Continuous development of the technology
The levels of performance and flexibility currently achieved by the ZSK twin screw extruder are the result of intensive, continuous development work by the engineers at Werner & Pfleiderer – as it was back then – and Coperion today. These developments include the following examples:
- The transition to a process section with modular barrel sections and screw elements facilitates the versatility needed to fulfill a wide range of processing tasks while remaining cost-effective.
- The type of connection between the screw shaft and the screw elements is vital in determining the maximum transferable torque. Over the years, development has progressed from the simple taper and keyway to the spline shaft, and then to an involute toothing optimized with the aid of the FEM and produced in a special cold hammering process for increased robustness. This type of connection is capable of transmitting extremely high torque.
- Improved materials and production methods have made it possible to gradually increase the screws’ ratio of outer diameter Da to inside diameter Di from an original value of 1.22 to a current value of 1.55 (on the ZSK Mc18 and the ZSK MEGAcompounder) and 1.80 (on the ZSK Mv PLUS), which has led to a significant increase in the free volume in the process section.
- Numerous developments with the aim of pushing back the boundaries of process feasibility enabled the torque available today to be used to the fullest. These include the new Feed Enhancement Technology (FET) for considerably improved feeding of fillers with a low bulk density and the ZS-EG side devolatilization unit for more efficient and reliable devolatilization.
- Today, various materials and coatings are available for areas of the screws and barrels which come into contact with products to ensure both a prolonged service life and a high purity of product.
A bright future
There is no end in sight for the ZSK success story. Our developers already have their sights set on the machines of tomorrow – with an even wider spectrum of applications for new tasks in a vast range of industrial sectors. Energy efficiency, the conservation of resources and the integration of ZSK high-performance extruders into companies’ digital environments are the current hot topics that are shaping the future of the ZSK. Frank Lechner, Head of Process Technology at Coperion, states: “Current examples of our innovative strength are the changeover from batch processes to continuous processes, which are increasingly in demand by customers in the chemical and pharmaceutical industries in particular. We have already been able to achieve impressive results with our ZSK extruders when producing products such as sealants or cleaning agents. In many processes, we are also able to increase the throughput rates and the product quality many times over with our latest development, the recently introduced involute screw elements, thus contributing to more efficient use of the systems and resources. We are also equipped for the future requirements of the ‘Circular Economy’ as far as both extruder technology and our decades of processing know-how are concerned.”