Single screw granulation/regeneration line
MiReC™ and MiTeCh™ single screw extruders use one-piece extrusion screws made of chrome steel CrMo with nitriding heat treatment as well as screws with the addition of a wear-resistant and/or corrosion-resistant alloy, depending on the plastic materials handled. The extrusion cylinders, built in two pieces, have different L/D ratios depending on the production process for which they are intended, and can be thermostated by air, using electric fans, or by water/oil using a special thermostating unit. The basic materials for cylinder construction are special chrome steels CrMo, heat-treated for nitriding, or bimetal steels with the addition of a wear-resistant and/or corrosion-resistant alloy up to 3 mm. thick. For the MiTeCh™ line, a special solution adopted on the input openings, water cooled with the possibility of temperature control in the cooling zone, ensure a production increase of 15%-20% more than traditional machinery of the same type.
Granulation, regeneration and compound systems of the single screw type can be supplied either with forced infeed systems for materials having apparent density between 0.05 kg/dmc and 0.35 kg/dmc, or with volumetric and/or gravimetric dosing systems for materials with higher density.
For products of very low apparent density, between 0.010 kg/dmc. and 0.08 kg/dmc such as yarns, foam products, nonwoven fabrics, etc., special compacting infeed systems are used for high productivity, equipped with independent cooling systems.
With regard to the type of thermoplastic treated, different systems can be used for the production of granules: a) with cutting in a water head, by full immersion or with an external distribution ring, b) with cutting in an air head c) with a spaghetti system with cooling tank and cutter with blades in line.
For the regeneration of materials from washing installations, special extruders are used, with L/D ratios up to 54 DD equipped with multiple degassing systems (two or three) for total evacuation of solvents, monomers and above all for the elimination of residual moisture in the material for granulation, quantifiable at around 7% ÷ 8%.
For the regeneration of polyamide-based materials, polyesters or styrenes, the extruders used have an L/D ratio from 41 DD with a single high output degassing system positioned on the side.