Page: 4390
| Established in 1952 |
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Page: 4390
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A good deal of experience with cryogenic environments indicates some very basic fundamentals. High carbon steel parts are out. Glues of any kind, including silicon rubber, are out.
The component parts are simply held in place by threaded fasteners. These threaded fasteners (screws) should be made of 300 series stainless steel, not carbon alloy steel.
One good kinematic material that retains all its room temperature qualities, even at the lowest temperatures, is tungsten carbide.
Machining such as drilling and threading that is done to
tungsten carbide parts is accomplished using Electrical Discharge
Machining (EDM). This machining process uses millions of tiny
sparks to erode the desired shape into the part. This process
will slightly change the surface metallurgy of the
E.D.M.’ed material. For parts machined with very heavy
use of E.D.M.’ing, we have never experienced any negative
effect at low temperature, even at the temperature of liquid nitrogen.