Welding For Dummies
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Cleaning steel with mechanical methods
When you clean your steel mechanically, you clean the surface by scraping, brushing, or grinding. I usually clean pieces of steel by hand (without power tools) only when the pieces are very small because power tools are just faster otherwise. If you opt to clean steel by hand, I recommend using a very sturdy wire brush. (Check out Chapter 4 for information on wire brushes and other basic tools you need for welding.)
Tools powered by electricity or pressurized air have become the standard for cleaning steel in many welding shops, especially for shops that weld large pieces. The most common power tools used for cleaning steel are angle grinders, shown in Figure 2-2. An angle grinder in use is depicted in Figure 2-3.
FIGURE 2-2: A typical angle grinder.
Cleaning steel with chemicals
Chemical cleaning is, as you can probably guess, a way to clean steel by using harsh chemicals. I’m talking about some pretty rough chemicals here, so if you go the chemical cleaning route, please be sure to treat the materials with the utmost respect.
FIGURE 2-3: Cleaning steel with an angle grinder.
You can clean steel with several different chemicals, and here are a few that you may want to consider.
❯❯ Acetone: This harsh chemical removes rust and oxidation from steel. Welders usually use acetone by spraying it on and rubbing or wiping it off with a clean rag. Compared to some of the other solvents sometimes used to clean metal, acetone is relatively mild, but it’s still a toxic material, so proceed with caution.
❯❯ Alcohol: You can use alcohol for light cleaning and for degreasing. I recommend spraying it on and wiping it off with a clean rag or cloth.
❯❯ Acid: You can use sulfuric or hydrochloric acids to remove rust scales and oxidation from steel before welding it. These substances are dangerous, so use extreme caution if you go this route – in fact, I recommend cleaning with acid only as a last resort. After applying the acid, make sure you rinse the area thoroughly with hot water and dry it as soon as possible.
Exploring steel welding methodsYou can weld steel with just about any of the welding methods I describe in this book, but I recommend sticking with the big three arc welding techniques – stick, mig, and tig. Here’s a quick look at a few steel welding specifics to keep in mind for each of those processes.
Stick welding
Stick welding works just fine for joining steel. It’s extremely portable – which comes in handy when you need to weld a huge piece of steel that you can’t easily move – and as you can read in Chapters 5 and 6, stick welding is versatile and inexpensive compared to the other welding methods. You can use stick welding on virtually any piece of steel that’s 1/8 inch thick or thicker.
Mig welding
You can mig weld steel in any position, and that’s one of the reasons mig is the most popular choice for steel welding projects. Another reason: You can get a very smooth steel weld with mig, and you can also avoid a lot of the spatter and waste that you may get with stick welding. You’ll have a hard time finding a piece of steel you can’t weld with mig; very thick pieces of steel work out fine as long you have a powerful mig machine, and you can even weld extremely thin pieces of steel with mig welding.
Tig welding
Like mig welding, tig allows you to join all different thicknesses of steel. Tig also affords the advantage of a very clear view of your welding area, because tig produces very little smoke or slag (waste).
If you choose tig for your steel welding jobs, make sure you have your equipment set up correctly. Ask your welding supply shop for the charts that help you determine the correct amperage, shielding gas flow rate, and polarity for tig welding steel. You also need to be sure that you use the right filler rod (a metal rod that melts and becomes part of your welding puddle to add strength to your weld), or the quality of your weld may suffer greatly.
Going with Stainless Steel
Stainless steel is pretty incredible stuff. It’s remarkably durable and strong, and as a result it’s used in countless applications all over the world. I doubt you’ll be able to practice welding for long before some stainless steel object catches your eye as a possible project component (if it hasn’t already).
Understanding the differences between steel and stainless steelStainless steel is different from regular steel because it contains 10 to 30 percent chromium. Chromium is added to the steel to create the resistance to corrosion that makes stainless steel so famous (and useful!). Stainless steel can contain a few other substances that make it perform at an even higher level; nickel is the most common.
Stainless steel today is classified into two general series:
❯❯ The 200 to 300 series includes stainless steels made with chromium, nickel, and sometimes manganese. They’re more resistant to corrosion than the 400 series, and they generally have better qualities for welding.
❯❯ The 400 series includes stainless steels that don’t contain nickel. They can’t be hardened as much as the 200 to 300 series.
Stainless steel’s most notable (and desirable) quality is its resistance to corrosion. The combination of steel and chromium creates an outer surface that’s terrific at resisting rust. Because of that quality alone, stainless steel is used in a huge variety of applications, from beer kegs to hypodermic needles to the St. Louis Gateway Arch.
Deciding when to use stainless steelWhy would you want to use stainless steel in one of your welding projects? Here are a few examples.
❯❯ You need part or all of the project to be rust-proof. This goal is pretty self-explanatory, but if your project is going to be located outside – especially in an area that gets a lot of precipitation or salt abuse – and you can’t let it get rusty, stainless steel is one option to consider.
❯❯ You don’t mind spending some extra money. Compared to other metals (carbon steel, for example), stainless steel is expensive! It can cost as much as five times more than steel.
❯❯ You need part or all of the project to be hygienic. The strong, consistent surface of stainless steel means that it doesn’t have tiny irregularities in the surface that bacteria and other critters can cling to. It also means that you can clean the surface with some pretty powerful cleaners without damaging the material. For those reasons, stainless steel is a popular choice for food preparation and storage equipment, and also for medical purposes.
Looking at stainless steel welding methodsIf you want to weld stainless steel, your three best options (by a mile) are stick welding, tig welding, and mig welding. Generally speaking, stainless steels are slightly more difficult to weld than carbon steels. That’s because stainless steels have lower melting temperatures, and more thermal expansion (they expand more than steel when heat is applied).
❯❯ To stick weld stainless steel, you have to use a flux-coated electrode, which protects the metal from the air while you’re welding and helps make the weld even more corrosion resistant. Keep in mind that stick welding is the messiest of the arc welding methods, and that can be a drawback when you’re welding stainless steel. The random arc marks and spatter caused by stick welding can compromise stainless steel’s pristine surface and appearance.
❯❯ Tig welding stainless steel is a great option when you’re looking to weld thin pieces. I recommend using argon as your shielding gas. You can read more about shielding gases for tig welding in Chapters 7 and 8.
❯❯ Mig welding is nice and fast, so it’s the ticket if you want to weld thicker pieces of stainless steel. In those cases, tig welding can just take too long.
Working with Aluminum
If you’re looking for a strong, lightweight metal, chances are your search can stop at aluminum. It’s a remarkably versatile material that’s usually at or near the top of the list of most-welded metals. If you stick with welding for very long, you’re probably going to want to weld some aluminum, and I can’t blame you. Read on to find out more about welding this wonderfully dynamic metal.
Perusing the properties of aluminumSo what makes aluminum so special? For starters, it reacts with oxygen in the air and produces a very tough oxide film on the surface. This aluminum oxide is extremely durable, and it effectively protects the metal underneath it. (That’s why aluminum is so resistant to corrosion.)
Aluminum conducts heat about five times better than steel, and interestingly, it doesn’t change color when you heat it up. (Steel, of course, turns all kinds of different colors as you heat it up to different temperatures.) It weighs about one-third as much as steel.
Pure aluminum is a popular choice for welders, but many different aluminum alloys have also been developed. A classification system of four-digit numbers has been created to identify the various aluminum alloys. The first digit is the really critical one because it tells you what is included (other than aluminum, of course) in the alloy. Here are the details:
❯❯ 1XXX: Unalloyed aluminums made up of at least 99 percent pure aluminum
❯❯ 2XXX: Copper
❯❯ 3XXX: Manganese
❯❯ 4XXX: Silicon
❯❯ 5XXX: Magnesium
❯❯ 6XXX: Silicon and magnesium
❯❯ 7XXX: Zinc
❯❯ 8XXX: Other materials (tin is one example)
The two types of aluminum you’ll probably weld most often are pure aluminum and aluminum alloy 3003.
If you ask me, welding aluminum isn’t any more difficult or problematic than welding steel. It can take some getting used to, but after you have the hang of it, you can weld aluminum quickly and efficiently by using any one of the three major arc welding methods: stick, tig, and mig.
❯❯ My first choice for welding aluminum is always tig welding. You need to use alternating current (AC) with continuous high frequency to get the best results. (If those terms don’t make any sense, flip over to Chapters 7 and 8 for more information on tig welding.) And as with all other tig welding endeavors, make sure you select the right tungsten electrode and shielding gas for the job.
❯❯ If you’re going to be welding thicker pieces of aluminum, consider going with mig welding. As with stainless steel (see “Going with Stainless Steel” earlier in the chapter), aluminum can take a long time to weld if you’re working with thick pieces, and mig welding makes the process go faster. Be sure to keep your electrode wire clean, use a 30-degree leading travel angle, and go with pure argon for your shielding gas. (If those details are Greek to you, check out Chapters 9 and 10.)
❯❯ So what about using stick welding for aluminum? Well, it can be done, but I wouldn’t recommend it if you can go with tig or mig instead. Not many stick welding electrodes are available for working with aluminum, and maintaining good arc stability is tough. On top of that, you have to fight a constant battle to make completely sure that you keep the covering on the electrode extremely clean and dry, or you’re sunk. Bottom line: Avoid stick welding aluminum unless you simply have to do it.
Considering Other Metals
You can do a whole lot of welding with only steel, stainless steel, and aluminum, but you’ll inevitably want to branch out a little and work on some less commonly welded metals. Here’s a quick rundown of some of those metals, and you can find more information on them sprinkled throughout the other chapters of the book.
❯❯ Copper and copper-based alloys
Used for: Plumbing, electrical products, roofing, and as an additive to gold and silver to increase the strength of jewelry.
Welding process: You can use mig or tig welding for copper and copper-based alloys. Mig welding works in all positions and it’s especially useful for thicker pieces of copper. If you use mig for welding copper, be sure you use direct current electrode positive (DC+). Go with tig if you want to weld thinner pieces of copper – I recommend using direct current electrode negative (DC–).
❯❯ Magnesium
Used for: An alloy in steel. Makes steel resistant to abrasion, so it’s perfect for rock crushers, grinding tools, grinding mills, and so on.
Welding process: Use tig for welding thin pieces of magnesium-based alloys; use mig if the pieces are thicker.
❯❯ Nickel-based alloys
Used for: An alloy in stainless steel. Nickel in the 200 and 300 series stainless steels is the most resistant to corrosion.
Welding process: You can use any of the big three arc welding methods for welding nickel-based alloys. Stick welding gives you a weld that’s stronger than the base metal. (That’s good!) Tig welding a nickel-based alloy involves using a 2 percent thoriated tungsten electrode and argon as your shielding gas. You can tig weld a nickel-based alloy in any position. (If some of those terms look a little wacky to you, flip over to Chapter 7 for some gory tig welding details.) Finally, if you’re going to be mig welding a nickel-based alloy, plan to use a 50/50 mix of argon and helium for your shielding gas. Like tig, you can mig weld these alloys in any position.
PRECIOUS METALSYou may think it sounds crazy, but you can definitely weld precious metals like gold, silver, and platinum. Gold can be soldered (welded at a temperature below 840 degrees Fahrenheit) or brazed (welded at a temperature above 840 degrees Fahrenheit), and I recommend doing so with a gas torch – check out Chapter 13 for more on brazing and soldering. The same goes for silver. Platinum is a little different; oxyfuel (see Chapter 11) and tig are your best bets when welding platinum. Oh, and you may want to be sure you have a good lock on your welding shop before you start welding metals that cost thousands of dollars per ounce!
Chapter 3
Setting Your Sights on Welding Safety
IN THIS CHAPTER
❯❯ Making sure you have the right safety gear
❯❯ Understanding basic safety rules for welding
❯❯ Knowing how to prepare for and handle accidents and injuries
What’s the most important aspect of welding? The answer is simple: safety. What good does a beautiful weld and a job well done do you if you’ve hurt yourself (or others) in the process?
Many dangerous elements make up any welding operation. You use massive amounts of electricity to join metals (which are often sharp and heavy) through melting. You’re constantly at risk for electric shock, serious eye injuries, and burns. It’s not exactly a pillow fight, is it?
You can’t change the basic elements that make welding dangerous, but you can (and should, without fail) take every precaution to make sure your welding projects are as safe as possible. Your approach to welding safety should be complete and relentless; just one careless move or lack of safety preparation can result in serious injury or death.
In this chapter, I cover all the aspects of welding safety that you need to understand and remember when you get started as a welder. As I mention many times throughout this book, this chapter is really the most important one, and I hope you read it carefully and take its information to heart.
Gearing Up to Protect Yourself
A big part of welding safety is making sure you have the right safety equipment on hand for every job, and that’s what I discuss in the following sections. Figure 3-1 shows a welder in full protective gear; make sure you have all these items available before you get going on any welding project.
FIGURE 3-1: A welder wearing recommended safety gear, including ample eye protection.
Choosing eye protection
To protect your eyes from flying debris (usually metal), which you encounter plenty of if you weld regularly, make sure you wear safety glasses in your shop at all times. Make a habit of putting them on as soon as you walk in the door – that way, you’re always protected.
To fully protect your eyes from the damaging effects of ultraviolet welding rays, you need a welding helmet. These helmets protect your eyes (and the rest of your face) from damaging rays, and they include special lenses that allow you to see your work clearly without suffering eye injuries, which I discuss in “Shielding yourself from burns” later in the chapter. (Check out Figure 3-1 for a look at what a welder with a welding helmet looks like.)
You need to get a helmet appropriate for your particular welding work. New welders often buy helmets that don’t cover all their needs, or purchase ones that are far too heavy duty (and therefore expensive) for the projects they want to do. The following list explains the features of welding helmets that can help you figure out which helmet is right for you:
❯❯ Shade number: The lenses in welding helmets are rated according to shade number. Shade numbers for welding range from #8 to #14. The higher the shade number, the higher the amperage (the amount of electrical energy flowing through a circuit) you can use when welding without damaging your eyes. Most welding operations are carried out at shade #10, but if you get above 140 amps you must get a darker lens with a shade in the #12 to #14 range.
❯❯ Auto-darkening or passive lens: Many welding helmets now offer an auto-darkening lens that automatically increases the shade number to account for more-intense welding rays. The alternative is a passive lens, which is the older style of helmet that has a fixed shade number. Auto-darkening helmets are nice because you can see through the lens when you don’t have a live welding arc, so you don’t have to constantly take your helmet off and put it back on when you’re working on a project. However, auto-darkening helmets are much more expensive. Passive lens helmets are cheaper, but you’ll likely have to remove them and put them back on over and over while you’re welding.
❯❯ Comfort: Make sure you get a helmet with an adjustable headband that feels comfortable on your head and neck. The helmet should stay in place and shouldn’t pinch your head.
With all the extreme heat and sparks created during a welding job, you shouldn’t be surprised if something catches fire at some point. Because fires are a very real threat, keep a fire extinguisher on hand at all times.