WHAT ARE THE TYPES OF INDUSTRIAL ROBOTS?
Adding automated robotic systems to a factory saves money, creates higher-quality parts, and increases production. There are six types of industrial robots that can be classified according to the type of movement, the application needs, reach and payload requirements, and manufacturer preference. The robot types are Articulated, Cartesian, Cylindrical, Polar, SCARA, and Delta. Read more about each type of industrial robot below.
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These are the most common types of robots in manufacturing. Articulated robots have rotary joints, also called axes. The range of motion depends on the number of axes. The axis structure for articulated robots can vary from two up to ten or more axes with six axes being the most common.
Articulated robots look similar to a human arm and can have the ability to rotate all of the joints or axes. The robot's servo motors are used to power the movement of each axis. This allows for precision and speed. There are three ways in which these robots can move: pitch is up and down, yaw is right and left, and roll is exactly that - rotation. This mobility makes articulated robots an excellent choice for arc welding, assembly, packaging, painting, palletizing, part transfer, pick & place, machine tending, and material handling. Some articulated robots are even designed to perform multiple applications.
The flexibility that comes with articulated robots allows them to easily adapt to the production process or part changes making them ideal for manufacturing. Read about the differences between industrial robot arms and collaborative robots here.
A Cartesian robot moves in a linear, straight-line motion as opposed to a rotating motion. They have three control axes (X, Y, Z) that are linear and are at right angles to each other. The base (X) axis is wholly supported, whereas the Y and Z axes are cantilevered meaning their rigid structure extends horizontally and is supported at one end. The axes work together in a coordinated motion through a common motion controller.
Cartesian robots can be used in some of the same applications as SCARA and Articulated robots and they share some of the same technical specifications. There are some benefits that Cartesian robots have over SCARA and Articulated robots. Cartesian robots have a rectangular work envelope so the entire work area is utilized. Articulated and SCARA robots, on the other hand, have circular work envelopes that can result in unused space especially if it is a long reach.
For positioning accuracy and repeatability, Cartesian robots can be superior to the Articulated and SCARA types because they can be fabricated from almost any type of linear actuator with an array of drive mechanisms such as a ball or lead screw, belt, pneumatic actuator, or linear motor. Rack and pinion drives are possible but are normally used in gantry systems with very long strokes. Cartesian robots can be easier to program because they have three axes, rather than multiple rotational axes.
Using their rigid structure, Cartesian robots can carry high payloads. They can perform functions such as pick & place, loading & unloading, material handling, assembly, and dispensing applications.
In some applications, either Cartesian, SCARA, or Articulated robots can do the job. For help determining which robot fits your application, reach out to one of our automation experts.
Cylindrical robots are akin to Cartesian robots in their axis of motion. The majority of Cylindrical robots are designed with linear and rotary actuators. They have a cylindrical work envelope which makes them ideal for smaller spaces. Cylindrical robots are can be used for assembly operations, handling of machine tools and die-cast machines, and spot welding. These stationary robots are fairly simple to install and use.
Polar robots are also referred to as spherical robots in that the axes form a polar coordinate system. The arm has two rotary joints and one linear joint connected to a rotary base with a twisting joint. They have a spherical work envelope. Polar robots work well for simple applications such as diecasting, injection molding, material handling, arc welding, and gas welding. These stationary robot arms were some of the first in manufacturing. Polar robots are rarely used due to advances in industrial robotics.
SCARA is an acronym for Selective Compliance Assembly Robot Arm or Selective Compliance Articulated Robot Arm. This means it is compliant in the X-Y axis and rigid in the Z-axis. For small robotic assembly applications, manufacturers typically turn to SCARA due to their low cost and high speed.
SCARA robots have four-axis or degrees of freedom. A SCARA robot moves in the X, Y, Z planes like a Cartesian robot; however, SCARAs have a theta axis at the end of the Z plane in order to rotate the end of arm tooling (EOAT). This makes SCARA robots a good choice for vertical assembly. The arm however is like a lever that limits a SCARA robots reach. When the arm extends, strong bearings and high-torque motors are needed at the joints to handle the loads.
SCARA robots typically have a cylindrical work envelope. The total length of arms one and two determine the circle's diameter and the Z stroke determines the cylinder's depth.
SCARA robots have excellent repeatability making them a good choice for dispensing applications. They are also the most popular geometries for vertical assembly and small parts pick-and-place operations. In addition, SCARA robots can be used for laser engraving and 3D printing applications.
Delta robots are parallel arm robots and can also be referred to as spider robots. They have three arms that connect to universal joints at the base. The joints at both ends of each parallel rod typically move freely in ball joints. End of arm tooling (EOAT) can be attached to the lower platform. Delta robots can have three to six-axis with the majority having four-axis or degrees of freedom allowing objects to be rotated.
In applications requiring high speed and light payloads, Delta robots can be used. They can quickly pick up products in groups and place the products in an assembly pattern or container. To differentiate and select shapes, sizes, and color, vision technologies can be added allowing Delta robots to pick & place according to a programmed pattern. Deltas can be used in assembly, part transfer, and pick & place applications.
Delta robots can be an expensive investment. Reach out to our Automation Experts to discuss your application and if less expensive options are viable for your application.
Our Automation Experts share their suggestions on how to choose the right robot, click here.