Two types of cleaning in one machine. The automatic filter is designed to adapt to the most varied filtration requirements and to the impurities present in the plastic material. This approach lead to the creation of two different filtration systems:
The scraping process uses a thick steel breaker coupled with a second breaker that has the goal of improving the passage and increase the flow of plastic material, especially for the finest filtrations setting and a interchangeable laser drilled filter for filtration from 100 to 2000 microns.
A two-blade impeller acts on the sheet metal filter suitably spaced from the filter itself so as not to damage it during scraping cleaning.
The impeller blades holder is hollow to collect impurities and is connected to a discharge valve for the expulsion of contaminated material. It is also possible to adjust the rotation speed of the impeller and the opening time of the discharge valve in order to optimize the filtration process.
The scraper cleaning system can be set in two modes:
Scraping in “pressure mode” is regulated by a sensor that detects the pressure of the material inside the filtration chamber. During the filtration process the pressure tends to increase due to the increase of impurities that accumulate on the filtering section. Once the pre-set pressure level is reached, the filter cleaning is automatically activated by removing the impurities through the discharge valve.
Scraping in “continuous mode” involves a constant rotation of the impeller and therefore a continuous cleaning of the filter. This operation mode is indicated when the plastic material contains high level of impurities. The discharge is set at time intervals regulated by a timer bypassed in case a preset internal warning pressure is reached. With scraping cleaning, the waste rates are very low and are close to 1% of the hourly production.
The backflow process is suitable for slightly contaminated materials or for a possible second filtration and is suitable for filtrations from 80 to 300 microns. The BREAK automatic screen changer elements can be easily replaced to switch from Scraping to Back-flushing mode.
In this case, a wire mesh is used instead of micro-perforated steel plates, an additional protection breaker and a cleaner connected to the discharge valve that replaces the blade-holder impeller.
The backflow system uses the pressure generated by the extruder to filter out the impurities. When the pre-set pressure value is reached, the cleaner starts to turn automatically and at the same time the discharge valve opens to eliminate the impurities that clog the wire mesh. The biggest advantage of the backflow system with the same filtration as the scraping system is that it significantly reduces the cost of spare parts, i.e. it completely eliminates the cost of the impeller blades and reduces the cost of the filters.
In fact, with the same uses and filtration, the wire mesh filter costs ten times less than the laser-drilled steel plates (filter).
With back-flush cleaning, the percentage of waste can reach a maximum of 5% of the hourly production.
All the adjustments and operating parameters of the machine can be customized according to the customer's needs and this allows a great versatility of use and to optimize the production process in the best way.
Whatever the cleaning method used, the BREAK automatic self-cleaning screen changer guarantees high purity of the treated plastic material and this is why it is suitable for recycling plastic contaminated by any material such as scrap metal, aluminum, wood and derivatives, rubber, glass, cellulose, etc.
Switching from scraping to backflow cleaning
The average time to change from one cleaning system to another is about 15-20 minutes. This is because it is possible to access the heart of the machine simply by unscrewing with a power tool the nuts that secure the cover to the filtration chamber and then replace the 3 accessories and switch to the other cleaning system, saving machine downtime and therefore hourly production.