I've always enjoyed watching a blacksmith work. It's an art form, and a fascinating process to watch them pull red-hot metal from the forge, then a few minutes later with some skillful hammering and shaping, see an everyday object take shape. There's just something intriguing about it, from the smell of the fire to the red-hot metal to the rhythmic clanking of the hammer.

Wrenches are one of our most used tools, and they can take some serious abuse, so I thought it a perfect time to take a first-hand look at how they are made. Here's a rundown.

Most wrenches are made from an alloy steel, and more specifically, 6140 Chrome Vanadium steel. The reason is that 6140 Chrome Vanadium is a proven material for products that require both strength and durability. While those two aspects initially might seem to be one in the same, they are two different things.

Since wrench manufacturers receive materials in large quantity, for example long steel rods, as a pre-production process these rods are cut to specific sizes, then o­ften sand-blasted to remove any impurities that could affect the production process. The billet, at that point just a piece of metal, is then heated close to its melting temperature.

Now it moves on to heat treating. All wrenches are heat treated to meet the hardness standards set forth by both American and international governing societies. Minimum and maximum hardness levels are very specific. A wrench cannot be too soft­ where it would potentially round off during use, and not too hard, causing it to be brittle. The heat-treating process, which is a critical and very scientific part of manufacturing, is often followed and combined with quenching and tempering.

An example is heat treating which heats the wrench and allows the absorption of carbon into the surface layer, followed by a cooling process called quenching, which dips it into a heated oil to precisely control the cooling time. Tempering is then an immediate follow-up heating and cooling process with different parameters. Heat treating strengthens the wrench, tempering prevents it from becoming too brittle.

The heat-treating process can take hours, and it's a very specific formula that can be difficult to get it right on, so there's always an acceptable variance. After the wrenches are heat treated, they are checked with a hardness tester to make sure they are within the required tolerance.