Manufacturers generally classify suction pads as universal or special purpose. Universal pads cover a wide range of requirements, while specific-duty pads are designed to meet special requirements, such as handling thin automobile body parts or porous workpieces in the woodworking industry. The two most-common types of universal products are flat and bellows vacuum pads.
Flat vacuum pads are particularly suited for handling objects with flat or slightly curved surfaces. They come in a wide range of materials, sizes, and shapes, including round and oval, with steep or flat sealing lips. Low overall height and small internal volume produces short evacuation times, letting them grip workpieces quickly. The flat shape ensures good stability when attached to a load, and they withstand high lateral forces during fast movements.
Flat vacuum pads also are typically used for handling smooth or slightly rough workpieces, such as metal, glass, and wood sheets, cardboard boxes, and plastic parts. Wear-resistant versions can handle higher loads and give up to 10 times the life of standard NBR (nitrile-rubber) units. Flat, oval suction pads produce high forces despite relatively small dimensions. They’re best suited for thin and curved objects, such as extrusions, pipes, and sections of door and window frames.
Bellows suction pads compensate for varying workpiece heights and can handle parts with curved or uneven surfaces or those that are easily damaged. Like flat pads, they come in many shapes, sizes, and materials. Bellows suction pads can lift products when vacuum is applied. Typical versions have bellows with 1½, 2½, or 3½ folds. More folds are generally better for handling workpieces with extremely uneven surfaces, or when a longer vacuum pad lifting stroke is necessary.
Upper portions of a bellows often are stiffer for stability during horizontal acceleration, while the lower portions and sealing lips are softer and more flexible to conform and give good sealing, even on non-rigid workpieces. The bellows also provides damping when it contacts the workpiece, beneficial when handling fragile parts. Bellows pads are typically used on parts such as car-body components and pipes; cardboard boxes and blister-packs; and easily damaged items such as electronic components and injection-molded plastic parts.