Sizing screens divide in feed material into separate portions based on particle size.
The quantity of decks determines how many times the product is cut. For example a single deck screen will have an over and under size. A double deck will have an over, middle or under size. More decks are used to further separate material.
Where a scalping screen will only have a small percentage of material at an undesired size, a sizing screen will process material that has a more even distribution. As a result, sizing screens need to be designed larger to provide more product retention time.
Aperture sizes are decided by process or client requirements. In some cases aperture size is chosen due to on site physical space availability for the vibrating screen.
Screening media can vary. Polyurethane panels are common in mining and recycling applications. Woven wire mesh is more often used in quarries.
Vibrating sizing screens are designed to operate horizontally to maximise the screening area for particles. Declines can be used for difficult materials but at the cost of screening efficiency. Inclines can be used where space is restricted or high retention times are desired.
As there are multiple categories of product there needs to be some consideration in designing discharge chutes work. Undersize and oversize can be dropped under or over respectively. Separate chutes are used for the middle portions. They can be discharged to the front of the unit.