Although typical coolant fluids seek to accomplish the same result, they are only capable of lowering cutting edge temperatures to between 60º and 80º F, while the latest cryogenic technology delivers liquid nitrogen directly to the cutting tool to reduce these temperatures to -321º F.

Promoters of cryogenic machining claim a number of benefits for manufacturers, including:

• Faster feed rates and cycle times
• Improved part quality
• Less cutting edge wear
• Significantly increased tool life
• Less machine maintenance
• Elimination of used coolant disposal
• Less environmental impact

One study, by liquid nitrogen supplier Air Products Co. as reported by CNC Cookbook, focused primarily on turning applications and reported these results:

• Stellite (55-58 HRc) machining time reduced from 20 minutes per part to 2.5 minutes
• A2 (62 HRc) Tool Steel yielded 62.5% greater material removal rates (MRR) and 130% increased tool life
• Cobalt Chrome had 290% better MRR and 50% longer tool life
• Titanium milling increased MRR by 60% with 260% increased tool life

So, is cryogenic machining a good fit for your shop? The current data indicate that for extremely hard and other difficult-to-machine applications, it may well be worthwhile. The key issue is how the liquid nitrogen is delivered to the cutting edge. Earlier methods involved spraying the cutting tool, which meant much of the liquid nitrogen vaporized before significantly impacting the tool temperature. Current technology uses contained delivery systems that are much more reliable. A number of major CNC machine OEMs and distributors now offer cryogenic machining options.

Of course, if you’re planning to give cryogenic machining a try, remember that your bar stock still needs proper support to optimize performance, and it’s important to have a chip conveyor that’s capable of handling all kinds of chip types and materials. Your local LNS representative, can match the right bar feeding and chip conveying solutions to your specific processes.