Four-Axis vs Six-Axis Robots
When selecting an industrial robot for your production process there are a number of factors to consider. Robot type, size, payload capacity, reach, and axes are some of the key characteristics that define an industrial robot and should be considered when automating an application. When it comes to robotic axes, articulated robots can have as few as two or have more than ten. Most industrial robots have between four to six, with six-axis robots being the standard in manufacturing. Not every application can benefit from a six-axis robot, there are some cases in which a low-DOF robot, such as a four-axis robot, is better suited. This brings up the question of how four-axis and six-axis robots compare to one another.
Structure
Most four-axis industrial robots fall into one of two structural categories, being either articulated or SCARA. Articulated four-axis robots feature an axis in the base, lower arm, and upper arm. The fourth axis is located in the robot wrist to allow for rolling movements of the end-effector. The FANUC M-410ib/160 is an example of a four-axis articulated robot.Most six-axis robots consist of articulated robot structures, but they can also consist of delta or collaborative robot types. Six-axis robots feature the same axes as four-axis robots but with an additional axis in the robot wrist for pitch and yaw movements as well as an additional axis for full 360 degree movements, allowing for complete part rotation. One reason six-axis robots are so popular is because they have a full range of motion. The FANUC M-10ia is ideal for automating production related tasks since its range of motion is similar to a human. Another reason for their popularity is because there are a wide variety of options for six-axis robots. There are small robots, short arm robots, high payload, large robots, and everything in between. Automating a large work envelope? The FANUC R-2000ib/125L is an extended reach robot capable of covering large work areas. Or maybe you need a robot for light part handling. The Motoman HP3J is a low payload robot with the precision for handling small parts.
Applications
Four-axis robots are often used for automating palletizing and depalletizing applications. The reduced number of axes provides the FANUC M-410ib/700 with extra stability for heavy lifting. Since most palletizing processes only require up and down motions, extra axes are not necessary. Four axes allow for faster and more efficient lifting.Six-axis robots are able to automate just about any manufacturing application. Traditional six-axis applications include welding automation, painting, material handling, assembly, and material removal. Advancements in robotic technology is now allowing six-axis robots to automate more complex processes such as inspection and 3D printing.
Deciding whether to automate with a four-axis or six-axis robot will largely be determined by the type of application, workpieces, and future automation needs. Those looking to automate a simple lifting application and do not foresee future changes can benefit from the speed and stability of a four-axis robot. While more complex processes or the possibility of application changes down the road would be best for the versatility of a six-axis robot.