How Much Do You Really Know About Metalworking?

Forming, cutting and joining are three broad categories of metalwork. Annealing is more specific, and we'll get into its specifics in another question.

This word can also be used as a verb. To mix metals to make an improved, hybrid type is called alloying.

"Blacksmith" is sometimes used interchangeably with "metalsmith." But if you want to be technically correct, he or she should be working with one of the metals mentioned above.

Steel is iron alloyed with carbon to give it greater tensile strength. Industrial processes that allowed steel to be made in large quantities allowed for high-rise buildings and the growth of densely populated cities.

Smelting is an early process in metalworking that gets the valuable metal out of ore. Fun fact: "Ore" is related to the Old English and German words for "bronze" and "brass," indicating how important those two alloys were to very early metalworking.

To understand why, you have to understand that this term uses the broader definition of "plasticity," which means flexibility or ability to change shape. In metal, this is a good thing.

Ductility is a good quality in a metal. It's not, though, to be confused with "conductivity," which is something else.

Like in other industrial trades, a mask, goggles and gloves are all standard safety gear. But a lead apron is for people working around X-rays -- you might remember this from the last time your dentist took some.

There are various kinds of casting, including sand casting, die casting and lost-wax casting. Objects that are created in this way include practical items like tools, and artistic ones, like sculptures.

Though there is such a thing as "die casting," that's not where the phrase comes from. The "die" referred to is a single dice cube, and "cast" means thrown. The original phrase is Latin, "alea jacta est," and supposedly was said by Julius Caesar when he crossed the Rubicon river.

Forming reshapes metal without any loss of material. Cutting always involves removing material to get the desired shape. (Note: When we say "loss of material," we don't mean it's usually thrown out -- the metal being worked is often valuable and is used for something else.

We often think of forming as requiring high heat, like forging. But many other techniques can be done at ambient temperatures, using only pressure.

Incredibly, there are references to welding in writings from the classical era. Of course, this wasn't the kind of high-powered arc welding we think of today, but earlier methods of joining metals using high heat.

This type of welding creates an electric arc between an electrode and the material to be melted/fused. It's what people usually think of when they think of welding.

Arc welding wasn't new in the early 20th century. But it was put into wide practice building and repairing warships, as the times demanded. It was also used in the making of airplanes, which were first significantly used in WWI.

The question sounds like a short Philip K. Dick title, but yes, welding processes have been completely mechanized. The advantages are several: Robots do not risk eye damage from improper use of goggles, or lung damage from inhaling particulate matter. Of course, job loss is a whole other issue.

Both brazing and soldering take place at lower temperatures than welding. For this reason, they don't melt the main pieces of metal, but create small open spaces called "capillaries" that then fill up with a molten filler to make a join.

Sorry if you were thrown off by "broaching," but that's an entirely different metalworking process (and the piece of jewelry is spelled "brooch.") Jewelry makers, even hobbysits, commonly use a soldering iron -- you might find classes in this at your local community college.

OK, there are actually a number of items that involve soldering. Airplane bodies aren't among them, though; the high stresses that airplanes are placed under requires full welds. Stained glass, on the other hand, does not. Take a look sometime at the irregular, almost lumpy metal joins between panes of stained glass -- it's oddly pretty.

Annealing is heating a substance past its recrystallization point. When it cools, it will be more ductile and workable. This has to do with changes at the atomic level, which sounds dangerous to us, but we'll trust metalworkers know what they're doing.

This is the classic process you see in movies about the medieval era, when the smith plunges the glowing sword into a bucket of water. Today, quenching is usually done in a factory setting with no horses or knights around. But it's still useful -- water was nature's first coolant, after all.

Hot metal cools faster in salt water. The reason for this is a bit too technical to go into here, but if you enjoy chemistry, do look it up.

We should explain here that rivets are generally permanent, which is why they have two heads, unlike a regular bolt, which has a one head and a nut at the other end. But it's possible to remove rivets if needed, like in time of repairs.

A farrier's job is two-fold. He or she makes the metal shoes, then nails them to the horse's hooves. Don't worry; the horses have no nerves there, like humans and their fingernails.

One reason gold has been valued since ancient times is that it is found in nature in its metal form (instead of having to be extracted from rock) and it is relatively workable as found. Later, its ductility and its attractive color added to its appeal.

Bronze is an alloy of copper and tin. For a time, it was the hardest substance humans knew of, giving us the term "Bronze Age."

These are similar alloys. Why, then does "bronze" sound classy to us ("a bronze medal") and brass sound cheap ("brassy")? It's a mystery!

Knurling is usually done to make surfaces easier to grip. This includes dials on instrument panels or the butts of guns.

Cutting removes material from the main object being created, as we mentioned in another question. Sometimes that means one or two large pieces of metal. But when it's many small pieces, like shavings, it's called swarf.

Here's something that seems like a paradox: Tempering makes metal tougher by making it less hard. This is because hard or rigid things break more easily.

There are several types of cutting, of which chip forming, including sawing, is one. Others include abrasion, shearing and electrochemical cutting.

A lathe turns the pieces being worked on so that some kind of tool can be applied, whether it is a cutting or a grinding tool. Fun fact: If you've ever seen gyro meat on a rotisserie, with a fixed knife cutting pieces off, you've seen a culinary "lathe"!

The forge was the hearth that metal was heated in. Afterward, it was commonly worked, often hammered, on the anvil. One of a good anvil's remarkable properties was its ability to "rebound" energy back into the piece being worked -- Newton's Third Law in action!

The word "forge" is sometimes expanded to mean the whole metal shop. And it can serve as a verb, meaning "to shape or create," usually by fire (or metaphorical fire, i.e. hard times).

Wrought iron is a low-carbon alloy, but an alloy nonetheless. The low carbon content gives it its rough, grainy surface.