Plastics extrusion: Gear pump optimized for sensitive materialsPlastics extrusion: Gear pump optimized for sensitive materials
A new series of pumps, branded GPX, are said to help processors avoid the random peaks in melt temperature which may be caused either by the heating control system or by frictional heat. Key to the manufacture of these was to optimize the fluid heating system, leading to minimal frictional heat, and thus prevent an increase in the melt temperature.
February 10, 2011
The manufacturer of the GPX pumps, Kreyenborg, says they are aimed at processors of thermally sensitive products such as thermoplastic elastomers or thermoplastic olefin elastomers (TPEs and TPOs, respectively). In plastics extrusion, gear pumps meter the melt and also the melt pressure. Typically the pumps are electrically heated by means of cartridge heaters or band heaters.
According to Kreyenborg, these relatively simple heating systems work fine for applications where the polymer being processed is not sensitive to slight fluctuations and increases in temperature that 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, states the company, as it claims these offer more even temperature control without local overheating or hotspots in the pump body.
The problem has been solved by a newly developed design for the oil channels in the pump housing. The new designs, says the manufacturer, optimizes control of the melt temperature, especially in areas of the pump housing that are subject to heat generated by frictional energy. The new pumps have proven their mettle already in a pilot installation at a customer's facility and now are ready for broader marketing.
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