The roller compaction processes of the 21st century look to produce consistently high quality product while reaching financial targets related to manufacturing costs.  Modern roller compaction machines commonly use a screw feeding system to deliver raw material to the rollers. To support our customers with the best possible technology, Alexanderwerk has worked to optimize the powder feeding system by developing the patented Combi-Vent-Feeder®.


The unique design of the Combi-Vent-Feeder® allows the air which is displaced during the compaction process to escape through a second chamber of the feed hopper without disruption of the flow. This design leads to a uniform feed of raw material into the slip and nip regions and then to the rollers. In addition, this second chamber can be used as an entry point to recycle undersize and oversize material from the process.  By homogeneously adding to the raw material feed, the process efficiency is maximized and the production of off spec material is minimized or eliminated altogether. In addition, the feeding unit can be assisted by applying a vacuum through a sintered metal bushing, which creates a minimal product layer on the inside of the screw housing. This design feature greatly improves the processing of fluidized products with low bulk density.  All of these process improvements work together to maximize the process efficiency and reduce cost.

Overall, this provides the following advantages:


  • direct, positive influence on the compaction results
  • defined, reduced resistance to venting of the entrained air released from the powder during compression through the screw housing and exhausted through the “open” smaller chamber
  • consistent quality of flakes and granules produced
  • gentle processing in both  compaction and granulation units often resulting in less “fines”
  • protection of the sealing between screw shaft and housing
  • enables simple control of raw material feed