Lesson 1: Why Use Pneumatics?
An efficient workcell needs to be able to control the flow of an object through the workcell, from its entry point to the desired destination. This could require moving multiple objects in different directions. There are many ways to direct the movement of objects within a workcell, including pneumatic systems. Pneumatics uses compressed air as a force to create motion.
In this Lesson, you will learn about:
- Different mechanical solutions for controlling the flow of objects in a workcell
- The difference between linear and rotational movement
- Advantages of pneumatic systems in an industrial setting
- Industrial applications of pneumatics
In the video below, pneumatic components on an assembly line construct parts of a product.
Controlling the Flow of Materials within a Workcell
In the previous Unit, you moved an object through the workcell using the conveyors. You figured out how to optimize the process by moving the conveyors more efficiently. This was a successful method for moving one object to one location. However, how would this work to move multiple objects in the system? What if those objects needed to move to different locations? You would need to be able to control how objects entered the conveyor system, to ensure that materials entered at an appropriate rate. You would also need to be able to divert objects to send them in different directions. This would require other systems to work in conjunction with the conveyors.
Let's imagine a factory where a workcell is used to pack and sort materials for shipping. Different objects move along conveyors, and need to be directed to different locations. The materials first need to enter the system in way that enables them to be sorted successfully. They will then need to be diverted effectively along different paths. There are a number of different mechanical solutions that could help control the flow of materials. 
Using Multiple Robotic Arms
Previously, you have used the 6-Axis Robotic Arm to pick up and place objects onto a pallet. A robotic arm can move objects repeatedly, so it could be useful for picking up objects and placing them into the conveyor system. A robotic arm could also pick up an object from a specific position and move it to a different conveyor. However, that means that you would need a robotic arm at every possible entry and exit point in the workcell. While this could be effective, it is also very expensive and potentially dangerous. Using many robotic arms would require placing a large amount of equipment into a small space, which could create an unsafe environment.
There is also a question of whether a robotic arm is the right tool for this task. Robotic arms are capable of moving in a variety of ways, which makes them versatile and easy to use for pick and place tasks. However, situations like moving objects onto and off of conveyors, or placing objects into packages, often repeat simple movements and do not require a fully articulated robotic arm to be completed effectively. When thinking about how to control the flow of materials within a workcell, it is important to consider the type of movement that is needed at each entry or exit point.
Linear vs. Rotational Movement
Repetitive tasks like diverting a package from one conveyor onto another, often involve simple movements, like moving up and down, forward and backward, or turning a specific amount. Knowing the type of motion that is needed to complete a task can help you choose the appropriate solution. Let's think a little more about these two types of motion.
Linear Motion is movement in a straight line, along one axis.
There are many everyday mechanisms that use linear movement like elevators, that move vertically along the elevator shaft; or sliding doors that open and close by moving horizontally along tracks.
In manufacturing, pneumatic cylinders, like the one shown here, are used to move materials in a straight line. A pneumatic cylinder can be used to push items onto a conveyor belt, raise or lower a mechanism, or position an object. You will learn more about pneumatic cylinders in the next Lesson.
In the video to the left, the VEX Pneumatic Cylinder is shown extending as air pressure enters the cylinder, and contracting as it leaves the cylinder.
Rotational Motion is movement around a central axis. With rotational motion, an object spins or rotates in a circle around the axis.
There are many everyday mechanisms that use rotational movement like car wheels, which rotate around their axles to propel a vehicle forward or backward; or revolving doors that rotate around a central axis to move people into or out of a building.
In manufacturing, motors provide rotational movement for turning, positioning, or operating mechanisms. These can be used to rotate conveyors, or manipulate tools to assemble products.
In the video to the left, a wheel rotates around its axle illustrating rotational motion.
Using Multiple Motors
When thinking about how to move an object using just one type of motion, a motor seems like it could be a viable solution. On your CTE Workcell, motors turn, using rotational motion to move the conveyors. Let's think about if adding more motors could help with the task of controlling the entry or exit of objects on the conveyors.
To cause an object to move from one conveyor to another, a motor could be used to manipulate a diverter by spinning it to open or block the path. Similar to how the arm of gate rotates to move up and down to block a car or open the gate to control the flow of traffic onto the roadway, a motor could be used to move a diverter in a similar way. 
While this could accomplish the task, motors take up a lot of space. Building in the space for additional motors could get in the way of the conveyors and other components of the workcell, again creating a potentially dangerous work environment. Spacing the motors out, could requiring a larger footprint for the workcell, and become cost prohibitive. If a diverter simply needs to be raised or lowered in a straight line, a solution that uses linear motion could be a better fit.
Fluid Systems
Fluid systems use fluids (liquids or gases) to perform work. Fluid systems are broadly categorized into two main types: hydraulics and pneumatics. These systems leverage the principles of fluid dynamics and mechanics to move, control, and manipulate fluids to create mechanical energy. Hydraulics and pneumatics create linear motion by using pressurized fluids (liquids in hydraulics, gases in pneumatics) to move a piston within a cylinder. This motion is controlled by valves that direct the flow of the fluid, allowing for precise and powerful linear movements. 
Hydraulics excel in high-force, precise control scenarios, making them indispensable in heavy machinery and industrial applications. They are often used on heavy construction equipment like excavators, bulldozers, and backhoes to operate their arms, buckets, and attachments. The high-pressure capabilities of hydraulic systems make them ideal for lifting and moving large loads, and for transporting heavy materials, such as in concrete pouring and mixing.
Pneumatics, on the other hand, are ideal for rapid, safe, and cost-effective operations in manufacturing and everyday applications. They are used in everything from dentist chairs and truck air brakes to packaging lines and other tools in automated factories. Pneumatic systems are ideal for lightweight tools, such as jackhammers, nail guns, and drills. The air-powered nature of many pneumatic tools makes them portable and easier to operate.
Key Differences Between Hydraulics and Pneumatics
| Hydraulics | Pneumatics |
|---|---|
| Uses liquids as the medium (oil, water-based fluids) | Uses gases as the medium (air, nitrogen) |
| Operates at higher pressures, providing greater force | Operated at lower pressures, providing less force |
| Provides precise control for heavy-duty applications | Used for simpler, lighter tasks where rapid movement is needed |
| Requires careful maintenance to prevent leaks and contamination | Clean and safe, using air that is abundant and non-hazardous |
| More expensive due to higher cost of components and fluids | More cost-effective and easier to maintain |
In choosing between a hydraulic or pneumatic system, it is important to consider the size and scale of the task. Hydraulics are designed for larger scale, heavier objects that require a lot of force to manipulate. For smaller, quicker, repeatable tasks, like moving a diverter or pushing an object onto a conveyor belt, pneumatics are an effective and efficient solution.
Advantages of Pneumatic Systems
Throughout this Unit you will learn about the components of pneumatic systems and how they function to create motion. Before diving into what makes the system function, let's look at why pneumatic systems are advantageous in many situations. There are many reasons why pneumatics are widely used in industrial and factory automation.
- Efficiency and Speed
- Pneumatic systems can achieve rapid movements due to the high speed of compressed air flow, which makes them a good fit for tasks that require fast and repetitive actions. This contributes to higher productivity in manufacturing processes, as more materials can be manipulated in less time.
- Simplicity and Reliability
- Pneumatic systems can have fewer moving parts compared to other electrical systems, which makes them simpler to design, maintain, and repair. This also enables pneumatics to be more reliable over time, and require less downtime due to maintenance during the lifetime of the equipment.
- Cost-Effectiveness
- Pneumatic components and systems tend to be less expensive than hydraulic or electrical systems, both in upfront costs and ongoing operational costs.
- Safety
- Since pneumatic systems use air, they are a safer alternative to other systems, like hydraulics, as the air can be safely vented and does not pose a risk of contamination or fire in hazardous environments.
- Power and Flexibility
- Pneumatics can generate a significant amount of force relative to their size and weight, making them versatile, and able to be scaled to suit different applications and tasks easily.
- Environmental Benefits
- Pneumatic systems use air as a medium, which is readily available and does not contaminate the environment. This is particularly beneficial in industries like food and pharmaceuticals, where a clean environment is key.
Industrial Applications of Pneumatics
The ability to manipulate materials with mechanisms that perform repetitive, rapid, precise movements in a cost-effective, safe, and environmentally friendly way has made pneumatics a mainstay in manufacturing and industrial automation. Pneumatic systems are incorporated to do many things, including:
- Material Handling - pneumatics are used in conjunction with other systems in a workcell, like conveyors, to divert objects and control the flow of materials.
- Clamping and Holding - pneumatic clamps and grippers can securely hold parts in place during machining or assembly processes.
- Packaging - pneumatic systems are used in packaging machinery for sealing, cutting, and labeling products quickly and efficiently.
- Tool Operation - pneumatic tools, such as drills, grinders, and wrenches, are frequently used in assembly lines for their reliability and ease of use.
Pneumatics are a cornerstone of industrial automation and contribute to the efficiency and effectiveness of modern manufacturing processes. Watch the video below to see pneumatics being used in industrial automation.
Check Your Understanding
Before beginning the next Lesson, ensure that you understand the concepts in this Lesson by answering the questions in the document below in your engineering notebook.
Check Your Understanding questions > (Google Doc / .docx / .pdf )
Select Next > to move on to the next Lesson to learn about the components of pneumatic systems.