How quickly can product changeovers be carried out in a container mixer with a dead-space-free design?
An important preliminary note: during the phases of docking, that is to say when the mixing tool moves in, and of undocking, that is to say when the mixing tool moves out, the entire cross-section of the container is open. Relatively large amounts of dust can therefore be emitted into the surroundings. In return, however, the handling is comparatively quick.
As a rule, product changes in container mixers with a dead-space-free construction can be carried out within a few minutes. Depending on the degree of automation and the process requirement, changeover times typically lie below five minutes for the pure container change and at approximately 5 to 15 minutes for the complete product change including docking, cleaning of the mixing tool and documentation.
Through the combination of the container mixing principle with a dead-space-free, hygienically compliant design, the product change is essentially reduced to the exchange of the container and a brief cleaning of the product-contact components. Compared with conventional stationary mixing systems, the downtimes caused by cleaning can thereby be markedly shortened.
Why are the changeover times so short?
The container simultaneously performs the function of mixing, transport and storage vessel. The product remains in the same vessel, so that no time-consuming transfer operations are required and the base unit generally does not have to be cleaned. The product change therefore takes place mainly by docking a prepared, new container.
With a dead-space-free construction, the product-contact surfaces of the mixing head and the tools are designed so that hardly any product residues can be deposited. Smooth surfaces, optimised radii and hygienically compliant seals support rapid and reproducible cleaning. This also reduces the risk of cross-contamination between individual batches.
Typical time components depending on container size:
- Container change and docking: mostly 1 to 6 minutes.
- Complete set-up process: typically 5 to 20 minutes.
- Cleaning or changing the mixing tool: 5 to 10 minutes.
- Formulation changeover and documentation: 5 to 15 minutes.
Advantages over stationary mixing systems
Compared with permanently installed mixers, the long cleaning times of the mixing vessel are dispensed with. Plant availability and overall equipment effectiveness (OEE) thereby increase, while smaller batches and frequent formulation changes can also be implemented economically. This is particularly advantageous in sectors with a wide product range and strict requirements for hygiene and protection against contamination.
Prerequisites for minimal changeover times
For particularly short product changes, standardised docking systems, automated centring and locking devices as well as hygienically designed quick-change tools are important. In addition, barcode-supported identification systems facilitate formulation assignment and documentation. Product changes can thereby be carried out efficiently, safely and reproducibly.
amixon® container mixers: mixing directly in the vessel – without transfer
The principle
With the COM system, the bulk material container itself serves as the mixing chamber. The SinConvex®-MultiPlane® ribbon mixing tool is introduced into the product from above, the container is then sealed gas-tight, and mixing takes place directly in the vessel. After the mixing process, the tool moves back out of the product in a controlled manner in reverse operation, and the container with the finished mix is removed. Dimensionally accurate Mixtainers® are the standard vessel here; on request, amixon® also realises such plants on the basis of standard IBCs. The container thus serves at the same time as the dosing, mixing, transport and feed vessel for subsequent process steps such as filling, extrusion or liquid preparation.
Alongside the COM system there is also the elegant AM system, which works with commercially available containers and is of extremely low-dust design. It combines the advantages of container mixing with particularly clean, reliable handling.
Precision mixing instead of tumbling
Unlike tumbling or rotating mixers, the COM works with a dynamically moved mixing tool that controls the space. Component ratios of up to 1:100,000 can therefore also be homogenised in a technically ideal manner, even with differing bulk densities and particle sizes or when liquid or moist components are added. The three-dimensional total flow – upwards at the periphery, downwards in the centre – provides high mixing qualities even at a low fill level. Optionally, a cutting rotor can be switched in for de-agglomeration, particularly with simultaneous liquid addition within the active area of the rotor. The mixing chamber is designed for ATEX Zone 20.
Decoupled production
Both amixon® designs are conceived for flexible contract and one-off manufacture. Weighing in, mixing and filling take place decoupled in separate areas; while one area is being set up or cleaned, production can already continue in another. For automatic wet cleaning and drying of the mixing tool, a Washtainer® can be docked on. The sizes range from 100 to 4,000 litres batch size; on request the design is EHEDG-, FDA- and 3-A-compliant.
Design and integration
Container logistics, lid handling and periphery are designed project-specifically, so that every plant arises as a one-off in accordance with the URS. The mixing and cleaning parameters for the respective formulations are verified in the amixon® pilot plant. This ensures that the plant is matched exactly to the product, the process and the hygiene requirements.
Hygienic design as the constructional basis
All the properties described rest on the amixon® hygienic design. The mixing chamber and mixing tool are welded free of crevices and ground smooth, and the mixing tool is mounted at the top only, so that the contamination-critical lower shaft passage is eliminated. Large Clever-Cut® inspection doors with a permanently dead-space-free OmgaSeal® seal make all product-contact surfaces readily accessible. Dead-space-free discharge devices and integrated washing lances – on request with fully automatic wet cleaning – make both dry and wet cleaning validatable, in accordance with the EHEDG guidelines, the FDA hygiene guidelines and the 3-A Sanitary Standards.