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Cutting tools are the largest market for the process, including drill bits, endmills, slitter knives, punches and dies. Cryo processing also is used to treat TiN coated tooling, HSS (high-speed steel) saw blades – bandsaws, circular saws, jig saws, M-series blades – and carbide-tipped saws (C-2, C-3 and C-4). In the 1995 ASM heat treater's guide, 67 out of 77 tool steels listed have cryogenic stabilizing specified as the only method to increase dimensional stability after heat treat. Cryo processing also is used to stabilize aluminum and titanium, since they are often hard to handle during machining. In aerospace applications, cryogenic tempering conditions the metal in aluminum optical benches, so that large temperature variations can be tolerated with minimal distortion. Once a part has been cryo treated, additional cryogenic processing will not usually make any difference. When a tooling manufacturer has included cryogenic treatment as part of the process, additional treatment by the end user will usually have no effect. Multifaceted tools or materials need to be separated into it individual components for cryo processing, since the rates of cooling may vary slightly between different grades of metal. Smaller items and more intricate tooling process better if disassembled. It is less critical on the larger items; for example, processing is not a problem for a cast iron or aluminum engine block with steel sleeves without disassembly. Consistent
Results for a Wide Range of Applications:
The teeth of the backhoes (called “frosties”) used to dig frozen perma-frost in Alaska were wearing out too quickly. After cryo treating, the life of the teeth increased from about four hours to 16 hours. In another heavy-duty application, a paving equipment manufacturer builds and supports paving equipment to mix asphalt. The company uses 12 flute endmills, called “slugger bits,” to cut stainless steel. The bits, some of which are coated, cost $20 to $50 each. After cryo processing the tooling life increased by two to three times. Gears in heavy equipment or transmissions, cast iron or forged items also can benefit from processing. When the military tested cryo treating helicopter gears in the 70’s, they found that the process improved durability and reduced noise, which turned out to solve several problems in combat. Noisy working environments are improved through cryo treatment by providing greater longevity and safety for gears and moving parts.
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Last modified: November 11, 2002 |