While pneumatic conveyors have a host of advantages over other methods of transporting products, two drawbacks commonly cited are its relatively high energy costs and the need for back up against power outages.
In some material delivery scenarios these drawbacks can be overcome by combining pneumatic power with magnetism. Permanent magnets can be driven by non-continuous pulses of air pressure or vacuum pressure, and transported products retained in place by the magnetism even when power is off.
The use of magnets on production lines is, of course, well-proven technology. Magnetism is widely used for gripping sheet metals for rotation and stability whilst drilling, milling or laser welding. Robotic car production lines are a familiar example. Magnetism has clear advantages over suction cups as a way of lifting sheet steel components into place. It uses less energy and doesn’t have to drop the part if the power disconnects.
For separation, magnetism has been used on conveyors since at least 1844, e.g. for separating wolframite from cassiterite. It requires a little ingenuity embedding the same principle into pneumatic lines, but technology is well advanced and equipment readily available.
A common application is in safeguarding foodstuffs from contamination by fine ferrous pollutants. This will often be a dilute phase scenario and involve inline plate magnets within the vacuum conveyor tube controlled through compression couplings. Non-corroding rare earth magnets and silicone seals with sanitary approval for food contact are commonly used. An ideal location is on the outside of an elbow in the conveying tube or in a bottom position where layers typically move more slowly. A variety of methods are available for removing the trapped contaminant, for example a drawer magnet can be cleaned in place with one quick pull.
Nevertheless, many people still don’t immediately think of magnetism within vacuum conveying scenarios, especially for moving particulates and non-ferrous materials. Yet pneumatics and magnetism can often be combined into solutions for specific processes and situations. A conveying specialist like http://www.aptech.uk.com/pneumatic-conveying/vacuum-conveying/ can design bespoke solutions for many industrial scenarios using combinations of magnets and pneumatic control systems.
Pneumatics are often the ideal way to control other processes, whether based on pneumatic, magnetic or mechanical technologies. Pneumatically controlled permanent magnets only need pulses of compression to switch them on and off – something that is also easy to fully program and/or centrally control.