Reducing Drill Bit Wear The Cryogenic Way

There are a lot of ways that metals can be formed into various shapes. Forging, casting, and cutting are some methods of getting the metal in the correct shape. An oft-overlooked aspect of smithing (at least by non-smiths) is the effect of temperature on the final characteristics of the metal, such as strength, brittleness, and even color. A smith may dunk a freshly forged sword into a bucket of oil or water to make the metal harder, or a craftsman with a drill bit might treat it with an extremely cold temperature to keep it from wearing out as quickly.

Welcome to the world of cryogenic treatment. Unlike quenching, where a hot metal is quickly cooled to create a hard crystal structure in the metal, cryogenic treatment is done by cooling the metal off slowly, and then raising it back up to room temperature slowly as well. The two processes are related in that they both achieve a certain amount of crystal structure formation, but the extreme cold helps create even more of the structure than simply tempering and quenching it does. The crystal structure wears out much less quickly than untreated steel, therefore the bits last much longer.

[Applied Science] goes deep into the theory behind these temperature treatments on the steel, and the results speak for themselves. With the liquid nitrogen treatments the bits were easily able to drill double the number of holes on average. The experiment was single-blind too, so the subjectivity of the experimenter was limited. There’s plenty to learn about heat-treated metals as well, even if you don’t have a liquid nitrogen generator at home.

Thanks to [baldpower] for the tip!

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Retrotechtacular: Forging Of Chain By Smiths

drop-forgingAh, the days when men were men and people died of asbestos related illnesses in their 30s. Let this video take you back to the ancient times when chains were forged by hand, destructively tested using wooden capstans, and sent off to furnish the ships of the line, way back in the year 1940.

The video is something of an advertisement for the Netherton iron works, located in the English midlands. Founded sometime in the mid 19th century, it appears the tooling and machinery didn’t change much the hundred years before this was filmed.

The chain begins as a gigantic mass of wrought iron bars brought in from a forge. These bars are stockpiled, then sent through chain shears that cut them into manageable lengths a foot or so long. The next scene would probably look the same in 1940 as 1840, with gangs of men taking one of the bars, heating it in a forge, beating it on an anvil, and threading it through the last link in the chain they worked on. This isn’t the satisfying machinations of industrial automata you’d see on How It’s Made. No, this is hard manual labor.

Whether through simple quality control or an edict from the crown, the completed chains are tested, or more specifically, proofed. Yard long samples are tested to their failure point, and entire chains are proofed to their carrying capacity in 15 fathom ( 90 feet) long lengths. These chains are then examined link by link, stamped and certified, and sent off to mines, factories, tramp steamers, and battleships.

Although the Netherton iron works no longer exists, it did boast a few claims to fame in its day. It manufactured the anchors and chain for both the Titanic and Lusitania. Of course, such a large-scale production of wrought chain in such an archaic method would be impossible today; today, every wrought iron foundry has been shuttered for decades. If you’ve ever wondered how such massive things were made with a minimal amount of machinery, though, there you go.

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