ROTARY BACKFLUSH |
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A ribbon type screenchanger also requires a specific screen which costs double or even triple that of the rotary backflush screens. The savings on screen costs with a rotary backflush system are substantial especially when using a high percentage of regrind or recycled material. Leakage is a problem with most screenchangers. In use they are usually torqued up to prevent leaks and then backed off when a screen change is needed. Rotary backflush screenchangers have a huge sealing surface and leakage is not a common problem. The body blocks and the faces of the disc are superbly machined and polished to mirror like finishes. Using very precise torquing techniques, manufacturers squeeze the disc to unbelievable values. |
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In addition, both the manual breaker plate and slide-plate systems use circular screens which can only utilize about 65% of the surface area for filtration. These screens will typically clog up in the middle and by that time the back pressure has increased to a point that a change is required. The rotary backflush, on the other hand, can utilize about 95% of the screen area since the screen changes only on demand and in small increments. The filtration area in the melt flow channel is constant at all times. Follow the graph above and you will see exactly what is happening to your melt when using a slide-plate. |
When the pressure readings approach or exceed setpoint, the controller signals the pneumatic drive system to initiate a stroke. The stroke is converted into rotary backflush motion via a one way clutch and linkage |
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