The length of the screw is specified exclusively in relation to the screw diameter.
Doing it like that allows to compare different screws much better.
The process-engineering effective length of the screw is specified as L.
This value represents the distance the granules/melt travels along the screw.
For the determination, the length from the front edge of the hopper to the backflow barrier is always used.
The effective length is set in relation to the diameter D of the screw.