Cooling Strategies For Cryogenic Machining From Materials Viewpoint

Well,

It just goes to show you. There's no such thing as a free "Cooling strategies for cryogenic machining from a materials viewpoint".

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"Cryogenic machining - Patent 5901623" Look at this patent the author is also the second on the author list of the paper you try to find. Most probably you will find information about the research paper in it.

As you are a student you can use your university library facility to download this paper or you can contact any of your professors to get it download

These studies of cold machining were done in the late 80ies and early 90ties to overcome the high wear of diamond tools in steel and other metals that may react with diamond to carbides.

In total this approach was not a success as diamond turning is used in high precision applications and this is contradicted by cooling as thermal deformation will damage the result.

So nowadays titanium is machined with natural diamond despite affinity to carbon. Do not turn with high speed and use an ordinary coolant. (Beware the possibility of igniting titanium and let it burn under water!)

And iron-alloys are turned with sintered CBN (cubic boron nitride) that does not have this affinity to carbon. Same for grinding.

There was another approach that had more success (done at NIST) that used hydrocarbon gas as coolant. Also cooling with nitrogen that expands from near 8 bar pressure through a Laval-nozzle had some remarkable results.

All these approaches missed the intended goal - I suspect because cooling was done with constant cooling capacity delivered to tool and workpiece whereas a constant temperature should be achieved at the tool and workpiece together with the smallest possible temperature rise.

This approach would need two independent cold gas (nitrogen) jets and two infrared temperature measurement pyrometers with readout and proportional valves for servo control of the gas flow rate.

RHABE

Lockheed Martin appears to have renewed its interest in cryogenic machining

Given a contract to develop an in-tool method of delivering the coolant while machining the workpiece

Lockheed Martin F-35 Leads To New Titanium Machining Process

[quote]

A groundbreaking cryogenic titanium machining process, planned for use in the production of Lockheed Martin's [NYSE: LMT] F-35 Lightning II stealth fighter, will make its public debut at the International Manufacturing Technology Show (IMTS) 2010, Sept. 13-18 in Chicago

[/quote]

That seems to be great, thank you, may be really important to other "impossible" tasks.

Until now the cooling methods were either too low and insufficient (gas cooling) or

too much and not at the right place.

RHABE