Are there any different
melt pump designs used in extrusion?

In principle, all extruder melt pumps have the same design: two externally toothed gear wheels mate with each other when they rotate (see also The working principle of the melt-x gear pump). There are differences when it comes to the gear design itself: helical, spur and herringbone are the most common types. eprotec uses the slightly helical type as this design is suitable for almost all applications and ensures a continuous and smooth process. In addition, the helical gear design features less friction and has best self cleaning characteristics.
There are also special executions of gear pumps for applications where frequent colour changes are required, for example in TPE compounding. Here the melt-X pump has a so-called “drainage system” for specific discharge of melt which was used to lubricate the slide bearings.