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Are you a candidate for a continuous screen changer?

Modified on Saturday, 31 January 2015 11:24 PM by mpieler Categorized as Consultants Corner
Are you a candidate for a continuous screen changer?
Vol. 26 #1, March 1999

In today’s market, there are a myriad of choices in screen changers for the extruder. However, all of these units can be broken down into at least two distinct categories, continuous and discontinuous. A continuous screen changer may be defined as such because its design allows for the screens to be changed without interrupting the extrusion process. By the same token, a discontinuous screen changer is defined as such because it requires an interruption of the extrusion process in order to make a screen change. Following are two basic considerations to help determine which type of unit is best suited for your application.

- Screen change frequency vs. normal line shutdown frequency.

Simply stated, if it is necessary to change screens more frequently than it is convenient to shut the line down, you may be a candidate for a continuous screen changer. You should determine if your process will benefit from using finer screens.

- Material loss and down time during the screen change process and restarting of the line.

If the loss of material and production time exceeds the calculated cost of the purchase price and installation cost of a continuous screen changer, based on the normal pay-back period for capital equipment designated by your company, you may need a continuous screen changer. A general rule for pay-back is one year or less. Be aware, however, that the price of continuous screen changers has dropped in the last few years. A good continuous screen changer for a 4-1/ 2" extruder can now be purchased for around $25,000.

By reviewing the above, it will be easy to determine whether you are a candidate for this type of unit. If the answer is yes, you must then begin to evaluate specific designs to determine which one is best for your application. Good luck!

- Dan Smith LCI Corp.

See also:
  • Polymer filtration
  • Polymer filtration II
  • Screw tip to screen changer

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