The new CFO (Continous Filter Operation) system makes possible uninterrupted extrusion, even when processing highly contaminated materials. Unlike conventional screen changers, which require extensive and constant operator attention, the CFO – which stands for Continuous Filter Operation – can operate automatically. As extruded material enters the unit, it passes through a stainless-steel screen plate that is micro drilled and hard faced, while contaminants are caught on the screen-plate surface. When waste builds up and back pressure reaches a present level, a rotating blade sweeps the screen and removes the contamination through a discharge port. The CFO handles a broad range of materials including PE, PP, PS, PC, and ABS, and can operate at temperatures up to 315 °C and pressures up to 240 bar. The filter can handle up to 10% paper and other foreign objects up to 18 mm in diameter. Contaminants such as metal, wood, paper, textile fibres, unmelted plastic granules, and low percentages of aluminium, lead, copper, rocks and other impurities readily tolerated.
Most frequent application: extruder continous filter.
HOW DOES THE MELT FILTER WORK
The melted material crosses permanently the filtering screens, as they are supported on a perforated back-plate.
A rotating scraper can move brushing the screen with blades. The scraper rotation of regulated according to the material to be filtered. It can work on ‘pulse mode’ or ‘continuous mode’. Melt pressure sensors and time are use in priority to start moving the scraper.
The contamination can not pass through the screen, it is therefor collected by the scraper to our inside purging valve (centre of the screen). The opening of purging valve (pneumatic actuator) discharges the contamination outside the process.
Operating mode / temperature sets / pressures sets / purging time / scraping speed are automatically managed by our Siemens PLC system. All parameters are adjustable, and they are optimized on the process.
CFO main characteristics:
- Self-contained and mobile
- PLC control with touch screen
- Continuous or intermediate wiping
- Pressure control system that activates cleaning action
- Filter impurities down to as low as 180 microns with typical filtration at 250 microns
- Process proven to reclaim such materials as PP, PE, PS, ABS (polymer filter) and molten synthetic resins
- Equipped with Micro-plate filters that are available in different materials and hole diameters to optimize filtration. Micro-plate treated to 70 HRC
- Screen life of 1,500 to 3,000 wipes. Typical life is 1 week of use.
- Extra heavy-duty drive system (oversized)
- Complete set of over bolts – no gaps like others. So no leakage.
- Designed for a simple change of filters screens and scraper blades
- Capable of removing up to 10% waste
SCREEN CHANGE PROCEDURE
Designing our CFO continuous filter, we put great attention on making fast and safe the changing of the filtering screens.
- Stop polymer melt flow
- Open filter front round door by pneumatic screwdriver (access to filtering chamber)
- Disconnect the scraper
- Changer the screen (a new one in place)
- Clean the scraper, place it back
- Close the front door
- Start melt flow
- Unimpeded flow through large passages
- Tolerates up to 10% of paper/ labels or cardboard
- Can handle contaminants up to 18 mm in diameter
- Minimal discharge of good material with contaminants
- Filter screen duration highly improved (special treatment available)
- Filter screen change extra rapid: 30-40 min clock time
- Attractive price due to scale economy
Low operating costs
- Screens and blades are stocked in Europe
- Europe -supplied electrical parts
- Wear parts readily available and easily replaced
CFO 635, diameter 635 mm
CFO 500, diameter 500 mm