When manufacturing insulation panels, packaging foils or molded parts, blowing agents must be metered into the plastic melt under high pressure and extreme temperatures in order to achieve a high-quality result. The Ecofoam system from Lewa GmbH is a new complete solution including pump, measuring and control technology that stands out thanks to its precision and minimized downtimes. It pumps the blowing agents in quantities proportional to the speed of the extruder, thereby guaranteeing precise metering, even when pressures are fluctuating. Both the hydraulically actuated Lewa ecosmart diaphragm pump and heatable systems for additive metering will be displayed at this year's K Trade Fair in Düsseldorf.
Using the Lewa Ecofoam, you can add precise quantities of blowing agents such as CO2, propane, butane, halogenated hydrocarbon and pentane to the plastic melt in an extrusion process. The design of the metering system is optimized to account for the fact that the quality of the end product depends first and foremost on the constant expansion of the blowing agents. Consisting of an Ecoflow metering pump, a suction-side strainer and two contact pressure gauges for pressure monitoring in the pipeline, the system is suitable for a pressure of 50 to 500 bar, allowing between 0.5 kg/h and 250 kg/h to be pumped.
High operating reliability, minimized downtimes
The speed of the extruder is selected as a reference value. This means that the metering pump conveys the blowing agents in a quantity proportional to the speed. The Smart Control system continuously compares the signal of the flow meter with the request signal and adapts the flow rate accordingly. To do so, the speed of the drive motor is regulated to correspond to the process requirements. As a special feature, the controller memorizes the characteristic curve of the pump. This ensures the system can be balanced significantly more quickly than when a conventional PID controller is used. The pressure stiff characteristic curve of the pump guarantees precise metering, even when the extruder pressures are fluctuating. A safety valve is also attached to protect the system from overpressure. Thanks to this robust, hermetically tight pump technology, the Ecofoam system achieves high levels of operating reliability. This results in minimized downtimes, requiring maintenance only once per year, as well as high levels of productivity.
Diaphragm metering pump with unique suction capacity
One of the most frequently used Lewa pumps in the plastics industry is the ecosmart diaphragm metering pump, which will also be on display at the trade fair. With an absolute suction pressure of up to 0.1 bar, the pump provides a wide array of safe installation options. The pump is able to achieve very high levels of metering accuracy regardless of the fluid being used as a result of adjusting the motor speed and because of the manual stroke adjustment option. The hydraulically actuated PTFE sandwich diaphragm is monitored by the DPS (diaphragm protection system) during continuous operation. With discharge pressures of up to 80 bar, ecosmart is suitable for additive metering, e.g. of flame retardants, lubricants or plasticizers and can be used as a single pump to convey flow rates up to a maximum of 300 l/h.
Heated systems for metering additives into plastic extruders
For liquids that naturally display a wax-like consistency, Lewa has also developed heatable systems that are designed for a temperature range of up to 130 °C and a pressure of up to 500 bar. These metering systems are ready for operation and suitable for a large variety of additives, including flame retardants, lubricants and static inhibitors as well as plasticizers. The system usually consists of single or multiple metering pumps as well as a filter, safety valve, pulsation damper and flow meter. The flow rates range from 0.1 and 200 kg/h whereby the fully automatic control ensures safe and flexible metering.
The systems are being presented at the K Trade Fair at the joint booth for the Specialist Association Foamed Plastics and Polyurethanes (FSK) in hall 7a at booth B35-4. Employees from Lewa GmbH will be there to answer questions and participate in discussions.
K Trade fair, October, 19 to 26, 2016
Contact Person: Roland Schwab, Product Manager