Robots seem to be everywhere these days — in movies, airports, food production, and even working in factories that make other robots. Robots have many different functions and uses, and as they become easier and cheaper to manufacture, they are becoming more common in the industry. As the demand for robotics increases, robot manufacturers need to keep up, and one fundamental method of manufacturing robotic components is CNC machining. In this article, learn more about robotic standard parts and why CNC machining is so important for manufacturing robots.
CNC machining is tailor-made for robots
First, CNC machining enables parts to be produced with extremely fast lead times. Almost as soon as you have your 3D model ready, you can start making components with a CNC machine. This enables rapid iteration of prototypes and rapid delivery of custom robotic components for specialized applications.
Another advantage of CNC machining is its ability to precisely manufacture parts to specifications. This manufacturing precision is especially important for robotics, since dimensional accuracy is key to making high-performance robots. Precision CNC machining keeps tolerances within +/- 0.0002 inches, and this part allows for precise and repeatable movement by the robot.
Surface finish is another reason to use CNC machining to produce robotic parts. Interacting parts need to have low friction, and precision CNC machining can produce parts with surface roughness as low as Ra 0.8 μm, or even lower after post-processing operations such as polishing. In contrast, die casting (before any finishing) typically produces surface roughness close to 5µm. Metal 3D printing produces a rougher surface finish.
Finally, the types of materials used by the robot are ideal for CNC machining. Robots need to be able to move and lift objects stably, requiring strong, hard materials. These necessary properties are best achieved by machining certain metals and plastics. Additionally, robots are often used for custom or low-volume manufacturing, which makes CNC machining a natural choice for robotic components.
Types of Robotic Parts Made by CNC Machining
With so many possible functions, many different types of robots have evolved. There are several main types of robots that are commonly used. An articulated robot with a single arm with multiple joints is something many people have seen. There are also SCARA (Selective Compliance Articulated Robot Arm) robots, which can move things between two parallel planes. SCARAs have high vertical stiffness because their movement is horizontal. The joints of the Delta robot are located on the bottom, which keeps the arms light and able to move quickly. Finally, a gantry or Cartesian robot has linear actuators that move at 90 degrees to each other. Each of these robots has a different build and a different application, but there are generally five main components that make up a robot.
There are mainly several types of robots that are commonly used. An articulated robot with a single arm with multiple joints is something many people have seen. There are also SCARA (Selectively Compliant Articulated Arm) robots, which can move objects between two parallel planes. SCARAs have high vertical stiffness because their movement is horizontal. The joints of the delta robot are on the base, which keeps the arm light and able to move quickly. Finally, a gantry or cartesian robot has linear actuators that move at 90 degrees to each other. Each of these robots has a different build and a different application, but generally has 5 main components:
1. Robotic arm
Robot arms vary widely in form and function, and therefore use many different components. However, one thing they all have in common is their ability to move or manipulate objects - not unlike a human arm! The different parts of the robot arm are even named after our own parts: the shoulder, elbow and wrist joints rotate and control the movement of each part.
2. End effector
An end effector is an appendage attached to the end of a robot arm. End effectors allow you to customize the robot's capabilities for different operations without building an entirely new robot. They can be grippers, grabbers, vacuum cleaners or suction cups. These end effectors are usually CNC machined components from metal (usually aluminum). One of the components is permanently attached to the end of the robot arm. An actual gripper, suction cup, or other end effector is fitted to the component so it can be controlled by the robotic arm. This setup with two different components makes it easier to swap out different end effectors, so the robot can be adapted to different applications. You can see this in the image below. The bottom puck will be bolted to the robot arm, allowing you to connect the hose that operates the suction cup to the robot's air supply. The top and bottom discs are examples of CNC machined parts.
3. Motor
Every robot needs motors to drive the movement of the arms and joints. The motor itself has many moving parts, many of which can be CNC machined. Generally, the motor has some kind of machined housing for power and a machined bracket that connects it to the arm. Bearings and shafts are also usually CNC machined. Shafts can be machined on a lathe to reduce the diameter, or on a mill to add features such as keys or slots. Finally, the motor motion can be transferred to the joints of the robot or gears in other parts by milling, EDM, or gear hobbing.
4. Controller
The controller is basically the brain of the robot, which controls the precise movements of the robot. As the robot's computer, it takes input from the sensors and modifies the programs that control the output. This requires a printed circuit board (PCB) to house the electronic components. This PCB can be CNC machined to the desired size and shape before adding the electronic components.
5. Sensors
As mentioned above, sensors receive information about the environment around the robot and feed it back to the robot controller. The sensor also requires a PCB, which can be CNC machined. Sometimes these sensors are also housed in CNC-machined housings.
Custom Jigs and Fixtures
While not part of the robot itself, most robotic operations require custom jigs and fixtures. You may need a fixture to hold the part while the robot is working on it. You can also use fixtures to precisely position parts, which is often necessary for robots to pick up or put down parts. Because they are often one-off custom parts, CNC machining is ideal for jigs.
