© Gernot Walter

No card­board char­ac­ters!

Black strap­ping has become some­thing we take for granted, but it constantly demands creative solu­tions from the devel­op­ment team at Mosca GmbH. A prime example is the drive system for their new flag­ship product for strap­ping card­board.

The postman rings and hands over a parcel. The customer takes a pair of scis­sors and cuts through the black plastic straps, which end up in the trash. Though these straps are some­thing we take for granted and barely notice, strap­ping (as it is called in the pack­aging industry) prod­ucts poses many chal­lenges. For example, when a do-it-your­selfer buys a bundle of roof laths, he is pleased to see that they are bound together tightly. But that is not to be taken for granted; the wood is strapped while still moist after cutting and dries out quickly in a hard­ware store envi­ron­ment. That results in shrinkage, and then perfect tensioning in the strap­ping begins to matter. “Our strap­ping machines are often used in the food industry, where they have to with­stand temper­a­tures of minus 20 degrees Celsius in cold stores, or salt water from fish processing,” says Michael Zimmer­mann, Sales Manager for Germany, Austria and Switzer­land at Mosca GmbH.

The company is based in Wald­brunn in Germany’s Oden­wald region and is the leader in strap­ping tech­nology. It produces both the strap­ping mate­rial and machines used with it. The company’s largest volume comes from strap­ping machines for tempo­rary strap­ping during indus­trial processes — strap­ping that normal consumers never see. “For example, corru­gated card­board gets strapped up to five times during its produc­tion process.”

Wanted: an econom­ical jack-of-all-trades

There are 18 drives installed in the machine, but only five different mechan­ical designs.

Mosca is partic­u­larly proud of its latest strap­ping machine for corru­gated card­board, the UCB, which is repre­sen­ta­tive of Mosca’s creative approach: The machines need to be versa­tile but remain in the spec­i­fied price range. After all, customers expect optimum value for money. “We have to imple­ment customer require­ments like high-preci­sion posi­tioning or high computing power even with rela­tively simple compo­nents,” says Markus Haas, who heads the elec­trical design depart­ment. Servo­mo­tors or large amounts of memory are much too expen­sive for these tasks, so Mosca needs alter­na­tive concepts. “That’s the ‘spice’ in our work, but of course it also makes life diffi­cult for us.”

The elec­trical engi­neers some­times reached their limits, espe­cially when dealing with the move­ments of the numerous axes in the machines, as Rainer Ihle, a devel­oper, can attest. “Our dream was to avoid using pre-para­me­ter­ized motors,” he says. “If we use a specially para­me­ter­ized motor for all of the different tasks, then we have a huge variety of drives in a machine. But there used to be no other way.”

“We have to imple­ment customer require­ments like high-preci­sion posi­tioning or high computing power even with rela­tively simple compo­nents.”

Markus Haas, Head of the elec­trical design depart­ment at Mosca

That made it diffi­cult not only to control the drives, but also to service them. Once the Mosca tech­ni­cian at the scene had iden­ti­fied the type of drive that was faulty, the search began in Wald­brunn for the right PC tool, the inter­face adapter, the para­me­ter­i­za­tion and the current version of the firmware. The tech­ni­cians would then customize the replace­ment drive and send it to the customer. Then the tech­ni­cian was deployed for the second time, to install the replace­ment drive. “In the worst case, that some­times meant the machine was out of service.”

An elec­tri­fying solu­tion

A solu­tion came into view when Markus Haas became acquainted with the K4 drive regu­lator at a presen­ta­tion of the ebm-papst drive port­folio. “It elec­tri­fied me, and right away I asked the sales repre­sen­ta­tive who had told him what we need. That was exactly the solu­tion we had been looking for.” The regu­lator provides speed, torque and posi­tion control, is config­urable and is enabled for commu­ni­ca­tion via RS-485 bus system. The Mosca team’s dream of elec­tron­i­cally neutral instal­la­tion was almost within reach.

But a few creative solu­tions were still needed on the soft­ware side. For example, to make the drives work with other compo­nents in the same bus system. Since the different compo­nents do not commu­ni­cate iden­ti­cally, a sort of trans­la­tion is needed for different “dialects” of data trans­mis­sion. Through an assigned address, every drive always knows whether it or another is being addressed and what is to be done.

In a pilot project, the team over­came other obsta­cles on the way to the perfect drive solu­tion. Armed with that knowl­edge, they began to work on the imple­men­ta­tion of the new UCB. “We can only imple­ment our solu­tions with our expe­ri­enced devel­op­ment team,” says Haas.

The result simpli­fies handling in general, and also the machine’s archi­tec­ture. Func­tion assign­ments for the drives can be made at runtime, and their inte­gra­tion in the Mosca bus system also enables condi­tion moni­toring. In addi­tion, the new UCB’s control box is only a quarter as large as the one on the prede­cessor machine — with iden­tical func­tion­ality. That has many bene­fits, such as access to the machine.

“There are 18 drives installed in the UCB, but only five different mechan­ical designs. That’s ideal, because a service tech­ni­cian can easily take them along on a service call.”

Daniel Treu, elec­tri­cian at Mosca

And service calls are reduced to a few hours, as elec­tronics tech­ni­cian Daniel Treu enthu­si­as­ti­cally reports: “There are 18 drives installed in the UCB, but only five different mechan­ical designs. That’s ideal, because a service tech­ni­cian can easily take them along on a service call.” When installed, a drive is auto­mat­i­cally addressed, para­me­ter­ized and given the correct firmware when the machine is switched on; it is auto­mat­i­cally customized for the func­tion to be performed.

The Mosca team is happy about more than just the solu­tion. As Michael Zimmer­mann says, “By April we had already sold the quan­tity we had planned for the entire year, and the customers aren’t giving back our proto­types because they work so well.”

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