Robots Used for Arc Welding

Six-axis are used almost exclusively for arc welding tasks. These robots feature a balance of range, payload capacity, speed, and—most importantly—flexibility of movement. The dexterity of six-axis robots is an essential factor for welding performance. Arc welding typically involves complex motion. These movements are required to move precisely around angles and curves to weld joints together. This motion isn’t easily achievable for most other robot types, a limitation that gives the six-axis robot a near-monopoly on the arc welding robot market. Other robot types deployed in arc welding tasks include:

• SCARA
• Cartesian/Gantry
• Collaborative

The collaborative robot (cobot) is a subset of six-axis robots. These smaller six-axis models ship with features allowing them to work in hybrid working environments, such as speed and force limitations. Moreover, those with little or no robot programming experience can easily program most cobots. Hand-teaching mechanisms and teaching pendants lower the barrier to entry for beginner robot programmers. Because of these features, along with their smaller size and payload capacity, cobots have helped smaller manufacturers gain access to a market solution that typically requires a high up-front investment. Additionally, those needing hybrid working solutions between machines and technicians can find valuable solutions in the cobot market.

SCARA, cartesian, and gantry robots all suffer from the lack of flexibility offered by six-axis robot types. Their more rigid construction limits them to the simplest of welding applications. Welding tasks that occur in a single plane of motion are typically the only ones suited for these types. An example might include welding simple flat plates together. SCARAs are an interesting choice for small, simple welding applications. Cartesian and gantry robots offer unmatched scalability compared to six-axis and SCARA robots and should be considered for your exceptionally large applications.

Enhancing Your Robot’s Performance

Examples of these types of systems include:

• Robotic Transfer Units (RTUs)
• Workpiece Manipulators
• Conveyors

Robotic Transfer Units

Robotic transfer units are used to extend the range of traditionally reach-limited robots. RTUs are typically combined with six-axis robots for large welding applications that still require exceptional flexibility. A platform mounted to a track transports the robot back and forth horizontally across the workpiece. RTUs offer a theoretically unlimited bidirectional range. These systems also feature rapid movement and precise movement. It’s common to command an RTO to move a full-sized six-axis robot several meters at over one m/s and stop within 1 mm of the commanded stopping point. Fast and reliable communication between the two systems is required to facilitate the precise motion that arc welding demands. Vertical RTUs also exist for welding tall workpieces.

Workpiece Manipulators 

Workpiece manipulators are a collection of tools used to rotate and transport a workpiece. Manipulators differ from RTUs, which are used to transport the robot. These systems are a good choice for small to medium-sized products that need to be moved for the robot to perform its welding task. Examples of workpiece manipulators include:

• Turntables
• Headstock/Tailstock Units
• Turning Rolls

As with RTUs, communication is key to a successful partnership between the robot and workpiece manipulators. The robot, or other master control system, typically sends commands to the workpiece manipulator. This tells the system how and where to move. Once the positioner is in the commanded position, it sends a signal back to the robot to allow it to move on with its welding task. 

Conveyors

Conveyors are used for high-volume welding tasks. Conveyors move raw parts to the welding cell. Arc welding robots weld the pieces together, often with the help of clamps or other machinery to ensure alignment. After this, the welded piece is moved out of the weld cell down the same conveyor for further processing.

Considerations Before Buying an Arc Welding Robot

Arc welding robots are a great solution for automating your arc welding tasks. However, there are challenges that can limit the effectiveness of your investment. Awareness of these limitations can save you time and money by keeping you from choosing the wrong solution for your automation project. Communication with your supplier(s) is crucial for ensuring that all your needs are covered. 

Are you having trouble finding suitable suppliers? HowToRobot makes it easy to search for suppliers and receive offers. Our platform offers the most extensive global robot market featuring over 16,000+ suppliers. Get in touch with us today—we’ll help you find custom offers and quotes based on the specifics of your project.

Communication Compatibility

In the previous section, we discussed the concept of pairing your robot with an external system used to move either the robot or the workpiece. Due to the precise nature of arc welding, it’s vital to ensure these systems are compatible. Ask your supplier(s) about the communication protocols of these systems. Common protocols include Ethernet/IP, Profinet, EtherCAT, and DeviceNet. It’s common for OEMs to provide a few communication options to facilitate compatibility between devices. Making a mistake here can be costly, as both the upfront investment to purchase these devices and the installation can be expensive.

Selecting the Right Sensing Equipment

Arc welding robots often require sensors to maintain peak welding performance. These sensors perform several functions, from controlling the arc's size to monitoring the weld's quality. Some pieces of sensing equipment might come with your arc welding package, while others might need to be sourced separately. You must also select components that will withstand the demanding welding environment. This means sensors that are spatter, light, fume, and heat resistant. They might also need to withstand high current and interference created by the welding equipment. Standard sensing equipment includes:

• Weld quality sensors
  • Optical cameras, laser scanners, or ultrasonic sensors
• Arc length sensors
  • Voltage measurement devices
• Welding system current measurement
  • Current shunts and hall effect sensors
• Seam tracking
  • Probes, optical cameras, or laser scanners
• Safety equipment
  • E-stops, light curtains, and safety scanners

Conclusion

Arc welding systems are critical for the productivity of modern manufacturing facilities. They offer faster production, higher weld quality, and flexible welding solutions over traditional methods. Understanding their variations, applications, and potential pitfalls will help you successfully choose and integrate your first arc welding robot.