The payload, which defines the maximum weight a robot can lift safely, plays an important role in robotics. Robots such as the Yu 5 Industrial, Diana 7 or the Franka Research 3 even carry it in their name. Industry observers will have noticed that the payloads of collaborative robots have significantly increased recently. But is more also better?
Large differences in payload
The load capacity of industrial robots varies greatly, ranging from a few grams to several tons. This is highly dependent on the area of application. Robots that can carry heavy loads are often used in the automotive industry, steel production or metal processing. They lift metal blocks, cast parts, car bodies or engines. Their design reflects their performance: they are large, heavy and robust.
In contrast to their bulky counterparts, lightweight robots are more compact, space-saving and - as the name suggests - lighter. They are used in laboratories, electronics production, packaging and precision mechanics, among other areas.
One robot for all applications?
Since payloads represent different weight classes, they cover a wide spectrum. A robot capable of lifting 100 kilograms can also handle one kilogram. This might suggest that heavy-duty robots could cover all application areas, rendering low-payload robots obsolete. Yet, why do so many users still prefer lightweight robots?
Choosing lightweight robots is like deciding against using a crane to carry a glass of water. It's all about selecting the appropriate tool for the specific task.
Sensitivity instead of strength
Conventional industrial robots are ideal for maneuvering medium to heavy loads, which is why lightweight robots often fall short in strenuous tasks.
Instead, lightweight robots excel in precision and sensitivity, crucial for handling small and fragile objects where load capacity is less relevant.
These capabilities are particularly valuable in the electronics industry, where most components and parts are relatively light and objects weighing more than 5 kilograms are rare.
Reliable precision
In robotics, precision refers to the end effector’s capability to consistently and accurately reach a specific endpoint, known as repeatability. This is achieved with the help of modern sensors and advanced speed control.
Robotic arms built for heavy loads often exhibit lower repeatability, achieving precision of approximately 0.1 mm—the thickness of standard printer paper. Such precision is typically sufficient for more robust tasks like palletizing.
Lightweight robots such as the Yu 5 Industrial from Agile Robots offer a repeatability of 0.05 mm. That is often twice as high as the repeatability of standard industrial robots. Depending on the application, this difference can be decisive. In electronics, even a 0.05 mm deviation can cause inadequate connections or short circuits, especially in fine conductor paths or components. This precision is also essential for PCB testing, where a high degree of accuracy is necessary to ensure reliable test outcomes.
Applying the right force
Sensitivity among robots can differ greatly, and this is where integrated torque sensors become crucial. These sensors measure the force applied to the joints of the robot arm, helping to prevent overloading and malfunctions. Such precision is vital for handling products carefully, which is particularly important in sensitive applications.
While many conventional industrial robots have torque sensors, these are generally less sensitive. This is because the force requirements for tasks vary: assembling a car door demands significant force with minimal sensitivity, whereas assembling a circuit board requires high sensitivity with minimal force.
Traditional industrial robots, with torque sensors designed for heavy loads, are often unsuitable for delicate components. In contrast, lightweight robots like the Yu 5 Industrial, which feature highly sensitive torque sensors in all 6 axes, excel in such applications.
Bulky or compact?
The higher the payload, the more robust the robot needs to be. Maneuvering large loads requires a high degree of stability, which is supported by both the base plate and the robot's design. A larger base plate provides a more stable structure, allowing for better weight distribution and absorption of the mechanical load.
In addition, robots with high payloads have larger, reinforced joints that are designed for more powerful motors and actuators so that they can cope with the increased requirements.
These reinforcements can lead to a restriction in use as they take up a lot of space. This is particularly problematic for small and medium-sized companies, as they often do not have the financial resources for large-scale production facilities. At the same time, the size makes it difficult to integrate the robot into existing processes.
This is where lightweight robots like the Yu 5 Industrial have a distinct advantage. With a base plate diameter of just 171 mm, it can fit almost anywhere, making it ideal for confined production environments. Additionally, its flexibility is a significant benefit: with 6 axes and a reach of up to 1000 mm, the robot can easily manage both close and distant objects.
The right tool
Robots are tools. They are versatile and take the strain off us. When selecting them, it is important to keep the application in mind: What do I need? Heavy equipment or precision tools? Pliers or tweezers?
The payload is an important indicator here: it plays a key role in determining which robot category we choose. It does not determine the quality of the robots - only the specialization and the area of application.
When precision and sensitivity are paramount, lightweight robots like the Yu 5 Industrial are the optimal choice. Designed for handling small to medium-sized objects, its payload capacity is ideal for this purpose.
The Yu 5 Industrial can reliably and accurately manage both light and medium-heavy items, making it particularly suitable for machine tending and precision assembly tasks. A key advantage is its intelligent camera: It helps the robot to recognize and classify objects autonomously. Since it is already integrated, it won’t reduce the robots payload capacity.
When the priority is force over precision, high-payload robots are the more suitable choice.
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About the author: Henner Brandes
As a Communications Specialist, Henner Brandes supports the corporate communications of Agile Robots. He is dedicated to presenting robotics topics in a practical, clear, and engaging manner, catering to all levels of expertise. He accomplishes this by collaborating closely with Agile Robots' technical experts. Furthermore, Henner leverages his extensive industry experience, which has been closely connected to robotics and technical communication since the beginning of his career.