Manufacturing is becoming more and more automated and increasingly demanding of easy-to-use solutions. In the welding sector, due to the lack of qualified welding personnel, automated and robotic welding solutions are in high demand and at the same time becoming more cost effective for manufacturers and fabricators. Many existing welding solutions can be considered “semi-automated” however such solutions require constant operator interaction, require a lengthy period for weld setup and require a highly trained operator. Completely automated robotic welding can be called “Automatic Welding”. However, if very little operator interaction is required and setup tasks are greatly simplified, then this solution can be called “autonomous”. But it is difficult to achieve autonomy with minimal operator activity. A robotic welding solution requires improvement to the process to become truly autonomous or driverless, such as laser seam tracking / finding sensors with adequate integrated intelligence for executing optimal welding strategies at any point in time.
GarLine PLC applied to Column and Beam welding of tanks and pipes
Technologies available for Automated or Semi-Automated Welding
In an article published on the Motoman.com website, March 31, 2022, Joshua Leath provided a guide to the various options for automated welding. He identified five general categories: Touch Sensing, Wire Sensing, Through-the-Arc Sensing, Laser Point Sensing and Laser Profile Sensing. He also divided the automated tasks between Seam Finding and Seam Tracking:
Seam Finding vs. Seam Tracking
“What is the difference between seam finding and seam tracking?” and “How do I know when to use seam finding vs. seam tracking?” These are common questions our robotic welding experts are frequently asked. With that in mind, here are several things to consider when deciding how to proceed with the robotic welding process:
Seam Finding
For a robot to precisely locate a weld joint before welding begins, high-speed seam finding or joint finding is recommended. Work pieces will inevitably have some range of variation, but your goal is to minimize that variation with spec’d parts and fixturing, and be within the half-width of a weld wire into your joint seam. This process can be done in several ways via various technologies, enabling the robot to find the weld joint. Once the seam is discovered by finding usually two or more known points on the part, the program path is shifted by the robot to complete the weld. The type of seam finding required is dictated by two primary factors: the expected cycle time and the type of joint. Seam finding is one of the most popular welding functions, and is often achieved through the following contact and non-contact options:
Touch Sensing – Ideal for finding the orientation of parts with simple joints and geometries, this method, also known as “wire touch”, involves the physical touch of a weld wire from the end of the torch to detect the conductive surface of the part about to be welded. The slow speed of the robot and the eventual touch complete a circuit with a low amount of voltage fed through the wire. This can also be done with the nozzle of the torch in some scenarios. Completed through built-in features on a welding power supply designed for automation, systems like Yaskawa’s Touch Sense package use a low voltage circuit during a low-speed search to determine the best position for the weld joint.
Wire Sensing – Similar to touch sense, where a wire from the torch makes tactile contact with the part, this option uses a servo motor in the torch to rapidly move the wire up and down while the robot moves across the part. This enables easy location of lap joints, and it can measure items like material height and gaps.
Laser Point Sensing – Two to five times faster than touch sensing, the use of a basic, laser dot sensor (that is mounted to the weld torch) captures the location and orientation of a part nearly as quickly as the laser fires, providing fast and accurate seam finding.
Fanuc integrated with Garmo GarLine R sensor
Laser Seam Finding (Search) – Capable of picking up more characteristics in a single scan over a laser dot sensor, the utilization of a profile laser interface (software option), such as Yaskawa’s MotoEye™ SF, provides extremely fast joint measurement. The FANUC America Corporation provides a similar feature called the R901 SW option. This solution works well with a sensing device that uses 3D multi-laser range imaging optics to provide the needed measurements/joint gap data to the robot before welding begins.
Pros:
Works on different materials in all lighting
Easy to teach with macro jobs
Provides joint gap data
Long focal length; mount away from arc
Locates 2.5D; offset and depth
Compact and self-contained
I/O interface can be retrofit to older controls
Cons:
Medium- to high-complexity; Training on vision system suggested
May restrict access into part/tooling
40 or 50mm FOV may require multiple searches for large offsets
Often simplifying programming, this option uses innovative technology to equip the robot to track the weld position in real time, during the welding process. Seam tracking is popular for applications where distortion can occur while welding a part or for heavy cast parts, and it is commonly performed using the following methods:
Through-the-arc Seam Tracking – Best for parts with long or curved seams, varying from part to part, a through-the-arc seam tracker, like Yaskawa’s ComArc LV (low voltage), utilizes a solid-state sensor mounted near the welding power supply to actively measure arc characteristics during the weld sequence. This determines variations between a robot’s taught path and the actual seam path.
Laser Seam Tracking – Suggested for material with varying seams that demand the fastest cycle time possible, this method combines a high-performance laser with a high-speed controller to find the seam and part location in real time while the part is being welded. This is the ideal solution for high mix, low volume parts production as might be found in a job shop environment. The approach also requires less fixturing than semi-automated or automated welding approaches. A dedicated program compensates the path, even if the part is moved, as well as adapts to welding parameters for seam location and variation.
Pros:
Reliably tracks thin gauge lap joint
Supports high travel speeds (>100 IPM)
Weaving Motion with tracking possible
Tracking is not affected by weld settings
Supports coordinated motion
Ethernet interface available
Camera hardened against welding arc
Adaptive welding function; speed and weld settings
Cons:
High-complexity and sometimes (not always) high cost
Training on vision system required
Torch-mounted sensor restricts joint access to tight spaces
Tracking radii is limited to 40-60 mm
L
imited to two robots on one system
Benefits of using GarLine Seam Tracking and Seam Finding Laser Profile Sensors
We can see from Mr. Leath’s detailed analysis that there are several ways to provide welding automation. But many of the techniques fall short of true autonomy, meaning untended operation, adaptive control and high ease-of-use. The last solution Mr. Leath offered was laser profile seam tracking / finding. It offers the highest degree of autonomy as it looks ahead on the seam to define the robot path to conduct the weld and through an onboard processor (with GarLine) has fast signal processing and can make on-the-fly adjustments of the required weld based on measured width or depth.
Garmo Instruments of Zaragoza, Spain has developed a range of laser profiling welding seam sensors, #GarLine, that have the ruggedness, flexibility and adaptability for many different welding applications and on a wide range of materials.
Here is a summary of how welding autonomy benefits the manufacturer:
Improved working conditions
With GarLine sensors, workers are performing in a safer environment, avoiding traditional health-related and ergonomic welding risks since there is no longer a need to work close to the weld.
Quick Change-overs for Short Run Production
The GarLine sensors have a very user-friendly menu-driven setup on either a personal computer or integrated on the robot or cobot teach pendant for a wide range of brands and models including Fanuc, ABB Robotics, #Universal Robotics (UR) and others. This simplifies operator training and allows for fast program changes based on part production changes. GarLine is the ideal solution for job shops with high mix and low volume and is also beneficial over a wide range of part sizes and shapes with its large range of menu options and inherent weld adaptation
Enriched product quality
GarLine’s optical precision and automatic corrections are communicated to the robot at a very high rate, and therefore, the GarLine welding solution benefits the manufacturer by achieving better quality welds, faster welds, lower percentage of unnecessary waste and, hence, a higher rate of finished product in lower time, avoiding re-process and production losses.
Enhanced productivity
The simplicity of the “less is more” concept is the goal for every business, including manufacturers in the welding sector. The less time invested in production, including machine setup and part fixturing, while still getting high quality results, improves overall productivity (OEE).
GarLine C for UR Cobot Setup and Operation
GarLine sensors’ features
Robust sensor
GarLine surpasses the IP67 insulation grade and successfully performs in a -20 ºC / 70 ºC working range. Its design incorporates materials for aerospace use that ensure an optimal EMI insulation, including in TIG welding processes.
Smart electronics
Its electronics consist of 4 parallel processors utilizing 4Gb of RAM which processes images at 42 frames per second in full resolution. Additionally, GarLine sensors include innovative algorithms for dynamic adaptation of sensor and laser parameters to correct reflection problems in applications involving varying material surface conditions. The laser bandwidth is well outside of any light bandwidths produced by welding arcs.
Easy maintenance
GarLine features a disposable polycarbonate protective shield and an internal Gorilla Glass window. The sensor is air-cooled which also serves as an air curtain across the sensor face for additional protection. There is a water cooling option for very hot environments. The water cooler is integrated into the mounting plate, with ARC-Swiss fixing. This solution grants rapid and easy sensor replacement, if ever necessary.
For all types of autonomous welding (cobots, industrial robots and PLC operated machines), GarLine seam finding sensors are a Plug & Play solution, as their interface is displayed directly on a robot welding systems’ pendant, without the need for additional computers nor other extra and special software, cables or any additional devices.
Beside seam tracking and seam finding functions, GarLine sensors also include other very useful functions very demanded in autonomous welding.
Seam search: real-time look-ahead calculation of corrections to move the torch towards the seam. The sensor finds the right teach points of the welding joint before the weld, compensating for the part deviation.
Location function: GarLine scans 4 points of the piece, capturing its shape and placing it on the plane. This scanning and location process is done 10 times faster than with Touch Sense function only. GarLine measures rotation and translation in 3 axes each, calculating in total 6 seam positions.
Multipass: easy-programming function for multilayer welds.
End-detection tracking: the sensor detects the end of the seam and stops the welding.
Pre-tag-avoid configuration: the sensor can be configured to weld straight and skip pre-programmed gaps along the joint
Weaving and adaptive weaving: thanks to the Garline sensor’s “look-ahead” vision, the trajectory of the torch adapts to the seams width, ensuring zig-zag filled-in gaps.
Knowing the needs of the welding market, Garmo Instruments has also developed an all-in-one easy welding kit with its SharpTrack solution, providing the ultimate customized and convenient solution for autonomous welding applications.
Effortless welding automation with SharpTrack system and GarLine sensors
access the multiple and flexible PLC programming options
customize SHARPtrack to application requirements (selection of slide model, PLC brand (Siemens, Rockwell and Panasonic PLCs are currently available), drivers, cable length and customized enclosure cabinet features according to the application);
Pendant access to all welding features (welding seam tracking, real-time monitoring, manual slide move, live offset control, and configuring welding speed and source related parameters).
GarLine’s look-ahead function ensures an accurate real-time seam tracking and micro corrections of welding torch trajectory. GarLine sensor carries out trajectory corrections at such speed that it is imperceptible to the human eye. This precision, in addition to providing flawless quality welds, ensures a pristine perceived value in the end product.
SHARPtrack already includes pre-defined and personalizable programming, turning welding automation into a Plug&Play. Simple installation, and no extensive programming required.
Thinking of upgrading your welding application?
Get in touch with Garmo Instruments‘ team for more information about GarLine sensors and SharpTrack system.
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