Welding robots have been used in the industrial sector for years because of the many advantages they bring, such as reduced waste, improved safety and enhanced weld quality. This article highlights different robotic welding systems and how they can be used to automate welding tasks.
Welding is the process of fusing two materials together permanently, and many different robotic welding methods are used in the industrial sector. Among the most common ones are:
- Resistant Spot welding
- Types of arc welding such as GMAW and GTAW
- Laser beam welding (LBW)
- Hybrid of arc- and laser welding (HBLAW)
The most important features of welding robots: Payload and reach
In common, the robotic welding systems have an articulated robot with a welding torch as the end effector which replaces the human arm of the manual worker. The robotic welding system is highly dependent on the dimensions of the workpiece as well as the complexity and variation of the welding.
The two most crucial parameters in robotic welding are the payload and reach of the robots. Payload, which is how much the robot arm can carry, is not important in the welding business because welding torches and other equipment on the robot arm is usually not that heavy.
However, you need to consider the reach of the robot. If you have large or heavy workpieces such as structural beams, building frames or work in the shipbuilding industry, you might need to have robots that can move along tracks horizontally or move across and above the workpiece from a gantry. If you have a tall workpiece like for instance the side of a ship vertically dynamic column tracks are a possibility to weld higher than with a fixed robot.
As a user, you must consider your product with integrators and welding experts to discuss whether you should have a stationary confined robot cell – where the workpiece is secured in a positioner or a fixture – or you should look into having moveable robot cells.
Things to consider when switching from manual to robotic welding
It is not always simple switching from manual to robotic welding. Many things may work differently for a robot, and switching from manual work is more than just replacing a person with a machine. In the first place, additional hardware and welding equipment is required.
Secondly, the robots work with a higher throughput rate than manual workers. Therefore, it’s important to consult the integrator regarding types of cooling units, how the wire is fed to the robot etc. to make sure to uphold the increased productivity, which is typically one of the major reasons for switching to robotic welding.
When being used to doing manual welding in the shop floor, welding disturbances like welding spattering and small movements of the workpieces are old news. A person may adapt the working style to the environment in a way that can be difficult for a robot. In robotic welding you have a programmed robot which cannot think for itself, which makes it crucial that workpieces be fixed into either a fixture or clamped into a positioner, so they do not move while the robot is welding.
A rule of thumb is: The more fixed parameters, the less complex the robot program – which is convenient for a welding company because lower complexity means lower price.
In continuation, it is important to decide if the system should be a semi-automated or a fully automated system. In the semi-automated solution, only the welding process is automated. Here, a manual worker feeds the robot with workpieces clamped in a fixture or a positioner and unloads again after the welding is done.
If one decides to go for a fully automated system, loading and unloading must also be considered and connected to the robot. This can make the system more complex and expensive. Therefore, the user needs to make sure the operators know how to deal with this complexity.
If they do, a fully automatic system can release labour, and throughput is improved giving a feasible return on investment. Otherwise, there will be a risk of downtime, not reaching full potential of throughput and productivity, and so forth.
It could be beneficial for users to consider vision and data monitoring of the welding processes. The right sensors could be of value to the company. These could help ensure the right quality by reducing defect rate and increase productivity.
Furthermore, the data could be used for preventive maintenance of the robots. This is an an additional investment, but it might pay off in the long run due reduced defects and therefore reduced waste and rework.
Finally, users must make sure that the shop floor can accommodate a robotic welding cell. Including a positioner and safety fencing, the robotic cells’ blueprints are significantly bigger than those of a manual welding cell.
When to go for robotic welding systems - and when not to
Robotic welding won’t be better in every aspect; there will be some drawbacks when going from manual to robotic welding systems. When switching to automated systems, often the system compromises with flexibility unless smart solutions are thought through.
Such smart solutions could be flexible positioners, easy change-over of fixtures for workpieces, or the moveable robot systems as mentioned earlier. With increased flexibility, however, follows higher complexity and therefore initial investment size and also a higher risk of breakdowns and downtime.
Considering the high initial investment and the risk of lower flexibility, the ideal situation to integrate robotic welding would be with highly repetitive welding processes with large volume of parts and low complexity welds. It is typically not feasible for smaller projects.
But, when switching to robotic welding you get many advantages especially in terms of increased precision and accuracy, higher productivity and velocity, reduced waste and perhaps most importantly, safety. Burns, arc radiation, contamination of the air and eye damages from the light are not a problem for robotic systems as it is for the workers. Therefore, thinking the project through is important to ensure that the advantages of automating the welding process outweigh the drawbacks.