,

There are some materials (maybe even steels) which benefits from quick and sub-zero cooling but that is all I know. The right guys to ask would be those materials gurus in Metal and Metallurgy engineering forum and you should know which alloy you are talking about.

Ciao

 

[Snork]

My wife - one of the afore mentioned Metallurgical gurus - has looked into this for applications on engines, drivetrains, and gun barrels (this last at my request - it's a hobby), and tells me that at this point it's all voodoo science. There does seem to be an affect, but she thinks its from the heating of the part prior to cryo treatment, and not the cryo itself. So far no one has provided her an explanation of the affect of cryo that she is willing by buy, but she keeps looking if only because we Mech Eng's keep thinking there's just got to be a trick out there to make our designs work.

 

[ChetSzy]

Here is some interesting information I have gathered in the past few days:

Enjoy!

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Parts Life Extended Through Deep-Freeze Technology
Aviation Week & Space Technology; New York; September 11, 2000; Anthony L. Velocci, Jr.;

Abstract:
Deep cryogenic tempering - a technology pioneered by Cryocon Inc. - is helping aerospace manufacturers increase the performance of many types of metal and nonmetallic tools and parts. The process involves subjecting objects to extremely cold temperatures of minus 170-317F, depending on the material being treated, and then heating them to plus 175-1,100F. It is computer-controlled to within 1/100 of 1F and completely dry. Cryocon's deep cryogenic tempering is used by some airframe manufacturers as well as some major producers of subsystems and large components. A few of these contractors have joined with Cryocon in researching new applications and improvements to the process. The company expects to soon introduce a more efficient process in which the various stages are integrated into a cost-saving, expense-saving single unit.

Full Text:
Copyright 2000 The McGraw-Hill Companies, Inc.

Deep cryogenic tempering--a technology pioneered by Cryocon Inc. of Ogden, Utah--is helping aerospace manufacturers increase the performance of many types of metal and nonmetallic tools and parts.

The process involves subjecting objects to extremely cold temperatures of minus 170-317F, depending on the material being treated, and then heating them to plus 175-1,100F. It is computer-controlled to within 1/100 of 1F and completely dry. Instead of spraying or immersing objects in liquid nitrogen, they are exposed to liquid nitrogen that has been flashed to a gas. This technique--versus traditional liquid nitrogen quench applications--eliminates any chance of thermal shock.

Cryocon's deep cryogenic tempering is used by some airframe manufacturers as well as some major producers of subsystems and large components. A few of these contractors have joined with Cryocon in researching new applications and improvements to the process. The company expects to soon introduce a more efficient process in which the various stages are integrated into a cost-saving, expense-saving single unit.

THE SCIENCE BEHIND DEEP cryogenic tempering and its ability to improve the strength of steel is still being investigated. However, the consensus of many researchers is that the explanation lies in the precipitation or growth of fine carbide particles. The Cryocon process realigns a material's molecular structure, with treated objects showing dramatic increases in wear-resistance, machinability, durability and thermal stability.

Virtually any metal part subjected to high stresses and temperatures will exhibit some level of improved performance after it has been tempered with the deep cryogenic process. As a general rule, the process reduces stress fractures, extends the life of parts and increases the time between rebuilds. The result is lower cost through less breakage, less retooling, less maintenance and less downtime. Some parts that would require FAA certification after treatment are being tested in conjunction with major aerospace subsystem suppliers.

There are numerous applications of deep cryogenic tempering in the aerospace industry. These include, among others, turbine blades, landing gear system components and gears.

Treated metallic brake pads in commercial aircraft exhibit nearly a 200% increase in wear, according to President and CEO Robert Brunson, a nuclear engineer who holds the patent for the Cryo-Accurizing process. This represents a potentially huge savings in reduced maintenance costs and less downtime of the aircraft, given that brakes must be replaced about every 30-40 landings and each wheel contains multiple brake pad assemblies.

Tooling is another area that can generate substantial savings, as demonstrated by a Phoenix, Ariz., aerospace supplier that machines components from high-nickel alloys, such as waspalloy AMS-5706. The actual machining is done by 8% cobalt high-speed M-42 drills. After they underwent deep cryogenic processing, wear life increased to 78 cuts per resharpening from just three. Thirty-nine fewer tools were required to drill the same number of holes, reducing machine downtime. Moreover, resharpening the end mills after deep cryogenic treatment required only one-third the amount of stock removal to restore tool geometry and extend overall tool life.

A cost analysis illustrates the savings resulting from these improvements. Prior to treatment, which ran $2.45, tool replacement costs were $14.72 each and dropped to $4.91 after treatment. Tool sharpening costs dropped to $4 from $28.

In another example, Northrop Grumman conducted a comparison of 0.5-in. dia., M7 plain, trinitrided-coated and cryogenically-treated twist drills. The test consisted of drilling holes into 0.4-in. titanium annealed alloy sheets at various speeds and feeds, followed by four resharpenings of the drills.

M7 deep cryogenically treated drills produced 102% more holes than plain M7. The new M7 trinitrided-coated drills performed slightly better than the plain tools but dropped off to an average of 73% as efficient after resharpenings. Northrop Grumman has elected to use deep cryogenically treated M7 drills for general drilling.

In addition to drill bits and end mills, there is a long list of tools that probably can benefit from deep cryogenic tempering. In die molds, the process converts the undesirable Austenite (a soft form of steel) into the stronger Martensite.

Other tools whose performance can be improved through such tempering include grinders, computer numerical-controlled tooling, injection molds, rivet bucking machines, worm gear drives, punches, forming tools, bandsaw blades, stamping dies, extruders and copper welding electrodes.

DEEP CRYOGENIC TEMPERING has been used to treat a variety of exotic materials, from waspalloy to inconel. In addition, Cryocon has been researching the use of the technology on nonmetallic substances used in aerospace applications and other industries. These include polymers, composites and glass. For example, NASA is taking advantage of the process to improve the performance of its ultra-high altitude scientific apparatus balloons. The material used for the inflatable part of the balloon is tougher after deep cryogenic tempering.

Some gun barrels used on military aircraft are also being tempered with the process. Cryo-Accurizing, a division of Cryocon Inc., has more than six years of success in bolstering the performance of rifle, shotgun and handgun barrels and components. The tempering improves the weapon's accuracy, extends barrel life and makes them easier to clean. Many records, regional up through international, have been set with guns whose barrels have been treated with the process.

Cryocon doesn't sell treated material; the company treats the end product that will be used by the manufacturer. In addition, it plans to manufacture and distribute a full line of standard and custom deep cryogenic processors, from very large on-site systems to smaller custom units.

``We are really a service-based industry,'' Brunson said. ``Our job is to educate our customers and consult with them regarding their processes in an effort to identify opportunities that can become more productive and profitable.''

Cryocon Inc., 2250 North 1500 West, Ogden, Utah, 84404. Web address:

http://www.cryocon.org.

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Cryogenics: A technology seeks legitimacy
Manufacturing Engineering; Dearborn; Mar 2000; Sharon Hogarth;

Abstract:
Plagued by controversy and populated by small mom-and-pop companies, cryogenic processing is a growing industry. It exists in a Wild West environment, with slick operators selling money-making opportunities making things difficult for small business people interested in serving their customers. The industry is fighting for respect and for recognition of cryogenic processing as a legitimate technology. Proponents of cryogenic processing claim dramatically improved wear resistance for perishable tooling and dies. Confusion about the cryogenics process and terminology, however, coupled with inconsistent results, a wide variety of applications, and differing effects on various types of materials, make it difficult to determine the value and feasibility of using cryogenic processing.

Full Text:
Copyright Society of Manufacturing Engineers Mar 2000
[Headnote]

Plagued by controversy and populated by small, mom-and-pop companies, cryogenic processing is a growing industry. It's not going away, but it exists in a Wild West environment. Slick operators selling money-making opportunities make things difficult for small-business people interested in serving their customers. Approximately 150 cryogenic processing companies are operating worldwide; most have annual sales of less than $10 million, and fewer than 10 employees.

The industry is fighting for respect and for recognition of cryogenic processing as a legitimate technology. Under-capitalization and limited research hamper the industry, but there's an abundance of anecdotal evidence that cryogenic processing works. Users often conduct their own tests and experiments during their cost-benefit analysis. Results, however, are not routinely shared outside those companies. Legitimate cryogenic processing companies are usually happy to provide customer references.

Proponents of cryogenic processing claim dramatically improved wear resistance for perishable tooling and dies. Longer tool or die life and reductions in machine downtime and maintenance, they assert, can significantly cut operating costs. Confusion about the cryogenics process and terminology, however, coupled with inconsistent results, a wide variety of applications, and differing effects on various types of materials, make it difficult to determine the value and feasibility of using cryogenic processing.

Simply chilling metals to sub-zero temperatures for stress relief and stabilization is a very old technique. In fact, Swiss watchmakers have reportedly used cold mountain caves to condition and stabilize parts for more than 100 years. Extreme temperatures and computer-based controls are key elements that set cryogenic processing apart from this sort of traditional cold treatment.

Cryogenic processing to increase wear resistance is a fairly recent development that has spawned a new industry. Although cold conditioning reportedly increases the stability and wear resistance of some materials, questions remain as to which materials benefit from cryogenic treatment. It's also not clear whether the results of cryogenic processing offset its cost.

Cryogenic treatment is accomplished in various ways. The most popular approach in the United States is a deep, dry, controlled cryogenic process. Deep cryogenic processing takes place at around -320 deg F (-196 deg C), near the temperature of liquid nitrogen. Shallow cryogenic processing takes place around -120 deg F (-84 deg C), near the temperature of dry ice. When material is immersed in liquid nitrogen, the process is considered "wet." A dry process is one during which the material is not immersed in a liquid. A computer (usually microprocessor-based) controls the process.

Tools sent to a commercial cryogenic processor are generally batched with items from other companies until enough are obtained to fill a specially constructed freezer that uses liquid nitrogen as the refrigerant. The temperature is gradually lowered or ramped down to -320 deg F. Items remain at that temperature for 20 to 60 hr (commonly referred to as the soak). Then, the temperature is gradually raised to room temperature or beyond. If the material requires additional tempering (to stabilize freshly transformed martensite, for exampie), the system slowly raises the temperature (to around 375 deg F or 191 deg C for most tool steels) before gradually reducing it to room temperature.

The effectiveness of cryogenic processing can be hampered by insufficient soak time, cooling or warming too quickly, and skipping the post-soak temper. Any one of these factors can cause inconsistent results-a problem that has dogged the cryogenic processing industry. Fortunately, today's cryogenic processors are able to provide more consistent results than older equipment.

Materials for myriad applications can reportedly benefit from cryogenic treatment. Property enhancements are claimed for steel, aluminum, brass, copper, nylon, plastics, and carbides. Applications include-but aren't limited to-aerospace, manufacturing, sports, music, firearms, motorsports, and tooling. New applications are being found all the time, and each seems to stir up its own share of controversy.

When it comes to tool steels, there's a little more acceptance of the technology. Metal tools and parts that may benefit from cryogenic processing include drill bits, end mills, cutters, dies, punches, bearings, cams, crankshafts, blocks, and pistons.

Cryogenic processing is commonly referred to as cryogenic tempering. One person who cringes at this term is Bill Bryson, Advisor In Metals (Union, NH), who says "there's no such thing as tempering with cold treatment." He explains that cryogenics is a continuation of the heat-treat process during which a ferrous steel's molecular structure continues its transformation from austenite to a more desirable, wear-resistant martensite. After cryogenic processing, however, this newly created martensite must be tempered with beat to stabilize the freshly transformed, unstable microstructure. Driving his point home, Bryson says, "Make sure you are not misled by thinking 'temper' is anything less than grain refinement and structure stabilization accomplished by heat tempering. Cryogenic processing IS NOT a tempering process."

Ask Pete Paulin, CEO, 300 Below Inc. (Decatur, IL), about cryogenic tempering, and he cheerfully claims, "That's a term we coined about 14 years ago." When asked about some who take exception to that particular term, he responds, "well, those are people who don't understand that the term refers to more than just going down in temperature-it includes coming up in temperature. So, the process is cryogenic and tempering, and that's why we came up with the term cryogenic tempering." Improved wear resistance of tool steels after cryogenic processing, he says, is due to three factors: retained austenite (RA) conversion, carbide precipitation, and thermalmechanical stabilization. Changes from the last two factors, hob ever, can only be seen under a microscope. Paulin observes that many people schooled in metallurgy accept the notion that cryogenic treatment of steel converts retained austenite to martensitic structure. They maintain that if you heatquenched properly in the first place, then you wouldn't have any retained austenite; so, cryogenic processing is unnecessary. "It's a true statement with an inaccurate conclusion," says Paulin, "some metallurgists conclude that RA conversion is the only thing going on because it's the only thing they can see."

That view, according to Paulin, ignores benefits of cryogenic processing that can be seen in plastics, aluminum, copper, brass, and other materials that don't have retained austenite to convert. Those materials may be enhanced by thermalmechanical stabilization-expansion and contraction of the crystalline structure-which decreases latent stress in materials, and is one of the factors responsible for gains achieved with cryogenic processing. It's crucial, however, to transition material uniformly and maintain equilibrium to avoid thermal shock. In steel, a differential in the rate of expansion from core to surface results in thermal shock, which makes the material brittle and very susceptible to cracking. "What we're doing," says Paulin, "is removing those stresses-not imparting them. That's diametrically opposed to the way that most heat treaters and metallurgists think about this process."

He also points out that "heat treating is really a misnomer because nothing happens when you heat steel to eutectoid temperatures-no changes take place there. All of the changes take place on the quench, which is just cooling from a higher reference temperature than the planet happens to be at." Martensitic start and finish temperatures (M^sub s^, M^sub f^) are a function of the amount of carbon in the structure of steel. As carbon content approaches 1%, the M^sub s^-M^sub f^ curve drops, which means at more than 0.4% carbon-most tool steels-a sub-ambient quench is needed to fully convert to martensitic structure. "Metallurgists have long overlooked the fact that physical processes don't stop because the planet happens to be at 70 deg F. This is actually a continuum, it's a function of physics, and that's what we're doingextending that quench to where it should be, optimally, as a function of heat treating."

Because there are no readily visible changes, skeptics abound, and a lot of metalworking professionals take a wait-and-see approach. A cryogenic processing company-claiming they could improve the performance of ceramic and carbide cutting tools-contacted Bill Russell, director of research and development for Valenite (Troy, MI), about their treatment. He chose not to do business with them at that time. "It's somewhat of a fringe project for us. We don't know whether cryogenic processing is something we're going to get into seriously or not at this point; but, I'm keeping a file on it." For Valenite, -and many other companies, the decision on whether or not to investigate cryogenics involves such considerations as limited resources and higher priorities. "We have to decide what things we can focus on," says Russell. "So, I don't want to say cryogenics is or is not valid, because we just don't have the data. But I like some of the theory. We just need to prove to ourselves whether that theory translates to machining."

Some manufacturing practitioners enthusiastically embrace the technology. Steve Chapman, CNC machining department supervisor, Federal-Mogul Aviation Inc. (Liberty, SC) routinely uses cryogenic processing for drills. "It's one of those things you have to try because there are all kinds of stories." He inherited the practice from another engineer and continues it based on his own cost-benefit analysis. He's conducting additional trials and says he's looking at doing even more tool trials. Chapman believes the effort is worthwhileespecially since cryogenic processing is a one-time cost based on weight. He also comments that keeping an open mind and being willing to try new things is vital in today's competitive environment where, "we're constantly looking for ways to cut cost, improve processes, and improve our overall throughput."

Chapman explains they've been using cryogenic processing services from CryoPlus Inc. (Wooster, OH) for more than two years. He confirms that the life of a cryogenically treated 1/16" (1.59 mm) carbide drill increased from 120 to 416 holes when compared to an untreated drill. "We use the 1/16", 3/64" (1.19 nun), I mm, and a small quantity of number 63 Bassett drills. As soon as they come in, I send them up to CryoPlus and have them treated. It has produced drastic life improvements on all four drills." The cost for cryogenically processing these drills is roughly 33% of tool cost, says Chapman, but it's definitely worth it. "We machine the exotic, high-temperature nickel-alloy metals for turbine engine igniters. And a lot of times, you just don't get a lot of tool life out of standard, uncoated drills." He mentions that with some largerdiameter drills, you can keep resharpening and still see gains, because cryogenic treatment is a one-time process. Once you've identified the tool by etching or engraving, he says, you can use it over and over. "It's going to give you more tool life. It seems to stabilize the granular structure in the carbide."

Cryogenically processing carbides baffled the industry for about 25 years, says Paulin of 300 Below. "We've done some work in carbides. We process about a million pounds of steels per year, and have been able to find out why some carbides work and some carbides do not work-at a cost of a couple hundred thousand dollars." Paulin claims the process is not grade-dependentit's even more specific. It depends on the actual structures and target temperatures of carbides being treated, along with how they are processed.

"We've been experimenting a little over a year. And, there's no doubt about it; the process has increased the life of the product that we use," says Glenn Pisching, manufacturing engineer, Lincoln Electric Motor Division (Cleveland). He uses cryogenic processing on molds, broaches, and drills, and has pushed the process for about two years. "It's definitely put a rose on the top of my head, because it has demonstrated significant cost savings. Now, we have a group, consisting of three engineers, who will be working with this process and introducing it to more areas in our plant." Next, he says, they're going to try it on punches and dies.

Pisching began using the services of CryoPlus Inc. about a year ago. The very first mold he did was an $18,000 mold, and cryogenic processing nearly doubled its life. He's particularly impressed with what cryogenic processing has done for his premium-quality H13 molds. Molten aluminum (1300-1500 deg F or 704-816 deg C) is poured into the molds to cast rotors. Exposed to very high temperatures,_ molds are- usually susceptible to heat checks, the aluminum starts sticking, and it's harder to release the casting from the mold. "But right now, the mold that I have in this process hasn't even shown that type of wear-and it should have-it hasn't shown any type of heat checking, yet."

Broaches can only be used for so many pulls-or passesbefore they must be ground and resharpened. Usually, Pisching says, he can broach 150-200 rotors. Now, he's finding that he can broach 500 or more rotors. As this article is written, he's still using the treated broaches, while he's sending untreated broaches out to be ground. "So, cryogenic treatment increases the life," he says, "even if it's 50-60%, it's definitely an increase. For what it cost to have the broaches treated, the process pays for itself."

Drills exhibited a significant improvement in life after cryogenic processing, says Glenn Pisching. The average drill costs $20-30 and his group would sometimes go through 5-7 drills per day, which is quite costly. Now, at Lincoln Electric Motor Division, they cryogenically treat 3/16" and 1/4" (4.76 and 6.35 mm) standard, TiN-coated Cleveland Twist Drills that are 12-18" (304.8-457.2 mm) long. The drills are used for plunge-drilling motor brackets made of cast iron and cast steel. Typically, he says, you can only drill to a depth 1 1/2-2 times the drill diameter before you need to pull it out to expel chips. After cryogenic processing, the Lincoln Electric team quadruples that depth. "The process has better than doubled the life of these drills-before, we might get out 200-300 pieces, now we get 400-600 pieces."

Some companies have taken steps to move the industry forward. One step in that direction is involvement in the Cryogenic Society of America, Inc. (CSA) (Oak Park, IL), Compared to other cryogenic technologies, however, cryogenic processing is considered low tech. Another step intended to move the industry forward was the recent formation of an ASM International (formerly American Society for Metals) (Materials Park, OH) committee on cryogenics to address the need for more information, standardization, and training.

Like an unruly teenager, the cryogenic processing industry has lots of room for improvement, disagreement, and growth. Although the technology has come a long way, it's not part of the mainstream and should be scrutinized carefully. There's an undeniable credibility gap in the industry, but the promise of this technology is tantalizing. The challenge that users and serviceproviders face is learning when, where, and how cryogenic processing does or does not work or add value. Consider total cost and the nuances of each situation, ask probing questions, and experiment to determine whether it's practical and costeffective for you.

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Handbook of Cryogenic Engineering
Mechanical Engineering; New York; Feb 1999; Anonymous;

Abstract:
"Handbook of Cryogenic Engineering" edited by J. G. Weisend II is reviewed.

Full Text:
Copyright American Society of Mechanical Engineers Feb 1999

Handbook of Cryogenic Engineering. J.G. Weisend II, ed. Taylor S Francis, 325 Chestnut St., Philadelphia, PA 19106. 1998. 504 pp. ISBN 1-56032-332-9. $125.

Topics covered include properties of cryogenic fluids, properties of cryogenic materials, heat transfer in cryogenics, cryostat design, cryostat instrumentation, refrigerants for normal refrigeration, small cryocoolers, superconducting magnet technology, cryogenic equipment, superfluid helium (He II), and cryogenic safety. Numerous tables, graphs, and equations are included.

 

[Frederick]

Quite a thorough job by ChetSzy. I am glad someone takes the time to research when they publish. I would like to make some comments about the articles quoted. First of all let me say that this is not reflection on ChetSzy as he did not write the articles.

Yes, Cryogenic processing has had a lot of get rich quick people out there who knew nothing about metals or materials. They did know how to promote and sell, but left a bad taste in peoples mouth.

To call Cryocon a pioneer in the field is a real stretch. Cryocon was started by Bob Brunson, who worked with Pete Paulin at 300 Below. Mr. Paulin got his start by having parts treated by Dr. Jeff Levine at Applied Cryogenics, Inc. of Massachusetts, and by Mr. Jim Birks at Controlled Thermal Processing, Inc. Mr. Paulin has also claimed to have worked with Ed Busch. Ed is a true pioneer, having touted cryogenic processing for years in the Detroit area. The most notable pioneer in the process would be Dr. Randall Barron. Dr. Barron's research is legendary in the field. His papers are widely quoted and respected. Another notable pioneer was Dr. Xener, who went on to create the Xener diode. He worked with cryogenic processing during WWII. All this makes Cryocon at least third generation, hardly a pioneer.

RE: Tempering vs. Processing
The American Society for Materials has decided that tempering is an improper term for this process. The preferred term is cryogenic processing or cryogenic treatment. Calling cold treatment shallow cryogenics is not correct, as the Cryogenic society of America defines cryogenics as temperature below 120 K (-244 F)

I am surprised that Mr. Bryson talks in terms of molecular structure of metals. Metals are crystalline in structure. It is the crystal structure that gives them their properties as metals. They are not molecular.

There has been significant research on cryogenic processing lately. A Master's thesis published at Illinois Institute of Technology states the process is real and is there, even if we do not understand exactly why it works. It is always surprising to me the way some people get so upset when cryogenic processing is brought up. They claim there is no research. This is wrong. The research is there if you care to read it. They claim it cannot be explained. This is true, but not being able to explain something does not disprove its existence. For example, Columbus probably could not explain what South America was doing there, but every time he went there, it still existed. Cryogenic processing is much the same. We get reliable, reproducible results that we cannot fully explain. The process is real.

 

[DangerousNerd]

Not exactly what you're looking for but may be of interest

http://www.frozenrotors.com

Scott

 

[crysta1c1ear]

Regarding not understanding how it works, I think the basic idea is the contraction at low temperatures forces the molecules to be as tightly packed as possible and some of the errors in the crystal structure are removed by errant molecules being forced into place. It is therefore important not to disrupt things by cooling or heating too rapidly.

 

[Frederick]

There is a very good possibility that crysta1c1ear is correct that the crystal structure is probably being refined by the process. There are papers published by a researcher (I can't look up his name at the moment, but it was Eberhardt or something close to that.) from the Colorado School of Mines that postulate that metallic bond is very much like a chemical bond. That said, there would be a preferred distance between atoms in the crystal structure. Any other distance, whether farther apart or closer together would represent a crystal structure that would not be at a minimum energy level. As crysta1c1ear indicates, cooling the material brings the atoms closer together and takes energy out of the crystal lattice. The result is a stronger lattice if the part is not brought up to temperature too fast. I probably have stepped on a lot of toes here, as the physics and chemistry of this is beyond my total understanding. However, if someone out there can take the ball and help us develop this theory, we all would benefit.