Berstorff sells continuous compounder to tyre maker

By David Shaw, ERJ staff

Düsseldorf, Germany - The Berstorff division of Krauss-Maffei has sold a production-scale continuous compounding machine to a tyre company for the production of butyl rubber-based compounds. The twin-screw unit has a capacity of around 900 kg/hour. According to Dipl.-Ing Harald Hepke, the unit is making a compounds, for use in tyre curing bladders. However, he said that now the unit is in place, there is plenty of scope for the customer to run trials in other application areas.

Hepke declined to name the customer, but said the project is a co-development between the customer and Krauss Maffei Berstorff. The main twin screw extruder is now delivered and is installed, leaving just a feeding unit available to be shown at the K show. This unit is a 150 mm rubber extruder with gearpump for accurate dosing.

Hepke said the machine is just performing mixing; there is no chemical reaction in the unit. There are five feed ares: the first is for certain dry ingredients, followed immediately by one for rubber. Further down the mixer the carbon black is added in two steps; and a final one for extender oils. Each is at a different point on the extruder, with the oils inserted last. The final step is another gear-pump-powered straining extruder to remove any impurities added along with the carbon black.

Hepke said the unit can accept full bales of rubber. He said this is a big advantage of the machine and a high priority for the customer. The bales are automatically cut into manageable strips, rotated through 90° and ascend a conveyor into a feed hopper. The feed unit displayed onthe K stand then pushes the rubber into the main twin-screw extruder.