What is a 3-axis robot arm?

3-axis robot arm: Explained

A 3-axis robot arm is a mechanical arm with three rotary joints that provide motion in three degrees of freedom.

It's not as flexible as a human arm, but it's perfect for repetitive tasks where precision is extremely important. 

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Components of a 3-axis robot arm

While 3-axis robot arms have just three joints, they have many components that make them operate. 

They are: 

• The base: This is the arm’s foundation, typically mounted to a surface and providing stability.
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• The shoulder joint: This joint connects the base to the upper arm and allows for up-and-down and side-to-side movement.
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• The elbow joint: This joint connects the upper arm to the forearm and enables the arm to bend and extend.
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• The wrist joint (optional): Some 3-axis robot arms have an extra wrist joint for added flexibility, allowing for rotation or tilting of the end-effector.
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• The end-effector: This is the tool that’s attached to the end of the arm, designed for specific tasks such as gripping, welding.

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How a 3-axis robot arm works

Here’s how a 3-axis robot works:

• Three joints give three axes of movement: The base joint rotates the entire arm left and right, the shoulder joint moves the arm up and down, and the elbow joint bends the arm in and out. This coordinated movement gives the robot a wide range of motion within its workspace.
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• Actuators provide the power: Electric motors, or other types of actuators, generate the force needed to move each joint and the arm itself. This lets the robot lift and manipulate objects of varying weights.
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• The end-effector acts as a robot-hand: Attached to the end of the arm, it's the tool that interacts with the environment. This could be a gripper for picking up and moving objects, a welding torch for joining metals, or any number of other specialized tools.
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• The control system is the brain: A programmable logic controller (PLC) or similar system orchestrates the movement of each joint, ensuring smooth, coordinated actions. It receives input from the user or a pre-programmed sequence and translates it into precise instructions for the motors.
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• Sensors for feedback: Encoders track the rotation of each joint, while load cells monitor the forces exerted by the end effector. This sensory information allows the control system to make real-time adjustments, which maximizes accurate positioning and grip.

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Common applications of 3-axis robot arms

While 3-axis robot arms are a bit more limited than their more modern cousins, they’re still fantastic for a wide range of applications: 

Assembly

Three-axis robots are common in simple assembly operations like placing components on circuit boards or joining parts together. Their repeatable movements ensure accuracy and quality control in high-volume production.

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Packaging

For packaging applications, 3-axis robot arms pick up and orient items before placing them into boxes, crates, or pallets. They can handle a variety of pack sizes and are excellent for sorting different products.

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Machine tending

3-axis robots are frequently used to load and unload parts from CNC machines, injection molding equipment, and other automated machinery. They can transfer raw materials and finished parts to and from the equipment, which allows the machines to operate continuously without human intervention.

Advantages of using 3-axis robot arms

A 3-axis robot arm offers several benefits over other types of robotic arms:

• Very simple. Three axes of motion are easy to visualize and program. With just base rotation, shoulder joint, and elbow joint to control, 3-axis arms are simple to operate and ideal for basic tasks. This makes them perfect for beginner robotics users and small operations.
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• They won’t break the bank. Only having three joints significantly reduces the cost to manufacture and maintain these robot arms. They need fewer motors, controllers, and sensors compared to more complex multi-axis arms. This makes 3-axis robots more budget-friendly, with many models available for a few thousand dollars.
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• You can redeploy them. While less skilled than higher-axis arms, 3-axis robots can still perform a wide range of useful functions. They can grasp, lift, and move objects, assemble simple components, and interact with their environment. Their limited range of motion allows them to operate in tight spaces where more complex arms won’t fit.
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• Very reliable. With fewer moving parts, 3-axis robot arms tend to be very reliable and durable. They have a minimal chance of joint failure or misalignment and often provide many years of continuous service. Their rugged build and simplified control systems give 3-axis robots an advantage in demanding industrial settings.

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Limitations of 3-axis robot arms

If you’re going with a 3-axis robot arm, remember that simplicity also comes with drawbacks:

• Limited range of motion: 3-axis robots move along three perpendicular axes (X, Y, and Z), like moving a chess piece across the board. This restricts their ability to reach around objects or manipulate items from various angles.
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• Challenges with complex orientations: While they can move up and down, side to side, and in and out, 3-axis robots can’t twist or turn their end-effectors independently. This limits their ability to precisely orient objects or work in tight spaces that require more difficult maneuvering.
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• Not the best fit if things get too complicated: For applications that demand a little extra skill, such as intricate assembly or tasks that require complex manipulation, 3-axis robots fall short. They lack the range of motion necessary for these types of jobs.

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Comparison with other multi-axis robot arms

Since a 3-axis robot arm is the simplest type, we’ll help you out by seeing how they stack up against other robot arms. 

Let’s go deeper: 

• 4-axis robot arms add an extra joint, which increases their range of motion. This allows them to reach more places and handle objects in different ways compared to 3-axis robots.
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• 5-axis robot arms can move more like a human arm, with a wrist that can pivot and rotate. They're capable of more complex movements than 3- or 4-axis robots, making them better for a wider range of tasks.
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• 6-axis robot arms offer even greater flexibility and precision with an extra wrist pivot. They can handle complex tasks that require precise positioning and manipulation of objects.
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• 7-axis robot arms are much more versatile, with one more joint that allows for maximum flexibility. They can reach almost any position and orientation, making them ideal for complex manufacturing and research applications where adaptability is key.
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• SCARA robot arms have been designed with pick-and-place operations in mind. They have a different design than articulated arms and are great at quickly and accurately moving objects over a large area.

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Summing up

As you can see, 3-axis robot arms are versatile machines capable of performing quite a few tasks. But they’re still limited compared to robots with additional axes.

If you don’t have the budget, 3-axis arms strike a great balance between flexibility, precision, and cost. 

However, for more demanding applications, you may want to aim a bit higher.

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Next steps

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Try out RO1 risk-free for 30 days and discover its transformative potential for your business. Reach out to us to arrange a demo today.