What Is a Scara Robot?

A scara robot (also known as a four-axis parallel link robot) is a robotic mechanism with two axes that fold in on each other, allowing them to move in the X and Y planes. It also has a rotational movement in the Z axis that allows it to drive screws. This combination of axes makes it ideal for dispensing, small assembly, and screw driving applications.

Compared to cartesian robots, SCARA robots have more dynamic movements. However, they do not provide the same dexterity and flexibility as a six-axis articulated robot. Because of this, they are best suited to applications that do not require full 3D motion.

These robots are available in three and four-axis models. The G1 series offers payload capacities between 0.5 and 1 kilogram, while the four-model G3 offers a maximum payload of 1 to 3 kg and arm lengths ranging from 175 to 225 millimeters. Both versions can be tabletop or multiposition mounted and are compatible with a wide range of accessories, including linear and screw dispensing.

While SCARA robots are most commonly used in assembly, they are also effective at many other tasks. They can dispense adhesives, tend machines, install fasteners, perform finished product inspection, and more. They are also very quick and can deliver high throughput.

In addition, they have good repeatability. It is common to see a SCARA robot with a repeatability of 10 microns, which is less than a single millimeter. They are also easy to use, as they can be programmed using a simple pendant and do not require a complex enclosure.

Depending on the application, it is important to select the right robot for your needs. This can be done by evaluating its performance against the requirements of your process. One key metric is its optimal kinematic performance index, or OKPI.

This is a calculation that determines the minimum number of axes needed to achieve a given motion path. It is determined by comparing the total number of axes required to reach a target position with the distance traveled along each of those axes.

Another factor to consider is the speed at which a robot can travel between points. This is an important metric for some applications, especially those that are time-critical. The faster a robot can move between positions, the more productive it will be. This is why it is important to evaluate the speeds of various models when selecting a robot.

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