Myths in Robotic Welding

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. 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” 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-to-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.

For example, when wire is fed from a large drum, an undersized contact tip may improve welding performance. Wire from a large drum tends to have less cast, causing it to feed through the contact tip with little to no contact. A tip that’s too big for the type of wire can cause erratic wire feeding, poor arc performance or premature tip failures. Taking the time to consider the wire package size and the job to be done will help ensure the right tip size is being used for the best results.

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.

www.tregaskiss.com

Subscribe to learn the latest in manufacturing.