Developing processes together03/28/2007 Time and again, Bühler technologists develop new processes in close cooperation with customers. The Pasta and Extruded Products (PE) business unit has revolutionized the production technology for making multicolored products by taking this approach. Developing processes together. That, in a nutshell, is the philosophy of the extruder specialists from Bühler. Customers are involved in process development in order to achieve the best possible results. In this effort, customers contribute their precise product knowledge, and Bühler provides the associated equipment and process expertise. The required process is then customized in the process laboratory. Depending on the specific situation, the customer may be present during the tests. This approach has already enabled a large number of processes to be developed, some exclusively for a particular customer, others for successful further marketing.
A current example of a process developed in collaboration with a customer is the new method of producing colored breakfast cereals. In this case, a customer requirement was satisfied by creating a new process for a well-known existing product. To date, extruded product mixes of different colors have been made by different methods. One option is to operate several extruders in parallel, with each machine producing a specific product color. Another variant is batch production of the different colors. A third option is to color the extruded products by spraying on different colors. All these processes have their specific drawbacks, which increase costs and space requirements.
The joint development effort described here has produced a novel solution for which a patent is pending. A single extruder allows the continuous production of multicolored extrudates without requiring any downstream process to mix batches of individual colors. The heart of the new process is an add-on module consisting of colorant tanks with pumps plus the system for connection to the process unit of the extruder. Also included is an adjustment of the process geometry to prevent color smears at the transitions between the individual colors.
Color circle theory applied
During the production process, the colorants are alternately metered into the process section of the extruder. The special thing about this approach is that the time intervals are kept very short to eliminate the need for subsequent mixing in an additional stage. Mixing during conveying, spraying, and drying is sufficient to obtain a homogeneous mix. Moreover, it is possible to make use of the color circle theory to obtain intermediate colors. The development of the new process has paid off. The new approach has proved to be superior to the three other methods. Its capital cost is lower and it requires less space, since less equipment is needed.