I'm afraid with so little context to go on, it's almost impossible to tell exactly what this is, because 'axe' can have so many different meanings.

It might be 'axis', as in Thomas's robot reference.

It might be a 'shaft' — something that rotates

It might be a 'centre-line' — something that defines the alignment of somthing

It might be a 'pin' — something that something else articulates around.

The latter would seem unlikely in terms of product dosing, though of course it might only be one smal part of a more complex assembly.

Then again, it may well require a specific term in the field involved.

It might help to know how the term is being used in context, as this may give a clue to the type of 'thing' it would have to be; or, if it is just a list item, to have some of the other surrounding items on that list, so we can see at what sort of detail level it is talking, and perhaps work out by elimination what kind of part it might be. Of course an illustration would also no doubt be immensely helpful!