The typical use for eccentric screw pumps for food and cosmetics applications is the traditional conveying pump. The pumps are used in the dairy-business, brewing industry or also in the bakery industry to pump dairy products, dough or sugar pastes. This technology is proven and tested and the pumping results are perfect. A completely new approach is the idea to use eccentric screw pumps as dosing pumps or dispenser to realize decoration or filling applications in the bakery and sweets industry. Only by this new area all advantages of the eccentric screw pumps could be shown and the use of this technology is not any more limited to the conveying pump field. In other branches, like Electronics or Automotive Industry, dosing systems based on the eccentric screw pump technology are used for years in order to get accurate and repeatable best dispensing results with adhesives, sealants or chemicals.
The Endless Piston Principle / Eccentric Screw Pump Technology
The eccentric screw pump belongs to the group of rotating positive displacement pumps and is based on a volumetric pump technology. The operating mode is similar to an endless piston, which pumps the liquids from the suction side to the pressure side and therefore creates a pressure difference. The combination of an eccentric moving rotors and stators results in a dosing characteristics which correlates with an endless moving piston.
Advantages and Benefits of the Endless Piston Principle
The dosing geometry allows having a constant volume per one turn of the pump (proportional to the angle of rotation). It is possible to reverse the flow direction by changing the direction of rotation. Therefore the volume is clearly defined by the angular degrees. This technology offers a pressure constant, linear pump performance curve.
With this curve it is possible to define exactly the ratio of turns, time and dosing volume. This guarantees a theoretically dosing accuracy of +/- 1% at the outlet of the pump (depending on the fluid), which is in most of the cases even less. Another advantage of this technology is that the created cavities are always constant during the whole movement. These cavities offer the chance to pump and fill liquids with fillers, particles or pieces. Another advantage compared to other pump technologies: in more than 95 % of the applications it is not required to use closing valves as the pump uses a suck-back (short reverse movement of the pump at the end of the dosing process). By using this suck-back, it is a clean process without dripping or stringing and even difficult, high-viscosity liquids could be dosed in a safe and reliable way. There is no stress on the liquid, no pulsation and no interruptions in the dosing process.
All these advantages and benefits are now used by the bakery and sweets industry. The eccentric screw pump offers completely new possibilities and chances especially for high-viscosity liquids and pastes like icing sugar, fondant or sauces with fruit pieces. Where classic piston pump systems do have their problems, the eccentric screw pump could be used as dosing pump to dispense difficult liquids in a safe way. The simple handling guarantees that the dosing pump could be used for automated solutions e.g. could be integrated with all available robot systems. One major application is the fully-automated decoration of cookies, cakes or sweets with sugar paste or fondant. The supply of the sugar paste is realized with a barrel emptying system, which is also based on an eccentric screw pump. This pump, in combination with a follower-plate, guarantees a nearly perfect emptying process (residues less than 1% in the barrel) in a very sensitive way. In comparison to piston pump emptying systems, the emptying process is mainly done by the suction capability of the eccentric-screw pump rather than the high pressure put on the follower plate and cylinders. Therefore the sugar paste will be not pressurized and not stressed (there will be no sedimentation due to high pressure). The features and the structure of the sugar paste will be unchanged by this shear-sensitive emptying process. After that the sugar paste is dosed – with the help of robots and software- onto the cookies and sweets in any possible pattern or writings. There is no limit for your creativity and phantasy, anything is possible, like the seasonal decoration of Christmas cookies, ginger bread, Easter cookies or classic cake decorations with even most difficult lines or patterns. This automated decoration offers bakeries and sweets manufacturers completely new possibilities and chances. Their production could be revolutionized and huge quantities could be produced in a process-safe way by guaranteeing standard quality and production standards. As this is only the beginning of this new application area for the eccentric screw pumps, the future will bring interesting and exciting new applications for automation. Very labour intensive operations will be replaced by fully automated dispensing solution and will safe cost and time.
Perfect Filling Results
Another application area for eccentric screw pumps are filling applications for sweets and bakery products, where traditional piston pump systems reach their limit. For example for high viscosity pastes and cremes with particles, nowadays piston pump systems are modified with extreme efforts to fulfil the dosing application or they finally quit this application as it is not possible. The solution is again the eccentric screw pump as dosing or dispenser pump: even most difficult and high viscosity liquids, like honey based pastes could be dosed and filled. Another advantage for the sweet manufacturers is, that they could develop completely new products, e.g. mixtures with high viscosity pastes. With the technology of the eccentric screw pump these new products could be now realized and finally produced and therefore offers the manufacturers a completely new business possibilities.
The eccentric screw pumps fulfil these requirements hassle-free and special mixtures (caramel or chocolate based pastes) will be filled in a very precise way. For each turn of the pump a defined volume is dosed. The filling quantity could be modified very easily – only the rotation speed has to be changed according to the requirements.
The high-viscosity pastes or cremes are dosed in a very sensitive way without destroying their structure. It is also possible here to pump liquids with particles (e.g. fruit particles or fibres or small cookie particles) without any problem. According to the application the dosing pumps could be mounted directly in a fully automated system or for example in a semi-automatic filling station. It is also possible to realize many different applications, for example filling of sweets or Danish pastry with different cremes or also filling applications in small cups or sachets.
Decoration and icing applications as well as filling applications are new areas for eccentric screw pumps in the food business, which allow the users to automate their processes and build up a completely new structure. Only by using eccentric screw pumps in the sweets and bakery manufacturing as dosing and filling pump, the technology unfolds and offers its best advantages and benefits. Besides the conveying pump, the eccentric screw pump will have a glorious future with this new usage and application area.