Robust drive systems show their sweet side

Many steps are necessary to make chocolate from cocoa beans. During this process, ingredients and mixtures in various states remain in near-continuous motion for hours and days on end, which requires reliable drive systems. In Zotter Schokoladen’s factory in Southeast Austria, the durability and fail-safe operation of these drives is doubly significant: firstly, smooth operation ensures top quality of the final product. Secondly, the production line is always open to thousands of visitors who should of course not witness any malfunctions. For years now, the facility has been using geared motors from NORD DRIVESYSTEMS for conveying, mixing and pumping tasks.

Illustration 1: Zotter exclusively uses fair-trade, organic ingredients – first of all, cocoa beans from select growers

Chocolatier Josef Zotter is a man of principle, and sustainable production is his prime directive. His factory in Riegersburg in the South of Austria completely relies on renewable energy and generates most of it from burning in-house waste products. Fair treatment – of both farmers and consumers – is equally important to Zotter. Therefore, he is the only chocolate manufacturer in Europe to exclusively use fair trade materials in organic quality. Zotter expects the same sort of commitment from his suppliers. The Riegersburg factory therefore has strict requirements regarding the standard of machines and plant equipment and the customer service of his technology partners. Swiss process engineering expert Bühler was responsible for the design and implementation of the chocolate production facility. Geared motors from NORD DRIVESYSTEMS significantly contribute to smooth operation during all process steps. “Our suppliers, including NORD, are very reliable”, says Thomas Linshalm, head of cocoa processing at Zotter. “Reliability is essential in all our machines. Therefore, it is good to know that NORD is there to react quickly in case of a problem. We can simply call them and be sure to immediately talk to someone who can help – we are very pleased with that.”

Illustration 2: Thomas Linshalm, head of cocoa processing at Zotter’s Riegersburg factory

Black gold, roasted and ground

Safe in the knowledge that smooth operation of the plant can always be relied on, the Zotter masterminds can bring their power for innovation to full fruition. The company introduces dozens of new flavors with a wide variety of ingredients every year. These range from pineapple to lemon, from celery to asparagus, from coconut to cheese, and to even more extravagant raw materials. Zotter currently offers bars and other sweets in 365 different varieties. But regardless of exotic flavors and new creations, classic chocolate remains an indispensable ingredient for a large part of the product range. For years now, chocolate has been produced in-house according to Zotter’s recipes, which is quite unusual for a small manufacturer. Cocoa beans delivered to the factory are cleaned and then roasted for several minutes at temperatures above 100 °C, and subsequently sterilized under steam pressure. Conveyor drives with 0.75 kW rated power ensure transportation between the cleaning, roasting, and sterilizing stations. The next step is a crusher, where the cocoa nibs are de-shelled. A grinder with a NORD drive then turns the nibs into liquid cocoa paste, which is piped to a mixer. The pumps required for this stage feature 4 kW geared motors. Inside the mixer, sugar and – for some recipes – dried milk are added to the cocoa paste. On top of that, extra cocoa butter is added from neighboring tanks which are equipped with several 1.1 kW pump drives.
Illustration 3: The raw mixture must be re-ground in a rolling machine. A conveyor belt transports the mixture there.

Liquid turns solid …

Mixing the cocoa mass with the other ingredients results in a pourable mass, which is ground in a rolling machine in order to achieve a fine texture. A dedicated worm gear unit powered by a 4 kW helical geared motor then ensures compression. Based on the current NORDBLOC.1 design, this drive features an innovative construction: The gears are introduced and mounted through the bearing bores. While the axis-to-axis distance is the same as in conventional helical gears, the NORDBLOC.1 design allows for using larger bearings in an overlapping offset configuration. The shafts are also larger than in other market-standard one-piece systems. Thanks to the larger bearings, the drive systems are considerably stronger and more durable, since wear through radial and axial forces is further minimized. The larger shaft journals allow for a very flexible implementation of customer specifications, for example regarding shaft diameters or the shape and length of the shaft studs.
Illustrations 4, 5: The cocoa paste is compressed by a dedicated worm gear unit powered by a helical geared motor

… and solid turns liquid

Conveyor drives then transport the solidified intermediate product through five rolling machines, where it is gradually refined. Only then does the mixture arrive at the last step of chocolate production. Developed by Bühler with special industry know-how, the single-shaft conche is used to reduce the water content, which ensures a smooth, silky consistency. Bitter compounds are evaporated through sophisticated temperature monitoring while the desired aromas remain. In this application, NORD drives are used for transportation, agitating, and pumping tasks. A helical geared motor serves as a belt drive for filling the conche. Depending on the recipe, the chocolate mass is agitated for up to 48 hours at increased temperatures in a liquid state, until a product with the finest glaze and the desired aromatic profile is created. The agitator arms are moved by a space-saving direct drive. The parallel shaft geared motor used for this purpose provides a rated power of 55 kW. The conched mixture is evacuated via a pump system driven by a helical geared motor.
Illustration 6: Belt drive during conche loading

Illustration 7: Parallel shaft geared motor driving the conche

Illustration 8: Ingredients and intermediate products are moved from tanks and from one machine to the next by means of several pump drives; shown above: conche evacuation

Conclusion:

In chocolate production, machines such as grinders, mixers, and agitators as well as many conveyors and pump lines rely on robust drive technology. Various geared motor types from NORD DRIVESYSTEMS accomplish a wide range of these tasks in Josef Zotter’s factory. Thomas Linshalm, head of chocolate processing at the inspired confectionery company, explains: “We operate a large number of geared motors. Just in case, it is therefore very important for us to always have quick access to spare parts. In general, however, the drives perform very reliably.”

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