Welding is a process where two materials are fused together through heating, intermixing, and then cooling the materials and/or a filler to form a strong join. From arc welding to spot welding, new and used welding robots are typically used in welding processes where the weld required is repetitive and quality and speed are crucial. Robotic welding is an automated process that increases efficiency, consistency, and ROI.
What is Robotic Welding?
Robot welding is the use of mechanized programmable tools (robots), which completely automate a welding process by both performing the weld and handling the part. Processes such as gas metal arc welding, while often automated, are not necessarily equivalent to robot welding, since a human operator sometimes prepares the materials to be welded.
Robot welding is a relatively new application of robotics, even though robots were first introduced into the US industry during the 1960s. The use of robots in welding did not take off until the 1980s when the automotive industry began using robots extensively for spot welding.
Since then, both the number of robots used in industry and the number of their applications have grown greatly. In 2005, more than 120,000 robots were in use in North American industry, about half of them for welding. Growth is primarily limited by high equipment costs and the resulting restriction to high-production applications.
Robot arc welding has begun growing quickly just recently, and already it commands about 20% of industrial robot applications. The major components of arc welding robots are the manipulator or the mechanical unit and the controller, which acts as the robot’s “brain”.
The manipulator is what makes the robot move, and the design of these systems can be categorized into several common types, such as SCARA and cartesian coordinate robot, which use different coordinate systems to direct the arms of the machine.
The robot may weld a pre-programmed position, be guided by machine vision, or by a combination of the two methods. However, the many benefits of robotic welding have proven to make it a technology that helps many original equipment manufacturers increase accuracy, repeatability, and throughput
The technology of signature image processing has been developed since the late 1990s for analyzing electrical data in real-time collected from automated, robotic welding, thus enabling the optimization of welds.
Robotic Welding Equipment
Robotic welding combines welding, robotics, sensor technology, control systems, and artificial intelligence. The components include the software with specific programming, the welding equipment delivering the energy from the welding power source to the workpiece, and the robot using the equipment to conduct the welding.
The robot’s process sensors measure the parameters of the welding process and its geometrical sensors the geometrical parameters of the welds. By acquiring and analyzing the input information from the sensors, the control system adapts the output of the robotized welding process based on the welding procedure specifications defined in the program.
Depending on the intended usage, robots can be robotic arms or robot portals. Normally, six-axis industrial robots comprising a three-axis lower arm and a three-axis wrist are used since they enable the welding torch to be mounted at the wrist to achieve all the positions necessary for three-dimensional welding.
The system needs to be integrated with the robot, and the welding equipment needs to be compatible with and preferably specifically designed for robotic welding because then, all processes can be controlled by the robot.
How Robotic Welding Works?
When using robots for any process, the method requires amending to accommodate automation. The same is true of welding, which uses several tools not found in its manual equivalent. People don’t need programming the way robotic welders do.
The robot itself has an arm that can move in three dimensions for rectilinear types and through more planes with articulating versions. A wire feeder sends the filler wire to the robot as it needs it for a welding job. A high-heat torch at the end of the arm melts metal to enable the welding process. Because the temperatures reach thousands of degrees, using robots for this process keeps people safer.
Certified human operators still need to remain close to the robots. These workers should hold certification from the American Welding Society, AWS, which certifies not only manual welders but also robotic welding arm operators. The operators program the controller using a teach pendant. This device sets new programs, moves the arm, and changes parameters for the process. To start the welding, the operator uses the buttons on the operation box.
The tool in the robotic arm heats to melt metal to conjoin the desired pieces. As needed, a wire feeder delivers more metal wire to the arm and torch. When awaiting the next parts to weld, the arm moves the torch to the cleaner to clean any metal splatters from the arm, which could solidify in place without this process.
Because one of the primary reasons to have robotic welders is protecting human workers, these automated systems come with multiple safety features. Arc shields prevent the high-heat arc from mixing with oxygen. Enclosed areas protect operators from the temperatures and bright light.
Benefits of Robotic welding
There are several advantages to automating a factory with welding robots, including faster, consistent cycle times, no break in production, and better weld quality. Basically, by using welding robotic automation, the process takes less time, and manufacturers can cut the cost of direct labor and safety and conserve materials.
Robotic weld cells provide an even safer work environment, dramatically reducing arc glare, overspray, and direct contact with the robot and part. A robot welder is more consistent and can move from one weld to the next quickly, speeding up the entire process.
- Taking Less Time: Robotic welding systems will get the job done quickly. Whether you have new or used welding robots, they have fewer mistakes than manual welding. Unlike laborers, robots don’t require breaks, vacations, etc. Your work can continue without interruption, 24/7. This in turn, will increase your throughput & productivity.
- Cut the Cost of Direct Labor & Safety: The cost of manual welding can be steep. It requires time, skill and concentration. It is also dangerous. Flash, fumes, sparks and heat make manual welding a taxing and hazardous job. With robotic welding, you will protect workers and reduce costs. These systems endure the hazards and often increase production. Insurance and accident-related costs are also reduced considerably.
- Conserve Materials: Even the most skilled welders make mistakes. However, with new and used welding robotics, everything is regulated, including power and wire. Automated used welding robotic systems conserve energy by running consistently (fewer start-ups). Plus, the welds that are created are more consistent. The accuracy of robot systems means there is less wasted material and time. Conserve your material and increase your product quality at the same time!
Some companies switch to robotic welding applications gradually, starting with a single welding cell and slowly converting to a fully automated welding process. Robots can be helpful when access to a part is limited or difficult to reach. Manufacturers have created designs that allow for a slender robotic arm to reach smaller areas.
One problem when welding with robots is that the cables and hoses used for current and air etc. tend to limit the capacity of movement of the robot wrist.
A solution to this problem is the swivel, which permits the passage of compressed air, cooling water, electric current, and signals within a single rotating unit.
The swivel unit also enables off-line programming as all cables and hoses can be routed along defined paths of the robot arm.
Other limitations of robotic welding:
- Complex end-user programing, not user friendly, only for specialists
- Limited APIs, making a simple change complicated
- The human machine interface (HMI) not really working. Systems require customization and training. Difficult to customize robotic welding systems.
- Connectivity challenges, lack of inter-connectable standards
- Replaces human labor
- Technology becomes out of date
Robotic Welding Processes
Welding requires a high level of education and skill. However, the number of professional welders does not meet the needs of the industry. According to the American Welding Society, by 2022, the industry will experience a shortage of 450,000 welders. Instead of letting critical projects, these workers would complete fall behind, robots can pick up the slack.
Robots automate the process, which ensures higher accuracy, less waste, and faster operation. With the range of machinery available, robots adapt to a wide variety of welding processes including arc, resistance, spot, TIG, and more.
1. Arc Welding
One of the most common types of robotic welding is the arc process. In this method, an electric arc generates extreme heat, up to 6,500 degrees Fahrenheit, which melts the metal. Molten metal joins parts together, solidifying into a stable connection after cooling. When a project requires a large volume of accurately conjoined metals, arc welding serves as an ideal application.
2. Resistance Welding
When projects need heat-treating or a way to lower costs, robots may use resistance welding. During this process, a current of electricity creates a pool of molten metal as it passes between the two metal bases. This molten metal joins the pieces of metal together.
3. Spot Welding
Some materials resist electrical currents, precluding them from other forms of welding. This situation frequently occurs in the automotive industry for piecing together parts of an automobile body. To overcome the issue, robotic welders use a variation of resistance welding to connect a pair of thin metal sheets in a single spot.
4. Tig Welding
Robot welding applications requiring high levels of precision may require TIG welding. This method also goes by the term gas tungsten arc welding or GTAW. An electric arc passes between a tungsten electrode and the metal base.
5. Mig Welding
Gas metal arc welding, also known as GMAW or MIG, is a fast and straightforward method that uses a high level of deposition. A wire moves continuously to the heated tip of the welder, which melts the wire, allowing for a large amount of molten metal to drip onto the base for joining the base to another piece.
6. Laser Welding
When welding projects require accuracy for a high volume of parts, laser welding is the preferred method of metal joining. Small parts, such as jewelry or medical components often use laser welding.
7. Plasma Welding
Plasma welding offers the most significant degree of flexibility because the operator can easily change both the speed of gas passing through the nozzle and the temperature.
Robotic Welding Applications
Due to its time-saving benefits and high productivity, robotic welding has become important in metal and heavy industries, and especially in the automotive industry that employs spot and laser welding.
It is best suited for short welds with curved surfaces and repeatable, predictable actions that don’t require continuous shifts and changes in the welding process. With the help of external axes, the robot is also suitable for long welds, for example in the shipbuilding industry.
Although robotic welding is mostly used in mass production, in which efficiency and quantity are essential, programs can be made to suit any needs, and robotics can be utilized for smaller and even one-off productions while maintaining high cost-effectiveness.
Robotic Vs. Manual Welding
Manual welding still has a place in modern manufacturing. For projects in which you need an expert to quickly change the styles of welding used, manual welding will be your best choice. A professional welder can promptly change what he’s doing, but robots do not adapt as quickly to uncertain situations.
Because manual welding remains a process that many companies still need, professional welders will not disappear any time soon. In fact, with the shortage of expert welders mentioned above, those who hold certification will easily find work, even with multiple businesses investing in robots.
Replacing manual welders with robots will not put AWS out of its certification business. Most robot welder operators need to hold certification in the robotics side of this field, for which the AWS also offers certifications. Having robotics experts who know about welding ensures the projects get properly programmed to finish as quickly and cost-effectively as possible.