02/01/2011

www.plasticker.de

Kreyenborg: New series of pumps for thermally sensitive polymers

Current technology offers different types of gear pumps, (e.g. the pump body of steel plate construction or forged steel construction) which are used in extrusion lines for metering the melt and also to increase the melt pressure. Generally speaking, the pumps are electrically heated by means of cartridge heaters or band heaters. These relatively simple heating systems may be used in applications where the polymer being processed is not sensitive to slight fluctuations and increases in temperature which may result from overshooting of the heating system or from frictional heat.

In contrast, for applications where the polymer being processed is temperature sensitive, gear pumps with fluid heating systems are preferable. These are characterized by a more even temperature control without local overheating or hotspots in the pump body. Due to Kreyenborg the fluid heated pumps which are readily available on the market, can offer only marginal control of increases in temperature which are caused by frictional heat.

For very sensitive applications, Kreyenborg has therefore developed a new series of pumps, the type GPX. These pumps avoid the random peaks in the melt temperature which may be caused either by the heating control system or by frictional heat. The problem has been solved by a newly developed design of the oil channels in the pump housing, which enable optimal control of the melt temperature. This is especially true in areas of the pump housing which are subject to heat generated by frictional energy.