4 Benefits of Cryogenic Hardening for Precision Machined Parts
Here at Area Tool & Manufacturing, Inc., we’re always exploring ways to exceed our customers’ expectations. One of our tricks of the trade is a frequently overlooked treatment for precision machined parts: cryogenic hardening.
In partnership with the wonderful team at Peters’ Heat Treat, a business right down the road from our Pennsylvania shop, we expose metal workpieces to an evaporated liquid nitrogen freeze, slowly reducing the metal’s temperature to -300 degrees Fahrenheit, then hold it at that temperature for up to 24 hours. A post-freeze tempering treatment completes the cryogenic hardening.
Of course, we don’t utilize cryogenic hardening just for fun. This treatment lays the groundwork for efficient machining and optimum-quality parts.
4 Benefits of Cryogenic Hardening
Here are the four main reasons our precision machine shop uses cryogenics:
1. Increases stability
Material stability is essential when making parts with precision tolerances. That stability is challenged, however, by heat treating and precision machining, which create stresses in the metal and can destabilize the material. “Stressed out” metals are prone to warping, bowing, bending, and twisting during machining—issues that certainly don’t meet our shop’s high standard of quality.
Cryogenic hardening mitigates material stress by deadening the molecular energy and stabilizing the metal for a smooth, speedy, machining process.
The value of cryogenic hardening is particularly notable when we machine 400 series stainless steel parts for medical use. The material itself is challenging to machine, and the parts often possess intricate features and exacting tolerances. Thanks to cryogenic hardening, we can achieve excellent positional and straightness tolerances when machining these high-value medical parts.
2. Increases durability
When undergoing cryogenic freezing, a metal’s atoms reconfigure to decrease the material’s retained austenite, which is soft and pliant. Simultaneously, the metal’s martensite increases, strengthening the grain architecture and enhancing hardness and durability.
3. Increases wear resistance
Cryogenic hardening improves the corrosion resistance and wear resistance of metal materials. The freezing treatment triggers fine eta-carbides to bind and support the metal’s martensite matrix, further extending the longevity of the metal parts.
4. Increases cost savings
Cryogenic hardening has a reputation for being costly. However, the cost of cryogenics is minimal compared to the extensive machining time invested into “fighting” an unstable material to create tight tolerance parts.
When machining tiny, complex parts, unstable metal is shockingly tricky to machine, forcing the machinist to work at a snail’s pace to ensure accuracy and quality. Cryogenically hardened metal can be machined 3-4 times faster, slashing machining costs while achieving exceptional quality.
From Raw Material to Cryogenically Hardened Parts
We most commonly utilize cryogenics for heat-treated steels, but we can also use it for aluminum, iron, and other metals. Since the purpose of cryogenic hardening is stabilization, the treatment is most valuable on workpieces that we will machine into unusually-shaped, fragile, or fine parts. To avoid any stress-related issues during machining, we send cut-to-length billets to cryogenics before placing them in our machines.
Our cryogenics process is exemplified in the aluminum recurve bow risers we make for one global customer. To shape a bow riser, we machine a large percentage of the material off of one side of the part. Typically, this would put the part at risk of warping, but by first cryogenically hardening the workpiece, the material is made stable for intense, detailed, precision machining.
Is cryogenic hardening right for your parts?
While very few precision machine shops offer cryogenic hardening, we believe the treatment will become more common as manufacturers and customers realize its value—both in the shop and in the final product.
If you’re an Area Tool & Manufacturing, Inc. customer, you may have already received a cryogenically hardened part from us! Like many of our continuous improvements, it’s not one we’ve put much effort into advertising. When cryogenic hardening makes sense, we simply do it.
Join the ranks of happy customers whose parts last longer, function better, and cost less.
