A Perfect Solution in Bakery Automation


For the pre-ferment, Bühler has developed a solution – JetMix - Better hygiene thanks to KOLLMORGEN’s stainless-steel servo motors


No hearty rye bread without sourdough. The stollen becomes deliciously soft when some of thebaking ingredients are first mixed together and left to rise (thanks to the properties of yeast) beforeall the other ingredients are blended into the main dough. The mixture made mainly from cereal flourand bulk liquids such as water and milk is known as pre-ferment among bakers. With the JetMix, Bühler has developed a solution for the fully automated production of pre-ferment and sourdough.By using AKMH stainless steel servomotors from KOLLMORGEN, Bühler successfully combined high productivity with maximum hygiene.


Combine water and flour into a smooth and lump-free pre-ferment using dough hooks – this view is shared indomestic kitchens and among the medium-sized bakery sector. If the focus is on larger bakeries, then the JetMix is the ideal solution. The compact machine from Bühler does not combine water and flourmechanically, but through effective hydration. During this continual process, each flour particle is evenlyhydrated by the finely atomized water spray. The result of this process has impressed users, mainly thanksto its high productivity and the quality of the fine and smooth pre-ferment.


The quicker way to the perfect pre-ferment:


The technical aspect of the JetMix consists of four servo axes: Two of them form the pump drive for thewater and ensure the pre-ferment is pushed along. Each of these axes drives the dosing screw as well asthe centrifugal stirrer. “There, the flour is accelerated radially so that we can create a perfectly formed ringfrom flour”, describes Heinz Lauermann, team leader of Material Handling Powder & Liquids at Bühler. Thering of flour that arises from the centripetal force reacts with the water spray in the mixing tube, which isintroduced from the outside through fine nozzles by the servomotor driven pumps. The pressure is accuratelyregulated by the precisely operated servo drive. This precision is therefore necessary, because when theflour and water come into contact, they coalesce into a lump-free dough. “Mechanical kneading methods fordough production are always associated with a high energy input. With the JetMix, the production of pre-ferment is significantly faster and more energy efficient”, emphasizes Lauermann. The Swiss works at Bühler’s Headquarters is in Uzwil.


Always enthusiastic about special ideas and alternative solutions, for Heinz Lauermann, the advancement of the JetMix, fitted with a stainless-steel servomotor from KOLLMORGEN, which was first presented at aspecialist trade fair in the USA, illustrates a highlight in the industry from a hygiene perspective. The mostpowerful of the four AKMH stainless-steel motors drives the centrifuge that produces the ring of flour –comparable to a hand blender. “The broad speed control range of the motor helped us a lot duringdevelopment to identify the correct speed for different types of flour and pre-ferments”. The finely balancedinterplay between the spinning speed and the water spray being introduced with a pressure of up to 16 barultimately guarantees the perfect mixture – and can therefore also be stored as a tried-and-testedreproducible pre-ferment recipe in the control system. “If we had small drops rather than a fine spray, wewould get lumps. Drops create lumps”, says Lauermann, who explains that after being mix in the JetMix, the pre-ferment is pumped into a storage tank for further fermentation. According to Bühler, the JetMix’s performance stands at 3.0 tons per hour. “If we multiply this amount by four, then we get the quantity offinished dough”. This makes 12 tons – and they are needed. The capacity of the ovens is especially large inindustrial bakeries associated with discount stores. 100 to 120 tons of flour are processed daily for bread,bread rolls, cakes, and baked goods.


A high speed control range for production and cleaning:


Considering these quantities in a price-sensitive market with low profit margins, there is the risk that littleattention will be paid to cleaning the machines. “This task reduces productivity. The longer the cleaningtakes, the less the companies earn”. During the development of the JetMix, Bühler was adamant that itwould be equipped for CIP i.e. that it must be attached to a central cleaning system (Clean In Place). TheAKMH stainless-steel motors from KOLLMORGEN must, therefore, operate at a high rotational speed, asthat is required during the production phase. “That was an important discussion in the design of the drivesystem, to obtain a water velocity of up to 3 m/s, so that during cleaning, leftover dough does not remainstuck on the sides”. Moreover, the drive systems must deliver such a performance that they can even push aso-called pig through the pipes. This is shaped in a figure-of-eight, nestles up to the sides and pushes thedough caught in the pipe in to the fermentation tank. Bread factories waste less food because of this and donot excessively burden the CIP system or the local sewage plant. Furthermore, bread dough does not passwell through the sewage system and quickly begins to rot.


A more hygienic stainless-steel motor with a single cable:


Heinz Lauermann even describes the exterior handle of the AKMH stainless-steel motors fromKOLLMORGEN as pioneering. The use of stainless-steel 1.4404 makes the AKMH series corrosion-resistantagainst aggressive cleaning products. The design of all the edges to have a radius of at least 3 mm and thesurface finishes with a roughness of <0.8 μm prevents the accumulation of dirt. The AKMH stainless-steelmotors are connected by just one cable, including recirculation to the AKD servo controller, so that the installation of Bühler’s JetMix also contributes to the hygienic aspect. On the one hand, halving the cableshalves time and space during installation and, on the other hand, is also an advantage for hygiene andoperational safety. Using just one cable means soling and leaks are less likely. “Integrating the recirculationsystem in the motor cable was worked out very well by KOLLMORGEN”, acknowledges Heinz Lauermann. He describes a hygienic motor including “very perfectly rounded motor mountings”.


The compact units of sizes two to six are also used outside of the baking industry, especially in machineareas with direct product contact and aseptic processes. The AKMH stainless-steel motor dissipates any lostheat effectively to the outside and therefore lowers derating. As a consequence, the FDA certified series,developed according to the EHEDG guidelines, supplies higher continuous torques at lower volumes.


The Bottom Line:


Bühler’s JetMix clearly demonstrates how hygiene properties and cleaning capabilities of machines inthe food industry can effectively be improved when stainless-steel motors are used. It is not enough,however, to be satisfied with the material selection for the motor housings. Rather, the contour guide,connection technology and function must perfectly meet the requirements of Food Safety. “Our eyes havebeen opened from a hygienic perspective by AKMH”, summarized Lauermann.