What is SCARA Robot?

 

The SCARA acronym stands for Selective Compliance Assembly Robot Arm or Selective Compliance Articulated Robot Arm.

Scara is a type of Industrial robot.

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.

Industrial robots are defined as ‘multi-functional manipulators designed to move parts through various programmed motions’. As such, robots provides consistent reliable performance, repetitive accuracy and are able to handle heavy work loads and perform in harsh environments. Additionally, robots can be quickly reprogrammed to reflect changes in production needs and cycles.

Scara Robots configuration

Four axis SCARA robot that consists of an inner link that rotates about the World Z-axis, connected to an outer link that rotates about a Z elbow joint, which in turn is connected to a wrist axis that moves up and down and also rotates about Z.  An alternative configuration has the linear Z motion as the second axis. These are the most popular geometries for vertical assembly and small parts pick-and-place operations.

Scara Robot Characteristics: reliability, accuracy, speed.

Some SCARA characteristics like high reliability, high accuracy and speed, minimum maintenance, ease of use and extremely compact design make this kind of robot really suitable to work with FlexiBowl®; the composed system guarantees high performances in term of productivity and, at the same time, high flexibility in assembly lines and production systems. Thanks to FlexiBowl®, the innovative parts feeder that doesn’t work with vibration, but through the combined actuation of servomotor and impulse generator, assembling can be very flexible. Once bulk components lie on feeder surface with the right orientation, the vision system can locate them and send coordinates to the robot for pick up. FlexiBowl® is capable of feeding entire families of parts and does not require any retooling cost for product changeovers: product changes can be made in a matter of seconds without any trouble.

Scara Robot: how does it works?

SCARA Robots what is SCARA

The SCARA robot is a manipulator with four degrees of freedom. This type of robot has been developed to improve the speed and repeatability ON PICK&PLACE TASKS from one location to another or to speed and improve the steps involved in assembly. This is why it is often used with FlexiBowl®.

Morover these robots are used in the automotive field, as well as electronic, and other industrial fields where manufacturers needs to feed bulk components of all sizes; in these areas FlexiBowl® is performing so good that is replacing others parts feeders.

SCARA kinematics makes this robot particularly suitable to perform assembly tasks with tight tolerances, such as putting a shaft into a hole, thanks to the capability to adjust the movement on the horizontal plane, while at the same time maintaining high rigidity on the vertical direction.

The mechanics of the SCARA arm is generally quite strong and can withstand without problems unexpected stress and collisions.

In a SCARA robot junctions of the shoulder and elbow are vertical and the wrist moves vertically. This  configuration minimizes the effects of gravity on the robot by downloading them to the ground and allowing the use of this machine in cases of strong pressures as in vertical perforations.

For example in the case of cosmetic Industry, during a feeding test of mascara brushes, FlexiBowl® has been used with an Adept cobra i600 and Ace AdeptSight vision system, creating a perfect synchronization with the hopper and uniform part distribution on the feeder surface and giving very regular and efficient performances.

The communication with robot controller and vision system is done by sending simple commands through the available communications ports: ethernet, ethercat, digital i/o signals.

FlexiBowl® shaking movements allow parts to lie on feeder surface with the right orientation; the vision system can then locate them and send coordinates to the SCARA robot for the pick up phase. This is possible thanks to all electronics and motion controls embedded in robot arm.

Advantage and Limitation of Scara Robots

Advantages of SCARA robots

  • Generally a SCARA robot can operate at a higher speed and with optionals like cleanroom specifications.
  • The SCARA robot is commonly used for pick-and-place or assembly operations when high speed and high accuracy are required.
  • SCARA Robots currently available can achieve tolerances lower than 10 microns. This tolerances can be compared to 20 microns for a six-axis robot.
  • The compact layout of SCARA Robots also makes them more easily re-located in temporary or remote applications: by design, the SCARA robot suits applications with a smaller field of operation and where floor space is limited.

 

Limitations of SCARA robots

  • SCARA robots, because of their configuration, are typically only capable of carrying a lighter payload. Typically, they carry 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 robots (e.g. six-axis robots).