Understand the Truth About These 7 Robotic Welding Myths

Estimated reading time: 7 minutes

Speed, accuracy, repeatability — welding automation boasts some big benefits. Using robots across a myriad of manufacturing applications has been a boon to the welding industry, but it hasn’t come without its fair share of misconceptions. Accepting those misconceptions could actually negate those big benefits — and no one has the time (or money) for that. Here are some common myths heard ’round the manufacturing floor — and where we land on them.

Myth 1: The more anti-spatter solution you use, the better the results

There seems to be a halo effect around the word “anti” — if it’s anti-“something,” it’s often assumed that the more you use, the better off you’ll be. In welding, that’s not necessarily the case. Using too much anti-spatter spray can actually cause more problems than it solves. When applying it to hot consumables, spraying just enough for it to dry on contact will create a sacrificial barrier that spatter won’t stick to as easily. If the solution is applied to the point where it’s dripping from the torch, it’s too much — and the excess spray will leak all over the parts and weld cell, leading to compromised weld quality, a messier weld cell and premature failure of the torch parts/consumables. Some operators will “dip” the consumables into a cup of the anti-spatter instead of spraying it, but this is also problematic because excess solution can cause the nozzle to become saturated and fail prematurely.

When welds are off location, there’s usually an underlying issue that’s causing the problem. Tip bore wear, variations in stamping batches or parts being misaligned due to tooling/spatter can all create a situation where welds are off location. Here, reassessing TCP can help determine what the root problem is rather than just blaming the torch and touching up points.

Apply only enough to get the job done. Tips to keep in mind when applying anti-spatter solution include:

• Position the nozzle at least 1 inch above the spray head
• Spray duration should be 0.5 seconds
• Adjust/reduce the spray frequency until the nozzle is perpetually wet
• The use of a spray containment unit allows the anti-spatter solution to be more effectively applied to the nozzle/consumables, while also keeping the weld cell cleaner by capturing over-spray

Myth 2: Using a contact tip that matches the size of the wire always leads to the best results

Contact tips can be the difference-maker between running an efficient welding process and accruing unwanted downtime. For smaller wire sizes in semi-automatic (or handheld) welding, using a contact tip that matches the size of the wire often leads to the desired results. However, in larger industrial operations where robotic welding is common, wire package size (vs. wire size) becomes more of the determining factor for selecting the proper tip size. Large-scale operations often use 1,000–2,000-pound drums or spools as the go-to options due to their high-volume output needs. The connection between the wire and the contact tip needs to be optimized for the tip to last as long as possible, which may require deviating from matching the tip and wire size.

Myth 3: The cheapest products will work

The adage goes, “You get what you pay for,” and that sentiment can definitely impact the quality of the work in welding. Investing in robotic welding equipment can add up quickly, so if there’s an opportunity to save a few bucks along the way, selecting a cheaper alternative seems like an appealing option. However, those savings often come at the expense of sacrificing product performance and weld quality, while creating more downtime. The issues experienced during the welding process will show in the end result, along with the bottom-line burn of frequent (and costly) consumable changeovers and excessive downtime for troubleshooting issues. Selecting high-quality, long-lasting consumables over cheaper alternatives will help reduce overall operating costs in the long run because it increases throughput while reducing inventory and downtime.

Myth 4: Changing the contact tip will always solve the problem

Well … not necessarily. If the contact tip fails and you replace it, you can consider the problem “solved” for at least a short time. However, if the tip keeps failing quickly, it’s safe to say that there’s a greater issue at play. Many factors can cause a tip to fail, including feeding or grounding issues. In those cases, if you put a new tip on, you’re inevitably just waiting until it fails again because you’re not addressing the root cause. If you’re going through tips at a high rate, this is the time to assess your operation and make sure that the drive roll tension is correct and/or the liner is trimmed properly. These are two common issues that can easily cause excessive “burn backs”/tip failure.

Myth 5: Higher drive roll tension results in better wire feeding

Choosing the right drive roll style and size for the wire being used is key to smooth and consistent wire feeding. However, if the tension is too high, or too low, it can diminish productivity, quality and efficiency. Tension that’s too tight can deform the wire, resulting in arc instability or burn backs (and too little tension can cause the wire to slip). If the system constantly needs more tension to push wire through, it likely means something else within the system is failing. For example, debris buildup in the liner can inhibit the right tension setting from being effective. To help mitigate the need to crank up the tension, make sure it is set correctly each time the wire spool/drum is changed. Additionally, be sure that the inlet guides are clear/not worn and clean the drive roll surfaces with a wire brush periodically to help maintain proper wire feeding.

Myth 6: Increased gas flow results in less porosity

This is another instance where the idea of “more is better” can be misleading. You definitely need enough gas to cover the weld pool, but turning up the gas doesn’t necessarily result in less porosity — in fact, it could create turbulence and MORE porosity. Proper gas coverage is based on flow, not pressure. If a system isn’t set up properly and the nozzle gets blocked with too much spatter/debris, there won’t be sufficient gas volume (flow) to protect the pool.

Leaks in the gas system or excess air flow within the weld cell can also impact the coverage of the weld pool, regardless of how high the gas flow rate is set. Instead of just defaulting to increasing the flow, do a quick run-through of the robotic system to verify that there is a proper tip-to-work distance and that the rest of the system is configured and running correctly.

Myth 7: Off-location welds are always the gun’s fault

In many applications, weld locations are extremely important. Even though the robot is physically going where it’s programmed to go, if the wire isn’t placed in the joint properly, it could be detrimental to the end product.

When welds are off location, there’s usually an underlying issue that’s causing the problem. Tip bore wear, variations in stamping batches or parts being misaligned due to tooling/spatter can all create a situation where welds are off location. Here, reassessing TCP can help determine what the root problem is rather than just blaming the torch and touching up points.

Avoiding these common missteps in robotic welding will help you maximize uptime and throughput while minimizing costs — a win from start to finish.

Written by Ryan Lizotte (ryan.lizotte@tregaskiss.com), Technical Services Manager, Tregaskiss.
Republished with permission from Fabricating and Metalworking, (October 2023)

Best Practices For Weld Cell Layout

Today, even the smallest weld shops are making the jump to robotics, and even the largest, highly automated OEMs likely have semiautomatic weld cells for repairs or for welding parts that don’t lend themselves to automation. In automotive manufacturing, these manual cells may be midway through the line for welding frames or at the end for minor rework. If you’re in heavy equipment manufacturing, you might automate multipass welding on thick parts and reserve semiautomatic welding for tacking the parts or adding specialized components.

No matter your industry or your level of welding automation, an effective weld cell layout can help. Work needs to flow in an orderly fashion. Power, grounding, and wire feed cables need to be properly managed. And, of course, you need to ensure welders can work safely, consistently, and with good ergonomics. Proper layout supports high productivity and quality, along with cost savings.

The Big Picture

Whether robotic or semiautomatic, a well-designed weld cell makes efficient use of available space, where every component—the power source, welding gun, weld table, cables—ensures parts can be produced with little interruption. Streamlining workflow is a good first step. This involves setting up equipment in a way that helps operators avoid handling parts multiple times. Double handling of parts adds non-value-added seconds to the overall manufacturing cycle time and reduces the capacity for completed parts sent out the door. Think with an assembly line mentality.

Look beyond the weld cell to how parts are being delivered. For example, when an operation requires that parts receive semiautomatic tack welds before robotic welding, work must flow at a consistent pace to prevent the welding robot from sitting idle. To ensure a steady supply of parts and prevent bottlenecks, the cell should have a single point of entry. For optimal workflow, parts should move out of the weld cell in the same direction.

Minimize the distance a part needs to travel by keeping assembly points close together. Weld cells contributing to the completion of a single weld assembly should be in the same area of the facility. This proximity not only reduces time for moving a part, but it also lessens the number of footsteps operators need to make. Excessive movement in a welding cell is considered non-value-added work.

If you notice bottlenecks or operators or welding robots standing idle, or operators walking too far between weld cells, you might consider performing an audit. Any idle operation results in a failure to capitalize on the investment of that process. An audit can help you identify the causes behind these problems and implement solutions. The aim is to balance out the operations so that every aspect contributes to value-added work and high productivity.

The Semi-Automatic Weld Cell

Welding ergonomics are at the center of a semiautomatic welding cell layout. A more comfortable, healthier welding operator is a more productive one. Setting up the weld cell in a way that minimizes the need to reach repetitively or move awkwardly can reduce the risk of work-related musculoskeletal disorders.

Try to position the workbench or workpiece between the welding operator’s waist and shoulders, since this promotes a neutral posture that reduces stress on the body. When welding large components, use positioners or weld tables that move or rotate the part to the correct height and angle.

The same holds true when providing operators with a MIG gun that suits them, whether it be a curved or straight handle. Locking triggers help support comfort, as do rubber mats to stand on.

Strategically locating the power source and wire feeder can make the cell more efficient. Keep the two pieces of equipment as close as possible, so the operator can easily access them. Close proximity allows for shorter power cables for smoother wire feeding and also reduces electrical resistance drops so welding parameters remain more consistent.

Keep ground cable connections to a minimum. Some companies string together welding cables between weld cells for the same power source. This practice is inefficient, however, and can lead to problems. The multiple junctions can wear out easily, which causes electrical resistance and poor weld quality over time. The electrical resistance also can shorten consumable life, resulting in erratic arcs and burnbacks, leading to more downtime for contact tip changeovers.

The Robotic Weld Cell Layout

Implementing an effective robotic welding cell layout requires careful planning and attention to detail. One of the best approaches is to test the layout through virtual modeling or 3D simulation. These software programs can simulate the welding gun configuration—neck length, nozzle, and mounting (solid versus clutch)—to ensure it will operate properly within the work envelope. They also consider weld sequencing, robot arm movement, fixturing, and the parts to be welded so that you can be confident everything will work as planned.

Take the time to simulate the weld cell layout and process before equipment integration to avoid issues once the welding robot is in service. Simulations help prevent downtime during mass production for troubleshooting and potential expenses for revamping tooling or replacing components.

They also can model another key factor—welding robot reach. Be sure to match the size of the part with the reach of the robot. The robot must be able to reach all weld joints on the part; otherwise, you might need multiple robots for the application. A single, small welding robot won’t suffice for welding on a large part. If you have a weld on the edge of the reach envelope, you might not be able to achieve the optimal welding gun angle to create quality welds. This can add costs for rework, and you’ll likely need to replace stretched power cables that fail prematurely.

Regarding tooling, you might be tempted to purchase less expensive options—though such tooling might not have the features you need, such as the appropriate number of clamps or location pins. This can lead to inconsistent part fit-up or locating that requires multiple passes to fill the weld joint, adding to cycle time. You might experience more downtime as you reprogram the welding robot to accommodate the gaps, or you may end up needing to invest in touch sensing to locate the joint. Even worse, you might need to upgrade your tooling after the initial design phase—a costly step.

Also consider the positioners. Their size and weight capacity must account for both the weight of the part and the tooling. Design the robotic cell for the heaviest part to be welded.

Where you place the power source and wire feeder matters as they both impact power cable management and grounding. If space is at a premium, you may want to place the welding power source above the robot cell on a mezzanine. This way, you can run the power cable and ground leads down channels in the cell’s back wall directly to the tooling and welding robot.

These leads are stationary—except for the ones on the robot, so be sure to account for the robot’s air movements to minimize wear on the cables. Placing a junction power block at the base of the robot and running a high-flex power cable from that base up to the wire feeder can help save time in repairs, and it can save money. If the high-flex cable becomes worn, you just replace that shorter piece instead of the entire cable. The same approach works for the grounding leads.

Finally, determine the best location for the nozzle cleaning station or reamer. This peripheral cleans the nozzle of spatter during routine pauses in welding. It helps extend consumable life and reduces downtime for changeover.

The reamer needs to be close enough for the robotic welding gun to engage fully for the ream cycle. If you’re operating two robots close together, you can program them both to use the same reamer. Avoid mounting the reamer anywhere but a flat surface, since positioning it at an angle can cause anti-spatter to leak over equipment or fixtures.

Avoid interrupting the weld cycle by cleaning the nozzle during robot idle time. For example, consider cleaning the nozzles while parts are being transferred in and out of the fixture or while components are being loaded into a weld cell.

Small Moves, Big Impact

If you’re experiencing bottlenecks or missing productivity or quality goals, take a look at the welding cell layout. In a semiautomatic setup, never overlook welder comfort and safety. In a robot cell, moving power cables, power sources, wire feeders, or anything else can change how much that cell can produce over a shift.

The little things matter, and missing just one detail can snowball into bigger problems down the road. Small changes can make a big impact on the efficiency you can achieve.

Written by Justin Craft (justin.craft@bernardwelds.com), Field Technical Services Specialist, Tregaskiss and Bernard, Republished with permission from The Fabricator (August, 2023).

Proper Robotic Welding Gun Configuration

Estimated reading time: 6 minutes

The welding gun is a vital piece of equipment in a robotic welding system, serving as the conduit for the welding wire, gas, and power. However, it can sometimes be an afterthought when companies implement an automated welding solution. Unfortunately, this oversight can lead to a host of problems, not to mention frustration. That is especially true for first-time users making the investment.

The wrong robotic welding gun can also cause issues for those more experienced with robotic systems. It’s not uncommon for companies to purchase the same gun for a new robot and tooling when, in fact, it may not be the best option.

Companies also need to determine their welding amperage and arc-on requirements for the application. This ensures that they purchase a robotic welding gun with the proper duty cycle — the amount of welding that can occur at a rated output over a period without causing damage to the gun.

Robotic welding guns are available in a variety of ratings, including air-cooled models that operate at 350 or 385 A at 100% duty cycle.

Today, most robotic welding systems are through-arm models in which the power cable runs through the casting of the robot arm. As a first step in configuring a robotic welding gun for these systems, it’s important to know the make and model of the robot, power source, and wire feeder. Each equipment manufacturer has a different interface that dictates how each piece of equipment connects with one another.

There are higher amperage water-cooled options, which are typically 400 A and above, available in the marketplace. Some of these may be rated at 100% duty cycle, while others are rated at 60%. Don’t be fooled by high amperage unless it’s at 100% duty cycle.

Hybrid options are available for companies that want the simpler construction of an air-cooled robotic welding gun with the added cooling capacity of a water-cooled one. These guns have external water lines that circulate water around the nozzle to keep the front-end consumables cooler.

For a robotic welding gun to access the weld joints, it’s critical that the work envelope is adequate. Companies need to consider not just the size of the gun but also the space that is available when the tooling, fixtures, and parts are all in place. Joint design and weld sequencing also factor into the equation. It’s important that there is room and time for the welding gun to weld the joints in a sequence that keeps heat to a minimum. Companies should avoid heat soaking the parts, so they don’t become distorted.

A robot integrator can conduct a 3D simulation using models provided by the robotic welding gun manufacturer through computer-aided design (CAD) to make sure the gun and neck have the proper access and reach within the given space. The CAD model can also show whether the selected gun has the correct tool center point (TCP) and can extend to the nozzle cleaning station for reaming or to a service window for consumable changeover. A service window supports safety in the operation by eliminating the need for an employee to physically enter the cell.

Configuring the Gun

Some robotic welding gun manufacturers offer online configurators that allow companies to customize the equipment for their exact application. These configurators guide the user through a step-by-step process, providing options to choose from for each component. With or without this tool, companies need to consider what their needs are based on their upfront assessment.

Gun mount: There are two mounting options for a robotic welding gun to protect it in the event of a collision — a solid arm mount and a clutch. If the robot or end user’s safety procedure requires external collision detection, a clutch can be added to the system. This component functions both mechanically and electrically by recognizing a collision and sending a message to the robot controller to stop the system. If procedures allow for reliance on only the robot’s collision detection, then a solid mount will suffice. 

Neck: The neck length and angle must provide the approach angle to weld parts properly and to allow for smooth wire feeding. Standard neck angles are 22, 45, and 180 deg. Through-arm robots generally use a 45-deg neck; however, that should be verified with the CAD model/simulation before implementing. Companies will also need to take into consideration the welding wire they are using. For example, aluminum wire requires a straighter neck to feed through properly since it is so soft.

Welding cable: For through-arm robots, the make and model dictate the cable length. For conventional robots (where the cable assembly runs outside the robot arm), the gun cable length also depends on the robot make and model along with the location of the feeder. It may be remotely mounted or mounted on the robot itself. There is more flexibility with cable length for these robots, but it’s important not to use too long of a cable since this can lead to wire-feeding issues. Conversely, a cable that is too short can stretch and break down quickly.

Welding consumables: When choosing contact tips for the robotic welding gun, look at the welding process. Pulsed gas metal arc welding (GMAW-P), for example, is quite hard on contact tips due to its high-frequency waveforms. This process requires a harder tip or a contact tip specifically designed for pulsed welding.

The chosen nozzle needs to allow proper access to the weld joint. A tapered nozzle works well when using smaller-diameter wire and contact tips. Higher-premium consumables are a good choice since these last longer and reduce downtime and labor for changeover.

Welding supervisors and operators should schedule time to perform preventive maintenance, such as checking connections and visually inspecting consumables for spatter, during routine pauses in welding.

Liners are another factor to consider, and the welding wire being used affects the choice. Flux- and metal-cored wires tend to be stiffer and harder to feed than solid wires. They require an extra-heavy-duty liner to support the wire and gain smooth feedability as it moves toward the contact tip. A D-wound galvanized wire works well. Companies can also use this liner for solid wire with good success.

Maintaining Efficiency

Companies invest in robotic welding systems to increase quality, productivity, and cost savings through a fast, repeatable process. To gain those benefits, every part of the system needs to be functioning optimally. Ensuring that the robotic welding gun has been configured properly before implementing the system can prevent downtime and extra expenses.

This article was written by Ryan Lizotte (project manager, Tregaskiss, Windsor, Ontario, Canada) for the American Welding Society.