CRYOGENICS
THE RACER’S EDGE
R
Extremely low-temperature acing pushes The concept of changing metal
through the use of low temperatures
engine and
treatments boost the drive train is relatively new and not well under-
stood. Yet it is certain that exposure
performance and service components
to very low temperatures does make
to the ab-
life of critical components. solute limits permanent changes in virtually all
of their dura- metals and to some plastics. Observed
bility. Ex- changes include:
By Roger Schiradelly and tending those limits means more • Increased resistance to abrasion
speed, better safety, and more races • Increased resistance to fatigue.
Frederick J. Diekman* won. For this reason cryogenic pro- • Precipitation of very fine carbides
Controlled Thermal Processing, Inc. cessing is becoming a necessary part in ferrous metals that contain carbide
Streamwood, Ill. of the manufacturing process for forming elements.
racing components. This racing ex- • Transformation of austenite to
perience will serve as an example to martensite in ferrous metals.
manufacturing industries — now sim- • Change in vibrational damping.
ilarly engaged in their own competi- • Increased electrical conductivity.
tion against manufacturing costs and • Anecdotal evidence of changes in
waste, and the challenge to provide heat transfer.
high quality products with superior • Stabilization of metals to reduce
performance. warping under heat, stress, and vi-
Using extremely low temperatures bration.
to make permanent changes in metal In practice, cryogenic processing af-
and plastic components, cryogenic fects the entire mass of the part. It is
processing is not the typical -84°C not a coating. This means that parts
(-120°F) cold treatment most heat can be machined after treatment
treaters use. It essentially involves ex- without losing the benefits of the
posing materials to temperatures process. Additionally, cryogenics
below -184°C (-300°F). If done cor- apply to metals in general, not just fer-
rectly, it creates a permanent change rous metals. For many years, it was
to the material that alters many wear assumed the only change caused by
characteristics. extreme cold was the transformation
Connecting rods usually fail in fatigue. These lightweight, forged 300M steel connecting rods use
*Member of ASM International cryogenic processing to resist the forces generated by an engine turning over 9000 rpm.
HEAT TREATING PROGRESS • NOVEMBER 2001 43
of retained austenite to martensite in allows an increase in durability
steel and iron. Because of this, many without an increase in weight or major
misinformed engineers still believe modifications to component design.
that cryogenic processing is “just a fix In addition, the use of cryogenic pro-
for bad heat treat.” It is now known cessing has helped some racing teams
that cryogenic processing has a defi- reduce costs, enabling some expensive
nite affect on copper, titanium, carbide, parts to survive the stresses of racing
silver, brass, bronze, aluminum, both for use in subsequent races.
austenitic and martensitic stainless
steel, mild steel, and others. It is also Performance advantages
known that plastics such as nylon and Cryogenic processing has become
Fig. 1 — Cryogenically processing brake phenolics show property changes. an integral part of the production
pads yields a service life 2 to 3× that of untreated
process for many racing components.
pads. Race drivers also report better braking ac-
tion and feel. Racing applications Many top racing teams have the
Cryogenic processing is currently process done if the manufacturer does
in use in every form of racing imagin- not provide it. They do so because
able. It is used in virtually every class cryogenic processing has proven its
of NASCAR racing, IRL, CART, worth time and again under extremely
NHRA, IHRA, SCCA, IMSA, and competitive conditions. Racers are
ARCA, not to mention tractor pulls, generally people in a big hurry and
go-karts, motorcycles, boats, and even would not take the time for cryogenic
lawn mower racing. Controlled processing if there was no advantage
Thermal Processing (CTP) has even to it. Applications that benefit from
done a fair number of axles for soap cryogenic treatment probably number
box derby cars. Over half of the cars more than anyone expects.
competing at any given NASCAR Brakes and Clutches. Brakes of a
Fig. 2 — Racing technology adapted for Winston Cup race run parts that are racing car take a real beating. It is not
street use. The use of cryogenic processing to cryogenically treated by CTP alone. unusual for a racing vehicle to finish
triple the life of brake rotors is now spreading Cryogenic processing can have a pos- a race with the brakes totally worn
to fleet vehicles such as police cars and taxi cabs.
itive affect on virtually every engine, out. This is especially true during road
transmission, and drive line part, as races and endurance racing, where
well as many chassis parts. brake rotors can get so hot they glow
Are there definitive tests and data visibly at night. Cryogenic processing
on racing and cryogenic processing can be applied to both rotors and
that we can point you to? Not yet. pads. The net result is two to three
Racers do most of their testing on the times the life of untreated components
race track or on the dynamometer. even under severe racing conditions.
These are not controlled experiments As a side benefit, the rotors are less
in the classical sense, and in most cases prone to crack or warp. It is inter-
they do not allow the results to be esting that drivers report better
Fig. 3 — Valve springs show dramatic im- published because of the risk of losing braking action and feel. Some drivers
provement in fatigue life, lose less preload, and competitive advantages. We do know are so sold on the concept that they
show a smaller loss of spring constant when
cryogenically processed. Vibrational character-
that the use of cryogenic processing is have their street vehicle equipped with
istics are also changed. on the upswing. Its use by manufac- treated brakes.
turers of racing components has been Clutches are a form of brake, and
growing sharply. We also know that the results are very similar. Drag
very experienced racing experts have racers have been doing some work on
examined the effects of cryogenic pro- clutch plates to measure the coefficient
cessing and have been very im- of friction in highly instrumented cars.
pressed. They find that treated clutch facings
Increasing the durability of compo- will develop a higher coefficient of fric-
nents in the vehicles is the main reason tion but exhibit significantly less wear.
for using cryogenic processing. Racing As an offshoot of racing develop-
continually presents the engineer with ment, cryogenically treated rotors and
the challenge of designing engine and pads are making their way into fleet
Fig. 4 — Jerico Performance Products is one of chassis components that will survive operations on the road. The U. S.
the racing component manufacturers that has long enough to win a race, but will not Postal Service specifies cryogenic pro-
recognized the value of cryogenic processing in have any excess weight as a conse- cessing for their rotors and is experi-
extending component life. All gears, shafts, dogs quence. Put in too much mass, and a encing up to three times as many
made by Jerico are now cryogenically treated. car will be slow and handle poorly. miles as they were getting on the un-
In the year 2000, two thirds of the Winston Cup
Make components too light, and they processed rotors. Similarly, many po-
(NASCAR’s premier series) race winners used
transmissions made by Jerico. will not survive the race. There is al- lice fleets are starting to adopt treated
ways this delicate balance: weight rotors and pads. They, too, are expe-
versus reliability. The great thing riencing large maintenance savings on
about cryogenic processing is that it both parts and labor. What is metal-
44 HEAT TREATING PROGRESS • NOVEMBER 2001
lurgically interesting is that the brakes can cause the chassis to lose its cor-
are a gray cast iron that has a pearlitic nering ability, which drastically slows
structure. This rules out the austenite the car. Loss of spring constant also
to martensite transformation as the alters the height or road clearance of
mechanism for increased life. the vehicle. The vehicle height is crit-
Springs fail in one of two modes. ical at high speeds because it has a big
They either break or their spring con- affect on the aerodynamics of the car,
stant starts to decline. Either way, it and hence on the handling and the top
can have catastrophic effects on the speed of the car.
performance of the vehicle. Most valve Other ramifications of springs sag-
springs are made of specially made ging are evident. Watch the pit crew
chrome silicon steel. The automotive after a Winston Cup race as the car is Fig. 5 — All connecting rods made by
valve spring is a fatigue failure waiting pushed up on to a platform for in- Dyer’s Top Rods are cryogenically processed.
to happen. It typically can lose up to spection. If the springs have settled Dyer’s has modified its heat treating to take full
one third of its spring constant during too much, the car may be disqualified. advantage of the benefits of cryogenic processing.
a long race. In some forms of racing, it So the pit crew will often be lifting on
is just hoped that the valve springs the chassis as they roll it along to set
will last through the race. Some drag it up a little higher. When they get the
racers routinely change the valve car to the measuring surface, they
springs before every run down the gently let it down so it does not
drag strip to ensure consistent perfor- bounce and settle farther than neces-
mance. Typically valve springs ex- sary. You have to know the tricks if
hibit a longer life after cryogenic pro- you don’t want to lose.
cessing. How much depends on the The chassis itself is basically a very
type of racing, the type of spring, the large, complex spring, having nu-
manufacturing lot of the spring and merous welds and using not very pre-
the criterion for a failure. cise tubing. The metals used here vary, Fig. 6 — Cryogenic processing of ball and
Cryogenic processing of springs depending on the type of racing. roller bearings increases their resistance to con-
will usually triple the life before fa- NASCAR frames are made from 1020 tact fatigue and increases life.
tigue failure occurs, and it will reduce steel; other forms of racing use 4140
the amount of spring constant lost steel. Of course, other high strength, that cryogenic processing cuts the gear
from 20 to 30% down to about 7%. lightweight materials are also used. wear dramatically. This also holds
This makes it easier to set up the en- As the chassis experiences vibration true for road racers of Porsches and
gine, as there is not such a wide vari- during the race, residual stresses in the BMW’s and other SCCA race cars
ation in the spring performance. It is welds and the tubing can start to re- who are now getting about three times
difficult to determine absolute spring lieve. This causes the chassis to the life on their gear boxes. The major
life increases, because the racers typi- change shape during the race, af- problem all of these racers see is wear
cally discard them long before they fecting the handling of the vehicle and on the pitch line of the gear. Breakage
break. We do know one drag racer therefore its speed. We are now is sometimes a problem, but that can
who used to change springs after each working with several teams to do a usually be traced to driver error, bad
run: he now makes seven runs before heat stress relief on the chassis fol- heat treatment, or inferior material.
changes. There is a caveat here. Oc- lowed by a cryogenic treatment. Jerico Performance Products, a well
casionally we come across groups of Gears, shafts, and assemblies. A study known producer of racing transmis-
springs that will not respond to cryo- for the U. S. Army Aviation and Mis- sions, supplies gearboxes to over 50%
genics. Analysis of these springs usu- sile Command, by the Illinois Institute of the racers in Winston Cup, and to
ally discloses large inclusions in the of Technology Research Institute con- many other racers. The company cur-
wire, which become stress concentra- cluded that cryogenic processing of rently has all of its gears and shafts
tors, causing failures at these locations. carburized 9310 steel increased the cryogenically processed.
A further advantage for cryogenic gear contact fatigue life by 100%, and Cryogenic processing also increases
processing of springs is that the the ability of the gear to handle load the life of other heavily loaded gears.
process seems to eliminate or reduce by 10% over the same material that We see a doubling of the life of ring
harmonic vibrations. If you have ever had undergone a -84°C(-120°F) cold and pinion gears in differentials, even
seen a high-speed movie of a valve treatment per military specification. under such severe usage as tractor
spring at high engine rpm, you will They also found that the conversion pulls. Quick-change gears also show
notice that the spring does not simply of retained austenite is only part of the dramatic increases in life. Axle shafts,
move up and down. It does a very effect on the gear. Most racing gears universal joints, and constant velocity
complex hula dance because of the are 9310 carburized steel, although joints all show dramatic increases in
harmonic vibrations. Racers typically 8620 is also used. It is interesting to durability. As the racing of front
have to design the spring and valve note that there is an experimental gear wheel drive cars becomes more pop-
trains so that harmonics do not inter- material under test that specifies cryo- ular, we begin to see more and more
fere with the valve action. genic processing as part of its heat constant velocity joints being
Not unexpectedly, chassis springs treat. processed, as this is one of the weak
are also affected by cryogenic pro- One major racing transmission points of the drive line. Axles are
cessing. Chassis springs lose their maker, after inspecting numerous treated to stave off fatigue failures in
spring constant during a race. This gearboxes after races, has ascertained the splines.
HEAT TREATING PROGRESS • NOVEMBER 2001 47
edges and stress risers all over. Even 52100 steel) because they get a three
Engines respond so, one customer reports that he gets to five fold increase in life. Rod ends
Virtually every part of an engine about five runs down the drag strip used in steering and suspension sys-
will respond to cryogenic processing, unless he cryogenically processes his tems get the same treatment and per-
with all components exhibiting life in- lifters. After cryogenic processing, he formance gains.
creases. Several component manu- typically gets over 100 runs. Cylinders, pistons and rings
facturers are starting to take advan- Winston Cup rules specify solid Cryogenic processing of piston
tage of this and are treating their lifters. These cars are turning around rings and cylinder walls has been
racing components as part of their pro- 9300 rpm, so valve spring pressures shown to reduce wear substantially.
duction. Some of the main applica- have to be very high to slam the valve One go kart racing customer claimed
tions are: shut. The current practice is to create that he got a five fold increase in en-
• Connecting rods usually fail in fa- a cam profile that will actually loft the gine life before he had to freshen the
tigue. This occurs because of the high lifter. The lifter is thrown up in the air, engine. Better ring seal was born out
“g” loading of the piston and pin. forcing the valve to open very fast and in pressure readings on a dy-
Winston Cup engines currently run then the spring slams the lifter down namometer. Apparently, this happens
around 9300 rpm. They have a stroke back against the cam. This creates ex- because the parts machine and hone
of around 86mm (3.375 in.) Pistons treme wear, but it gets the valve wide better after treatment as a consequence
and pins typically have a mass of open as quickly as possible and leaves of a more uniform hardness distribu-
around 650 grams (23 oz.). Given it wide open to the last possible mi- tion over the surface of the part. (This
these figures, it can be calculated that crosecond. fellow was a national champion, so he
the upward force the piston and The lifters start with a slightly convex must know his business.) CTP has
piston pin exerts on the connecting rod surface and wear into a concave con- done tests that show a significant re-
during the exhaust stroke is over 4800 figuration. Typically, they are cast iron duction in the standard deviation of
g’s. Although this calculation ignores and heat treated to the mid 50’s HRC. hardness readings taken before and
the weight of the small end of the con- In use, any wear increases the valve after cryogenic processing. In some
necting rod, it can be seen that there lash and delays valve lift, creating a loss cases, the standard deviation is one-
is a repeated stress on the rod, which of power. It also leaves a lot of wear third of what it was before the process.
has a cross sectional area of under 230 particles in the oil. It can take up to Processed piston rings typically
mm2 (0.35 in.2). Cryogenic processing three sets of lifters to get an engine wear both less and more evenly than
increases the fatigue life of connecting through dyno testing and the race due untreated rings. More tribologically
rods considerably. Dyer’s Top Rods to the extreme wear caused by these compatible with the cylinder walls,
in Forrest, IL, claims that they would radical cam profiles and high spring they tend to flutter less due to the vi-
not release a rod from their shop pressures. Cryogenic processing re- brational damping the process imparts
without cryogenic processing. We duces this wear by about half. into the material and due to the more
process steel, titanium and aluminum Camshaft wear is also a problem. even hardness of both the rings and
rods. The steel rods are generally AISI Camshafts are generally carburized the cylinder walls. All these factors
4340 or 300M steel, aluminum rods are 8620 steel, but typical Winston Cup combine to give better ring sealing,
usually 7075 T6. camshafts are 8620, with a layer of stel- and therefore more power.
• Cylinder heads. Both aluminum lite welded or spray coated onto the Cryogenic processing of engine
and cast iron heads usually fail by lobes to help reduce wear. The stellite blocks also stabilizes the blocks and
cracking, which results from both has a hardness of about 52 HRC. It reduces warping and distortion due
thermal cyclic fatigue and the flexing wears and chips badly during a race, to vibration and heat during use. The
of the head under combustion pres- changing the valve lash and also the same is true for pistons. Several en-
sures. Further, the heads are often valve timing. In other forms of racing, gine builders, who specify the process,
subjected to the extreme pressures cre- camshaft wear is not as drastic, but still have taken careful measurements of
ated when the fuel mixture detonates. a definite problem, especially for pistons before and after use, finding
All these pressures can cause the head racers who cannot afford a tear down that cryogenically processed pistons
to flex so much that it is not unusual after each race. Cryogenic processing distort less under use.
to find debris such as piston coatings has proven a boon to these racers be- Cryogenics plays a vital role in a
under the heat gasket, blown there cause it reduces wear and therefore process developed by CTP to induc-
during a combustion stroke. reduces camshaft replacement costs. tion harden the bores of cast iron
Several Winston Cup teams have • Bearings. At least one racing blocks. This process reduces friction
concluded that 356 T6 aluminum bearing manufacturer cryogenically and wear. Here, initial reports indicate
heads yield about double the life after treats babbited bearings as part of their substantial horsepower gains from this
cryogenic processing. Other racers production process. They found it in- process.
have the heads (both aluminum and creased the life of the bearings and Crankshafts benefit greatly from
cast iron) treated as a matter of rou- also of the steel backing, which tended cryogenics. Several of the most re-
tine. Of course, treating the heads in- to fail in fatigue. It is interesting that spected names in the crankshaft busi-
creases the life of valve seats and valve cryogenic processing has an effect on ness use cryogenics as a part of their
guides. It is interesting to note that the babbit metal of the bearings. Sim- thermal treatment. Cryogenic pro-
the heads can be treated with the valve ilarly, bronze bushings used on wrist cessing greatly decreases wear on
guides and seats installed. pins also wear considerably less when crankshaft journals and stabilizes the
• Camshafts and lifters. Roller lifters treated. crankshaft. We have treated every-
usually fail by breaking, some of Many racers are processing ball thing from stock cranks through spe-
which is just poor design with sharp bearings and roller bearings (typically cial racing nodular iron cranks and
48 HEAT TREATING PROGRESS • NOVEMBER 2001
racing cranks made of 4340 steel. selected Midwest Thermal Vac Inc.,
Virtually all parts that are subject to Kenosha, Wisc. for their unflagging Car Racing Organizations
stress or abrasion can benefit from attention to customers’ needs and their NASCAR, National Association of
cryogenic processing. Even head gas- quest for doing things right. MTV’s Stock Car Racers. This is the organiz-
kets benefit because the armor around president, Frederick Otto states, “It is ing body for “stock” cars. From the
the combustion chamber is subject to becoming more and more obvious first race on the beach at Daytona in
both thermal cyclic fatigue and to that cryogenic processing is a neces- 1948, to last season’s door-to-door
flexing fatigue. sary and integral part of the thermal thriller at Atlanta between Dale Earn-
treatment of a quality component.” hardt and Bobby Labonte. NASCAR
Keys to the process By helping customers set up real- has provided 52 years of motorsports
Success of cryogenic processing is istic standards and specifications, we racing. www.nascar.com
critically dependent on the equipment have allowed them to develop so- IRL, Indy Racing League. This is the
in which the processing is done. The phisticated metallurgical standards to organization responsible for the Indi-
quality and function of the machines ensure the metallurgical performance anapolis 500 and similar races. Indy
available varies from very poor to ex- of their product. According to Roger cars are Open-wheel, single-seat cars,
cellent. So does the ability of cry- Friedman of Dyer’s Top Rods, “Inte- open-cockpit and ground-effect un-
derbody; outboard wings front and
oprocessor manufacturers to support grating cryogenic processing with our
rear.www.indyracingleague.com
their machines with technical and pro- materials selection, heat treat, and
cessing advice. (More details on the manufacturing methods has allowed CART, Championship Auto Racing
equipment will appear in an up- us to make connecting rods that are Teams. Open wheel racing in North
coming HTP article.) both light and have a long service life America and around the world in 21
events. www.cart.com
Cryogenic processing used to be under extreme racing conditions. The
fairly simple. Bring the part down to result? At the Eldora Million race, NHRA, National Hot Rod Association.
-184°C (-300°F) typically over an eight where there was a one million dollar Drag racing. Now in its fifth decade,
hour period. Hold the part at this tem- prize for the winner, seven out of the the NHRA is the world’s largest mo-
perature for eight to twenty hours, and first ten finishers used our rods, in- torsports sanctioning body with more
bring it back to ambient temperature cluding the winner.” than 85,000 members, 144 member
tracks, 32,000 licensed competitors,
over a 15 h period, followed by tem- The use of cryogenic processing is and nearly 4,000 member-track events.
pering at a 149°C (300°F). This general now starting to extend into the pro- www.nhra.com
formula can be used to good effect for duction processes of companies. Racing
many components, especially when component manufacturers are begin- IHRA, Independent Hot Rod Associ-
all the previous thermal treatment ning to treat their tooling and their cut- ation. Over 30 years of drag racing
make the International Hot Rod Asso-
specs are not known. As they say, ting tools. This is reducing their tooling ciation a pioneer and trendsetter in the
though, the devil is in the details. The costs considerably. One firearms man- motorsports industry. Headquartered
actual practice is harder than it looks. ufacturer currently saves over $3,000,000 in Norwalk, Ohio, IHRA sanctions pro-
There are several large companies that annually by treating its tooling. fessional, sportsman, and bracket
have spent a lot of time trying to de- racing competitions for drivers at all
velop the process unsuccessfully. In The cryo future levels. www.ihra.com
fact, the idea that almost anyone can More research into cryogenic pro- SCCA, Sports Car Club of America.
buy a cryogenic processing machine cessing is a certainty. When Illinois In- Sports cars of all descriptions. The
and set up a viable, reliable business stitute of Technology created it’s Sports Car Club of America is a 55,000-
is absurd. Metallurgical knowledge is Thermal Processing Technology member nonprofit organization fea-
not only helpful, but it is a require- Center in conjunction with the Na- turing the most active membership
ment to achieve effective processing tional Science Foundation earlier this participation organization in motor
The optimum process for any given year, it purposely used the term sports today, with over 2,000 amateur
part varies according to the metallurgy “Thermal Processing” in the name be- and professional motor sports events
each year. www.scca.org
and the failure modes of the piece. Al- cause elevated temperatures are no
though “standard” processes will longer the only means of thermal pro- IMSA, International Motor Sports
greatly improve components that are cessing. One of the first proposed pro- Association. Racing of Sports cars in
sent to us for processing, better results jects for this center is to study cryo- the LeMans series and others. www.
are achieved when the cryogenic genic processing to determine what professionalsportscar.com
process is part of an optimum package factors cryogenic processing changed ARCA, Automobile Racing Club of
of material selection, production in metals. There is current interest in America. The Automobile Racing Club
methods, heat treat and cryogenic pro- the use of the process on H13 steels. of America (ARCA) was founded in
cessing. We even spend time ana- Los Alamos National Laboratory, 1953 in Toledo Ohio as a Midwest-
lyzing component failures to allow us too, is very interested in doing more based stock car auto racing sanctioning
to optimize all factors in the thermal work on the subject. Their testing re- body. www.arcaracing.com
treatment of the part. This approach vealed that there were interesting
yields excellent results, especially for things happening with steels that were Controlled Thermal Processing, Inc., 1521
Bourbon Pkwy, Streamwood, Ill., 60107-
companies that do not have their own cryogenically processed. They are
1836; tel: 630/540-1510; fax: 630/540-1511;
metallurgical staff. eager to find industrial partners to e-mail: info@metal-wear.com; web: www
Cryogenic processing is destined to help fund the research to delve into .metal-wear.com.
become part of the standard produc- the process even further. HTP
tion process as opposed to being an
For more information:
add-on process as it now exists. CTP Mr. Frederick J. Diekman, president, Mr. Roger Shiradelly, Manager, Con-
HEAT TREATING PROGRESS • NOVEMBER 2001 49
trolled Thermal Processing Inc., 126 Con-
federate Rd., Mt. Ulla, N.C. 28125; tel:
704/660-3326; fax: 704/660-3437; e-mail:
ctpnc@netzero.net; web: www.metal-
wear.com.