Six Tips for Implementing Your Robotic GMAW Gun … and Getting the Most From It
As companies seek to gain a competitive edge, it’s not surprising that some turn to welding automation. It offers numerous advantages, including greater productivity, improved quality and cost savings compared to a semi-automatic welding operation. However, to gain the most out of the investment it’s important to follow some best practices in the weld cell. These considerations include the careful selection, installation and maintenance of gas metal arc welding (GMAW) guns.
As with any type of welding equipment, the goal is to implement the GMAW gun in a manner that optimizes performance, reduces downtime and prevents the accrual of unnecessary costs. It is important to note that the considerations for achieving these benefits may vary depending on whether the robotic welding system uses a through-arm gun or a conventional-style gun. Following are some tips to help.
Tip No. 1: Choose a solid mount instead of a clutch
All automated welding systems need some form of collision detection to minimize damage to the robot and the GMAW gun in the event of an impact. Today’s robots typically have built-in collision detection software, making it appropriate to use only a solid gun mount to connect and position the GMAW gun. In some cases, companies like the secondary insurance of using a clutch on robots featuring this software. Doing so, however, can add unnecessarily to the expense of the operation, increase weight on the front end of the robot arm and cause the tool center point (TCP) to be less repeatable. When possible, it is preferable to use a solid mount coupled with collision detection built into the robot, instead of a clutch.
Solid mounts offer numerous advantages, especially for systems using a through-arm style gun. A solid mount can aid in achieving a more accurate TCP, providing greater repeatability for more consistent welds. They are also more cost effective and lighter weight, which allows for quicker movement and potentially better productivity. The use of a solid mount, in conjunction with a through-arm robotic GMAW gun, typically opens up the work envelope, so the robot arm can better access the weld joint.
For systems with a conventional gun, a solid mount provides little benefit over a clutch in terms of opening up the work envelope or increasing productivity due to the position of the gun in comparison to the faceplate of the robot.
Tip No. 2: Use an air blast feature
Air blast is an optional technology on GMAW guns that can help enhance gun performance. This feature can be factory-installed or retrofitted into a gun. Utilizing air blast when possible helps eliminate debris in the front part of the robotic GMAW gun, reducing opportunities for weld contamination that can lead to poor weld quality, costly rework and downtime.
As the name implies, the air blast feature blows compressed air through the front of the gun to remove debris. It can be used with air-cooled robotic guns or water-cooled models.
In addition to removing debris that can cause poor weld quality or contamination, air blast can help increase the time between cycles by removing spatter from the front of the gun. The air blast function can also be used to cool down the gun between weld passes, to help operations avoid going over the duty cycle limit when using air-cooled guns.
Tip No. 3: Utilize a simulation program
Using simulation software to model the proposed weld cycle before selecting and implementing a robotic GMAW gun can help in achieving the best results with an automated welding system. While the goal with an automated welding system is often to move as quickly and freely as possible, it’s important to remember that it’s typically best to limit excessive robot movements, as it results in longer gun life thanks to reduced equipment stress. Simulation programs can be used to determine proper system setup, including TCP requirements and which nozzle and GMAW gun neck are best suited to get the desired joint access or angle.
The reach and access of the gun neck, in particular, is an important factor in system movement and stress. Changing the neck angle from 22 degrees to 45 degrees, for example, can have a significant impact on robot articulation.
This is where a simulation program is beneficial, since it can be used to determine the type of neck and the neck angle that are best for the application before making the investment. To gain optimum speed and performance from the gun, it may be as simple as slightly adjusting the height of the risers or tooling to gain better access to the weld and reduce stress on the gun.
Tip No. 4: Utilize a neck inspection fixture
Among several peripherals that can be added to maximize system performance, a neck inspection fixture is one that can help improve throughput, minimize unnecessary downtime — and help gain the best performance from the robotic GMAW gun. A neck inspection fixture verifies that the gun neck is set to the intended TCP and allows the neck to be readjusted after a collision or if it becomes bent during routine welding.
When neck adjustment is needed, the welding operator can simply adjust the neck to meet specifications. This helps prevent costly rework due to missed weld joints and can prevent the downtime it takes to reprogram the robot to meet the necessary welding specifications with a bent neck on the gun.
In some cases, the welding operator can simply remove the bent neck and exchange it with a spare neck to get the system back online quickly. The damaged neck can be set aside for inspection later, resulting in less interruption to the weld cycle.
Using a neck inspection fixture from day one of an automated welding system helps ensure a consistent TCP.
Tip No. 5: Ensure proper gun and cable installation
Choosing the right gun and cable for the application — and installing them properly — are key steps toward maximizing performance of the robotic GMAW gun. Consider the weld length, the required amperage and the type and thickness of material being welded when selecting a robotic GMAW gun.
Air-cooled guns work well on lower amperage applications and high-volume welds. In heavy equipment manufacturing and similar industries, a water-cooled GMAW gun may be necessary to weld on thicker materials for longer periods of time. Water-cooled guns offer high amperages — usually up to 600 amps — at 100 percent duty cycle.
Selecting the appropriate neck, power cable and other gun components can also have an impact on productivity and performance. Choosing the proper neck style and length for the application provides the gun with easy and complete access to the weld joint, which helps reduce weld defects and downtime for rework. Available neck angles typically range from 180 to 45 degrees, with varying lengths to accommodate most robotic welding applications. Necks can also be special ordered for custom TCP requirements when necessary.
Tip No. 6: Conduct proper gun maintenance
In addition, power cable style and length can also impact efficiency in robotic welding operations. For through-arm applications, the power cable is often sold in set lengths to match a specific model of robot, so the selection process is easier. For conventional style robots, it’s important to verify the exact length needed. Too long of a cable can easily kink or move during the welding process, while too short of a cable can stretch and shorten cable life. In both cases, it can result in downtime, premature cable failure and increased costs.
Also, look for a sturdy power cable that can withstand UV damage from the arc and resist wear. Cables with quick-change features can extend cable life, simplify cable changeover and maximize arc-on time when installed properly.
Choosing and properly installing the right gun and cable is just the beginning. Proper ongoing maintenance is also an important factor to optimize performance.
Regularly check all connections on the GMAW gun to ensure they are tight and secure. Doing so helps prevent issues that can lead to weld defect and downtime. Tighten front-end consumables and check that all seals are in good condition. Also be certain the power pin is secure. While checking that welding cable leads are secure, look for signs of wear and replace them as necessary.
Remove spatter from the GMAW gun nozzle regularly, ideally applying anti-spatter to protect against buildup. Implement a reamer when possible to minimize damage to the gun and front-end consumables. A reamer (or nozzle cleaning station) removes spatter from the nozzle bore and clears away debris that accumulates around the diffuser during welding, resulting in longer life of the consumables and higher weld quality. The reamer can be programmed to run between welding cycles — either during part loading or transfer — so it does not add to the overall cycle time per part.
In addition, track the life span of the GMAW gun liner and replace it prior to failure. Replacement liners should be trimmed to the appropriate length using a liner gauge.
Automated welding operations that are larger in size may need to do more frequent preventive maintenance. It’s especially important for companies that complete large weldments on thick materials because they stand to have greater costs and downtime for rework in the event of gun failure.
Optimize the system
Automated welding systems add speed, accuracy and repeatability to the welding operation. They can help companies increase productivity and reduce costs in a relatively short period.
Implementing some best practices can help companies extend the life of the GMAW gun and consumables, and optimize performance and efficiency of an automated welding system — offering them the most out of the investment.