Compared to 3- or 4-axis robots, 6-axis robots offer a wider range of operation, the ability to reach difficult positions in the production line, helping to reduce operating time and increase productivity.

Robot classification by number of axes

In the field of industrial automation, robots are classified based on the number of axes (DOF - Degrees of Freedom), showing their ability to move and rotate flexibly in space. Below are the popular types of robots according to the number of axes today:

3-axis Robot Arm (3-axis robots)

3-axis Robot Arm, also known as Cartesian or SCARA robot, can move in three directions X, Y and Z similar to 3-axis CNC machines or 3D printers. Often used in simple pick-and-place operations, where the part is fixed in a certain direction. 3-axis robots are suitable for jobs with high repetition and require positional accuracy rather than rotation angle.

4-axis Robot Arm (4-axis robots)

4-axis Robot Arm adds the ability to rotate around a fourth axis in addition to the X-Y-Z movement. Thanks to that, the robot can move and adjust the direction of the tool, increasing flexibility in operation. For example, SCARA robots, Delta robots are often used in assembly lines, or loading and unloading goods.

5-axis Robot Arm (5-axis robots)

Robots can move along three main axes X-Y-Z and rotate around two additional axes (Z and Y), allowing for more complex operations. However, 5-axis robots are not yet fully flexible because they cannot rotate around the X axis. This type of robot is often used in precision machining such as 5-axis CNC machines that require adjusting the cutting angle or tilting the worktable.

6-axis Robot Arm (6-axis robots)

With the ability to move in X-Y-Z and rotate around each axis, the robot can simulate the movement of a human arm. 6-axis robots are widely used in welding, assembly, painting, packaging and automatic pick-and-place, a typical example is Universal Robot, which represents a flexible robot line in modern production lines.

7-Axis Robot Arm

The 7th axis allows the robot to reach the same working point using many different joint configurations, providing outstanding flexibility in operation. The outstanding advantages of 7-axis robots include:

• Avoidance of singularities helps the movement process to be always smooth.
• Move around obstacles easily, especially suitable for narrow spaces or production lines with high equipment density.
• Optimize the path of the arm, helping the robot operate quickly, save energy and increase its lifespan.

A typical example of this type of robot is the Motoman SDA "redundant" robot line that simulates human operations almost exactly.

12 and 13-axis Robot Arms

12 and 13-axis Robot Arms are essentially a combination of two 6-axis robots, forming a two-arm robot system capable of synchronous operation. When the base can rotate, the total number of axes increases to 13, helping the robot achieve extremely flexible parallel operations. Although the operating range in 3D space is not superior to that of 6 or 7-axis robots, 12 - 13-axis robots stand out in their ability to:

• Perform multiple tasks at the same time, such as welding two spots, assembling or picking and placing two parts at the same time.
• Simulate human two-arm operations, helping to increase productivity and efficiency in complex production stages.

Learn more about 6-axis robots

A 6-axis robot is a type of industrial robot arm designed with 6 degrees of freedom (DOF), allowing it to perform flexible and precise movements in three-dimensional space.

These six axes correspond to the ability to move and rotate around the X, Y, Z directions, helping the robot to almost perfectly simulate the operations of a human arm. Thanks to its multi-joint structure and flexible movement, 6-axis robots can perform many complex tasks such as picking and placing products, welding, painting, assembling components, or packaging goods.

Structure of a 6-axis robot

A standard 6-axis industrial robot is made up of many main parts, which coordinate smoothly to create precise and stable movements:

• Robot body (Base): Is the foundation, usually fixed on the floor or operating table. Inside contains the central processor, power source and electronic control system.

• Robot Arm: Includes many segments (links) connected by joints. Robot arms are usually made of aluminum alloy or high-strength steel.

• Joints: Each 6-axis robot has 6 moving joints, which allow the robot to rotate, tilt and reach in many directions in the workspace.

• Actuators: These are high-precision servo motors or electric motors, responsible for creating movement for each joint.

• Control System: Includes a central controller (Controller) and programming software to receive signals from sensors, process data and control the robot to perform pre-programmed operations.

• End-effector: Is the part attached to the 6th joint where the robot directly interacts with the object. End-effectors can be grippers, welding heads, paint spray heads, cameras or product quality control sensors.

Operating principle of 6-axis robot

6-axis robot operates based on the principle of motion control, in which the central control system will send signals to servo motors to move the joints in a pre-programmed sequence and speed.

Axis 1 (Base): Rotates around the vertical axis

This is the base of the robot, allowing 360° rotation around the vertical axis, helping the robot change its working position horizontally. Thanks to this axis, the robot can reach a wide range without having to move the entire body.

Axis 2 (Shoulder): Moves up and down

Located at the "shoulder" part, axis 2 helps the robot arm lift or lower in an arc, adjusting the operating height. This axis is important in assembly, loading and unloading applications or picking up products on different floors.

Axis 3 (Elbow): Extend and retract

At the “elbow” position, axis 3 adjusts the robot’s reach, allowing the arm to be extended or shortened when reaching objects that are far or close.

Axis 4 (Wrist Roll) - Wrist rotation

This axis allows the wrist to rotate 360°, adjusting the direction of the end tool. In welding or assembly, it ensures the robot can maintain the correct working angle.

Axis 5 (Wrist Pitch) - Tilt the wrist up and down

Allows the robot wrist to tilt up or down in an arc, supporting tasks that require flexible tilt angles such as painting, spraying glue or surface inspection.

Axis 6 (Wrist Yaw) - Rotate the wrist left and right

Allows the wrist to rotate horizontally (left - right), helping to orient the end tool more accurately. Combined with axes 4 and 5, the robot can operate flexibly at any angle, suitable for wires that require high precision.

Motor and control system of 6-axis robot

Motor: 6-axis robots use AC servo motors or stepper motors, in which servo motors are preferred because of their fast response, high precision and smooth speed control.

Control system:

• PLC (Programmable Logic Controller): Used in simple robot applications, PLC helps control the operating sequence stably and is easy to program.
• Specialized robot controller: Designed specifically for industrial robots, integrating many complex motion processing algorithms, helping robots operate accurately in modern automation lines.

Applications of 6-axis robot arms in industry

With the ability to simulate human hand movements, combined with high precision and speed, 6-axis robots are widely used in many production stages such as:

Product inspection with image sensors

Modern 6-axis robots are integrated with image sensor systems (vision sensors), helping to identify and analyze technical parameters and product details on the conveyor. Thanks to that, robots can automatically detect errors, classify and arrange products according to pre-programmed standards.

Automatic component addition

6-axis robots can also automatically assemble and add missing components to the product. With optimal programming, robots perform the entire process from inspection - assembly - placing the complete product on the tray. This feature is especially useful in continuous processing and assembly lines, helping to minimize manual errors.

Loading and unloading products 

Thanks to the flexible sensor and shaft system, the robot can automatically pick up, move and arrange goods in the right predetermined position. The flexible lifting and lowering ability helps the robot easily stack products on many levels, ensuring safety, stability and saving storage space, suitable for logistics, warehouses and automatic packaging systems.

Assembling components and subassemblies

The 6-axis robot arm can perform sophisticated assembly operations such as screwing, joint mounting, circuit board mounting or small parts with high precision. Equipped with a variety of end-effectors, the robot can handle a variety of products in many industries: electronics, mechanics, automobiles, and home appliances.

Polishing and surface treatment of mechanical products

The 6-axis robot can undertake this process by programming according to contour or through the advanced 3D data processing system ROS software. This software helps the robot accurately determine the virtual product surface, create smooth movement paths, polish evenly and meet aesthetic standards, shortening the time between people and machines.

Automatic glue application, gluing and welding

Thanks to pre-programming, the robot can spray glue evenly on the surface of one or two sides, helping the product achieve perfect aesthetics and adhesion. In addition, robots can also perform automatic welding, replacing humans in toxic environments while still ensuring weld quality and stability for the production line.

Some notes when choosing an industrial robot arm

Choosing the right equipment not only helps increase productivity and accuracy, but also reduces long-term operating costs.

Clearly define the usage needs

Each line of industrial robots has different structures, loads, speeds, and features. Understanding the needs from the beginning helps businesses:

• Choose the right type of robot suitable for the production line.
• Optimize investment costs, avoid buying equipment with excess capacity or lacking features.
• Easily integrate robots into existing production systems without too much improvement.

Consider price and performance

A cheap but low-quality industrial robot can lead to premature damage, machine downtime, and high maintenance costs. Enterprises should consider the overall cost of initial investment, performance, and equipment life.

Currently, the price of industrial robot arms varies depending on:

• Brand and origin (Japan, Korea, Europe, China, Vietnam, etc.).
• Number of axes, load capacity, and operating speed.
• Control features, programming, and integration with automation systems.

Accuracy and repeatability

A high-quality 6-axis robot can achieve repeatability up to ±0.02mm, ensuring that each movement is stable and consistent.

Flexibility and programmability

A friendly and easy-to-use programming interface helps operators quickly set up, customize or integrate the robot with their existing production system. In addition, the robot is compatible with many industrial communication protocols (Ethernet/IP, Modbus, Profinet...) to make connecting to ERP or MES systems more efficient.

Working safety

Modern 6-axis robots are often equipped with force sensors, collision sensors and safe operating limits, helping to minimize risks and ensure that the robot can operate stably in the same space as humans.

Investment costs and total cost of ownership

Businesses need to consider operating costs, maintenance and future expansion capabilities. A suitable solution is to choose a robot that is high-performance, easy to maintain and flexible in configuration, ensuring optimal ROI for the business.

Technical support and after-sales service

Prioritize choosing a reputable industrial robot supplier with long-term deployment and technical support capacity to:

• Get advice on choosing the most suitable equipment.
• Support for installation, operation, programming and technology transfer.
• Ensure professional and fast maintenance and warranty services.

Intech Group - Vietnam's leading provider of loading and unloading robot solutions

With more than 14 years of experience in the field of automation and industrial robots, Intech Group provides solutions for robot stations for loading and unloading goods onto pallets, industrial robots combined with conveyor systems, conveyor belts, film wrapping machines, strapping machines, automatic carton sealing machines. We support customers from design consultation, equipment selection, programming to actual implementation at the factory.

Intech's robot products are optimized for each industry, meeting strict requirements for speed, accuracy and durability, helping businesses improve productivity, optimize labor costs, and minimize errors leading to smart factories in Industry 4.0.