Vacuum cups and vacuum pads engage an object and attach to it with an applied, sealed vacuum. The pads are then actuated to lift, move, or position the work piece in assembly or inspection applications. Vacuum cups and vacuum pads can include features such as bellows for surface conformance and swiveling action for versatile positioning.
Types of Vacuum Cups and Vacuum Pads
Common vacuum cup and pad types include standard, deep cup, oval, square, rectangular, curved, bellows, cleated, sponge, flat and ring. Standard cups are general-purpose cup-type vacuum pad. Typically used in multiple-pad systems. Deeper cup allows for some surface curve conformance. Consult with manufacturer for suitability on use with flat surfaces. Oval pads provide greater surface area than circular pads. They are often used for translational conveying due to their increased holding capacity. Square and rectangular pads or cups usually have rounded corners. Curved profile cups and pads are for use with cylindrical or spherical objects. Accordion-type bellows on the vacuum pad can provide irregular surface conformance or level difference compatibility. Contracting bellows can simulate a short stroke for pickup. Radial cleats provide increased holding strength. Foam or sponge type pads provide a high level of irregular surface conformance. Flat pads are typically large with some rubber cushioning and are used for large flat objects for which the gripping surface is always parallel to the pad face. In a ring pad or cup a suction element follows a circular path (or edge contour of non-circular pad); often used in disk holding such as CDs and DVDs.
Specifying Vacuum Cups and Vacuum Pads
Important parameters to consider when specifying vacuum cups and vacuum pads include diameter or maximum dimension, stroke (if applicable), materials of construction, vacuum porting and connection. The stroke is the retraction or lift stroke length for a bellows type pad or pad mounted on retractable hardware. The material of construction is the material used in the pad itself. Some materials may be more suitable for harsh temperature, high vacuum heavy loads, or chemical environments. Consult with manufacturer for specific pad material properties and applications. Material choices include EPDM, neoprene, nitrile (NBR), polyurethane, PVC, rubber, silicone, and vinyl. Porting options include top port and side port. A top port is an in-line or on top of the cup or pad. A side port is on the side of the pad; sometimes used in tight space applications. Connection choices include none, a pad only, threaded, quick connect and hose barb.
Mounting features common to vacuum cups and vacuum pads include spring mounted, swivel or pivot mounted, and suspension or multi-point mounted. Spring mounted cups and pads have integrally mounted springs for retraction under vacuum. Swivel or pivot mounted cups and pads have a free pivoting or swivel mount, which allows for angular surface misalignment. A suspension or multi-point mounting arrangement includes multiple mounts for a single pad; independent springs may allow for level conformance. This mounting arrangement is typically found on larger pads.
Other features common to vacuum cups and vacuum pads include anti-static construction, sanitary or food grade, and in-line filter for air supply cleanliness.