Don’t Let Consumables Consume Your Profits: Choose, Use and Troubleshoot Wisely

It doesn’t take much to create a MIG weld. All you really need is a power source, some CO2, a MIG gun, ground cable and a wire electrode.

Of course, that doesn’t mean you’ll end up with a mechanically sound or decent looking weld. Achieving those results requires a strong skill set, close attention to detail and the right MIG welding consumables (among other things, of course).

Often overlooked during the purchasing process MIG gun consumables — the contact tip, nozzle and diffuser — are the decisive variables in electrical transfer to the wire and shielding gas to the weld pool. No matter how well tuned the rest of your welding equipment is to your application, without the right consumables in properly functioning order, your weld quality will suffer.

Obtaining high quality welds and high productivity rates requires attention to the type of consumables you purchase, how they are installed and used by your welding operators and accurately troubleshooting consumables problems when they arise.

Choose Wisely

Selecting high quality consumables is paramount to obtaining high quality welds and avoiding unnecessary downtime.

High quality consumables provide better shielding gas coverage of the weld, resulting in less porosity and a more stable arc, as well as longer contact tip and nozzle life, reduced burnbacks and fewer weld defects caused by loose consumables fittings. With labor accounting for roughly 85 percent of a welding operation’s expenses, the slightly higher cost of high quality consumables can quickly be offset by these advantages.

Another labor-related factor to consider when selecting consumables is the time it takes to change contact tips. A non-threaded contact tip that can be changed by dropping it into the diffuser, without tools, and locking it in place via the nozzle can often cut changeover time in half.

Further, consumables systems that can be mounted to a wide variety of gun brands reduce the time it takes to locate a replacement tip and reduces the inventory footprint and time spent monitoring and ordering new product.

Equally important is choosing the right consumables for the application. For example, using heavy-duty nozzles, with thick-walls as well as wide nozzle bores, will only add weight and reduce weld pool visibility in low-amperage, thin-gauge applications. Likewise, using thin-walled brass nozzles with narrow nozzle openings in heavy-duty applications could result in inadequate shielding gas coverage, frequent burnbacks and

Use Wisely

MIG gun consumables are exposed to more heat and mechanical stress than any other component in your MIG welding system, so even the best consumables you can buy will wear out and need to be replaced on a regular basis. While this can’t be avoided, correctly using the consumables can lengthen their service life and improve weld quality.

Maintaining the correct contact tip stick out or recess, as it relates to the end of the nozzle, is crucial to ensuring good weld results. The amount that a contact tip is recessed or extended past the nozzle determines the wire stick-out and how much heat from the arc the contact tip absorbs. High current, high heat applications generally require a contact tip recessed up to 1/4” from the end of the nozzle. Lower amperage applications, or those with narrow joint configuration, might require a flush or extended contact tip.

Contact tips are available either as adjustable or with a fixed recess. Adjustable recess contact tips allow you to simply raise or lower the contact tip to your liking, but they also increase the potential for human error, particularly in welding operations where multiple operators use the same gun. Fixed recess contact tips need to be changed when changing to a different application, but they standardize the weld process and eliminate a variable that can affect welding performance. Below is a chart showing the recommended tip recesses for a variety of applications and processes.

Regularly inspecting, cleaning and adjusting the consumables is also critical to ensuring weld quality. A nozzle that becomes clogged by spatter can restrict shielding gas flow and lead to porosity. You can use a welder’s pliers or a nozzle reamer to clear out any spatter that builds up. Likewise, the contact tip can develop an oval shaped bore, called keyholing, from the welding wire passing through it, which can cause interruptions in electrical current to the wire, resulting in an unstable arc, porosity and other problems. Some brands of contact tips can be rotated to provide additional contact surface when the wire wears out a portion of the bore.

Troubleshoot Wisely

Unfortunately, no amount of deliberation and careful use can completely eliminate problems from occurring. Being able to quickly and accurately troubleshoot problems when they do occur, however, can reduce the impact of the problem and the downtime that you incur. Generally speaking, the best way to troubleshoot a problem is to use the process of elimination to move from the least to the most time consuming equipment to check.

Contact tip burnback, where the welding wire fuses to the contact tip, occurs occasionally if the tip gets too close to the weld pool, but it could also indicate an equipment problem if it occurs frequently or happens when the contact tip is not too close to the weld pool. Some common sources of contact tip burnback are: incorrect contact tip recess, a faulty work lead or ground, and erratic wire feeding (discussed below).

Erratic wire feeding is usually caused by an obstruction or kink in your liner, incorrect or improperly tensioned drive rolls or a worn out or wrong sized contact tip. If this problem is encountered, inspect the contact tip, then check the drive rolls and finally remove and inspect the liner if the first two items are functioning properly. Replace any of these items that appear worn or damaged.

An erratic arc can be caused by erratic wire feed, but is most commonly a result of inconsistent electric current being delivered to the wire. A gun neck that is too straight or a worn out contact tip are common sources of an erratic arc. If the contact tip appears in good working order and the neck is at least a 30 degree bend, check the electrical connections between the components to ensure they are tight and free of debris.

Spatter is a common occurrence in MIG welding, but excessive spatter could signal an equipment malfunction. Either too much or too little shielding gas flow as well as an improperly installed contact tip are common causes of excessive spatter. Try adjusting these components first, before moving on to other possible causes.

Porosity — small holes in the weld bead — is another common outcome of too much or too little shielding gas. Begin troubleshooting porosity by checking that the nozzle is not clogged by spatter. If the nozzle is clear, move on to check that the gas ports are not blocked by an obstruction, that the solenoid is working properly and that the o-rings at the back end of the MIG gun are not damaged. Also check the electrical connections at the MIG gun, ground clamp and consumables to make sure they are providing good electrical transfer.

Although some troubleshooting can’t be avoided, you can greatly reduce your downtime spent changing contact tips and troubleshooting weld defects by carefully choosing your MIG gun consumables and carrying out a regular inspection and maintenance schedule.

Laying down a strong, great looking MIG weld is no easy task, but doing so with poor quality or improperly configured equipment is virtually impossible. The little time you spend researching, choosing and maintaining your equipment will save you a considerable amount of time, and headaches, down the road.

Choosing Wisely: Simple Ways to Save Money and Reduce Downtime by Selecting the Right MIG Gun Consumables

Everyone is trying to save money these days. From implementing lean practices to repairing equipment instead of purchasing new, companies are seeking ways to reduce costs without sacrificing quality.

Selecting the right MIG gun consumables for your welding application can also help. Not only can the right consumables minimize unscheduled downtime for changeover, but they can also reduce the need to rework weld defects caused by a poorly performing contact tip, nozzle or liner.

The bottom line? You can spend more time welding, gain greater productivity and lower your costs.

Following are some suggestions for selecting the most appropriate MIG gun consumables for your application and ways you can best care for them.

Line Up for the Best Performance

Liners are responsible for guiding the welding wire from the wire feeder, through the gun cable and up to the contact tip. They are typically composed of steel coils, but can also be made of nylon or Teflon®, the latter of which is used for welding with aluminum wire.

Selecting a liner is a relatively straightforward process: you need to match the liner’s inside diameter (within a specific range) to the diameter of wire you are using. For example, if you are welding with a .035-inch wire, you can use a liner that measures .035 to .045 inches in diameter. Making this match helps prevent wire-feeding problems that can lead to poor arc stability, bird-nesting (a tangle of wire that prevents the wire from feeding) and/or weld defects. Also, using premium quality liners is best, as these maintain a more consistent inside diameter than less expensive ones and provide better feeding performance.

To prevent shielding gas leaks that can increase costs and jeopardize gas coverage of your welding puddle, make certain that your liner has a good O-ring connection at the back of the liner and that you select liners with a durable coating. Replace your liner at a regularly scheduled time and always follow the manufacturer’s recommendation for trimming and installation. Poorly trimmed liners, liners that are worn excessively or ones that are kinked from use can easily cause wire feeding problems or an erratic arc that leads to poor weld quality. They can also cause excessive spatter that will require post-weld grinding, minimizing throughput and adding to your overall costs.

Some manufacturers offer partial liners that replace only the most commonly worn part of liner (along the length of the MIG gun) instead of the entire liner. These partial liners help reduce downtime for changeover as they usually take about half the amount of time to install compared to a full-length liner.

Tips for Making the Right Contact

While they may look like a small, and perhaps insignificant, part of the overall welding system, contact tips play a critical role in helping achieve good weld quality, reducing costs for downtime and minimizing rework. In addition to helping direct the welding wire to the weld puddle, contact tips are responsible for transmitting the current to that wire in order to initiate the arc.

The contact tip you select should correspond with the diameter of welding wire you are using. Typically, contact tips are available to accommodate wire diameters ranging from .023 to 1/8 inches.

Depending on the type of joint your application requires, you may need to select a tapered style contact tip. These contact tips are good for applications that have restricted joint access, but they tend to be a bit more delicate than non-tapered contact tips. They should be coupled with a tapered nozzle. If joint access is not a factor in your application, however, choosing a non-tapered contact tip is the best option as it has more mass and will last longer.

Different manufacturers offer either threaded or non-threaded styles of contact tips. Threaded contact tips are the most common and, as their name implies, they are held in place in the gas diffuser by threading or twisting them. Non-threaded contact tips, conversely, drop into the gas diffuser. This latter style of tips can be rotated when the contact tip starts to wear on one side (called keyholing) in order to create a new wear surface, extend the life of the contact tip and prevent arc instability that can in turn lead to spatter and rework. Non-threaded contact tips also tend to be easier to change out after a burnback, which is the formation of a weld in the contact tip. It most often occurs because of placing the contact tip too close to the workpiece or using too slow of a wire feed speed. Regardless of whether you choose a threaded or non-threaded style of contact tip, it is important that you install these according to the manufacturer’s recommendations. Doing so will help ensure a good electrical connection and, with it, reliable welding performance and quality.  

Contact tips are generally available in sizes small or large and also in standard or heavy-duty varieties. If you are welding on higher temperature applications (generally, 300 amps and above) you should select a large contact tip, as these have greater mass and provide better cooling capacity than smaller contact tips. For higher amperage applications that also require prolonged welding, heavy-duty contact tips can provide greater conductivity, improve arc starts and they tend to provide longer lasting performance. Lighter amperage applications (generally, below 300 amps) are well-suited to using small, standard style contact tips.

To ensure the best welding performance, inspect the contact tip for spatter build-up on a regular basis and replace as needed. Waiting too long to replace a damaged contact tip can lead to arc irregularities and poor weld quality, not to mention unscheduled downtime for replacements, which can cut into your productivity and cost you money.

Know Your Nozzles

Depending on your application there are a variety of styles of nozzles from which to choose. Like contact tips, nozzles are an important part of gaining good weld quality and reducing costs. The main function of these components is to direct shielding gas to the weld. For that reason, you want to select a high-quality nozzle that is capable of providing smooth gas coverage and resisting damage (e.g., dents, scratches, etc.).  

Usually, manufacturers offer either brass or copper nozzles. Brass nozzles provide good protection against spatter, while copper nozzles withstand heat better, particularly on heavy-duty applications.

There are two main styles of nozzles — threaded and non-threaded — as well as a variety of different shapes and sizes. Threaded nozzles tend to maintain a more secure connection than non-threaded styles, which protects against shielding gas leaks that can lead to weld defects like porosity. These nozzles also help keep the contact tip centered for greater accuracy. Non-threaded nozzles, however, are easier to change over.

Nozzles are available with small and large varieties and a range of inside diameter measurements, often from 3/8 to 5/8 inches. Ultimately, the best option for any application is to use the largest nozzle possible that still provides you access to the joint. Doing so provides greater gas coverage to protect against contaminants. For restricted joints, however, you will need to use a small, tapered nozzle that allows you to place the contact tip close to the weld puddle. Or if you have a high-amperage application that requires high gas flow rates, select a large diameter nozzle, as it provides the best shielding gas coverage.

Some MIG consumable manufacturers provide nozzles that keep the contact tip at a fixed position: flush, recessed or extended. Each provides distinct attributes. For example, if you are welding in a short-circuit transfer mode, a nozzle that keeps the contact tip flush to the end of the nozzle or slightly extended helps minimize the spatter that tends to be generated in this welding process. Similarly for spray arc transfer or pulsed spray mode when welding with solid wire, having a nozzle that keeps the contact tip slightly recessed can help the contact tip operate at cooler temperatures and provide greater shielding gas coverage.

For all styles and sizes of nozzles, regular inspection for spatter is crucial to achieving good gas coverage. Also, careful handling and storage of these consumables is important. Always wear gloves when changing out nozzles to prevent debris or oils from adhering to them and entering the weld puddle. To prevent damage, keep them in the original packaging until you are ready to use them.

Remember, whether you are selecting a nozzle, contact tip or liner, having the right MIG gun consumable for your application can go a long way in reducing unnecessary downtime and lowering your overall costs.

Keeping an Open Mind and Reaping the Benefits: How One Company Reduced its Downtime and Costs Through a Simple Product Trial

When you have a company that fabricates its projects by the tons and measures its man-hours by the thousands, downtime simply isn’t an option. The welding operators and supervisors at Brooklyn Iron Works know that fact better than most. The Spokane, Wash.-based company, whose steel fabrication spans from bridges in Alaska to projects in Antarctica, tackles some of the highest-profile, high-inspection jobs around. And they rely on some good old-fashioned teamwork, among other attributes, to meet their deadlines.

“Everything we do is a team effort,” QA Manager Phil Zammit explains. “We’re a good company with skilled employees and good management. It makes us a premium company here in the Northwest.”

It also makes them a reputable one. Brooklyn Iron Works doesn’t maintain a sales force, but instead relies — and successfully so — on its reputation and word of mouth to generate business. Scott Allen, the company’s general manager, explains that they are invited to bids based simply on the quality work they do and the timeliness in which they do it.

Last year, Norco Gas & Supplies representative Tim McGrath approached Zammit and Allen with a proposition to make their welding operations even better: a two-week trial of Bernard Centerfire™ consumables on their existing MIG guns. According to Zammit, they had tried Bernard products years before and didn’t think they were the right fit for their application. Still, he decided to keep an open mind and agreed to the trial. Two weeks later, he invited McGrath to convert the front-end of all 25 of the company’s MIG guns to Centerfire consumables and shortly thereafter, converted to Bernard’s Q-Gun™ MIG guns too.

The reason? Less downtime.

The Projects and Challenges

Brooklyn Iron Works, according to Allen, fabricates projects ranging from 650 to 2,000 tons or more, including fracture critical structural components for bridges, demand-critical welding on columns, beams and moment connections bound for seismic locations, like California. Not surprisingly, the company maintains a workforce of highly skilled certified welders certified to the AWS D1.1 (Structural Welding Code – Steel), D1.8 (Structural Welding Code – Seismic) and D1.5 (Bridge Welding Code).  Many projects take between nine months and a year from start to finish. Depending on contract and/or code specifications, every weld at Brooklyn Iron Works is visually inspected and oftentimes includes 100 percent NDE (nondestructive examination) including MT, UT or RT. Others undergo random NDE testing for quality monitoring purposes. The company maintains a staff of certified welding inspectors (CWIs), as well as hosting contracted NDE inspectors, to manage these tasks. They also have a cleaning and painting facility to finish products after welding and prior to shipment to customers.

Gaining access to the weld joints is one of the biggest challenges welding operators at Brooklyn Iron Works encounter while creating these welds. They weld mostly structural steel grades, with the majority being A36, A572 Grade 50, A500 and A709 steel including weathering types. Thicknesses range from 1/4 to 2-1/2 inches. On deep and tight joints, reaching the root of the joint for the initial root pass requires not only the right type of MIG gun and nozzle, but also welder dexterity. With the company’s previous consumables, welding operators often had to extend their electrode stickout as far as 2 inches to access the joints, a practice that risked generating porosity since it could compromise the necessary shielding gas coverage.

Another challenge the company faced was the occurrence of burnbacks, the formation of a weld inside the contact tip, when using their old brand of contact tips. Brooklyn Iron Works welding personnel run their weld beads at high amperages (300 to 400 amps) using typically .052- or 1/16-inch FCAW wire diameters, which often proved too harsh on their previous contact tips. They would loosen after routine welding, causing the wires to arc back and create the burnback.

The trial of Centerfire consumables gave Zammit and his team of welding operators a solution to these two problems—and it led to a MIG gun conversion that provided some additional benefits, too.

The First Solution

When McGrath initiated the trial of Centerfire consumables at Brooklyn Iron Works, he started by installing them on just two MIG guns, using a conversion adapter offered by Bernard. Zammit and his welding operators quickly realized that the design of the Centerfire consumables provided a better solution for their welding operation.

The Centerfire nozzles they trialed, and now use, feature a tapered design that stays fixed flush with the end of the contact tip and allows welding operators to reach into the deep weld joints without having to extend their welding wire as much. As a result, the welding operators can gain better gas coverage and lessen the risk of porosity. The Centerfire consumables also include a built-in spatter shield that acts as an additional gas diffuser and ensures a more consistent gas flow, a feature that Zammit particularly likes.

“These consumables direct the gas exactly where we need it,” he explains. “It keeps our gas shielding coverage right at the weld, even when the doors are open or we have a breeze. We’ve never had a huge problem with porosity, but now we have even less of one.”

Just as importantly, Zammit and his welding operators have almost completely resolved their issue with burnbacks. Compared to the company’s previous contact tips, which threaded into the diffuser and tended to loosen after welding, the Centerfire contact tips “drop in” the diffuser and are held in place by tightening the nozzle. This non-threaded tip design features a tapered base and large diameter seat that helps generate consistent electrical conductivity and heat transfer—and it stays in place during welding.

We rarely get burnbacks anymore with the Bernard contact tips, before we had a substantial amount of downtime. And that’s money. It’s lost arc time for tip maintenance.

Phil Zammit Quality Assurance Manager, Brooklyn Iron Works

On the few occasions when a burnback does occur, Zammit notes that the Centerfire contact tips can be easily removed— without tools— and changed because of the threadless design.He also goes on to explain that the company is saving money by having to replace fewer contact tips. By his calculation, Brooklyn Iron Works now uses about a third fewer contact tips than before.

Finding Additional Benefits with New MIG Guns

Shortly after converting their front-end consumables, Zammit and his welding operators also decided to convert to Bernard MIG guns. They now use 400-amp, air-cooled Q-Gun MIG guns with 15-foot cables and have, since the conversion, found additional ways to reduce downtime.

According to Zammit and Maintenance Supervisor John Dahl, the maintenance on their Q-Gun MIG guns is much simpler than with the competitive guns they used previously. Changing the neck or liner on those guns required an Allen wrench to remove setscrews on the front and backend of the MIG guns, a process that Dahl says required disassembling the MIG gun and could take nearly an hour to complete.

To change the necks on the Q-Gun MIG guns Dahl simply unscrews a plastic ring surrounding the neck by hand and inserts the new neck or liner. It takes less than five minutes. And he finds that he doesn’t have to conduct maintenance as often, either. In fact, he said that one of the Q-Gun MIG guns has been used with the same liner for a year.

“Maintenance on these guns is so much easier and quicker now,” says Dahl. “Plus, we’ve gotten good feedback from the welding operators in terms of the neck options on the Q-Guns.”

The Q-Gun MIG guns have necks available in fixed, rotatable and flexible options in various lengths and bend angles, with the rotatable versions being able to changeover without tools. According to Zammit, these neck options help the welding operators better accommodate the varying welding angles they encounter on projects. They can reach the weld joints easier and reduce downtime to address issues like wrist fatigue. Welding operator Ricky Curtis agrees — especially when it comes to using the flexible neck versions of the Q-Gun MIG guns

“I can bend the neck in any direction I need,” he explains. “Even around the corners. I like that the gun does the work for me, instead of my wrist.”

Zammit and Allen also like that the welding operators are more comfortable and that it is taking less time to maintain the guns. Simply put, more arc-on time means better productivity.

Reaping the Benefits

Keeping an open mind isn’t always easy. It’s often human nature to stay with the routine of “doing things as they’ve always been done.” But sometimes, taking a chance can yield unexpected benefits. Brooklyn Iron Works clearly learned this lesson when they agreed to the trial of Bernard consumables. Now they are reaping the positive results that come with it, and passing those results on to their customers.

MIG Gun Consumables: Tips to Extend Life

Consumables for the welding gun can significantly impact the productivity and welding quality in an operation. This makes it important to keep consumables properly cleaned and maintained, to help minimize unplanned downtime, extend consumable life and optimize performance.

The Heat Factor

The heat produced in the welding process can have a significant impact on the cleanliness and longevity of MIG consumables. Processes like pulsed MIG and/or higher amperage applications tend to subject consumables to higher levels of heat, as do applications in which there is a large amount of reflective heat. Those include applications with tight tooling or those that require welding in restricted areas.

The hotter the consumables become during the welding process, the softer the material (usually copper or brass) becomes, resulting in a surface area that is much more prone to accumulating spatter and failing prematurely.

To avoid such problems, it is important to determine the best consumables for each application and consider how they will be managed throughout the course of a welding shift. For example, high-amperage applications (those above 300 amps) most often benefit from using heavy-duty consumables because they have greater mass and are capable of dissipating the heat more readily. However, if the welding procedure dictates that the contact tip must be changed frequently, a standard-duty contact tip may suffice. The goal is for companies to determine which consumables — heavy- or standard-duty — are most capable of withstanding the duty cycle and heat of the application. A reliable welding integrator can often help with the selection.

The Anti-Spatter Solution

Using an anti-spatter compound can help keep MIG consumables clean on both semi-automatic and robotic welding applications; however, it must be used sparingly. On a semi-automatic application, welding operators should dip only the front inch and a half of the nozzle into the anti-spatter compound. Submerging the nozzle in the anti-spatter compound can saturate the nozzle’s fiberglass insulator and also potentially plug up the gas holes on the diffuser. This build-up may cause the nozzle to fail prematurely or result in porosity in the welds due to the unbalanced gas coverage. In robotic applications, only the minimum amount of anti-spatter compound required for the application should be used. Using too much can cause build-up on the consumables and/or cause debris to accumulate and clog the nozzle, leading to poor gas coverage, inconsistent electrical conductivity or shortened consumable life.

Another important way to combat spatter is to inspect the nozzle for build-up on a regular basis and clean it with a soft wire brush or spatter-cleaning tool as needed. Welding operators should never hit the nozzle against the tooling or work piece to loosen spatter. Doing so can dent, misshape or compromise the smooth surface finish of the nozzle, which creates greater areas for spatter to adhere to and reduces the life of the consumable.

Proper Storage and Handling

Always keep MIG consumables in their original packaging until they are ready for use. Opening them and placing them in a bin can lead to scratches or dents that allow spatter to adhere and will ultimately shorten the products’ life. Similarly, removing contact tips or diffusers from their packaging and storing them in open or dirty containers can cause dirt and oil to accumulate in the threads, which can impede them from properly seating together. Also, companies should always keep storage containers for new consumables separate from those for discarded ones to avoid selecting an old contact tip or nozzle that may have dents or scratches and be prone to spatter accumulation. Finally, welding operators should always use clean gloves when handling or replacing contact tips, nozzles and diffusers to prevent dirt, oil or other contaminants from adhering to them.

Establish and Maintain Good Connections

Installing MIG consumables correctly and inspecting them periodically for good connections minimizes the chance of poor conductivity and with it, spatter accumulation or premature failure. Welding operators should always follow the GMAW consumable manufacturer’s suggestions for contact tip and gas diffuser installation, using a pair of channel lock pliers, welpers or other such recommended installation tool. Never use wire cutters or side cutters — too much pressure from these tools can damage the inside diameter of the contact tip, which leads to poor welding performance and a shortened lifespan. Also these tools tend to scratch the surface of the consumables leaving marks that attract spatter.

A good rule of thumb is to hand tighten the contact tip until it is fully seated into the diffuser, then grip the contact tip with an appropriate tool as close to the base as possible, tightening it 1/4 to 1/2 turn past finger tight. This procedure helps ensure a good connection that minimizes electrical resistance, overheating and damage to the consumables, as well as excessive spatter accumulation. Follow the same procedure for installing and tightening the diffuser so that it fully connects with the neck. Also note, some contact tips available in the marketplace can be installed and held in place by hand tightening the nozzle. Check the manufacturer’s recommendation for proper installation instructions.

Inspect consumable connections regularly to ensure that they are secure.

Trim Liners Correctly

An improperly trimmed and installed liner can cause a host of wire-feeding problems that lead to downtime to rectify. It can also affect the performance of MIG consumables, how clean they stay and their longevity. Cutting a liner too short can cause the liner to be misaligned with or in the gas diffuser. The result is a welding wire that feeds off-center, leading to premature contact tip failure. Liners that are too short can also lead to the build-up of debris between the liner and retaining head, which causes wire feeding issues and poor weld quality. In some cases, the gap that is present between the gas diffuser and liner when a liner has been cut too short may cause the welding wire to catch, resulting in small shavings that can plug up the contact tip and cause it to fail quickly. A liner that’s too long can cause kinking that again leads to wire-feeding issues that shorten the life of the contact tip. Always make sure that to remove any burrs or sharp edges after cutting a liner to ensure smooth and consistent feeding of the welding wire.

Recess/Extension	Amperage	Wire Stick-Out	Process	Notes
1/4-in. Recess	> 200	1/2 – 3/4in.	Spray, high-current pulse	Metal-cored wired, spray transfer, argon-rich mixed gas
1/8-in. Recess	> 200	1/2 – 3/4in.	Spray, high-current pulse	Metal-cored wired, spray transfer, argon-rich mixed gas
Flush	< 200	1/4 – 1/2in.	Short-current, low-current pulse	Low argon concentrations or 100 percent CO2
1/8-in. Extension	< 200	1/4 in.	Short-current, low-current pulse	Difficult-to-access joints

Welding operators should always consult with the liner manufacturer’s recommendation for proper trimming and installation instructions. It is also important that they wear gloves when handling the liner and avoid dragging it on the ground to prevent debris from being introduced into the MIG gun. Such debris can lead to weld contamination and/or poor consumable performance.

Mind the Contact Tip Position and Nozzle Size

The position of the contact tip (extended or recessed) affects how well consumables last, along with how clean they stay. So too does the nozzle used in conjunction with a specific contact tip and the wire size. The farther the contact tip extends from the nozzle, the closer it is to the arc and the more prone it is to reflective heat. The result is a greater tendency toward spatter accumulation and a greater opportunity for burnbacks. Using a recessed contact-tip-to-nozzle relationship when possible can minimize this problem and provide better shielding gas coverage at the same time.

For companies with applications that require access into restricted areas, it is important to select a nozzle that provides that access, but isn’t tapered so much that it minimizes the space around the contact tip. If there isn’t enough space for shielding gas to flow out of the nozzle, it can cause the shielding gas to hit the work piece and begin jetting back and/or swirling. The result is the pulling of oxygen into the weld pool and an increase in spatter. Too, the smaller the bore size on the nozzle, the more prone it is to absorbing heat (because there is less mass to that portion of the consumable) and having spatter adhere to it.

Other Considerations

As a general rule, companies should select the largest consumable that will work for the application and provide the necessary joint access. Larger consumables are more able to resist heat and spatter build-up, and they often last longer as a result.

Selecting consumables with the right material for the application is important, too. For example, brass nozzles tend to resist spatter well and are good for lower-amperage applications (100 to 300 amps), whereas copper nozzles are better for high-amperage applications (above 300 amps) or for those with longer arc-on time.

Lastly, companies should always pay attention to the manner in which they manage consumables. When possible, having the same consumables throughout the welding operation can help welding operators better maintain the consistency of the consumable performance and troubleshoot problems more quickly when they occur. The result can be longer-lasting, cleaner consumables that provide more reliable performance and quality.