When it comes to complex welding automation dilemmas, our experts at Yaskawa rise to the challenge. A keen awareness for industry trends and new technologies, combined with years of application experience, help our dedicated engineers answer an array of customer questions on a daily basis. Since you might have some of the same questions, we wanted to share them here. In the last few months, some of our most popular questions have been:
1) What is the best weld torch to use for a robotic application?
According to Chris Anderson, Associate Chief Engineer, it’s important to consider several things when looking to apply a torch to a specific application. For mild steel approximately 2 to 3 mm thick, choosing a particular weld torch over another is not a huge deal. However, if different or thinner materials will be used, some thought should be given to the best weld process. Often, this will dictate the power source – as weld torches are often compatible with a particular power source brand. This is particularly true for motorized pull torches which are controlled by the power source.
When a heavier material is being welded, it is typically suggested that a water-cooled torch be used. This is especially true for pulse welding and for jobs that require over 300 amps. For lower amperage tasks, an air-cooled torch is typically sufficient.
2) Should I use a shock sensor or clutch to mount the torch to the robot?
Robots are equipped with software that will detect an excessive torque when the robot collides with a fixed object. This will protect the robot axes, and at slow speeds, it can prevent damage to the torch. Collision detection software is effective at teaching speeds where most collisions occur. However, at full speeds the robot will have to decelerate after an impact, and this “over-travel” will likely result in the torch barrel deforming. A shock sensor allows the torch barrel to deflect when a crash occurs, which will reduce the chance of the torch deforming.
Therefore, a shock sensor is not required to mount the torch to a robot. Think of it as insurance to help prevent downtime when the torch might get bent from a high-speed crash.
Be sure collision detection software limits are set to a value just above normal program torques. For Yaskawa robots, an operator can reset the max torque levels, run the program, and then set the collision detection level +10-15% above the max value for each axis.
Torch manufacturers offer jigs to calibrate torch barrels. Using the jig to maintain a mechanical TCP position will help speed recovery from crashes (it is usually the neck that deforms).
Pointers in the cell can be used as a quick reference for torch alignment/TCP accuracy. ToolSight™ is an optional gauge that can check the TCP as part of a program and includes software that can update the TCP position if it is off.
3) What are software and hardware requirements for repurposing a general-purpose robot into a welding robot?
While it is always a good idea to reach out to the robot manufacturer for exact specifications, at a high level, Chris Anderson suggests thinking about the following items:
Motion capability – a general-purpose robot may not be equipped with certain features such as software weaving that aids in the welding process. Something else to consider is if the robot is set up for a pick and place task vs. a continuous-path trajectory. The latter is necessary for a smooth path motion.
Interfacing – welding robots have a more sophisticated welding interface where control parameters for amps, volts, etc. can be set. While a simple output can be used on a general-purpose robot to generate a trigger for something like a semi-automatic welder (toggling it off and on), this setup may lack the capability needed for more advanced welding tasks.
4) Compared to a decade ago, what’s trending in the automotive industry?
According to welding expert and Key Account Manager, Heath Lynnes, the process for welding has evolved considerably, greatly increasing quality and efficiency. Much in part to the wide selection of metals (in varying thicknesses) available today, alternative joining methods such as laser welding, flow drilling, brazing, friction element joining and self-pierce riveting are being used. Recent advancements for more affordable and capable technologies that can be combined with high performance robots are also driving the growing usage of these unique processes that often support the development of electric vehicles with lightweighting, new materials and battery tray production.
5) Should I consider laser welding vs. traditional arc welding?
Capable of forming strong, repeatable weld seams at high speeds with excellent precision, robotic laser welding is providing the ability to weld materials that were once viewed as non-weldable. When considering the use of laser welding, Heath encourages manufacturers to look at the material stack up, joint presentation (design) and tolerances being applied to the weld components, as well as the volume of parts being processed. To justify the capital investment that typically comes with laser welding integration, high production runs are suggested to offset the cost. If quality is paramount and there is concern about the size of a run, speaking to a knowledgeable robot manufacturer or integrator can help manufacturers weigh the pros and cons.
6) Should I, or can I, implement arc data monitoring?
As more robots and advanced technologies are installed on factory floors to improve processes for greater throughput, the amount of data available from these devices continues to grow. Harnessing this data to adhere to weld procedures and make informed decisions can be highly advantageous, especially for meeting traceability requirements.
Chris Anderson suggests that for arc monitoring to be beneficial in this realm it needs to be done at the power source where things can be controlled in microseconds. Hundreds (if not thousands) of times a second, a power source will measure output voltage, wire feed speed, weld time and other specific parameters when needed. This data is then compared to predefined limits for the weld in progress. If the power source detects a parameter outside of the acceptable limits, that specific weld is marked as “suspect,” and the information related to the weld is transferred to the robot and robot operator for proper handling.
Welding equipment manufacturer, Miller Electric Mfg. LLC, hosts these features within Insight Centerpoint™ arc data monitoring software that is available via a modern, smart and powerful Auto-Continuum™ power source. Lincoln Electric offers Production Monitoring™, along with a unique WeldScore™ feature that ranks the weld’s overall quality based on the previously mentioned criteria. And, Fronius offers a tool called WeldCube™ that is able to connect multiple TPSi welders from a single device, and generate daily production and quality reports, providing equipment status and health reports.
Manufacturers that successfully utilize arc data monitoring for weld traceability not only protect their business interests, but also, customer needs are met in a professional and timely manner, ensuring the parts produced are compliant when necessary.
7) Is offline programming beneficial for both automotive and non-automotive welding applications?
The short answer is, yes! Offline programming (OLP) gives programmers the ability to create, test and adjust a robot program or job from the convenience of a PC-based virtual programming environment before it is implemented on the factory floor. These programs can also help with robot reach studies, path validation, torch angles and cycle times before a cell is even built. This helps to minimize production downtime caused by robotic integration (especially for complex layouts), as well as part changeover. For this reason, a growing number of manufacturers are using these platforms. According to Heath, approximately 75 percent of workcells (automotive and non-automotive) are now programmed using OEM specific software such as Yaskawa’s MotoSim®, or third-party options like Robotmaster® from Hypertherm Inc. Delfoi also offers a robust variety of OLP software, including Delfoi ARC and Delfoi SPOT.
Hear More from our Welding Experts
To learn more from our Yaskawa experts, be sure to check out our webinar recordings. Welding presentation highlights include:
Josh Leath is a Product Manager