Types of vacuum generators
The classification of vacuum ejectors considers three key aspects: the number of vacuum stages, the physical principle of vacuum generation, and their mounting type.
Single-stage and multi-stage ejectors
The number of vacuum stages determines whether an ejector is single-stage or multi-stage:
Single-stage ejectors achieve vacuum in a single step, prioritizing simplicity but limiting the attainable vacuum level.
Multi-stage ejectors use a series of stages to gradually increase vacuum. This multi-step approach allows for higher vacuum levels with lower supply pressure, improving efficiency compared to single-stage models.
Venturi vacuum generators
Venturi vacuum generators use the Venturi effect, a principle grounded in Bernoulli's law. As compressed air is forced through a constricted nozzle, its velocity increases, leading to a decrease in pressure according to Bernoulli's principle. This localised pressure drop generates a suction effect, drawing in ambient air from the surrounding environment.
The simplicity and versatility of Venturi vacuum generators make them suitable for roughly 80% of applications. Certain applications, particularly those involving the handling of sensitive or porous workpieces, may necessitate the use of alternative vacuum systems, such as contactless vacuum grippers, which can provide a more suitable solution.
Individual and block-mounting type vacuum generators
Vacuum generators have two primary mounting configurations: individual and block.
Individual mounting is best suited for applications using a single ejector, offering a simple and cost-effective solution.
Block mounting is the preferred configuration when you need to integrate and operate multiple ejectors as a cohesive unit with centralized control. This approach optimizes space utilization and facilitates centralized control and management of the system through the implementation of industrial communication networks, such as fieldbuses.
SMC enhances flexibility by offering hybrid systems that seamlessly integrate valves and ejectors into a single, compact unit. These systems simplify the control of applications that necessitate both positive and negative pressure, while simultaneously streamlining the overall design and construction of the machinery. Furthermore, these hybrid units provide the capability for remote and adaptable vacuum control by utilizing a range of industrial communication protocols, including the advanced IO-Link standard.
Common applications for vacuum ejectors
The versatility of vacuum ejectors is evident across numerous applications:
- Low-flow vacuum systems
- Point-to-point handling using single or multiple vacuum grippers
- Environments without a vacuum supply
What advantages do vacuum ejectors provide over other vacuum generation systems
Key advantages of industrial vacuum ejectors include:
- Maintenance-free and flexible mounting: Unlike systems with moving parts, they have no rotating components, eliminating maintenance needs and enhancing mounting flexibility.
- Installation in any position and at any point in the application: These units can be installed anywhere within the system.
- High response speed and vacuum generation: They achieve the desired vacuum level rapidly.
- Compact and lightweight: They offer space-saving advantages and are easy to handle.
- No heat generation: They do not contribute to environmental heating.
- Energy-saving functions: They have incorporated functions for saving energy.
- Additional integrated functions: Controlling and monitoring are made easier.
Criteria for selecting vacuum generators
Selecting the most adequate vacuum ejector requires to consider several important factors:
- Nozzle and Diffuser Design: These components substantially influence both the maximum suction flow (speed) and achievable vacuum pressure (strength). Smaller nozzles offer higher vacuum levels, but at the cost of lower flow rates Conversely, larger nozzles offer higher flow rates, but the achievable vacuum is lower.
- Requirements for Suction Flow and Vacuum Pressure: Define the necessary suction flow (air volume) for your application and target vacuum pressure for effective handling. Keep in mind that both the chosen flow rate and the piping diameter influence the system's response time (how fast it reaches the desired vacuum)
- Leakage Considerations: The characteristics of the workpiece, such as shape and porosity, can create leaks and affect performance. For applications prone to leaks, SMC recommends lower vacuum pressure settings and ejectors with greater suction capacity. This helps to compensate for leaks and ensure successful operation.
