20 years of MULTITWIST -
An invention that embodies the power & spirit of innovation
Those who have ever had the pleasure of watching a master baker at work twisting pretzels by hand will have an appreciation of just how much engineering must go into teaching a machine to do the same complex task. There is a reason, after all, why the pretzel is the emblem of the German Bakers’ Guild.
Hardly any other machine exemplifies FRITSCH’s astonishing innovative power, and substantiates its claim to teach its machines to handcraft, as impressively as the MULTITWIST. The fully automated pretzel twister went into serial production for the first time in 1998, used commercially by the first customer the very next year, and presented at iba in 2000. Since then, it has continually undergone new developments until, today, it is capable of processing an enormous variety of baked goods in large quantities.
It all started with the ASB automatic pretzel twister (Automatische Schlingsystem Brezel), a dozen of which were sold. Along with the inventor Udo Bernhardt a German pretzel manufacturer has been the driving force to develop a marketable pretzel twister. “The ASB has been constructed in such way that the endings of the dough strands are grapped from below and twisted,” says engineer Fred Dorner, Head of Component Design at FRITSCH. “In the later machines, the product stays on the conveyor belt as it runs through. As a result, we can produce other twisted products on them today as well, when fitted with the appropriate tools.”
This invention was highly innovative due to its ability to align and position the strand, coming from typical bakery strand machines, so that the pretzels can automatically be twisted to the required shape. Thus, this was an essential milestone which allowed the automatic production of pretzels for the first time.
The first sold ASB line produced 12,000 pretzels per hour and therefore consisted of eight pretzel twisters. The complex design of the ASB required a lot of space and often the artisan bakeries were too small for it. Consequently, the incentive grew to minimize the complexity of the twister and the line and to develop the next generation.
The second-generation, the pneumatic pretzel twister PSB (Pneumatische Schlingsystem Brezel) brought considerable simplifications and improvements with it. The PSB, first released in 2002, had an upstream divider to portion the dough. The dough pieces ran over a conveyor belt and a strand machine fed two PSBs alternately with dough strands.
„The difference from the ASB is that the PSB has two gripper arms that grip and twist the product from above. This allows the production on continuous consecutive transport systems as we know them today,” explains Fred Dorner. “With the PSB new technical developments have been promoted. For example, the stretching of the strands while twisting the pretzel under tension, to tighten the knots of the pretzel. “
Fred Dorner - Head of Component Design
That means the machine can do in one step what normally takes two steps for a person to do. The pneumatic control ran fast and reliably at 1,750 pretzels per hour and was considerably more simply constructed than the ASB. However, the exchange of tools was still relatively difficult.
As customers started expressing wishes to produce pretzels of different sizes and a Greek distributor enquired about producing popular cultural sesame rings – Koulouri - on a MULTITWIST, these wishes became the inspiration for the next stages in development. The SSB servo-powered pretzel twisting system with initially pneumatic lift (Servomotorische Schlingsystem Brezel), developed in 2005, allows the usage of various customer specific tools due to its tool exchange unit. So, the customer could exchange the tools and thus the production by himself.
„The SSB achieved a capacity of 2,000 pretzels per hour. Such high performance rendered the strand distribution system obsolete. Instead, ever since, each twister has been fed by its own strand machine, which considerably simplifies the process” “
explains dough technologist Alfred Ströbel from the R&D department.
Shortly after, the SSB was given a tool recognition capability to determine by sensor, whether the installed twisting tool and twisting table were compatible. In addition to pretzels of various sizes, this system was also able to produce rings and sticks.
The development of the SSB with servo lift, which is still in use to this day, signified a further increase in the reliability, accuracy as well as the possibilities of usable tools. “The small servo motors, which could now be affordably installed, allowed the gripper arms to be set to different positions to the exact millimetre. That is a prerequisite for being able to produce single-strand braids and other twisted goods,” Fred Dorner emphasizes. The experts at FRITSCH drove this development onward under their own initiative, and it immediately met with customer interest, given that it had never been possible to produce braids and knots on machines before. “The crucial point during the production process is that the gripper arm releases the dough end and picks it up again at another point. So, it does exactly what normally has to be avoided when twisting pretzels,” Alfred Ströbel explains the difference in production methods.
Whether twisting pretzels or producing braids, a crucial factor is that the dough strands must be centered on the conveyor belt as well as must have the right length and weight as they run into the machine. To accomplish this, the FRITSCH engineers developed the camera-controlled centering device.
The camera takes a picture of the strand so that the center device recognizes its shape, checks its length and ejects the strand in case of failure. The measurement of the strand length is also used to trigger a strand length regulation to keep a stipulated length even if there are dough variations.
This was a sustainable improvement in the production of single-strand braids and pretzel sticks. As more tools were developed for the MULTITWIST, the tool recognition capability also became more important. In 2012, a specially developed radio-frequency identification chip (RFID) was added so that the MULTITWIST can detect whether the inserted tool and the corresponding program are active. If not, the system displays an error and thus helps to prevent damages to the tool kit.
The production of braids is also the inspiration behind the latest tool developments at FRITSCH, which can be used to produce products like knotted baked goods and even the Austrian specialty “Flesserl”. For its knot twister, in 2015, FRITSCH received one of the coveted “iba awards”, which are bestowed by an independent expert jury. One year later, a Polish customer bought the first MULTITWIST with the corresponding toolkit for twisting knots. FRITSCH delivered the first Flesserl tool last year to a Swiss maker of deep-frozen baked goods.
In over 20 years of intensive cooperation between FRITSCH and its international customers, the MULTITWIST has undergone extraordinary development. From the simple pretzel twister, it has matured into a multitalent that still inspires engineers like Udo Bernhardt and Fred Dorner as well as our dough technologists like Alfred Ströbel to keep coming up with new ideas.