Industrial robots can vary by a number of characteristics including size, payload capacity, reach, and number of axes. The number of axes an industrial robot has will determine how much range of motion it will be capable of and is a key factor to consider when selecting a robot. The more axes an articulated robot has the greater its range of motion. Typically, complex applications will require a robot to have a higher number of axes. Six-axis robots are the standard for robotic automation since their range of motion is most similar to that of a human arm. However, as robots have become more advanced so has the complexity of applications, which has some manufactures automating with high-DOF robots, mainly seven-axis models. Below is a breakdown of how six-axis and seven-axis robots compare to one another.
Configuration
Six-axis robots feature an articulated robot structure with a rotating base and single robotic manipulator arm. Axes one, two, and three are located in the robot’s base, body, and shoulder. While axes four, five, and six are located in the arm and wrist of the robot. Popular six-axis robots used to automate manufacturing applications include the FANUC R-2000ib and the Motoman MA1400.Seven-axis robots also feature an articulated structure. They have the same axes in the same locations as six-axis robots, but with one additional axis which is located in the robotic arm. The FANUC R-1000ia/120F-7B is an example of a seven-axis industrial robot. RTUs integrated with a six-axis robot are also considered seven-axis robotic systems. The track is the seventh axis which allows for linear movements.
Movement
Six-axis robots are capable of moving in the x, y, and z planes with axes one, two, and three. Axes four, five, and six allow the robot to create roll, pitch and yaw movements with its end-effector. With six full degrees of freedom, the FANUC M-710ic/50 can change a part’s orientation by an entire 360-degrees.Seven-axis robots are capable of the same movements as six-axis robots. Their extra axis allows them to bend their robotic arm to avoid or maneuver around objects without requiring part repositioning, an advantage they have over six-axis robots. The extra axis also provides better EOAT positioning and stability. In the case of RTUs, the seventh axis allows robots to travel in between workstations or cover the entire span of a factory.
Applications
One of the reasons six-axis robots are so common for automation is because they can be used for just about any manufacturing application. Welding automation, assembly, material handling, material removal, and palletizing are some of the most popular applications for six-axis robots. Six-axis robots are incredibly versatile with their multipurpose capabilities.Seven-axis robots do not have as wide of a scope as six-axis robots when it comes to the type of applications they can automate. Most seven-axis robots are used for material handling automation. Robotic manufacturers have recently started developing seven-axis robots for welding applications. Seven-axis welding robots are proving to be beneficial for welding automation as they provide better torch access and can eliminate the need for a robotic positioner. The Motoman VA1400 is a seven-axis welding robot.