Compact printed matter

Ceramic insulators for high-voltage applications must be able to withstand enormous loads. No irregularities of any kind may occur within the material. Air pockets, for example, can completely destroy the insulator under mechanical or thermal stress. If the components are manufactured using an extruder due to their complex cross-sections, the material must therefore be optimally mixed, kneaded and deaerated - with the highest possible throughput at the machine and a constant extrusion speed. ECT-Kema specializes in mastering this multitude of parameters depending on the composition of the raw material.

The special machine manufacturer based near Görlitz primarily produces screw extruders that enable the material to be fed continuously. The challenge with this type of extrusion is to ensure the homogeneity of the material throughout and to avoid undesirable stresses in the finished workpiece. In addition to the latest findings from materials research, technical innovations are also incorporated into the design of the special machines. For example, ECT-Kema controls the extrusion process with comprehensive sensor technology, because the requirements for the machines are just as specific as their areas of application.

Compact planetary gearboxes

The company has also optimized the process with the new P2.e series planetary gear units from SEW-Eurodrive. "With their help, we can achieve much better filling level control in the process," explains Dipl.-Ing. Torsten Seidel, Managing Director of ECT-Kema. "Thanks to the space-saving P2.e gearboxes, we can now also position separate drives for the clearing rollers in addition to the auger drive." The integration of the P2.e planetary gearboxes into ECT-Kema's extruders represents a significant step forward for the company. "The technical features of the P2.e gearboxes contribute significantly to the performance and reliability of the extruders," says Seidel.

The change from the previously installed drive to a three-stage planetary gearbox reduces the overall mass, overall length and overall height - while maintaining the same high throughput, as Torsten Seidel confirms: "There is a minimum installation space between the scraper rollers and the transport auger. Previously, the scrapers were therefore driven via a transfer gearbox." However, this meant that the speed of the scraper was dependent on the auger speed - a limitation that has been eliminated thanks to the P2.e gearbox. "We can also reduce the speed of the augers to below 2 Hz," adds Seidel. This enables smaller diameters at the end of the press channel without overloading the machine. In addition to the high power density, the P2.e gearboxes also meet all performance and robustness requirements: in ceramic extruders, typical torque ranges are between 1,000 and 200,000 Nm in order to achieve pressures of up to 200 bar. Forces that are absorbed by the fatigue-resistant gearing and the robust direct bearing of the planetary gearboxes. This contributes significantly to the high operational reliability of the P2.e series - another plus not only in extruder technology, where great efforts must be made to minimize wear.

Direct drive and integrated cooling

The gearboxes installed at ECT-Kema are driven by motors from the DRN series. These are connected directly to the planetary gearbox via a pinion shaft. The direct motor mounting eliminates the need for the usual adapter flange, which means that the drive unit is also very compact in length. The gearboxes also impress with their high thermal limit performance. A fan integrated into the motor interface draws in the ambient air radially, accelerates it and generates a cooling air flow. As a result, the gearboxes can be operated reliably within the intended temperature range even under high loads - without the need for complex external cooling systems.

"The ceramic material is very abrasive," explains Torsten Seidel. This abrasion requires protective measures, such as lining machine parts with resistant coatings or even carbide. Decisions on this are always made in close cooperation with the customer, says the Managing Director. The aim is to define the properties of the entire system in such a way that even maintenance cycles are achieved - usually just under a year. The low-maintenance and robust planetary gear units and the high availability of parts from SEW-Eurodrive support this objective. In the field of drive technology, the specialist from Bruchsal has been a preferred partner of ECT-Kema for many years. "When it comes to the design of the drive, the performance and the speed range of the extruder, SEW is usually on board at a very early stage. For us, this close cooperation is important from day one," emphasizes Torsten Seidel. You also need a partner who is active in the same foreign markets.

Complex technology including controls

Optimized kneading can significantly reduce the pressing pressure during extrusion. This is important in view of the increasingly delicate profiles, the limited load capacity of the extrusion dies and the required output. The extrusion speed is usually around 3 meters per minute. The customer uses it to clock through his entire system - cutter, oven, microwave dryer through to packaging. "Initially, we limited our business activities to extruders. However, each successful design formed the blueprint for the next customer-specific solution with additional options and the necessary regional adaptations. Today, we also supply the cooling technology, a powerful control system that integrates upstream and downstream devices, such as cutters, bypass technology, mixers and shredding technology. It's getting more and more complex," explains Torsten Seidel.

ECT-Kema now manufactures systems with pipes, cables, bypass, feeding system, measuring and weighing equipment. The entire system is assembled and its control system programmed at the company site. This saves the customer a lot of time during commissioning. "As a result, we are usually ready within a week," reports Torsten Seidel. "The customer just has to provide their ceramic mass and then we can get started!"

Christian Rüttling, Market Manager Industrial Gear Units at SEW-Eurodrive