Within rubber extruder machine there are two types depending on the type of drive: Direct and Bowden. In the direct extruder, as its name suggests, the filament runs directly from the cog of the extruder to the HotEnd. There are even systems in which these two parts are together, as in the Titan Aero.

Titan Aero extruder

Image 1: Titan Aero extruder. Source: E3D
In the Bowden extruders, on the contrary, the connection with the HotEnd is through a PTFE tube through which the filament passes.

Direct Extruders
Direct Extruder

Image 2: Direct Extruders
Advantages:

Print flexible materials, both PLA Soft or TPU, and TPE (FilaFlex) in 1.75 mm ans 2.85 mm.
Print all kinds of materials without problems, regardless of the abrasion presented by certain filaments. To print 3D abrasive materials, for example graphene, we recommend using the Olsson Ruby Nozzle, a brass nozzle with the ruby tip that has an almost infinite life.
This system needs short retraction lengths to obtain good 3D prints, which reduces the likelihood of a jam. To know more about the retraction consult the article of the following link.
Disadvantages:

Considerable inertia in the axis through which the extruder and the HotEnd moves. This factor is increased when you want to make 3D prints at high speeds by having to move the weight of the whole set (extruder, extruder motor and HotEnd), especially if the 3D printer has several extruders.
Temperature problems in the electric motor of the extruder. In closed 3D printers and with a tempered chamber, temperatures in the extruder motor can be reached that affect the performance of operation.
Bowden extruders
Bowden Extruder

Image 3: Bowden Extruder
Advantages:

Low inertias in the axis of displacement of the HotEnd. In the Bowden system, since the extruder and the extruder motor are anchored to the chassis of the 3D printer, the inertias in the movement to make the impression are greatly reduced. This allows for very fast and high quality printing.
High drag power of the filament. The majority of 3D printers that use this extruder system (BCN Sigmax, 3NTR-A2) have a set of pinions (reducer group) that increases the drag torque of the filament, thus being able to move coils larger than normal.
Disadvantages:

Problems printing with flexible filaments with a diameter of 1.75 mm. This is due to the fact that being a flexible filament it isn't possible to keep the pressure in the filament constant along the Bowden PTFE tube until the HotEnd as it channels the filament. In the 2.85 mm Bowden systems, however, it's possible to print the flexible filaments at low speed.

The rubber vulcanizing machine is also one of our products, welcome to your come and purchase!