Extrusion systems must be equipped with the right filtering equipment such as a screen changer to produce high-quality products. The screen changer removes the impurities that come with the raw material and disrupts any coagulates formed during extrusion. Besides this, its usage prevents damage to downstream equipment. Furthermore, an efficient extrusion process can be achieved by using a continuous screen changer since it does not require frequent change of filter which is time-consuming and costly.
Cofit provides the best filtering solutions to extrusion systems since 1968. AP screen changer is one of the products we designed to help you improve your plastic extrusion process. It is a manual, continuous, self-cleaning screen changer suitable for low-contaminated materials such as polymers for the production of cast films and blown films, filaments and more.
AP screen changer has two parallel filtering cartridges that are cleaned one at a time without being removed from the equipment. The flow of melt through the second filter continues while the other filter is being cleaned. With the uninterrupted extrusion process, a highly stable run is achieved. Therefore, a top-quality extrudate is produced. Also, the self-cleaning feature of AP screen changers extends the service life of screens, thus reducing maintenance activities such as filter replacement to a minimum.
Among the available continuous screen changers in the market, the AP screen changer is considered the best option since it is solid, reliable, and durable. It is also cheap and does not require expensive parts such as hydraulic units and control panels to operate. Apart from that, it is made of steel with nickel plating that serves as superior protection against wear and tear, thus ensuring its long-lasting service.
AP Screen Changers vs. Conventional Screen Changers
Conventionally used screen changers for low-contaminated materials are manual and hydraulic slide plate screen changers. Despite their low cost and low-pressure drop design, they are not the best choice for your filtering system because of the reasons discussed below.
Manual Slide Plate Screen Changers
Manual slide plate screen changers, which are also known as discontinuous screen changers, require stopping the extrusion process when screens need to be cleaned or replaced. When the screen is already clogged after several runs, the operator will slide the plate out to either scrape the accumulated impurities on the screen or change the screen with a new one. The production can only resume after the plate is safely returned to its closed position.
On the other hand, with continuous screen changers like Cofit’s AP, the filtering materials can be cleaned without interrupting production. The self-cleaning feature removes contaminants by itself regularly to maintain optimal filtering conditions. On top of that, periodic screen changes can be done with ongoing production.
Hydraulic Slide Plate Screen Changers
Unlike discontinuous screen changers, hydraulic slide plate screen changers can be operated without stopping the extrusion process. The hydraulic cylinder used in this setup facilitates clogged screen replacement. However, during the change-out, an off-specification melt could be produced since contaminants may pass through because of temporary stops and air entrainment. Furthermore, manual work is still needed to clean or replace the soiled screens while production continues.
Contrarily, AP screen changers maintain a high-quality melt because heavy build-up dirt on the screen that may affect filtering performance is prevented by the self-cleaning action. Moreover, occasional screen replacement does not negatively affect product quality.
As the demand for plastics increases due to a wide variety of applications, extrusion processes must be kept running without or at least minimal interruption. AP screen changers are the best option to achieve optimized and efficient plastic extrusion processes. The use of AP screen changers gives you significant savings in time and money.
Downtimes because of maintenance activities are reduced to a minimum since regular screen changing is not required unlike in conventional screen changers. Furthermore, higher profits can be attained since there would be an increase in the quantity of quality extrudate due to uninterrupted operations. Finally, labor cost is also reduced since periodic screen changing, rather than frequent, is possible.