Robotic Welding: A Comprehensive Guide

Robotic welding is a modern and highly automated process in the manufacturing industry. It involves the use of programmable robots to automate the welding process, thereby increasing efficiency and reducing errors. This technology has revolutionized the welding industry, offering numerous benefits such as improved precision, increased speed, and enhanced safety. However, like any other technology, robotic welding also has its challenges and limitations, which need to be understood and addressed for successful implementation. In this article, we'll delve into the intricacies of robotic welding and examine its many forms, parts, processes, advantages, and disadvantages.

1. Types of Robotic Welding

Depending on the welding method used, there are different kinds of robotic welding systems. Arc welding, spot welding, and laser welding are all examples of these. The materials being welded, the level of precision required, and the volume of production all play a role in determining which of these types is most appropriate.

1.1. Arc Welding

Arc welding is one of the most common types of robotic welding. It involves the use of an electric arc to generate heat, which is then used to melt the workpieces and join them together. The electric arc is created between an electrode and the workpieces. The electrode can either be consumable, in which case it also serves as the filler material, or non-consumable, in which case a separate filler material is used.

Robotic arc welding systems are widely used in the manufacturing industry due to their versatility and efficiency. They can be used to weld a wide range of materials, including steel, stainless steel, aluminum, and other non-ferrous metals. Moreover, they can handle a variety of joint types, such as butt joints, lap joints, and T-joints.

The precision and consistency of  arc welding industrial robot make them particularly suitable for applications where high-quality welds are required. For instance, in the automotive industry, they are used to weld car bodies and chassis. In the aerospace industry, they are used to weld aircraft components.

Electric arc welding

Diving deeper into the science of electric arc welding, it's essential to acknowledge the high temperatures and current requirements involved. The electric arc used in this process can reach extreme temperatures, typically around 6,500 degrees Fahrenheit, hot enough to melt most metals. To generate this intense heat, the welding power supply needs to provide a steady current that can range between 20 to 550 Amperes, depending on the specific materials and the welding process being used. To maintain a stable arc and control the weld pool, the voltage is usually kept between 15 to 40 volts.

Temperature regulation is paramount in electric arc welding as it directly influences the quality and strength of the weld. By precisely controlling the temperature, welders can ensure a proper fusion between the base materials and the filler, if used. Electric arc welding also necessitates a protective gas or flux to shield the weld pool from atmospheric contamination, ensuring the durability and integrity of the weld.

Just as its robotic counterpart, manual electric arc welding is prized for its flexibility, enabling welders to join a multitude of materials and navigate through various joint types. With its high penetration power and ability to handle thick materials, this method is used extensively in industries from construction to shipbuilding. Its nuanced yet robust mechanism underscores why it remains a cornerstone of the manufacturing and repair sectors.

However, arc welding also has its limitations. One of the main challenges is the need for proper shielding to prevent the molten metal from reacting with the surrounding air. This is typically achieved by using a shielding gas, such as argon or carbon dioxide. Another challenge is the high level of heat generated during the welding process, which can lead to distortion of the workpieces if not properly managed.

Despite these challenges, advancements in technology are continually improving the capabilities of  arc welding robots. For instance, the development of advanced control algorithms has enabled more precise control of the welding parameters, resulting in better quality welds. Similarly, the introduction of new electrode materials and designs has expanded the range of arc welding applications.

Robotic welding in industries encompasses not only simple arc welding but also includes the utilization of advanced techniques such as MIG (Metal Inert Gas) and TIG (Tungsten Inert Gas) welding. These methods are often performed by robots for their precision, efficiency, and consistency in high-volume manufacturing processes. With the ability to program and control various welding parameters, the robotic arms equipped with welding torches can seamlessly switch between different welding techniques based on the specific requirements of the task at hand. This integration of MIG and TIG welding alongside traditional arc welding by robots in industries maximizes productivity, improves weld quality, and enhances the overall efficiency of the welding operations.

Suggested read: Robotic Welding System to Save the Day For Welding

1.2. Spot Welding

Spot welding is another type of robotic welding that is commonly used in the manufacturing industry. It is a resistance welding process that involves applying pressure and heat to specific "spots" on the workpieces to join them together. The heat is generated by an electric current that is passed through the workpieces, causing them to melt and fuse together at the spot where the pressure is applied.

Robotic spot welding systems are particularly useful for welding thin sheets of metal, such as those used in the automotive industry for car body assembly. They are capable of producing high-quality welds quickly and consistently, making them ideal for high-volume production environments.

In a typical spot welding operation, the robotic arm positions the welding electrodes on the workpieces and applies pressure. The power supply then delivers a high-current, low-voltage electric pulse, which generates heat and causes the workpieces to melt and fuse together at the spot. The duration of the electric pulse, known as the weld time, is typically in the order of milliseconds, and it is a critical parameter that affects the quality of the weld. The temperature required for spot welding can reach around 2,500 to 3,000 degrees Fahrenheit. To achieve this, a high current is delivered in a short duration, typically ranging from 5,000 to 20,000 Amperes. This intense current, coupled with a precise control mechanism, results in the rapid heating of the metal at the welding point, followed by a quick cooling process to solidify the joint. Robotic spot welding systems offer exceptional precision and repeatability, ensuring consistent weld quality across production lines. These systems are extensively used in the automotive industry, where they provide efficient and reliable joining of car body panels, frames, and other metal components. The automation of spot welding not only enhances productivity but also enables superior control over process parameters, contributing to the overall strength and durability of the welds.

Spot welding robot in automotive industry

One of the main advantages of spot welding is its simplicity. It does not require any filler material, shielding gas, or complex preparation of the workpieces. Moreover, it can be used to weld a wide range of materials, including steel, stainless steel, aluminium, and other non-ferrous metals.

However, spot welding also has its limitations. One of the main challenges is the need for precise control of the welding parameters, such as the electric current, weld time, and electrode pressure. If these parameters are not properly controlled, it can result in poor-quality welds, such as weak welds, excessive indentation, or burn-through. Another challenge is the limited access to the weld spots, which can be an issue when welding complex structures.

Despite these challenges, advancements in technology are continually improving the capabilities of robotic spot welding systems. For instance, the development of advanced control algorithms has enabled more precise control of the welding parameters, resulting in better quality welds. Similarly, the introduction of new electrode materials and designs has expanded the range of applications of spot welding.

1.3. Laser Welding

Laser welding is a type of robotic welding that uses a laser beam to generate heat and join materials together. The laser beam is focused on the workpieces, causing them to melt and fuse together. The process can be either continuous, where a constant beam of laser light is used, or pulsed, where the laser light is delivered in pulses.

Renowned for their exceptional precision and adaptability, robotic laser welding systems have garnered recognition in the realm of advanced manufacturing. These systems exhibit remarkable versatility, enabling the welding of diverse materials, encompassing metals, plastics, and composites. Furthermore, their capabilities extend to accommodating an array of joint configurations, including butt joints, lap joints, and T-joints. Leveraging the precise nature of laser technology, these systems excel in applications that demand impeccable weld quality. Industries such as electronics, medical devices, and aerospace greatly benefit from laser welding's ability to deliver consistently high-quality welds, fortifying their products' reliability and performance.

In a typical laser welding operation, the robotic arm positions the laser head over the workpieces and moves it along the predetermined path. The laser head emits a beam of laser light, which is focused on the workpieces, causing them to melt and fuse together. The power and speed of the laser beam are critical parameters that affect the quality of the weld.This cutting-edge process harnesses the power of a focused laser beam to generate intense heat, reaching temperatures that can exceed 5,000 degrees Celsius (9,000 degrees Fahrenheit). The laser beam is precisely controlled and directed onto the workpiece, rapidly melting and fusing the materials together. Unlike traditional welding methods, robotic laser welding typically requires lower current levels, ranging from 0.1 to 10 Amperes. This reduced current requirement minimizes the risk of distortion or damage to delicate components, making it particularly advantageous in industries such as electronics, where precise and intricate welds are paramount. The controlled application of laser energy ensures minimal heat-affected zones, resulting in clean and high-quality welds. 

Laser welding robot 

One of the main advantages of laser welding is its precision. The laser beam can be focused to a very small spot, allowing for precise control over the welding process. This makes it possible to weld small, intricate parts, and to create welds in hard-to-reach areas. Moreover, the high energy density of the laser beam results in fast welding speeds, making laser welding a highly efficient process.

However, laser welding also has its challenges. One of the main challenges is the high initial cost of setting up a robotic laser welding system. This includes the cost of the laser source, the robotic arm, and the associated control and safety equipment. Another challenge is the need for precise control of the laser parameters, such as the power, speed, and focus of the laser beam. If these parameters are not properly controlled, it can result in poor-quality welds, such as incomplete penetration, porosity, or thermal distortion.

Robotic laser welding systems face these obstacles, but technological progress is enhancing their performance all the time. For instance, superior weld quality has been achieved through finer regulation of the laser's parameters made possible by recent advances in control algorithm design. New laser sources and designs have done the same thing for laser welding, greatly increasing its usefulness.

2. Components of a Robotic Welding System

A robotic welding system is composed of several key components that work together to perform the welding operation. These include the robot arm, the welding torch, and the power supply. Each of these components plays a critical role in the welding process, and their performance and coordination determine the quality of the welds produced by the system.

2.1. Robot Arm

The robot arm is the part of the robotic welding system that physically performs the welding operation. It is a programmable device that can move in multiple directions to position the welding torch accurately on the workpieces. The robot arm is typically equipped with several joints that allow it to move in a similar way to a human arm, enabling it to reach different areas of the workpieces and perform complex welding tasks.

The precision and speed of the robot arm are critical factors that affect the quality of the welds. For instance, an arm's positional precision of +/- 0.02mm is often required to ensure a high-quality weld. Moreover, a smooth movement along the path with an average speed of 1.5-2.5m/s can minimize errors like incomplete penetration or excessive spatter.

The robot arm is controlled by a computer, which is programmed with the welding parameters and the path that the arm needs to follow. The programming of the robot arm is a critical task that requires a high level of skill and expertise. Programming such an arm demands high skill and expertise, with variables including welding current (typically 80-350 Amperes), voltage (18-36 Volts), torch travel speed (ranges from 5-30 cm/min), and the torch angle (usually between 70-85 degrees relative to the workpiece). It also involves defining the path that the arm needs to follow, which can be a complex task, especially for intricate welds.

Despite the complexity of programming the robot arm, advancements in technology are making this task easier and more efficient. For instance, the development of advanced programming languages and software tools has simplified the process of defining the welding parameters and the path of the arm. Similarly, the introduction of new sensor technologies has enabled the robot arm to adapt to variations in the workpieces, resulting in more consistent and high-quality welds.

2.2. Welding Torch

The welding torch is another crucial component of a robotic welding system. It is the part of the system that directly interacts with the workpieces to create the weld. The welding torch carries the electrode (in the case of arc welding) or the laser beam (in the case of laser welding), and directs it onto the workpieces. It also often carries a shielding gas to protect the molten metal from the surrounding air.

In an arc welding system, the welding torch is designed to carry a consumable or non-consumable electrode, depending on the type of arc welding process. The electrode is connected to the power supply, which provides the electric current needed to create the arc. The torch also carries a shielding gas, which flows out around the arc to protect the molten metal from the surrounding air.

In a laser welding system, the welding torch carries the laser beam, which is generated by the laser source. The torch is designed to focus the laser beam onto a small spot on the workpieces, creating a high-intensity heat source that can melt and fuse the workpieces together. The torch may also carry a shielding gas, which flows out around the laser spot to protect the molten metal from the surrounding air.

The design and performance of the welding torch are critical factors that affect the quality of the welds. The torch needs to be able to carry and direct the electrode or laser beam accurately onto the workpieces. It also needs to be able to deliver the shielding gas effectively to protect the molten metal. Any issues with the torch, such as a misaligned electrode or an inconsistent flow of shielding gas, can result in poor-quality welds.

Despite the challenges associated with the welding torch, advancements in technology are continually improving its capabilities. For instance, the development of new torch designs and materials has improved the durability and performance of the torch. Similarly, the introduction of new shielding gases and delivery systems has improved the effectiveness of the shielding process.

2.3. Power Supply

The power supply is a fundamental component of a robotic welding system. It provides the energy needed for the welding process from the power source, whether it's an electric current for arc welding or a laser beam for laser welding. The power supply is connected to the welding torch, and it controls the amount and duration of the energy delivered to the workpieces.

In an arc welding system, the power supply provides a constant or pulsed electric current to the electrode. The magnitude and duration of the current are critical parameters that affect the quality of the weld. The electrode, connected to a power supply providing an electric current typically ranging from 100 to 600 Amperes, forms the arc. Concurrently, the torch delivers a shielding gas, with a typical flow rate of 10-25 liters per minute, around the arc to protect the molten weld pool from the surrounding air. A high current can result in deep penetration and a wide weld bead, while a low current can result in shallow penetration and a narrow weld bead. The power supply is typically equipped with controls that allow the operator to adjust the current based on the requirements of the welding task.

In a laser welding system, the power supply generates a laser beam, emanating from a laser source with power often varying between 500 and 6000 watts, which is directed onto the workpieces by the welding torch. The power of the laser beam is a critical parameter that affects the quality of the weld. A high-power laser beam can result in deep penetration and a wide weld bead, while a low-power laser beam can result in shallow penetration and a narrow weld bead. The power supply is typically equipped with controls that allow the operator to adjust the power of the laser beam based on the requirements of the welding task.

The performance and reliability of the power supply are critical factors that affect the quality of the welds. The power supply needs to be able to deliver the required energy consistently and accurately. Any fluctuations in the energy can result in inconsistent welds, which can affect the integrity and appearance of the workpieces.

Despite the challenges associated with the power supply, advancements in technology are continually improving its capabilities. For instance, the development of new power supply designs and materials has improved the efficiency and reliability of the power supply. New torch designs and materials enhance durability and performance, with modern air-cooled torches withstanding up to 200 Amps and water-cooled versions tolerating up to 500 Amps. The introduction of new shielding gases and delivery systems has also improved the shielding process efficiency. High-tech gas nozzles, for example, can offer gas flow control within a +/- 10% accuracy, improving weld consistency and quality.

3. The Robotic Welding Process

The robotic welding process involves several steps, from programming the robot to performing the actual welding operation using full robot automation. Each step is critical to the success of the process, and requires a high level of skill and expertise. The robotic welding process can be broadly divided into three main stages: programming the robot, setting up the workpieces, and performing the welding operation.

3.1. Programming the Robot

The programming phase is crucial to the robotic welding process. It primarily involves defining the welding parameters and outlining the path that the robotic arm should trace. The parameters for arc welding typically include the welding current and voltage, with ranges usually between 100-600 Amps and 18-36 Volts, respectively. In contrast, for laser welding, power (typically 500-6000 Watts) and laser beam speed are the primary factors. The trajectory of the robotic arm is determined considering the workpiece's size, shape, and the specific type of weld required.

The programming process is executed via a computer linked to the robotic arm. The computer employs specialized welding programs that enables operators to specify the welding parameters and map the arm's trajectory. This software often includes a graphical user interface (GUI) like CAD/CAM systems. This interface enables the operators to visualize the path and position of the welding torch with up to 0.1mm precision in path generation.

Despite programming the robot to operate autonomously, monitoring during operation remains critical to ensure adherence to predefined parameters and paths. Any deviations may result in substandard welds, necessitating immediate corrections.

Programming a robotic welder is a complex task, but technological advancements continue to simplify it. Advanced programming languages like VAL3 or KRL and software tools like RoboDK or OCTOPUZ offer high-level interfaces and simulations of the welding process, reducing programming time by up to 90%.

Integration of sensor technologies into robotic welding operations provides real-time feedback and adaptability. For instance, seam-tracking sensors with accuracy up to +/- 0.1mm allow the robotic arm to adapt to variations in the workpiece, thus ensuring more consistent, high-quality welds. 

3.2. The Welding Operation

The final phase in the welding automation, the welding operation, sees the programmed robot arm undertaking the welding task on the workpieces using the equipped welding torch. Each aspect of the welding operation is vital in achieving high-quality welds.

The operation begins with the robotic arm positioning the welding torch at the pre-determined starting point on the welding path. Following this, the power supply is activated, marking the commencement of the welding process. Guided by the robot arm, the torch traverses the programmed path as the power supply furnishes the workpieces with the necessary energy.

In an arc welding operation scenario, the power supply provides an electric current, typically within the 100-600 Amperes range, to the torch's electrode. This electric arc formed between the electrode and the workpieces generates the heat required for melting the workpieces and creating the weld. Guided by the robot arm, the torch traces the pre-determined path, laying down a continuous weld bead.

For laser welding operations, the power supply, usually producing between 500-6000 Watts, creates a laser beam. The welding torch focuses this high-intensity heat source onto the workpieces, causing them to melt and fuse together, forming the weld. Similar to arc welding, the robot arm maneuvers the torch along the planned path, forming a continuous weld bead.

Throughout the welding process, stringent monitoring is vital to confirm alignment with set expectations. Deviations from the predefined parameters or path can compromise weld quality, necessitating instant corrective measures. After the operation, weld quality undergoes inspection to verify compliance with the required standards.

Although complex, the welding operation continues to see improvements in efficiency and quality, thanks to technological advancements. For instance, advanced control algorithms have enhanced precision control over welding parameters, leading to better weld quality. The advent of new sensor technologies offers real-time monitoring capabilities during the welding operation, enabling swift identification and rectification of deviations, thereby enhancing overall weld quality and operational efficiency.

3.3. Quality Control and Inspection

Quality control and inspection are crucial aspects of the robotic welding process. These steps ensure that the welds meet the required standards and specifications. Quality control involves monitoring the welding operation in real-time, while inspection involves checking the quality of the welds after the operation.

Quality control during the welding operation involves monitoring the welding parameters and the performance of the robot arm. The welding parameters, such as the welding current or the power of the laser beam, need to be maintained within the specified range to ensure the quality of the welds. Any deviations from the specified parameters can result in poor-quality welds, and need to be corrected immediately.

The performance of the robot arm also needs to be monitored closely. The arm needs to move the welding torch along the programmed path accurately. Any deviations from the path can result in inconsistent welds, which can affect the integrity and appearance of the workpieces.

Inspection after the welding operation involves checking the quality of the welds. This includes checking the size and shape of the weld bead, the penetration of the weld, and the presence of any defects, such as cracks or porosity. The inspection can be done visually, or using non-destructive testing methods, such as ultrasonic testing or radiographic testing.

Quality control and inspection are critical to ensuring the quality of the welds and the success of the robotic welding process. Despite the challenges associated with these steps, advancements in technology are continually improving their efficiency and effectiveness. For instance, the development of advanced sensor technologies has enabled real-time monitoring of the welding operation, allowing for immediate correction of any deviations. Similarly, the introduction of new non-destructive testing methods has improved the accuracy and reliability of the inspection process.

4. Benefits of Robotic Welding

Robotic welding offers numerous benefits that make it an attractive option for many industries. These benefits stem from the unique capabilities of robotic systems, such as their precision, speed, and consistency.

One of the primary benefits of robotic welding is its high level of precision. Robots can move the welding torch along a programmed path with a level of accuracy that is difficult to achieve manually. This results in consistent welds that meet the required specifications and standards. The precision of robotic welding also reduces the risk of defects, such as undercuts or excessive penetration, which can affect the integrity and appearance of the welds.

Another significant benefit of robotic welding is its speed. Robots can perform the welding operation faster than human welders, without compromising the quality of the welds. This increases the productivity of the welding process, allowing for higher output and shorter lead times.

Robotic welding also offers the benefit of consistency. Robots can perform the welding operation in the same way every time, regardless of the complexity of the welding path or the duration of the operation. This results in consistent welds that meet the required specifications and standards.

In addition to these operational benefits, robotic welding also offers several economic and environmental benefits. For instance, the increased productivity and consistency of robotic welding can reduce the cost of the welding operation. Similarly, the precision of robotic welding can reduce the amount of waste produced during the operation, contributing to environmental sustainability.

Although robotic welding has many advantages, it is not appropriate for all projects. Robotic welding is effective depending on a number of variables, including the complexity of the weld, the dimensions of the workpieces, and the accessibility of trained personnel to control the robot. Robotic welding should only be used after careful consideration of all of the above factors.

Suggested read: Automation of a welding process

5. Challenges and Limitations of Robotic Welding

While robotic welding offers numerous benefits, it is not without its challenges and limitations. Understanding these challenges is crucial for businesses considering the implementation of robotic welding systems.

One of the primary challenges of robotic welding is the initial setup and programming of the robot. This process requires a high level of expertise and can be time-consuming, particularly for complex welding operations. The robot must be programmed with the exact movements and parameters for each weld, and any errors in this programming can result in defective welds.

Another challenge is the cost of implementing a robotic welding system. The initial investment for a robotic welding system can be significant, including the cost of the robot itself, the welding equipment, and any necessary modifications to the workspace. Additionally, ongoing costs such as maintenance, repairs, and training for operators can add to the overall cost of the system.

Robotic welding systems also require a consistent production volume to be cost-effective. If the production volume is low or highly variable, the cost benefits of robotic welding may not be realized. This makes robotic welding less suitable for businesses that produce small batches of custom products.

In terms of limitations, robotic welding is less flexible than manual welding. While a human welder can adapt to variations in the workpiece or the welding process, a robot can only perform the tasks it has been programmed to do. This means that any changes to the product design or the welding process may require reprogramming of the robot.

Furthermore, robotic welding is not suitable for all types of welds. Some types of welds, particularly those in difficult-to-reach areas, may still require manual welding. Similarly, the quality of the welds produced by a robot can be influenced by factors such as the condition of the workpiece and the quality of the welding consumables.

Despite these challenges and limitations, robotic welding technology can still offer significant benefits for many businesses. The key is to carefully consider these factors when deciding whether to implement a robotic welding system.

6. Conclusion

In conclusion, robotic welding is a transformative technology that has revolutionized the manufacturing industry. It offers numerous benefits such as increased productivity, improved quality, and enhanced safety. However, it also presents certain challenges and limitations that need to be addressed for optimal utilization. Understanding the working principles, components, and processes involved in robotic welding is crucial for leveraging its full potential.

Frequently Asked Questions

What is robotic welding? 

Robotic welding is a type of welding process that utilizes automated machinery, known as robots, to perform welding tasks. It is a highly efficient and precise method of welding that has become increasingly popular in the manufacturing industry.

What are the types of robotic welding? 

The main types of robotic welding include arc welding, spot welding, and laser welding. Each type has its own unique advantages and is suitable for different applications.

What are the benefits of robotic welding? 

Robotic welding offers numerous benefits such as increased productivity, improved quality, reduced waste, and enhanced safety. It also allows for greater precision and repeatability compared to manual welding.

What are the challenges and limitations of robotic welding? 

Despite its many advantages, robotic welding also presents certain challenges and limitations. These include the high initial cost of equipment, the need for skilled operators and programmers, and the difficulty of welding complex or irregular shapes.

What are the components of a robotic welding system? 

A typical robotic welding system consists of several key components, including the robot arm, the welding torch, and the power supply. Each component plays a crucial role in the welding process.

References:

A review of vision-aided robotic welding 

Robotic arc welding sensors and programming in industrial applications

Model-based parameter optimization for arc welding process simulation 

Optimal parameters for laser welding of advanced high-strength steels used in the automotive industry