What is a SCARA robot?

SCARA robots were first developed in the 1980’s in Japan and the name SCARA stands for Selective Compliance Assembly Robot Arm.  The main feature of the SCARA robot is that it has a jointed 2-link arm which in some ways imitates the human arm although it operates on a single plane, allowing the arm to extend and retract (fold) into confined areas which makes it suitable for reaching inside enclosures or pick-and-place from one location to another.  The SCARA robot is one of 3 major classes of robot which Cyan Tec Systems are experienced at integrating, namely:

• Cartesian Robots (Gantry type)
• Six-axis Robots
• SCARA Robots

The selection of which type of robot to choose is not always clear-cut, but Cyan Tec Systems are in a totally unbiased position to recommend the best solution for the particular automation requirement.  This article considers the specific case of the SCARA robot and when it is most likely advantageous to use one.  In some cases the selection of the most suitable robot is straightforward and in others it is mainly down to a comparison on cost.   SCARA robots normally have up to 4 axes (3 rotation and one Z linear).

 

Advantages of SCARA robots

The SCARA robot is most commonly used for pick-and-place or assembly operations where high speed and high accuracy is required.  Generally a SCARA robot can operate at higher speed and with optional cleanroom specification.  In terms of repeatability, currently available SCARA robots can achieve tolerances lower than 10 microns, compared to 20 microns for a six-axis robot. By design, the SCARA robot suits applications with a smaller field of operation and where floor space is limited, the compact layout also making them more easily re-allocated in temporary or remote applications.

 

Limitations of SCARA robots

SCARA robots, due to their configuration are typically only capable of carrying a relatively light payload, typically up to 2 kg nominal (10 kg maximum).  The envelope of a SCARA robot is typically circular, which doesn’t suit all applications, and the robot has limited dexterity and flexibility compared to the full 3D capability of other types of robot.  For example, following a 3D contour is something that will be more likely fall within the capabilities of a six-axis robot.

 

Choosing the right solution

With many different factors influencing the choice of the robot for a specific application, it is wise to discuss with an automation expert.  Cyan Tec Systems have been integrating all types of robots for several decades and can advise on alternative concepts for system design and help to select the most suitable configuration.   Working with an experienced and independent supplier is the best way to define the automation configuration that suits the cycle time, accuracy and budget of the required production system.

Cyan Tec Systems has experience of integrating robots for assembly and loading/unloading of machinery.  Cyan Tec also offers systems for paint spraying, assembly, test and laser processing applications. Standard and bespoke systems are offered with a full service from design through manufacture, a large installed base worldwide is supported by a dedicated team of engineers.