News | September 18, 2017

High-Accuracy Feeding Innovations And New Involute Screw Elements For ZSK Twin Screw Extruders

On their booth A6-6406 in hall 6 at this year’s Fakuma exhibition (October 17-21, 2017) Coperion and Coperion K-Tron present first-class plastics processing solutions. One highlight on the booth is a modular Loss-in-Weight Feeder for Liquids. The new modular design of the Loss-in-Weight Liquid Feeder allows for the combination of a broad range of pumps and tanks to constitute a reliable liquid feeding system representing the ideal configuration for the specific application. Also on display is a Twin Screw Powder Feeder with ActiFlow Technology and Electronic Pressure Compensation System which is ideal for accurate feeding of free flowing powders as well as other difficult, poorly flowing bulk materials. Furthermore, this year Coperion is celebrating the 60th birthday of its ZSK extruder series. Today’s ZSK extruders are high-performance processing machines for a variety of applications in the plastics and other industries. The latest in a long line of ZSK innovation highlights is the development of the new, patented involute screw elements.

New ZSK screw elements for significantly higher throughput

To significantly increase throughput rates of its first-class ZSK extruder series, Coperion has developed special involute screw and kneading elements with a new and patented cross section design. These screw elements are ideal for highly-filled recipes (70-85% CaCO3, TiO2, mainly based on PP/PE and 20-50% talc for automotive grades) for which the dispersion rating and the incorporation of the filler represents a limitation. Besides higher throughput rates, these involute screw elements ensure higher loading of filler, better dispersion and homogenization, lower energy consumption (SEI in kWh/kg) and a significant increase in profitability.

Comprehensive tests at Coperion’s test lab in Stuttgart, Germany, showed a remarkable throughput increase depending on the recipe. For example, when processing PP and 70% CaCO3 on a twin screw extruder ZSK 58 Mc18 the new screw elements achieved a significant throughput increase from 550 kg/h to 900 kg/h. Similar results have been reached when processing PE with 80% CaCO3 on a ZSK 92 Mc18. In this case throughput was increased from 2200 kg/h to 3000 kg/h.

Loss-in-Weight Feeder for Liquids in new modular design

When feeding liquids, the special requirements of each application vary widely. Thanks to the new modular design of the Coperion K-Tron Loss-in-Weight Liquid Feeders, various pumps and tanks can easily be integrated to constitute a reliable liquid feeding system for the specific application. Although each liquid feeder is custom designed to meet the desired feed rate, the process demands, and the characteristics of the liquid, the new modular concept streamlines the layout and engineering process of a feeder, thus reducing its lead time and initial cost. The new modularity also provides benefits in terms of a uniform mechanical construction as well as identical operation and maintenance for multiple differently sized units. This simplifies feeder operation, maintenance and spares inventory which in turn saves effort and cost. The same applies for retrofits. Some of the key features are: gear, membrane or other pump (depending on the liquid), highly accurate SFT weighing technology, liquid tanks starting from 7.5 liters, optional heating to maintain the process temperature and ATEX configurations.

High-Accuracy T35 Twin Screw Loss-in-Weight Feeder with ActiFlow Technology and Electronic Pressure Compensation

The T35 Twin Screw Loss-in-Weight Feeder is ideal for the accurate feeding of free flowing to flooding powders as well as other difficult, poorly flowing bulk materials. The interlocking, co-rotating twin screws form pockets in which the material is transported to the feeder discharge in a controlled manner. With flooding bulk material the intermeshing screw flights act as a valve to control material flow. The self-wiping effect of the twin screw prevents material buildup on screws or discharge.

Coperion K-Tron’s feeder on display comes with the ActiFlow technology that proactively and reliably prevents bridging and ratholing of poorly flowing bulk solids in feeder hoppers. The clever flow aid device applies gentle vibrations to the hopper wall, hereby carefully activating the contained material with the optimal amplitude and frequency. Owing to its tight integration with the feeder control it acts preventatively and only when required and thus does not additionally compact the bulk material. ATEX versions are available. Furthermore, ActiFlow can be retrofitted on existing loss-in-weight feeders.

Also part of the display is the unique Electronic Pressure Compensation (EPC) system for high-accuracy loss-in-weight feeders, which ensures accurate and steady pressure compensation in feeder hoppers and outlets. The main advantages of this innovative system include improved accuracy and reliability as well as lower initial cost and easier installation compared to traditional mechanical pressure compensation systems. The clever but simple electronic solution features a modular design and incorporates pressure sensors and electronics tailored to interact smoothly with Coperion K-Tron’s KCM feeder control system. Retrofitting options for existing feeders are available.

KCM Controller now with Integrated Variable Frequency Drive for AC Motors

The smart KCM feeder controller is now available with a variable frequency drive – ideal for use with AC vector motors. For situations in which Coperion K-Tron feeders run with AC motors, the new KCM with integrated VFD allows the use of AC vector motors with significantly higher turndown ranges than conventional AC motors. It sports closed loop control, providing better feed rate control and also diagnostics, direct motor status, alarm, and fault information. Accurate torque information can help predict and prevent feeder problems, stalls or motor overloads. The motor direction can be reversed without the need for external hardware. The KCM with integrated VFD comes with CE and UL conformity certification.

SOURCE: Coperion GmbH