What is a 6-Axis Robot? Structure, Benefits, and Application

Explore 6-axis robots: from definition, structure, and operating principles to applications and benefits across industries. Learn about selection criteria and leading 6-axis robot brands.

Table of Contents

What is a robot axis?

In robotics, an axis refers to a degree of freedom (DOF), which defines how a robot can move. A 3-axis robot can navigate along the X, Y, and Z directions but lacks the ability to tilt or rotate. As the number of axes increases, the robot gains greater mobility and access to a wider range of positions. However, robots are typically built with a fixed number of axes, and adding extra axes later is nearly impossible.

An easy way to determine a robot’s DOF is by counting its motors, though this can be challenging as they are often hidden inside the structure. In general, the more axes a robot has, the more flexible and capable it is of handling complex tasks.

Classification of robots by the number of axes

Below is an overview of different robot types, categorized by their degrees of freedom (DOF). Keep in mind that the number of axes may vary depending on the manufacturer, so this serves as a general guideline.

3-Axis Robots

Also known as Cartesian robots or SCARA robots, 3-axis robots operate similarly to a 3-axis CNC machine or a 3D printer. These robots move along three linear axes (X, Y, and Z) using three motors.

They are ideal for simple pick-and-place tasks, where objects remain in the same orientation throughout the movement. Since the tool cannot rotate, any object picked up must be transported without changing its alignment.

A typical example of a 3-axis robot is a crane.

4-Axis Robots

A 4-axis robot can rotate an object around a fourth axis while still moving along the X-Y-Z planes. Examples of 4-axis robots include SCARA, delta, and some traditional robotic systems.

These robots operate with four motors, with the main difference from Cartesian robots being the fourth axis, which enables tool rotation. For example, when picking up objects from a conveyor belt, the robot must first determine the position (X-Y axes), adjust for height (Z-axis), and finally rotate the tool to align with the part’s orientation.

5-Axis Robot

At this level, traditional industrial robots start to appear. Many industrial robots are designed with five axes, allowing movement along the X-Y-Z planes while also rotating the tool around two additional axes. Specifically, the tool can rotate around the Z-axis and Y-axis but not the X-axis, meaning it lacks complete freedom of movement, and certain positions remain inaccessible.

A 5-axis robot can be compared to a 5-axis CNC machine, where the tool moves along the X-Y-Z axes, while the table rotates around the Z-axis (creating four axes), and an additional tilting motion provides the fifth axis.

6-Axis Robot

What is a 6-axis robot

A 6-axis robot offers complete freedom of movement, allowing it to move along the X-Y-Z axes while also rotating around each of these axes. The key difference from a 5-axis robot is that axes 4 and 5 provide additional rotation, enabling more complex maneuvers.

An example of a 6-axis robot is the Universal Robot. You can easily identify its six motors, typically covered by blue caps, and observe how each motor contributes to the robot’s movement.

7-Axis Robot

7-axis robot

If a 6-axis robot can already reach any position in space, why do we need a 7-axis robot?

Although 6-axis robots can access any point in space, 7-axis robots offer additional flexibility. The extra axis allows the robot to reach an end effector position using multiple joint configurations. This helps avoid singularities and enables the robot to maneuver around obstacles by positioning the arm in ways a 6-axis robot cannot. A prime example of a 7-axis robot is the Motoman SDA series, which is often referred to as a redundant robot due to the additional axis.

12-Axis and 13-Axis Robots

12 or 13-axis robots essentially involve combining two 6-axis robots to create a dual-arm robot. If the robot’s base is capable of rotating, an additional axis is added, bringing the total to 13 axes. However, despite the added axes, these robots cannot extend their reach beyond the three spatial dimensions we work within.

What is a 6-axis robot?

A 6-axis robot is an industrial robot with six degrees of freedom, allowing it to move and operate flexibly in a three-dimensional space. These six joints (or axes) enable the robot to perform complex movements similar to a human arm.

Structure and Operating Principle

Structure of a 6-axis robot

A typical 6-axis robot consists of:

Robot Base: This is the foundation, usually fixed to the floor or a workbench. The base houses the central processing unit, power supply, and other electronic components.
Robot Arm: Composed of multiple segments (links) connected through joints. The arm is typically made of aluminum alloy or steel for rigidity and strength.
Joints: These rotating joints allow relative movement between the arm segments. A 6-axis robot has six joints, each corresponding to a degree of freedom (DOF).
Actuators: Electric motors (usually servo motors) are used to drive the joints.
Control System: The “brain” of the robot, including a central controller and software. This system processes sensor signals, programs, and commands the motors for precise movement.
End-Effector: The final component of the robotic arm, attached to the sixth joint. Depending on the application, it could be a gripper, welding torch, paint sprayer, camera, etc.

Operating Principle of a 6-axis Robot

The 6-axis robot operates based on motion control principles. The control system sends signals to the motors, guiding the joints through a programmed sequence and speed.

With six degrees of freedom, the robot can perform complex movements in a 3D space:

Rotation around the vertical axis (Axis 1): The robot arm can rotate left or right.
Raising or lowering the arm (Axis 2): Similar to a human shoulder movement.
Bending or extending the arm (Axis 3): Similar to an elbow movement.
Rotating the wrist clockwise or counterclockwise (Axis 4).
Tilting the wrist up or down (Axis 5).
Rotating the wrist along a perpendicular axis to Axis 4 and 5 (Axis 6).

Types of Motors and Control Systems

Motors: 6-axis robots typically use AC servo motors or stepper motors. Servo motors are preferred due to their precision and high-speed control capabilities.
Control Systems:
- PLC (Programmable Logic Controller): A specialized computer used to control industrial devices. PLCs are often employed in simpler robotic applications.
- Dedicated Robot Control Systems: These are specifically designed for robots, featuring advanced control algorithms for precise and efficient execution of complex tasks.

Benefits of Using a 6-Axis Robot

Utilizing 6-axis robots offers significant advantages for businesses, especially in today’s modern manufacturing environment where competition is fierce:

Flexible and Versatile: With the ability to operate in multiple directions and smooth movement along 6 axes, these robots can perform complex tasks such as assembly, welding, painting, and material handling across a wide range of applications, ultimately optimizing production processes.
High Precision: Advanced technology enables 6-axis robots to achieve exceptional accuracy and repeatability, minimizing errors and ensuring consistent product quality.
Easy Integration into Production Lines: With a user-friendly programming interface and high customization capabilities, these robots can be seamlessly integrated into modern automation systems, reducing deployment time and operational complexity.
Safe to Work Alongside Humans: Particularly for collaborative models, 6-axis robots are equipped with sensor technologies and designed with safety in mind, ensuring secure interactions between the robot and human workers and opening up opportunities for flexible manufacturing.
Cost Savings and Increased Efficiency: By automating processes with 6-axis robots, businesses can lower labor costs, boost productivity, and reduce production risks, thereby enhancing their competitive edge in the market.

Applications of 6-Axis Robots in Industry

6-axis robots are widely used across various industries, including:

Mechanical Processing: Cutting, milling, turning, grinding, etc.
Automotive Manufacturing: Assembly, welding, painting, quality inspection, etc.
Product Packaging and Assembly: Sorting, packaging, labeling, etc.
Electronics Industry: Component assembly, quality inspection, circuit welding, etc.
Welding Technology: Spot welding, arc welding, etc.
Other Applications: Medical (surgery), logistics (warehousing), services, etc.

Criteria for Choosing the Right 6-Axis Robot

To select the right 6-axis robot, you should consider the following criteria to ensure the product meets your technical requirements and maximizes production efficiency:

Specific Task Requirements: Identify the tasks you want to automate (e.g., pick-and-place, assembly, welding, painting, etc.) so you can choose a robot with the appropriate functions and features.
Payload Capacity and Working Range: Evaluate the robot’s maximum payload and its operational reach to ensure it can handle your materials and workspace effectively.
Precision and Repeatability: The robot must deliver high precision and consistent repeatability, which is particularly crucial for applications like assembly or welding.
Flexibility and Ease of Programming: A user-friendly programming interface and seamless integration with existing systems will save you time and reduce deployment costs.
Safety When Working Alongside Humans: For collaborative robots, safety is paramount to ensure secure interactions between the robot and your workforce.
Investment and Total Cost of Ownership: Beyond the initial purchase cost, consider operational expenses, maintenance, and potential scalability to ensure a sound investment.
Technical Support and After-Sales Service: Opt for a supplier that offers robust technical support, maintenance, and professional consultancy to maintain stable and sustainable operations.

Top 6-Axis Robot Brands

Universal Robots: Specializes in developing collaborative robots (cobots) that work safely alongside humans. Their products are distinguished by their ease of programming and quick deployment, making them ideal for a range of light to medium production applications.
ABB: As one of the world’s leading technology companies, ABB offers a diverse portfolio of 6-axis robot solutions for various industries—from welding and assembly to material handling—ensuring high efficiency in production.
Fanuc: Renowned for its exceptional durability and ability to operate continuously, Fanuc remains the top choice for applications that demand uncompromised performance and precision in challenging industrial environments.
KUKA: With advanced technology and German-standard manufacturing quality, KUKA provides 6-axis robots capable of managing complex production processes, from assembly and material handling to tasks requiring high flexibility.
Yaskawa: Known for its robust servo motor systems, Yaskawa delivers reliable, flexible, and adaptable 6-axis robot solutions that are well-suited for a variety of industries, ranging from automated manufacturing to material processing.

Why Choose Universal Robots?

Universal Robots is committed to providing flexible, safe, and easy-to-use industrial 6-axis robotic arms for businesses of all sizes worldwide. We develop collaborative industrial robots to automate and streamline repetitive industrial processes. This approach allows manufacturing teams to assign personnel to more engaging tasks, helping them develop skills in more challenging areas and ultimately increasing company value.

Popular Universal Robots Models

UR3e: With a payload capacity of up to 3 kg, the UR3e is the ideal solution for precise, light tasks such as intricate assembly, quality inspection, and applications in limited workspaces.
UR5e: With a maximum payload of 5 kg, the UR5e offers a balance between compact size and an extended working range, making it well-suited for tasks like packaging, assembly, and handling lightweight materials in modern production environments.
UR10e: With a payload capacity of 10 kg, the UR10e provides a wide operational reach and high performance for applications requiring interaction with complex automated systems, from assembly processes to the transportation of industrial parts.
UR16e: As the most powerful model, with a payload capacity of up to 16 kg, the UR16e is designed for heavy-duty applications. It ensures stable performance in harsh production environments and processes that demand high precision and robust load-bearing capabilities.

Servo Dynamics: Official Distributor of Universal Robots in Vietnam

Servo Dynamics proudly serves as the official distributor of Universal Robots in Vietnam. We are committed to providing high-quality collaborative robot solutions, consultation services, installation, and technical support, helping customers maximize the potential of Universal Robots cobots.