Vibrating Screen can be controlled mechanically or electromagnetically vibrating, oscillating, reciprocating or girating the screen. Gyration is preferred for fibrous materials. Screens are often rectangular but can be circular with the feed at the center with the flow spiralling towards de periphery. Screens can be stacked on top of each other to achieve mutiple size fraction and to increase the surface area.
The top deck will have bigger hole in the grid of the screen. The size of the particle remove from the top deck will be larger than that on the bottom. Only the small particle pass through the bottom screen. Multiple screens also protect the finer screens from damage by large tramp.
High frequency vibrating screens are the most important screening machines utilized in the mineral processing industry. They are used to separate feeds containing solid and crushed ores and are applicable for wetted and dried feed. The high frequency vibrating screens usually operates at an inclined angle, traditionally varying between 0 and 25 degrees and can go up to a maximum of 45 degrees.