In the field of industrial fluid transportation, the terms melt pump and metering pump are often mentioned, but they are not equivalent concepts and have a distinct hierarchical and overlapping relationship.
A melt pump is a specialized machine that serves high-temperature, high-viscosity polymer processes. It is a volumetric gear pump designed specifically for processing high-molecular materials such as plastics, chemical fibers, and rubber. Its core task is to transport polymer melts with temperatures reaching several hundred degrees and extremely high viscosity. In practical applications, melt pumps are often assigned the function of precise metering, which is why they are commonly referred to in the industry as 'melt metering pumps.' They can achieve linear and precise flow control through precisely meshed gears, ensuring stable and uniform discharge. In addition, they have significant pressure-boosting and pressure-stabilizing functions, effectively isolating upstream equipment (such as extruders) from pressure fluctuations and providing a stable, constant melt flow to downstream molds, thereby improving product accuracy.
A metering pump is a general term for a type of pump. It broadly refers to all pumping devices capable of precise flow control, and its application extends far beyond polymer processing. Common types of metering pumps include plunger metering pumps, diaphragm metering pumps, and hydraulic metering pumps. These pumps are typically used to transport water, oil, chemical agents, additives, and other normal temperature or low-viscosity media, widely covering industries such as petroleum, chemical, water treatment, and pharmaceuticals. Their core commonality lies in having high-precision flow adjustment capability, but their working principles, applicable media, and operating conditions vary greatly.
Conclusion: The melt pump is a 'special forces' member of the metering pump family. It inherits the precise delivery characteristics of metering pumps, while also enhancing resistance to high temperature, high pressure, and suitability for high viscosity according to the specific requirements of melt processes, and incorporates pressure boosting and regulation functions. It can be said that the melt pump is a metering pump specifically designed for high-temperature melt processes, representing a deeply specialized extension of general metering pump technology in a niche field. Understanding this relationship helps to more accurately match process requirements when selecting equipment.