Cryogenic and Cryogenic Tempering for Race Engines

As the cost of racing escalates, racers are seeking products and equipment that will last longer.  Not only are they buying higher quality components, they’re also looking for new ways to make the parts they already have more durable.  And as more racers seek this durability, the more racers seek this durability, the popularity and acceptance of materials treatment processes is growing.

There are a number of materials treatment processes that are designed to increase the strength and durability of racing parts.  Cryogenics, heat treating and stress relieving may sound like they’re best suited for secret, high-tech military operations, but these processes are quickly gaining in popularity among the higher levels of racing, and they’re also starting to filter down to the grass roots racers.   We talked to suppliers of these processes to find out what they are, how they’re being used in racing and what this all means for racing engine builders, fabricators and retailers.

COOL CUSTOMERS
 

The cryogenic process sounds like something out a science fiction novel: heat the parts up, then expose them to vapors of liquid nitrogen, slowly cooling the parts to below 300 degrees F.  This process helps to relieve residual metal stress and creates a stronger, denser, more uniform molecular structure.

According to Steve Klingbiel, One Cryo, Orlando, Florida, “The process entails taking steel, or sometimes aluminum or titanium parts, very slowly down from room temperature to –300 degrees below zero, roughly at about one degree per minute. At that point, about 12 hours later, we begin a hold cycle, which is normally from 24 to 36 hours, also at 300 below.  At the end of that period, we slowly warm the parts back up to room temperature, again at about one degree per minute.  Then we perform a triple heat temper, from 275 to 375 degrees in three different heat and cooling cycles.  This process will realign the molecules so they become more uniform, relieve the stress, and the surfaces will actually be smoother.”

A conventional heat treatment must be done prior to the cryogenic process, he said.   The cryogenic treatment improves the wear characteristics in metal fatigue, especially in short track pinion gears; abrasive wear in brake rotors and cylinder bores; and adhesive wear or galling in racing engines.  One Cryo also treats crankshafts, connecting rods, camshafts, pistons, valves and valve springs, heads, rocker arms, spark plugs, engine blocks, intake manifolds and rear ends.

Parts are loaded into a deep cryogenic processor and the freezing process is controlled by a computer,. “The computer has predetermined profiles for each part you are treating,” he explained.  “There are several things that happen during the process.  As the molecules in the part get colder, there’s less entropy, less energy, they slow down, and they get closer together, and better bonds form.  Anywhere there’s a weak molecular bond or no bond, that’s where the fracture zone is, where it’s going to break.  So when the part is slowly heated up, the bonds stay in place, so you’ve got a stronger piece.  One of the last things that happens is what we call a carbide precipitant growth, which fills the micro-voids.  When the gaps in steel are filled up, it can withstand more force.

“We take all types of tools and engine parts, and freeze them to 300 degrees below zero to improve their wear characteristics and durability.  The engine is more stabilized, the cylinder walls don’t warp and crack, it gives less blow by on the pistons, more compression and higher horsepower, and a longer time between rebuilds.”

The process is also used for aluminum, he continued.  “It’s fantastic on aluminum.  Not only is it tougher and more durable, but it machines so much easier.  We treat bare metal for machinists, and a lot of times, you get a more true machining, because when it heats up, it doesn’t bend and warp, because all the stress is gone.”

The cryogenic process compresses the molecules in parts such as engines, transmissions, rear-ends and brake components.  This forces the molecules into a uniform pattern that doesn’t allow for peaks and valleys –imperfections which aren’t visible to the naked eye, but can be seen when the part is viewed under a microscope.  Each one of these peaks and valleys can be a potential breaking point, he said.

“All of the engine parts can benefit from the cryogenic treatment, since it helps to increase the life of the part by reducing friction and increasing strength,” he continued, “All of the aluminum pieces can now be treated to be as comparable strong as steel, while still retaining their lightweight advantages.  One example of this is the cryogenic treating of cylinder heads.  This stabilizes the aluminum, so the racer gets less deflection and distortion in the head, and even heating across the combustion chamber to help with consistent power from start to finish.

“We’ve all seen the brake rotors on short track cars get hot to the point of glowing red.  In the past, this presented a major problem.  This heat will lead to the brake rotor warping and brake pads prematurely failing, as well as boiling the brake fluid.”

These brake problems can be addressed by treating not only the brake rotor and pads, but also the spindle, wheel bearings, hubs and calipers.   Basically, everything that could be affected by heat has been cryogenically treated.  This gives the aluminum a more equal heating characteristic to its steel counterpart.  With all of the pieces heating up at the same rate, there is less chance of brake failure,” he said.

“Cryogenics builds in more durability,” said Klingbiel.. The company works mainly with Winston Cup  and NHRA ProStock teams to freeze transmissions, ring and pinions, and engine components.

Klingbiel believes this technology will filter to the grassroots level eventually, because grassroots racers are more cost-conscious.  “We’re extending the life of the parts,” he said.

TURN UP THE HEAT

Advanced Heat Treat, Waterloo, Iowa, offers a variety of heat treating services including the company’s UltraGlow Ion Nitriding, which is generally applied to camshafts and crankshafts, according to Gary Sharp.

Ion nitriding is a case hardening process used to harden the surface of engineered steel and cast iron parts.  The parts are placed into a vacuum chamber, and ionized nitrogen gas is combined with other gasses.  High voltage is added to cause the parts to glow, and the parts and gasses react within the vacuum system to complete hardening.  The entire process is controlled by a microprocessor.

The UltraGlow process also helps to increase wear resistance in spring retainers, piston rings, gears and fuel injector components; helps to increase lubricity and reduce friction in tappets, lifters, rod ends and spherical bearings; and helps prevent galling and metal smears in gears, shafts, valves, valve train components and connecting rods, according to Sharp.

In addition, Advanced Heat Treat offers a process known as induction hardening.  This is a selective heating process normally applied to carbon steel, medium carbon alloy, carburized parts, and pearlitic cast irons.  High voltage is added to react to the surface of the part.  Hardening occurs when the part is rapidly cooled from a temperature above the transformation range using quenchants such as water or oil.   Duplex hardening consists of both ion nitriding and induction hardening, to produce deep heating characteristics with high surface wear resistance.

Certified Steel Treating, Los Angeles, California offers a variety of heats treating services to racing customers.  Some of the processes offered are gas carburizing and carbonitriding up to 12 feet long vertically, as well as normalizing, stress relieving and solution annealing.  Certified also has sandblasting, straightening and metallurgical services available.  According to Dan McConohy, “These services are used on suspension, transmission and engine components to improve performance and service, and are a must on fracture-critical parts.”

SHAKE IT UP
 

Vibratory stress relieving is gaining in popularity as a value added process as more high performance engine and chassis builders learn of its benefits, according to Chris Fischer, Stress Relief Engineering, Costa Mesa, California, manufacturer of the “Formula 62” vibratory stress relief system.  “Welding and machining processes leave behind unwanted stress in the component’s microstructure that can have a detrimental effect on performance, he said.  If left untreated, these areas can distort during or after machining.

In addition, welded joints contain high tensile residual stresses, that when combined with stress from normal service loads, have little choice but to distort to accommodate the stress load, or even ultimately fail,” he said.

The system uses low frequency, high amplitude vibrations to reduce the residual stress level to a point where it cannot cause distortion or other problems, Fischer explained.  A vibration generator is either clamped to the work-piece, attached to the tooling fixture or fixed to SRE’s “ Loadmaster 2000” vibration table.  The vibration level is then adjusted to produce the desired amplitude, and sine waves pass through the parts, relaxing the microstructure.  The treatment lasts between 15 and 30 minutes, depending on the size and weight of the work-piece.

One beneficiary of the process has been valve springs, Fischer said.  “Another direct beneficiary has been our own sprint cars.  Once the residual stress energy in the chassis has been dissipated, there is little chance that the chassis will suffer from random distortion once it’s placed in service, or that it will become difficult to tune and adjust.  Sprint car chassis are not known for their long life- once they’ve been in a crash, they usually won’t square up the same way when making chassis adjustments.”

Fischer noted that the stress relieving process has been used extensively on sprint car chassis, as well as blocks, heads, crankshafts and other components.  “We do everything on our car from the welded components and engine parts, right down to the driveline and suspension items, “ he said.

Bonal Technologies, Southfield, Michigan, is helping fabricators lend credibility to their welding work through the introduction of its Model 1700 MetaLax stress relief system.  Meta-Lax is the accelerated seasoning process which stress relieves engine components in 45 minutes, without treatment distortion or scaling.   Meta-Lax helps to stop premature cracking, thereby extending engine life and performance.

“The equipment generates a signature of the work piece on an XY graph,” said Tom Zhebel.  A printout of that graphic adds value to the work and sends customers home with added confidence that they got their money’s worth.  “Here’s the proof that its been stress-relieved,” Hebel said about the graphic certification, which, he noted, is a requirement of a growing number of industrial customers.

EFFECTS ON THE AFTERMARKET

With all these new technologies making their way into the racing marketplace, what are the opportunities for engine builders, fabricators and retailers?  We asked our contacts to give us the details.  In many cases, the performance retailer can either send the parts off to the manufacturer for treating, or offer the service himself.

“We do a little of both,” said One Cryo .  “We have dealers set up to offer that service to people who come in.  We have people who offer the treated parts as a premium line right then, they have them on the shelf to sell, and they offer it as a service.  And we have a lot of customers who ask the rebuilder to send it in, or they send it in themselves.”

One Cryo offers training along with its franchised equipment, said Klingbiel.  “Typically, we give them three to seven days of training.  It depends on how many areas they want to pursue with it,” he said.

Materials treatments are being used on nearly every part of today’s higher end race cars, and it’s only a matter of time before these processes become popular on Saturday night tracks near you.   Familiarize yourself with the benefits of these processes, and you’ll be well positioned to answer your customers’ questions. 

Contact the suppliers of these processes to find out how you can best become involved, and how best to offer these services to your customers.  Your customers will benefit from longer-lasting parts, and you’ll gain a reputation as someone who can help racers get more value for their money.