Continuous Belt Screen Changer Operation and Production

  • Gabriela Martin , Marketing Coordinator
  • John Whaley , Vice President - Key Filters

June 29, 2023

An extrusion melt filter, otherwise known as a screen changer, is a vital component that ensures the purity of the melt in extrusion manufacturing processes used by the plastics industry. A continuous belt screen changer is one of several approaches that accomplishes this filtration process by removing contaminants from the melted plastic in order to achieve the end production of high-quality plastic products. There are various subtypes of melt filters, which can function in either a discontinuous or continuous production process. While each filter operates in the same general format to perform its functional role of filtering the plastic melt, it is the continuous belt screen changer that optimizes this production process, as there is no manual interference or process disruption required for its operation.

How does a continuous belt screen changer machine operate?

As mentioned previously in our article on the benefits of a continuous belt screen changer, this melt filter is a device that allows for continuous filtration of contaminants in a polymer processing system by enabling a filter screen to be changed while the process is still in operation and under full process conditions. The body of the machine consists of an exterior housing with a moving belt that acts as the filter screen and it continuously introduces clean filter material as the belt moves across the melt flow. The used filter material exits the machine at the same rate with a small amount of contaminated polymer. While a discontinuous screen changer requires operator involvement through the process, a continuous belt system automatically maintains a consistent, uniform extrusion pressure without any outside interruption.

What factors could impact production rates of a continuous belt screen changer?

While screen changers have the same general mode of operation, there are certain factors that can make some machines more efficient than others and therefore impact the overall rate of production. These determinant elements are detailed in the list below:

Machine Size and Configuration- Because melt filter machines come in varying sizes and configurations, they allow for varying processing capacities. Bigger melt filtration machines with multiple screens will typically have higher production rates compared to smaller ones. As continuous belt screen changers function as though they have multiple screens because of the regeneration of the belt filter, they already possess an advantage in this area.

Polymer Type and Viscosity- Different plastics have varying melt viscosities, which will influence the speed that the plastic melt is processed. When a material has a higher viscosity (and is therefore thicker with a greater flow resistance), slower production rates are necessary to ensure effective filtration.

Filtration Efficiency- The desired refinement of filtration can often impact production rates in plastic melt extrusion. Finer screens or more intricate filtration systems will slow down the production rate, but they will also guarantee a higher degree of cleanliness in the finished plastic product.

Maintenance and Cleaning- Regularly scheduled maintenance and screen cleaning can often affect performance rates for screen changers. The downtime for maintenance activities should be considered as a crucial factor in the timeline of production. However, due to the lack of interruption required to maintain a continuous belt screen changer, its production rate should remain relatively unchanged when compared to other melt filters.

The production rate of a continuous belt screen changer will ultimately come down to its individualized specifications and performance abilities. These factors are important considerations when it comes to choosing the machine best suited to the specific operations of your company based on what is most valued in the production process. Regardless of your priorities, an effective screen changer is an essential part of the plastic extrusion process to ensure high standards of final production.

At Key Filters, our engineers and technicians have many years of accumulated knowledge about continuous belt screen changers and the advantages this technology offers to plastic extrusion operations. They understand how to best apply the technology to gain the greatest benefits from this machine while maintaining the highest possible production rate for your specific operating process. We look forward to answering any further questions you may have about the operations of a continuous belt screen changer and how it might benefit your company’s production process. In addition, we have a series of other articles involving screen changers and their specific functions, linked below for your convenience.

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