01
Applications
Application scenarios
First and foremost, engineers need to assess the scenarios and processes in which the introduced robots will be applied.
For compact pick- and-place robot applications, a horizontal articulated robot (Scara) can be selected .
For applications requiring rapid handling of small objects, the Delta parallel robot is the most suitable choice.
Collaborative robots (Cobots) are suitable for semi-automatic lines where the process requires collaboration between humans and machines, especially in situations where frequent changes in workstations or line shifts are needed, and in applications involving new torque sensors.
Connecting to a multi-axis vertical joint robot , it can be adapted to a very wide range of applications, from picking and placing materials to palletizing, as well as specialized processes such as painting, deburring, and welding.
Currently, industrial robot manufacturers have corresponding robot solutions for different application processes.
You need to be clear about what tasks you want the robot to perform for you, and then choose the most suitable model from the different types.
02
Payload
Payload
Payload refers to the maximum load that a robot can carry in its workspace, ranging from 3 kg to 1300 kg .
If you want the robot to move a target workpiece from one workstation to another, remember to add the weight of the robot's gripper and the weight of the workpiece to the workload.
One point to note is that the robot's load curve will vary depending on the spatial range and distance, and its actual load capacity will also differ.
03
Maximum action range
Maximum range of motion
When evaluating a target application, it's crucial to understand the maximum distance the robot needs to reach. Choosing a robot requires considering not only its payload but also its precise reach. Using the range of motion diagrams provided by each company, you can determine if a robot is suitable for a specific application. Pay attention to the robot's horizontal range of motion, noting its position in the nearby and rear non-working areas.
The robot's maximum horizontal actuation distance is the distance (X) from the center of the robot's base to the center of the furthest point that the wrist can reach horizontally . The maximum vertical height is measured from the lowest point that the robot can reach ( usually below the robot's base ) to the maximum height that the wrist can reach (Y) .
04
Degrees of freedom
Degrees of freedom ( number of axes )
The number of axes a robot is configured with is directly related to its degrees of freedom. For a simple, straightforward scenario, such as a simple 4- axis robot, it can easily handle the task of picking up and placing items from one conveyor belt to another.
However, if the application scenario is in a confined workspace and the robotic arm needs to perform a lot of twisting and turning movements, a 6- axis or 7- axis robot is the most suitable.
The number of axes is generally determined by the application. When cost allows, it is advisable to choose a robot with more axes, which provides greater flexibility and facilitates the subsequent reuse and modification of the robot for another application process. This allows the robot to adapt to different work tasks, rather than discovering that the number of axes is insufficient.
Robot manufacturers tend to use slightly different names for their axes or joints. Basically, the first joint (J1) is the one closest to the robot's base. The next joints are called J2 , J3 , J4 , and so on, until reaching the end of the wrist. Other companies, like Yaskawa/Motoman , use letters to name the axes of their robots.
05
Repetitive accuracy
Repeatability
Repeatability is also determined by the application and can be summarized as the robot's ability to reach the same position every time it completes a routine task.
Repeatability is typically between ±0.05mm and ±0.02mm , or even higher. For rougher processes like packaging and palletizing, such precise industrial robots are not necessary; however, if you need to assemble electronic circuit boards, then you will need a robot with ultra-precise repeatability.
Furthermore, the selection requirements for robot precision in the assembly process are also related to the transfer and calculation of dimensions and tolerances in each stage of the assembly process, such as the positioning accuracy of incoming materials and the repeatability of the workpiece itself in the fixture. This indicator is represented by positive and negative ± in 2D . In fact, since the robot's motion repetition point is not linear but rather moves in 3D space , this parameter can actually be located at any position within a spherical space within the tolerance radius.
Of course, with the motion compensation technology of current machine vision, the requirements and reliance of robots on the accuracy of incoming materials will be reduced, and the overall assembly accuracy will be improved.
06
Body weight
Body weight
When designing robot units, the weight of the robot itself is an important factor to consider. In applications where industrial robots need to be mounted on custom-designed machines or even on guide rails, you may need to design appropriate supports based on its weight.
07
Brake and moment of inertia
Braking and moment of inertia
Each robot manufacturer provides information on their robot braking systems.
Some robots are equipped with brakes on all axes, while other robot models do not. A sufficient number of brakes are needed to ensure accurate and repeatable positioning within the work area.
In another special case, when an unexpected power outage occurs, the axes of a heavy-duty robot without brakes cannot be locked, posing a risk of accidents.
Some robot manufacturers also provide the robot's moment of inertia. This is beneficial for design safety. You may also notice the applicable torque on different axes. If your motion requires a certain amount of torque to complete, you need to check if the maximum applicable torque on that axis is correct. If the wrong torque is selected, the robot may crash due to overload .
08
Speed
speed
This parameter is important to every user. In fact, it depends on the Cycle Time that the job needs to complete .
The specifications list the maximum speed of this robot model, but it's important to understand that considering acceleration and deceleration from one point to another, the actual operating speed will be between 0 and the maximum speed. This parameter is usually measured in degrees per second. Some robot manufacturers also specify the robot's maximum acceleration.
09
Protection level
Protection level
Users need to select a standard that meets a certain protection level (IP rating ) based on the robot's operating environment .
For different applications and different IP protection levels, some manufacturers offer the same robotic arm.
The IP rating will differ depending on whether the robot is used in the production of food-related products, medical devices, pharmaceuticals, or in flammable and explosive working environments . Generally, for example, the standard rating is IP40 , oil mist rating is IP67 , and the ISO cleaning rating is 3 .
