The main reasons why a melt metering pump cannot run dry are as follows:

‌Increased wear: When a melt metering pump runs dry, its internal gears, bearings, and other components will rub against each other without the lubrication of the medium, leading to increased wear. This wear not only reduces the performance of the pump but may also shorten its service life.

Seal failure: The seals of a melt metering pump are also prone to damage when idling. During idling, the absence of lubrication and cooling from the melt medium causes seals (such as spiral seals or O-rings) to wear out more quickly due to dry friction, leading to reduced sealing performance or even failure.

‌Temperature Increase‌: Idling can cause the internal temperature of the melt pump to rise, which may have adverse effects on the pump's materials and structure. High temperatures may cause material deformation, softening, or aging, thereby affecting the pump's stability and reliability.

‌Increased energy consumption‌: Melt metering pumps continue to consume electrical energy during idle operation, which not only wastes energy but may also increase operational costs.

Therefore, to prevent the aforementioned issues, melt metering pumps should ensure sufficient medium flow through the pump body during operation to provide necessary lubrication and cooling. Additionally, regular inspection and maintenance of melt metering pumps are crucial measures to ensure their stable operation.