Anybody who works with big iron is bound to do a little welding every now and then. The trouble with the occasional welder, however, is that he or she rarely achieves the proficiency or productivity of a full time certified welder. And productivity in welding matters. Welding with the wrong machine or technique eats up valuable time. Poor welds cause parts to fail or require a redo. And welding safety needs to be a lifelong learning experience.
We asked two of the top welding experts in the country to give us their list of the most common mistakes part-time welders make and to tell us how these mistakes can be avoided to improve productivity, quality and safety.
- Turn off the TV
A lot of the car and motorcycle shows on cable TV today demonstrate a blatant disregard for safety. Grinding without safety glasses and welding without a helmet may look cool, but there’s nothing cool about damaging your eyes, face or fingers.
“I won’t endorse many of those programs for that reason,” says Carl Peters, director of technical training for Lincoln Electric and a 35-year veteran of the industry. “It’s a shame. Kids think this is cool and then come into the industry and we have to train them back the other way.”
Even though you may know right from wrong, just watching bad safety practices can have an unconscious effect. Without realizing it you may start to repeat the bad habits you see on TV, just like some kids unconsciously mimic the styles of their favorite sports stars. If you’re a shop manager or field supervisor be aware that many of your technicians may watch these shows. Keep an eye out for those who start to act like they’re too cool to follow safety procedures.
- Start clean, prep well
It ought to be obvious, but it’s often ignored – start with clean metal, says John Leisner, product manager for Miller Electric. This applies to all processes, but on TIG and wire it’s a lot more critical, especially solid wire.
“A lot of people who are not professional welders think that the heat of a welding rod or electrode will burn through most rust, paint or scale,” Leisner says. “You burn through some of that, but some of it gets imbedded in the metal and causes a weak joint.”
To make sure your surfaces are clean use a stiff wire brush or a wire wheel to remove surface rust, paint or scale. If that doesn’t get it, a few light passes with a grinder, just enough to expose fresh, shiny metal, should suffice. For parts contaminated with oil or grease Leisner recommends non-flammable degreaser.
Along with having clean, well prepared material, it’s also important to have a clean surface to clamp your work cable to. “If you put the work clamp on something that’s dirty or rusty you might be able to stick weld, but try the same thing with TIG or wire feed and it won’t even run,” Leisner says. “You’ll think there is something wrong with the machine. You need a clean work piece to make a good ground connection.”
- Test your welds
Just because your welds look good doesn’t necessarily mean they’re strong. “The integrity of a weld is extremely important,” Peters says. “If possible you should become American Welding Society certified or at least have your welds tested by an AWS certified test facility.”
If lab testing of your welds is impractical, you can perform some of the AWS tests yourself, Peters says. “They have diagrams that show you how to take a particular weld sample and bend it. If you do these tests, your welds wouldn’t be certified but at least you’ll have the assurance that your welds are pretty good.”
- Weld thick material in multiple passes
A common amateur’s mistake is to try and weld something 3/8-inch-thick or thicker in a single pass. “They crank up the current and move slowly over the piece, but that usually results in the filler metal not properly bonding to the base metal,” Leisner says. When you take room-temperature metal and apply that much heat to it, you don’t get good penetration.
“If I’m going to weld something, 3/8-inch-thick, I’ll do three passes at a lower amperage rather than one pass at a higher amperage, especially if I’m stick welding,” Leisner says. “Multiple passes ensure good penetration.”
- Learn multiple welding processes
Different applications and different types of metal require different types of welding. The more processes you know, the more versatile you are and the more productive you become, Peters says. “You may not do it wrong doing everything with stick welding, but you might be doing it at a third of the speed. And that’s a mistake today because you have to be productive,” he says.
- MIG is probably the most popular process, Leisner says. It requires a lower skill level and produces a clean weld with no slag. It’s also fast. The same machine can use solid wire or flux cored wire. MIG is preferred when you need a high level of productivity. “People like it because you can point the gun, pull the trigger and go,” Leisner says.
- Stick welding requires a moderate skill level. It’s slower, but more forgiving and may be necessary outdoors where the wind might blow away the shielding gases used in MIG. Stick is often the best route to take if you only weld occasionally, weld for repairs rather than production or don’t need high productivity.
- TIG welding is usually done where aesthetics are important, or on thin material or non-ferrous material. It’s a slower process and requires a good bit of skill but produces the best looking welds.
A lot of people stay with MIG because they tried stick welding years ago and didn’t like it, Leisner says. “That’s one of the misconceptions people have, that stick is really difficult,” he says. “The old AC buzz boxes in the 1950s and 1960s were difficult, but today’s stick welders, especially the DC stick welders, are much easier to use.”
If you’re in the market for a new welding machine and want to diversify your welding skills and learn more processes, consider getting a multi-process machine that will do all three.
- Select the right electrode and wire
There are numerous stick and wire products to choose from, but using the wrong consumable will result in poor results. Some sticks are designed only for DC welding. Some flux cored wires are not suitable for multi-pass welding. Flux-cored and solid-wire welding require different polarity settings on the power source. A good all-purpose stick electrode is E6011 and a good solid MIG wire is a .035 ER70S-6, Leisner says.
Electrodes and wires also need the proper care. Wires rust in wet or humid conditions and some electrodes need to be stored in sealed containers or baked in a rod oven, Leisner says. A welding supply store is your best source of information, he says, and will likely give you better guidance than a consumer retail store.
- Perfect your technique
Good welding requires finesse. Holding the stick or electrode at the wrong angle can make or break a weld, says Leisner. “So you’re not really penetrating, you’re not driving down into the base metal. It may look OK but it’s not deep enough.”
Each process has its own particular technique and demands. If you don’t have any formal training on welding, there are plenty of books available and most trade schools and community colleges have beginner and basic courses. Another good place to learn the proper technique is the manufacturer websites. Here you’ll find diagrams, videos and tons of useful information. Check out www.millerwelds.com/education, or www.lincolnelectric.com/knowledge.
- Get an auto-darkening helmet
If you do a lot of fabrication that involves tack welds and small, repetitive welds it will save you time and aggravation if you get an auto-darkening helmet. This may seem like small potatoes, but constantly having to raise and lower the visor on a standard welding helmet eats up time and takes one hand away from the work. With an auto-darkening helmet you can inspect the work or the work area and reposition the assembly without a lot of wasted motion.
- Educate yourself
Peters cites a lack of basic knowledge about metallurgy as the most common shortcoming of non-certified welders. “They try to weld with trial and error rather than understanding the basics of metallurgy,” he says.
There are numerous resources available, many of them free, which can help you become a better welder without having to take formal classes. Peters recommends the AWS Welding Handbook as well as its Safety in Welding, Cutting and Allied Processes. (Both are available at www.aws.org.) Joining the AWS and getting its magazine Welding Journal and other resources is also a good idea.
Even if you’re fluent in the basics and have had some education, welding has changed tremendously in the past 10 years, especially the electronics. Keeping up with the changes will make you a better welder. “You need to be familiar with inverter power sources and new wave forms for adjusting your arc for peak performance,” Peters says.
Safety issues are also part of any welder’s self-education, including OSHA’s basic 10-hour safety course. “It’s a good orientation for on-the-job safety and health issues,” Peters says. And be familiar with OSHA’s Code 1910, which lists OSHA safety regulations that govern the workplace and Code 1926 specifically for the construction industry, he says.
Safety likewise, is evolving along with the technology. As an example Peters cites new OSHA rules that have cut the level of chromium fumes allowed when welding stainless steel by 90 percent. “If you’re not paying attention there’s a chance you could be in violation,” he says.
Finding the time for self-education presents a challenge, Peters admits. But it’s not different from any other technical profession. Doctors, engineers and accountants complete a certain number of hours of continuing education a year to retain their licenses. “A lot of this stuff you can learn if you just take a few minutes at lunch and do some reading. Or take time in the evening, 10 or 15 minutes a day. Make it a lifestyle to make yourself better,” he says.
- Give it back
“The best way to learn something is to teach it,” Peters says. “Then you really learn how little you know.” He recommends volunteering to teach welding to youth organizations such as 4-H, FFA or Skills USA. In addition to supporting the community, you might also be introducing yourself to some of your next employees.
“It’s always good to give back to the community when you can,” Peters says. “It makes you better yourself.”
A welding technique that helps parts last longer
Handling sand, gravel, limestone, granite, concrete or rock of any sort wears away bucket teeth and edges as surely as pushing them up to a grinding wheel.
And while bucket teeth and edges and other moving parts are designed to be “consumable” removing and replacing these wear surfaces still costs you money and time. If these components last the better part of a year, no sweat, you can replace them on a rainy day or during scheduled downtime. But if you’re regularly stopping work to replace them you might be better off doing some hardfacing, or what the welding industry calls hardsurfacing.
“Hardsurfacing is a welding technique that can help you save time and money,” says Chris Monroe, application engineer at Hobart Brothers. By doing it you can:
- Reduce costs. Hardsurfacing a worn metal part to a like new condition runs 25 to 75 percent of the replacement cost.
- Prolongs equipment life. A hardsurfaced part will last 30 to 300 percent longer than a non surfaced part depending on the application.
- Reduces downtime. When parts last longer you spend less time replacing them.
- Reduces inventory. There is no need to keep a stockpile of spare parts when you can rebuild or hardface them for longer life.
What’s wearing you down?
“Abrasion is responsible for approximately 60 percent of equipment wear,” Monroe says. But not all abrasion is alike. Before choosing the type of welding rod or wire you’ll use in a hardsurfacing project you need to determine what type of wear your equipment is experiencing. Then you can match the type of wear to the type of welding material.
In general, there are three types of alloys used in hardsurfacing: austenitic, martensitic and carbide, each with different properties. There are also three types of abrasive wear. Here’s how they match up:
- Low stress scratching: use alloys with chrome carbide or carbide.
- High stress grinding: use alloys with austinetic manganese, martensitic irons or titanium carbides.
- Gouging: use high carbide alloys supported by austenitic manganese.
In addition to abrasion, equipment can also suffer from:
- Adhesive wear, which requires a martensitic hard surfacing alloy, austenitic manganese or cobalt based alloys.
- Impact wear, which needs alloys with work hardening characteristics.
Hobart warns against a common misconception in alloys: that greater hardness will equal greater abrasion resistance or longer wear life. While two alloys can have the same hardness rating, they can vary greatly in withstanding abrasive wear.
You’ll also need to determine the content of the base metal you’ll be adding the hardfacing to, so you can correctly match it with the welding rod or wire. These might be carbon steels (high medium or low), different alloy steels or other specialty metals. Because there are so many differences in hardness and wear-ability and variables in base metals it’s best to consult your equipment dealer or welding supplier before determining the proper welding rod or wire for any application.
Choosing a process and pattern
Hardsurfacing is typically done with stick or MIG welding equipment. Stick is the most common process. It requires a medium level of skill, but it’s better for welding in awkward positions. MIG requires less skill and offers increased deposition rates thanks to the speed and ease of use offered by wire feed guns.
When hardfacing for abrasion resistance you generally weld against the flow of the abrasive material and create one of four basic patterns: herringbone, waffle, stringer or dot, or a combination thereof. (See photos below). The best way to determine which bead pattern to use it to look at the location and type of wear plus the type of material that causes the wear.
The waffle pattern, a crisscross pattern that forms squares pockets protects against abrasive wear from smaller grained aggregates such as dirt, sand and gravel. The pattern packs material between the beads thus protecting the base metal.
The dot pattern provides effective wear resistance against low impact, high abrasive wear and is suitable for base metals that are sensitive to overheating. Use trial and error to determine the spacing between the dots. This pattern is frequently used on equipment that wears on the sides including buckets and blades.
Stringer beads run parallel or perpendicular to the flow of material giving protection against abrasion. They require fewer pounds of hard surfacing wire compared to the waffle pattern. Stringer beads are typically placed parallel to the material flow on buckets used to handle larger dry aggregates. In sand or dirt, stringer beads are placed perpendicular to the material flow.
The combo pattern includes dots on the leading edges and herringbone patterns behind the dots. The herringbone pattern puts beads at various angles and protects much like a waffle pattern.
Weld beads are placed anywhere from / inch to 1 1/2 inch apart depending on the size of the component and the application. But determining the spacing of beads is as much an art as a science with experience being the best teacher. Here are a few other suggestions according to Stoody, a manufacturer of welding rod and electrodes for hardfacing applications:
- When handling larger pieces of rock, apply hardfacing beads parallel to the material flow. The beads will act as directional runners allowing the material to ride high on the beads and protect the base metal from erosion.
- Waffle or herringbone patterns work well in sand or dirt that has clay content. The material will pack into the spaces between the weld beads and offer further base metal protection.
- Apply a dot pattern to areas that do not see heavy abrasion but are still subject to wear. Also use this pattern on thin base metals where distortions may be a problem.
- In applications that involve impact and high compression side loading, hardfacing deposits applied to the surface and edges are vulnerable to spalling. To improve spalling resistance in these cases, apply hardfacing into grooves cut into the base metal or into grooves surrounded by high impact resistant weld metals.
When cracking up is good
Welders normally consider cracks a sign that something is wrong, but that’s not necessarily true when applying hardfacing, according to Lincoln Electric. Hardfacing electrodes are highly alloyed and since most hardfacing deposits have nearly no ductility, the welds will crack. This alarms many welders. Most often these cracks are transverse (cross) cracks, which are beneficial to relieve the residual stress in weld bead. This kind of cracking will not affect the wear resistance.