Finger roller screen
Müller finger roller screens are used as screening machines to prepare and clean materials in the pre-screening system that are still dirty but can be utilised. This means that more material is produced for further processing and, unlike normal screening machines, the finger roller screen achieves very good separation and classification even in bad weather and with poor pre-screened materials.
Like the Müller roller screen, the Müller finger roller screen achieves constant movement of the screened materials thanks to its special construction and the rotation of the axles and the rotation stars, which have a peripheral speed of approx. 2 m/sec. The rotation and throwing movement straighten out the feed material and sling it back and forth so that any loamy components are removed from the feed material. The key is the specially developed finger shape that flings the material up into the air.
The constant movement separates moist and loamy materials and materials that are hard to separate and clean such as sticky clay and stones by gap width.
For very dirty charging material and high outputs, we recommend switching between two graded finger roller screens. This means that the first finger roller screen is used mainly for separating and classifying the charging material, while the second one is used for cleaning off any sticky loam on the material.
Müller finger roller screens are made in various lengths, widths, gap widths and designs to suit the particular feed material, level of dirt and installation situation.
In order to flexibly adjust the machine’s sifting to the feed material, we recommend fitting frequency converters to the drives of the finger roller screen.
The finger roller screen has a capacity of up to 350 t/h, and is charged with rock materials measuring up to 250 mm. The materials are separated from 0 – 20 mm to 0 – 40 mm in the machine, and then cleaned. The size is determined by the opening between the round and finger discs, and can be adapted by ± 30% using the frequency converter.
The axles of the finger roller screen are made to suit the feed material from special steel in thicknesses of up to approx. 120 mm. The driving plates are made of wear-resistant special steel in the shape of crooked fingers. The spacers between the washers are also made of steel. The special shape and arrangement of the finger discs prevent blockages of the axles and gaps.
The finger roller screen is driven by three drive shafts that transmit the power to the opposite side, where the individual axles are driven by strong roller chains that run through an oil bath. A central pump provides the chains with the oil. The axles run in spherical roller bearings, and can also have central lubrication.
Depending on the size of the finger roller screen, the drive can be by means of standard electric motors of up to 3 x 15 kW bevel geared motors. The drive units stand on separate consoles that are connected to the steel construction of the finger roller screen.