In order to replicate a human welder’s skills, it is recommended to provide training in robotic programming. PHOTO courtesy Yaskawa.
By Josh Leath
The development of user-friendly technology coupled with flexible cobot designs is successfully filling the skills gap. This is especially true for innovation in the collaborative arc welding space. Modes of collaboration enable human-robot interaction to supplement the manual weld process, and highly flexible cobots are easily redeployed and rolled-up to large workpieces. Moreover, a growing number of intuitive interfaces and easy-to-use technologies for robot programming are helping to grow this user base, permeating facilities across the industrial landscape.
From cast aluminum construction and easy-to-clean surfaces to longer arm reaches and higher payload capacities, collaborative robots with industrial pedigrees are expected to be the fastest-growing segment for cobots through 20251. While Tier 1 suppliers and small- to medium-size enterprises (SMEs) are finding these well thought out designs extremely helpful, there are always a few safety issues and potential hazard areas for manufacturers to be aware of for application success. With that in mind, it is best to take the following steps:
Create a Safe Application Environment
Ideal for tackling risk-intensive tasks, robots (including collaborative models) can present their own set of concerns that should be addressed before implementation. Key to this is being sure the general workspace is robot friendly, where there is no presence of flammables or explosives, falling hazards or other items that have the potential to be detrimental. If incidents such as tripping on robot cables or parts are a concern, it is important to install the proper safeguards and necessary peripherals before operation to alleviate risks.
Keep in mind, using a collaborative robot in name and design is not enough to make any application safe. For an application to qualify as collaborative and truly be safe, the entire robotic system and application must be addressed. This includes the robot, workpiece, work envelope and end-of-arm tooling (EOAT). If any of these crucial areas fail to meet specified safety standards during a risk assessment, then the application cannot be approved as collaborative – unless the identified risk is mitigated appropriately.
Ensure Optimal Cart Stability
While the use of a portable weld cart or stand with wheels can be highly advantageous for redeploying a cobot to a different location and task on the shop floor, the cart must be secured per the supplier’s specifications. For example, the base should have the ability to be locked tightly to prevent unintended movement or oscillation, especially when the robot is trying to weave. Taking the proper precautions should confirm the proper center of gravity so the robot cannot slip, ensuring the best conditions for optimal weld quality.
Facilitate Fluid Robot Movement
The robot’s ability to move freely from point to point is extremely important to the success of an application. For this reason, it is suggested that a cable management device for the torch cable be used. This will alleviate cable interference during programming, as well as prevent false PFL stops on the robot. Either an on-arm device or a cable balancer for overhead cable management is best – with the latter allowing the ability to expand the robot work area, when needed.
Use a Reliable Weld Table or Fixturing
Most parts welded with cobots tend to be for high-mix, low-volume production, where the fixturing is often achieved by means of an existing weld table and clamps. To do this and achieve the optimal part quality in the safest way possible, innovative fixturing software now offers manufacturers a cost-effective way to produce a stable fixture.
Keep in mind, collaborative robots currently do not offer compatibility with an external axis positioner. Therefore, tasks requiring the use of specific positioners for coordinated motion or a robot track need to be mitigated by fencing, light curtains or other means. While items such as fencing may result in additional upfront costs, it is often the simplest and best way to mitigate common risk factors.
Collaborative welding workcells with “ride along” air filtration provide an easy-to-implement and economical solution. PHOTO courtesy Yaskawa.
Utilize Proper Air Filtration
Often required by national and local safety regulations and of the utmost importance to protecting workers throughout the facility from harmful fumes, having the proper air filtration system is critical. From ambient air extraction systems to hood fume collection systems, there are several options that work well for a variety of robotic welding applications. However, it is important to weigh the pros and cons of each before implementation.
For collaborative welding, the concept of source capture is especially appealing for robotic fume extraction. An easy-to-implement and economical solution, this option works at the torch level and features filtration packs that “ride along” with the cobot. The plug and play ability of a source capture device is ideal for welding large parts for heavy fabrication, as well as on-demand supplemental welding.
Implement Protective Light Barriers
Like any welding environment, welders should mitigate arc flash and UV exposure via personal protective equipment (PPE). Safety arc flash curtains or other barriers should also be put in place, as needed, to protect bystanders. Similarly, an interfaced stack light mounted on the robot cart or nearby can also help to visually confirm the status of a robot or provide sufficient warning to those close to the work area that a robot is about to weld. This allows workers and bystanders ample time to look away from the arc or get out of the way. Tone-emitting or “talking” versions that provide audible commands are also available.
Upskill Your Current Workforce
While many collaborative welding robots come with user-friendly features, such as hand-guided programming and pendant software for setting weld parameters, proper employee training should be offered – as a collaborative robot is still a machine that is best (and most safely) used with some know-how. From basic programming to robotic welding and maintenance, most robot suppliers offer training courses to maximize robotic equipment performance. Keep in mind, training a current human welder about robotic programming is ideal for replicating their welding skills and achieving optimal robot uptime.
Take Additional Safety Measures
Depending on application requirements, additional safety measures may be useful. For example, to provide extra robot speed and mitigate risk, an area scanner may also be added. This helps to ensure that no one is immediately around the robot before or during welds. Typically involving one to two area safety scanner units mounted below the robot, this usage allows the cobot to move at full industrial speeds until the protected area is broken. Newer units can also establish zones for multiple steps of safe speed options, optimizing things like air-cut speed. Most importantly, every robot system must have a fail-safe way to stop for any level of emergency. Often triggered by an external emergency stop (E-Stop) push button or an output from the safety controller, knowing how to activate this, when necessary, is a must.
Whether a Tier 1 manufacturer or an SME, safe collaborative welding provides the ability to add capacity for greater productivity gains. Those interested in pursuing this path should reach out to a robot supplier or integrator to conduct a thorough site audit, ensuring safety standard compliance and the utmost reliability.
Josh Leath is Sr. Product Manager, Welding at Yaskawa America Inc. – Motoman Robotics Division
1 Global Collaborative Robot Market, Statzon , 2021