Many homogenizer manufacturers use a high-pressure pump that is built into a cumbersome casing with motor and belted connection. Attached to the outside of this clunky shell is a spring-loaded variable mixing valve that functions like a relief valve, generating back -pressure. This spring-loaded valve mixing concept allows for some variability as the spring continuously opens and closes, albeit unnoticeable to the naked eye. This variability leads to variable results which then requires higher and higher pressures to make emulsions.
Other homogenizer designs tend to be of the rotor-stator high shear type that rely on mechanical shear to homogenize and given the fact that you can only turn something so fast, there are limits to its effectiveness. These types are also difficult to scale up because you quickly see that RPM and horsepower start to become your enemy as the amount of material you need to process increases.