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State of the Arc: Robotic Welding Trends and Technologies

State of the Arc: Robotic Welding Trends and Technologies

Posted: 5/7/2020 3:36:22 PM by Josh Leath
Topics: Arc Welding, New Technologies

Several months into a new decade, welding technology continues to advance and be implemented on factory floors throughout the Americas. Here’s a look at several trends that may be helpful in moving your operations forward. 

Complex Lasers: Making Manufacturing Simpler

Down to a fraction of a micron for repeatability and defect detection, the use of fast and incredibly precise lasers for inspection across industries is optimizing product quality. With automotive, the use of sensors gives the traceability needed for weld seam inspection, and it is also more expedient than wire touch for finding workpieces. Laser sensing can also be used for verifying or measuring assemblies, as well as for tracking a variety of arc and laser weld seams.

Specifications

Aside from being highly accurate and extremely fast, there are other specifications to note:

  • The same type of laser that is used for measurement or inspection can be the same laser that is used for weld line verification.
  • Typically, lasers will be red, blue or green in color: the blue and green laser are relatively new to the market, and they aren’t affected by the weld pool heat reflectivity (which can sometimes be associated with red lasers). While, red lasers have a higher install base and user experience.
  • There is a Z and X axis max range (Z: 20 to 1,000 mm height, X: 5 to 500 mm width), so very small parts to a larger range of workpieces are easily accommodated by sizing .

Use Cases

Laser Inspection: Robotic workcells are being designed today to complete a thorough weld sequence: 1) check for part position, 2) perform the weld, 3) inspect that weld and 4) provide a pass/fail response. Aside from checking for quality weld seams, lasers can be used for workpiece inspection, checking to see if parts are in the correct place on an assembly. For example, if there are different studs that need to come through or there are different screws that must be present on a particular weld, each model can be tracked to determine if a part is in place and if it is considered, “good” or “bad”.

Adaptive Welding: Lasers can also be used for adaptive welding. This can be done with a simple wire touch sensing, but lasers offer a faster pin-point touch process. With this type of welding, camera systems can be used, as well as high-tech laser inspection systems, to determine the correct start and position of a weld seam. Furthermore, with this method, the robot’s Relative Job function is used to shift the entire job point to be in the ideal space to complete the weld job.

Adaptive weaving, which compensates for variations in the weld joint, can also be enabled by sensor utilization. A laser can be used to track the weld joint path during the welding process to accomplish this, and can be complimented by thru-the-arc sensors that track the gains or drops in actual voltage and current values to ensure a consistent weld seam.

Data Usage: Harnessing Information to Optimize Production

While a plethora of data (process times, part count, weld parameters, consumption rates, etc.) can be collected on a wide selection of factory equipment, industrial robots, sensing devices and more, learning how to make sense of the data and to harness it for optimizing operations is another matter. Several things to consider would be:

  • Efficiency: From part production to cycle times, data can help operators visualize how efficiently machines are running.
  • Uptime: While a machine may be efficient, setbacks such as operator error or robot maintenance can cause downtime. Thus, utilizing data to effectively monitor user error or to implement data-driven planning for preventive maintenance is ideal for ensuring uptime and achieving ROI goals.
  • Quality: The data collected by sensors and equipment to determine if welds are good or bad helps to measure quality, giving greater assurance on the parts produced.
  • Visualization: Charts and graphs can be created from the data collected to visualize performance. This can be helpful for at-a-glance status and achieving different Key Performance Indicator (KPI) targets.

From built-in data collection capabilities to software platforms for factory devices, there are a variety of ways to collect, visualize and use data.

AI Welding: Using Intelligence to Simplify High-Mix Welding

A branch of computer science dealing with the simulation of intelligent behavior in computers, Artificial Intelligence (AI) is one example of how data can be harnessed. More specifically, Machine Learning can build models to classify and make predictions from the data collected (instead of following rules based on algorithms).

For example, a model can be trained, validated and tested through simulation, with the process repeating as necessary to improve the simulation output after each run until the ideal outcome is achieved. A unique example of this process can be seen with IBM’s cloud-based AI when it is used to determine the quality of a weld seam using arc soundwaves. In this instance, acoustics from thousands of welds are compared to an initially set standard, before providing a Go/No-Go result based on deviation.

While this type of deep learning is not commonplace with welding, the process of being able to “throw a random part at a robot” is gaining a foothold. Via offline programming software (i.e., simulation software) a part can be scanned, generating a point cloud where the programming software AI can set the weld seam locations and the correct parameters based on the material and process selection.

Welding Trends: Keeping up to Speed

When it comes to welding there are several trends to consider.

Materials

With respect to materials especially in the automotive market where the majority of robots are used, there are several trends to note.
  • Light Weighting: Entailing thin stamped parts, this process utilizes aluminum alloys, as well as next-generation advanced steels.
  • Dissimilar Metals: More and more parts, such as engine cradles and battery trays, are utilizing the different lightweight and high-strength properties offered by different materials that traditionally have not been compatible for conventional welding methods.
  • Higher Safety Ratings: Things like greater torsional rigidity and improved energy dispersion through HSS and structural adhesive are being used and changing the way materials are being joined.
  • Higher Aesthetics: Even though safety standards have increased, customers still want something that looks nice.

Advance Pulse and Servo GMAW

When it comes to welding aluminum and other thin metals, the power supply simplifies much of the process, alleviating the need for a lot of additional equipment. Gas metal arc welding (GMAW) is also utilizing servo torches to mimic the wire control that a human operator has. Traditionally, this  is something that has been considered a limitation to some robotic welding applications.

  • Pulse Wave Function: Allowing less heat input for thinner or high heat conductive metals, this function allows TIG-like cosmetics, even when a welding robot is equipped with a MIG torch. This method is ideal for aluminum and lowers heat distortion on thin steels.
  • Servo Torch Usage: As power supplies get smarter, more servo torches (or “pull” torches) are being used, dipping and retracting the soft wire (i.e., aluminum) in and out of the weld puddle. This allows for better cosmetics, as well as greater control of depth and energy.

Laser Welding

While still costly to implement (compared to other welding methods), laser welding is growing in popularity, especially for certain aerospace applications.

  • Remote Laser Welding (RLW): The most common form of laser welding, RLW uses a “wobble” laser head that sits inside a light-tight enclosure. While the robot controls some of the weld path motion during this process, most of the weld motion is done inside the laser head, creating a very precise weld seam.
  • Laser Seam Stepper: Also growing in popularity, this method utilizes a laser inside a “picker” or C-gun, and it does not require a light-tight enclosure. With this process, the laser head comes down to the part, before the C-gun applies pressure (similar to resistance welding). Note: the C-gun is only one-sided, so it can apply pressure against the tooling and reach far into a wide or deep part as needed. This is a very fast process with no consumables, so tip dressing is not required.

Multiple Weld Options for Dissimilar Metals

Thanks to their growing usage in the automotive industry, there are now several ways to tackle the welding of dissimilar metals.

  • GMAW / GTAW Brazing: While this method uses a fairly traditional GMAW- / GTAW-like process, the use of silicone bronze filler metal allows the brazing of materials, creating a metallurgical bond between two dissimilar metals, including dissimilar steels, or steel with aluminum.
  • Laser Welding: As previously mentioned, the use of a laser seam stepper can work on certain types of mixed metals such as steel and aluminum, also of different thicknesses.
  • Friction Stud Welding: This method is ideal for spinning a steel stud onto aluminum, or for fusing two different types of steel into place.
  • Flow Drilling: This very clean, single-sided process uses a mechanical fastener, where the consumable screw spins up fast enough to melt the base metals and join the two with the fastener. This provides a very strong joint, especially in thin materials.
  • Friction Stir Welding: A solid-state joining process, this process uses a non-consumable router bit that plunges into differing (or similar) metals, spinning at a high rate of speed while applying pressure as it travels along the weld seam to join the metals. This too is a clean process and is great for sealing battery trays.

Mixed Process

As greater flexibility is needed in the manufacturing sector to address the wide selection of advanced materials and unique parts being required, more and more mixed processes are being used. This means that a manufacturer may no longer have a workcell just for adhesive or spot welding. For example, spraying structural adhesive and spray foam may now take place in the same workspace as tacking and welding. Or, steps like inspection may happen at the same time as welding in a workcell to lower cycle time and save floorspace. Jigless operation can also be more useful in mixed lines, achieving greater efficiency.

Typically used for removal of a surface coating, laser ablation uses a lower powered laser to burn off any coating materials rather than the use of dangerous chemicals. This can often ready parts (i.e., high performance automotive parts) for a new coating or for inspection (i.e., a regular surface inspection of airplanes). 

Learn More

To learn more about these trends and technologies, as well as to see video examples of some of the methods discussed, check out our State of the Arc webinar. And, as always, if you have questions about a particular application, feel free to contact us – we’re here to help!



Josh Leath is a Product Manager


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