Top-quality buttered pretzels – at top speed

MFDO UG in Baden-Württemberg is using the logic module LOGO! to fully auto­mate the making of tasty, buttered soft pretzels.  
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Quick and easy

The southwest German region of Swabia is renowned for being a land of tinkerers and inventors, as well as for producing specialty foods such as buttered soft pretzels. However, this food product – which is known for being a popular breakfast item in Germany – can quickly become a source of stress if the bakery assistant needs to cut and butter each one by hand while serving the morning rush.

"There must be a quicker and easier way of doing it," self-­employed electrical engineer Dieter Obertautsch and design engineer Michael Feil believed. The two friends from Althütte, in Swabia, together developed a machine that pumps butter evenly and conveniently into pretzels at\the press of a button and – thanks to LOGO! 8 – in exactly the right amount.

"When we began developing our project around ten years ago, we first had to find out whether the idea of injecting the butter would in fact work at all," recalls Feil. "We tried it, with a needle head and a silicone press – and we had the perfect buttered pretzel." The two inventors founded a company and named it MFDO UG, initially experimenting with purely mechanical prototypes. But they encountered some problems ...   

"Cold butter, fresh from the fridge, takes a lot of force to push through the needles," Feil explains. "You need power, but don't want to be pumping 15 times before the butter gets into the pretzel. You also have to remove the pressure again when the pretzel is done, otherwise the butter will keep on flowing through." Therefore, Feil and Obertautsch decided to automate their machine. "A motor has enough force to push the butter easily through the injector needles," Feil continues, "and LOGO! 8 dispenses exactly the right quantity."


One concept, with many benefits

The Siemens logic controller was not unknown to the two inventors: they had used it before on a number of projects.

"We were convinced by the value for the money the product offered, and by its compact design," Feil reports. "Also, thanks to the software's modules and the facility to easily link functions by drag and drop, project configuration is simple even for people with no professional programming skills."

Now, in order to butter each pretzel the operator simply presses a button triggering a sequence stored in LOGO! 8. The motor drives a spindle for a preprogrammed number of pulses, activating a pusher to push the butter a specified distance from its metal container, forcing the programmed quantity through the needles and into the pretzel. LOGO! then switches off the green dispensing lamp on the control button, stops the motor and sends it back in the opposite direction for another preprogrammed number of pulses. This removes the pressure and the butter no longer flows through the needles. Colored lamps additionally ­indicate when the butter compartment is almost empty, completely empty, and when it should be topped up.


The future of buttered soft pretzels

LOGO! not only enables buttered soft pretzels to be produced over twice as fast as by hand, the logic module can also be expanded.
We were convinced by the value for the money the product offered, and by its compact design.
Michael Feil, Founder of MFD UG

"Our machine takes about ten seconds to butter a pretzel," says Feil, which is over twice as fast as doing it by hand. "Also, the quantity of butter is regulated exactly, so it's identical in every pretzel." A second-generation machine incorporates active electric cooling as an option. "That means the butter always stays as cold as when it first came out of the fridge," Feil asserts. "So it's always fresh to process – even in summer."

The SIMATIC Basic Panel KP300 can be installed to work with the automated machine, enabling the operator to monitor the butter-dispensing process at all times and make adjustments as necessary. But this isn't where it stops for MFDO. The company is always looking to expand its range of variants and products, and at present is developing a machine with a higher capacity butter container to handle more volume and serve larger bakeries. Thinking toward the future Feil says, "We are also looking to market injection variants for other products, such as nut cream, or machines featuring a built-in display."

Note on industrial security:
Appropriate security measures (e.g., network segmentation) must be taken to ensure secure operation of the system. Find out more about industrial security.

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