Maybe you’ve got a few projects around the house that require a welder. It could be that you want to learn how to weld. Perhaps you’re looking for a generator and a welder to use on the farm. Or you could be looking to replace a shop welder. Each of these situations has a different set of requirements and the best solution to each will be a welder based on your individual needs.
The first thing to think about is what do you plan to do with your welder. A small welding machine that can fix a cracked lawnmower won’t necessarily be able weld submarines. In theory it could but the reality is that you’d probably be disappointed with its performance. You should have a general idea of the metal thickness that you intend to weld. Keep in mind that most any thickness of metal can be welded with multiple passes. For instance, it is possible to weld 1″ steel plate with an 80 amp welding machine and 1/16″ welding rods–it’s just not very practical. You’ll quickly tire of this if you plan on welding a lot of thick metal. So if thick metal ( .25″ and up) is in your future, a larger machine is probably your best bet. On the other hand, if the bulk of your welding will be on thinner metals such as sheet metal, with the proper techniques you can still confidently take on the occasional big job using a smaller machine.
Another thing to keep in mind is that larger generator or transformer based machines may not perform as well as a smaller machines when welding at lower amperage levels. With modern inverter based welders this problem has largely been eliminated, but it could be an issue if purchasing an older welder. Test welding with it at several different power levels across its power ranges will help to eliminate any surprises later on.
The three main types of welding are SMAW, GTAW, and GMAW. SMAW ( shielded metal arc welding), also known as stick welding uses a constant current power supply and shielded metal electrodes. GTAW (gas tungsten arc welding), also known as tig welding, uses a constant current power supply and a non-consumable tungsten electrode along with a shielding gas. A filler metal rod is often used, but it’s also possible to fuse metal without it. GMAW(gas metal arc welding), also known as mig welding, uses a constant voltage power supply and a wire electrode with a shielding gas. You may be wondering what constant current and constant voltage means. As their names imply, they provide either a constant current or constant voltage output. One of the main benefits of a constant current machine is that it can be used for both stick and tig welding.
The type of metal that you plan on welding is an important consideration. For ferrous metals(steel, cast iron, or stainless steel) stick, tig, or mig will all provide excellent results. For non-ferrous metals like aluminum, certain processes will be easier to use. Mig, for instance, works well for welding aluminum. Tig will also produce excellent welds, but there is a steeper learning curve. The equipment costs are generally higher too due to the fact that you’ll need an ac power supply with high frequency. And finally, with the right procedure, technique, and electrode, stick welding will also provide good results with aluminum.
If you’re considering a typical constant current welder, you’ll note that they are available as an ac, dc, or ac/dc type power supply. AC welders are usually lower cost entry level welders that are limited in the types of electrodes that you can use. DC is the more popular of the two and has some advantages – easier arc starting, better penetration, smoother welds, and better control especially when position welding. Most of the popular electrodes require dc power. Combination ac/dc welders provide both types of power. That said, there is little difference in the quality of a weld done with either ac or dc. The difference is in how easy it is to obtain that quality.
For a constant voltage machine there are two variants, flux cored and shielded gas. The difference is how the weld is shielded as it cools. Shielded gas uses an inert gas to blanket the weld as it cools, and flux cored wire has a center core of flux that covers the molten weld. Even though most constant voltage machines are capable of doing both, you’ll need to decide what you’d prefer to run. Many entry level machines lack the gas controls and hoses and are strictly flux cored unless you upgrade them. Some of the benefits of flux cored welding are that it works better outside or in drafty areas, and has better penetration compared to mig welding. Mig welding is cleaner though and is often easier to produce better appearing welds. In either case, both types provide excellent results, and a shallow learning curve for inexperienced welders.
Duty cycle is a phrase you’ll often see when researching welders. The duty cycle of a welder is based on a ten minute interval and is defined as the amount of time that you can run the welder in a ten minute period. If you see a welder that’s rated at 200 amps-20% duty cycle, it means that you can run it at 200 amps for 2 minutes in every ten minute period. The other 8 minutes are used to allow the welder to cool down. Pay close attention to this number during your research. The maximum power rating of a welder often has a very low duty cycle. Make sure you choose a welder with a 100% duty cycle in the welding range that you’ll use most often. For this reason alone, it’s often good to go with a larger machine. Manufacturers will normally provide the maximum weld power duty cycle, and the power level at which the duty cycle is 100%.
One of the most important aspects to consider is how are you going to power your welder. If you’re planning on powering it with electricity, you’ll need to make sure you have an adequate electrical supply. It’s a good idea to get an electrician to check your electrical system before you purchase a welder. They’ll be able to give you recommendations on the maximum power that you’ll be able to supply and the extra costs that may result from hooking one up. It’s also good to know the amperage available when researching potential welders. If an electrically powered welder is not an option, then you’ll need to go
with an engine powered one. These are available as gasoline, diesel, or lpg. There are certain advantages and disadvantages to each of these. Diesel powered welders are generally more expensive but are strong and should provide a longer service
life. Gasoline and lpg powered welders have the advantage of a lower initial cost.
It’s often helpful to talk to welders to get their opinions. You could also take a welding class at your local community college or adult education center. And when you get ready to make a purchase, don’t forget to bring a welding hood and test it for yourself. You may think you’ve found the perfect welder until you’ve actually welded with it. Don’t rule out a used welder, many of the older ones are built extremely well and may last longer than a new one. It may seem overwhelming at first, but if you research your options and know your needs and limitations, choosing a welder can be an enjoyable experience.