Working Principle of Vacuum Adhesion Systems

Working Principle of Vacuum Adhesion Systems

The core of SMT vacuum board lifters lies in their vacuum adhesion systems, which generate negative pressure via pneumatic or electric vacuum generators to achieve precise PCB board gripping. The specific workflow comprises three stages:

1. Negative Pressure Generation Stage

2. Utilising the Venturi effect principle, compressed air passing through the vacuum generator creates a negative pressure zone at the intake port, typically operating within a working pressure range of 0.4–0.6 MPa. Electric vacuum pump solutions generate vacuum through high-speed rotor rotation, achieving vacuum levels of -80 kPa to -95 kPa, making them more suitable for high-precision applications.

3. Adhesion execution stage\

4. Suction cup assemblies, crafted from silicone or polyurethane, are activated via solenoid valve control. Upon contact with the PCB surface, the vacuum channel opens, applying atmospheric pressure to secure the board against the suction cup. Standard equipment features 3–6 suction cups, with maximum adhesive force calculated as:\

5. [ F = P × A × n ]\

6. Where P represents vacuum pressure, A denotes the effective area of a single suction cup, and n indicates the number of suction cups.

7. Release and Transfer Stage\

8. PLC-controlled solenoid valves switch the air circuit, injecting positive pressure gas into the suction cups for rapid release. The entire process response time is <50ms. Advanced pressure sensors continuously monitor vacuum pressure changes. Should leakage exceed the set threshold (typically 10%), an alarm triggers an immediate shutdown.

1.2 Functional Positioning within SMT Production Lines

As a critical front-end device in SMT production lines, the vacuum board lifter fulfils three core functions:

1. Material Handling Hub\

2. Interfaces with tray-based board loaders or bare board stackers to sequentially separate randomly stacked PCBs and convey them precisely to the track system. Typical cycle time: 12–15 seconds per board. Supports maximum board dimensions of 450×350mm (FWT-350XB model).

3. Process Coordination Node\

4. Interoperates with subsequent printers and placement machines via SMEMA communication protocol. Upon detecting downstream equipment readiness signals, the board lifter automatically executes ‘pick-up, traverse, release’ actions to ensure continuous production line operation. The built-in buffer capacity holds 3-5 PCBs, effectively mitigating cycle time variations.

5. Quality Control Outpost\

Integrated photoelectric sensors detect board presence, orientation, and warpage. Select high-end models feature vision positioning systems that correct transport deviations by comparing mark point coordinates, achieving positioning accuracy of ±0.1mm.