Operations

The sifter is a central tenet of our Sieving Equipment range. Easy to use, quiet in operation and very competitively priced the Powder Sifter is widely used in many chemical, pharmaceutical and food industries.

Material to be screened is fed to the center of the top screen. Oversize particles are moved by the multiplane motion to the screen periphery where they are discharged. Undersize particles or liquid passes rapidly through the screen. The screen separators are equipped to handle up to five superimposed screens and, in the case of multiple frame units, each screen is equipped with a feed tray to redirect the undersize to the center of the screen beneath. This greatly increases screen efficiency by forcing material to pass over a maximum amount of screen surface.

The three dimensional inertial/vibrational motions of the sieve screen was originally discovered and developed by G.H. Meinzer. It is based on a principle in which the motor imparts vibration to an entire screen assembly in both vertical and horizontal planes.

The system allows multiple deck construction, which reducees operating space, & makes maximum use of available screen surface. In addition, there is no flexing of the wires in the screen cloth, thereby maximising screen life.

The top eccentric weight of the double extension shaft operates in a plane which is close to the centre of the mass of the assembly. This generates a horizontal motion through to the screen assembly. The bottom eccentric weight rotates below the centre of mass, which creates a high frequency tilt on the screen.

The third component is a tangential motion produced by the combination of horizontal and vertical movements. The tangential component moves oversize material laterally across the screen whilst encouraging undersize particles to flow through the screen.

Both top and bottom eccentric weights of the sifter are independently variable for mass and angular relationship, giving a great degree of control over all vibration motions. This results in the ability to achieve optimum conditions for screening nearly all materials.

If the mass of the top eccentric weight is increased, the horizontal motion of the screen will also increase, causing oversize material to discharge at a faster rate. This is especially useful for applications such as dewatering in which the quality of solids is extremely high.

Bottom Eccentric Mass

Increasing the bottom eccentric weight increases the vertical motion. This promotes turnover of material at the screen surface, encouraging the maximum quantity of undersize material to flow through the screen. The vertical motion also inhibits binding of the screen by 'near-size' particles. When processing light or fragile solids, it is sometimes desirable to reduce the weight of the bottom eccentric to provide a maximum vertical motion whilst avoiding particle breakage and attrition.

Bottom Eccentric Lead

The tangential component of the motion imparted to material on the screen is controlled by the relative angular position of the top and bottom eccentric motor weights. The screening pattern is controlled, therefore, by altering the relative angle of the bottom eccentric to the top eccentric.

When the two eccentrics are lined up and in phase, the tangential component is at a minimum, and there will be virtually no tendency for the material to spiral; it will simply discharge radially from the center to the periphery. When the bottom eccentric is positioned to lead the top eccentric, a spiral motion is imparted to solids on the screen under some conditions, it is possible to prevent discharge of oversize particles from the screen surface.

Adjustments of any or all of these three components in the Screen Separators can be made in a few minutes by the operator. This complete control allows the Separators to be adjusted to give maximum screening efficiency.

 
 
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