Universal Robots – Nine Considerations for Industrial Robot Selection

1. Applications

First and foremost, the most important source is to evaluate the application and process of the robot being introduced.

If the application process needs to be completed by the machine next to the manual, the cobot should be a good option for the usual human-machine hybrid semi-automatic line, especially when it is necessary to change the station or shift the line frequently, and when it is used with a new torque sensor.

If you're looking for a compact pick-and-place robot, you may want to choose a horizontally articulated robot.

If you are looking for an occasion for quick pick-and-place of small objects, the parallel robot is most suitable for such needs.

2. Payload

The payload is the maximum load that the robot can carry in its workspace. Ranging from, for example, 3Kg to 1300Kg.

If you want the robot to complete the handling of the target workpiece from one station to another, you need to take care to add up the weight of the workpiece and the weight of the robot's gripper to its workload.

In addition, it is necessary to pay special attention to the load curve of the robot, and the actual load capacity will vary at different distances in the spatial range.

3. Degrees of freedom (number of axes)

The number of axes that a robot is configured is directly related to its degrees of freedom. If it is for a simple straight-to-go situation, such as picking up and dropping from one belt line to another, a simple 4-axis robot is sufficient.

However, if the application is in a small workspace and the robot arm requires a lot of twisting and turning, a 6- or 7-axis robot will be the best choice.

The number of axes generally depends on the application. It should be noted that, as costs permit, choosing a slightly more number of axes is not a problem in terms of flexibility. This makes it easy to reuse and transform the robot into another application process, which can adapt to more work tasks, rather than finding that the number of axes is insufficient.

4. Maximum actuation range

When evaluating the target application, it is important to know the maximum distance that the robot needs to reach. Choosing a robot isn't just about its payload – it's also about the exact distance it reaches. Each company gives a diagram of the actuation range of the respective robot, which allows it to determine whether the robot is suitable for a specific application. The horizontal range of motion of the robot, noting a non-working area near and behind the robot.

5. Repeatability

Again, this factor depends on your application. Repeatability can be described as the ability of a robot to complete a routine job task and reach the same location every time.

Generally between ±0.05mm and ±0.02mm, or even more precise. For example, if you need your robot to assemble an electronic circuit board, you may need a robot with super precision repeatability. If the application process is relatively rough, such as packaging, palletizing, etc., the industrial robot does not need to be so precise.

On the other hand, the selection requirements of the robot accuracy of the assembly project are also related to the transmission and calculation of the dimensions and tolerances of each link of the assembly project, such as: the positioning accuracy of the incoming materials, the repeated positioning accuracy of the workpiece itself in the fixture, etc.

6. Speed

This parameter is relevant to each user. In fact, it depends on the CycleTime that needs to be completed in that job. The specification table lists the maximum speed of this model of robot, but we should know that considering the acceleration and deceleration from one point to another, the actual speed will be between 0 and the maximum speed. This parameter is usually measured in degrees per second. Some robot manufacturers also mark the maximum acceleration of the robot.

7. Body weight

The weight of the robot body is an important factor when designing a robot cell. If an industrial robot has to be mounted on a custom-built machine, or even on a rail, you may need to know its weight to design the corresponding support.

8. Braking and moment of inertia

Basically every robot manufacturer provides information about their robotic braking system. Some robots are equipped with brakes for all axes, while others do not have brakes for all axes. To ensure a precise and repeatable position in the work area, a sufficient number of brakes are required. In another special case, when an unexpected power failure occurs, the load-bearing robot shaft without brakes will not lock, and there is a risk of causing accidents.

9. Protection level

According to the use environment of the robot, the standard of achieving a certain protection level (IP level) is selected. Some manufacturers offer the same range of robots with different IP ratings for different occasions. If the robot is working in a food-related product, medicine, medical equipment, or flammable and explosive environment, the IP rating will vary.

Universal Robots – Nine Considerations for Industrial Robot Selection

Universal Robots – Nine Considerations for Industrial Robot Selection

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