Vacuum generator types
Vacuum ejectors are categorised by three primary factors: the number of vacuum stages, the underlying physical principle of vacuum generation, and their mounting configuration.
Single-stage and multi-stage ejectors
Based on the number of vacuum stages, ejectors are categorised as single-stage or multi-stage.
Single-stage ejectors complete the entire vacuum generation process in a single step, prioritizing simplicity but restricting the attainable vacuum level.
Multi-stage ejectors employ a sequential series of stages to gradually enhance the vacuum. This multi-step approach enables higher vacuum levels with reduced supply pressure compared to single-stage models, resulting in improved efficiency.
Venturi vacuum generators
Venturi vacuum generators function based on the Venturi effect, a principle derived from Bernoulli's law. As compressed air accelerates through a constricted nozzle, its pressure drops according to Bernoulli's principle. This creates a low-pressure zone that induces suction, drawing in surrounding air.
Venturi vacuum generators are well-suited for approximately 80% of applications owing to their simplicity and versatility. In specific applications, like handling delicate or porous workpieces, alternative vacuum systems, such as contactless vacuum grippers, might be more suitable.
Individual and block-mounting type vacuum generators
Vacuum generators are typically mounted in two primary configurations: individual or block.
Individual mounting is optimal for applications requiring a single ejector, providing a straightforward and economical solution.
Block mounting is recommended when multiple ejectors need to be clustered together and managed centrally. This approach enables efficient use of available space and facilitates centralised control and management of the system through the implementation of industrial communication systems, such as fieldbuses.
SMC offers increased flexibility using hybrid systems, which seamlessly integrate valves and ejectors into a single, compact unit. This method makes the control of applications needing both positive and negative pressure simpler, while also streamlining machine design. These hybrid units enable remote and flexible vacuum control via industrial communication protocols, such as IO-Link.
Common applications for vacuum ejectors
The adaptability of vacuum ejectors is particularly evident in a wide range of applications, including:
- Low-flow vacuum systems
- Point-to-point handling using single or multiple vacuum grippers
- Environments without vacuum supply
What are the advantages of vacuum ejectors over other vacuum systems?
Industrial vacuum ejectors provide the following key advantages:
- Maintenance-free and adaptable mounting: No rotating parts mean no maintenance and flexible mounting options.
- Installation flexibility: Can be installed anywhere in the system.
- High response speed: Quickly reaches the desired vacuum level.
- Compact and lightweight: Space-saving and easy to handle.
- No heat generation: Does not heat the environment.
- Energy-saving functions: Built-in features to reduce energy use.
- Additional integrated functions: Extra features for easier control and monitoring.
Criteria for choosing vacuum generators
Choosing the optimal vacuum ejector requires thorough evaluation of several key factors:
- Nozzle and Diffuser Design: These components have a significant impact on both the suction flow rate (speed) and the attainable vacuum level (strength). Smaller nozzle diameters generate higher vacuum levels but with reduced flow rates. Conversely, increased nozzle size leads to higher flow rates, but lower vacuum levels.
- Requirements for Suction Flow and Vacuum Pressure: Determine the required suction flow (air volume) and desired final vacuum pressure for your application. The system's response time (how fast it reaches the desired vacuum) is affected by both the selected flow rate and the pipe diameter.
- Leakage Considerations: Workpiece characteristics, such as shape and porosity, can cause leaks and affect performance. For applications with potential leaks, SMC recommends setting a lower vacuum pressure and selecting an ejector with higher suction capacity. This helps mitigate leaks and ensures successful operation.
