Many details come into play when designing a vacuum handling system. On one hand, designers must contend with the size, weight, and type of material to be handled, and how fast and precisely it must be moved. On the other, there’s the size and type of vacuum generator, system operating pressure, components — such as valves, hoses, and connectors — as well as up-front and operating costs. (For more information on complete system design, see “Getting a grip on vacuum-handling systems,” Hydraulics & Pneumatics, May, 2010)
But a key component in any vacuum handling system is the vacuum cup or pad. This seemingly simple device must firmly and safely support the load, resist gravitational and acceleration forces, minimize air consumption, and not mar or damage the workpiece. And, of course, it must resist fatigue and abrasion, withstand dirt, contaminants, temperature extremes, and provide long, economical life with little or no maintenance.
Obviously, a lot should go into selecting a suction pad. Leading manufacturers offer extensive data on various types of pads and the advantages of each, along with load capacity, temperature limits, chemical compatibility, and so on. Designers should select vacuum pads based on the following criteria:
Operating conditions — Cycle rates, expected life, aggressive surroundings, temperature, and other environmental factors are all considerations when selecting vacuum pads.
Material — Vacuum pads come in a wide range of materials to meet specific application requirements. Common materials include nitrile, silicone, natural rubbers, fluoroelastomers, and polyurethanes. Some materials are particularly suited to smooth, rough, or oily surfaces, or easily damaged workpieces. Special antistatic vacuum pads are designed to handle electronic components, while others won’t leave marks on plastic parts. Environmental conditions can affect the material choice when the pads must resist ozone, chemicals, extreme temperatures, or be silicone-free.
Surface — The workpiece surface may make certain types of vacuum pads more suitable than others. The wide range of available products includes flat and bellows suction pads in many sizes and shapes with various types of sealing lips and sealing edges.