MAS
Since its founding in 2006, the Upper Austrian company MAS (Maschinen- und Anlagenbau Schulz GmbH), has been gaining attention through a variety of technical innovations in the area of extrusion and recycling technology.
This includes the co-rotating conical twin-screw extruder, the continuous melt filter system with a rotating disk filter (CDF series), and the dry cleaning system for film flakes. All three product groups are available in the throughput range of 300 to 2,000 kg/h and can be tailored to the specific needs of the individual application. MAS is capable of providing complete systems for plastic recycling, compounding and most importantly, the combination of both the re-compounding.
The conical co-rotating extrusion system from MAS combines the familiar good plasticising and homogenisation of a parallel twin-screw with the specific benefits of the conical twin-screw extruder in one machine. Through the large feed opening specific to the system, the conical design provides a good feed option for materials with low bulk density. Moreover, the MAS extruder scores high marks compared to single-screw extruders, which are normally used for recycling. This is accomplished with superior conveying and homogenisation performance, particularly gentle material handling, and a stable melt pressure. As such, a melt pump not necessary for pressure stabilisation or for pressure build up. The homogenous plastic melt produced because of this performance offers the best conditions for efficient melt filtering and degassing, an essential for the processing of recycled material. The fact that the polymer structure in the MAS extruder is only minimally loaded provides this superior efficiency. The affirmation of this is easily measured by the physical characteristics of the output material. When we study the viscosity, elongation at break, and tensile strength of the polymer, we notice that all characteristics remain at a maximum level.
The high level of the above-mentioned specific properties and efficiency prove that the MAS extruder is an exceptional recycling machine even for the most difficult materials. The MAS extruder excels where others fall short with low bulk density materials, eg. film flakes. Pre-compacting with special equipment is not necessary when using a MAS extruder. A wide variety of additives, such as talcum (magnesium silicate hydrate), calcium carbonate, stabilisers, or even dyes can be simultaneously added along with the film flakes and can be effortlessly drawn into the extruder’s intake due to the large feed opening. As such, bulky side feeders are not necessary with the MAS extruder. Kneading elements integrated in the screws support the homogenisation. The MAS conical screws come in a modular system that can be combined specifically to the application and as such, can be adapted to the respective application in a quick and uncomplicated process. When integrating the MAS extrusion system into a recycling compounding line the extruder is commonly combined with a CDF melt filter system (for continuous filtering with disc filters). The CDF is then attached to a single-screw degassing extruder, which produces a perfectly degassed melt into an adjacent pelletiser. Using this configuration, the MAS extrusion system boasts extremely low energy consumption. As an example, the MAS extrusion line shows energy consumption of only 0.24 kWh/kg when measured in a compounding facility using 60 percent PP film flakes and 40 percent powder additives!
“Continuous Disc Filters” (CDF) were matched to the throughput capacities of the MAS extruders or the customers’ needs and are available in three sizes: 704 cm² (CDF 300), 1,800 cm² (CDF 500), and 3,600 cm² (CDF-500-D). We believe the CDF 500-D to be the largest continuously working melt filter on the market today.
The core component of all CDF filters is a filtration disc, which rotates within the incoming melt flow. It catches contaminates such as paper, wood, aluminium, rubber and non-melting plastic particles. These contaminants are immediately removed from the screen by a stationary scraper and are discharged via a screw conveyor with minimal melt losses. The filter discs are manufactured from hardened steel and available for the separation of particles in the size range between 100 µm – 1,000 µm. The CDF housing has a vertically divided shell design that encases the filter. Both halves are connected by a hinge which allows the housing to be easily opened and the filter to be quickly and easily removed and changed. A potential replacement itself is extremely simple and can be done with a conventional tool in approx. 45-50 minutes.
Since being introduced to the market, the MAS CDF filters have not only proven themselves within MAS extrusion lines, but have also had a large success as an upgrade for existing extrusion plants.
To set MAS apart from the other competitors, the MAS system has added to its line a complete package for rapid product replacement and the associated cleaning of the system components that guide the melt flow. MAS has developed a specific vacuum chamber which has been recently introduced into the delivery programme. The chambers provide pyrolytic cleaning for extrusion tools, filter parts or laser discs. The pyrolysis systems, available in two sizes, are characterised by a very compact construction. The cleaning process runs in a vacuum (approx. 0.5 bar) and at an operating temperature of 350 - 450°C.
