LBR iisy cobot in quality assurance

LIGRE, a brand launched by Gronbach, is conquering the consumer goods industry with a fresh feature for household coffee grinders: grinding coffee to the exact gram. Previously reserved for coffee machines that were designed for the food service industry, Gronbach's development engineers relied on the support of the LBR iisy cobot from KUKA. To test for quality control, they put the new grinder's durability and compliance with the preset coffee weight through thorough examination.

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The Gronbach Group was originally founded in 1964 as a hinge manufacturing company. After rapid development, Gronbach currently manages five production sites in Europe, a sales office in the U.S. and around 1,200 staff members. As an original equipment manufacturer (OEM), they specialize in the development and production of technical assemblies and complex products. These products are delivered internationally to more than 500 customers that vary from start-up organizations to large corporations. They work predominantly in the household appliances industry with coffee machines, cooktops, steamers and numerous other devices. Gastronomy, medical and automotive industries are also represented among its customers.

For Gronbach, quality is their top priority. At the production and research and development (R&D) site in Niederndorf, Austria an in-house team is devoted to research and customer-specific development of product assembly. Everything comes together in terms of mechanics, electronics, software and several other technical categories. The commonality between these products is their high-quality standard for technology, sustainability and energy efficiency. For the quality control of this exacting coffee grinder, engineers relied on the support of the LBR iisy cobot from KUKA during testing.

Grinding and weighing 55,000 times: The LBR iisy cobot from KUKA supported Gronbach's development engineers in the quality control of a new coffee grinder.

As a premium OEM, Gronbach has broad manufacturing expertise with comprehensive knowledge in the R&D field. Built from hundreds of personalized and successfully completed projects, their broad knowledge has now resulted in its own brand name - LIGRE. LIGRE is actively entering the market as a manufacturer of high-end coffee machines. One of the first products to be launched on the market is the LIGRE siji coffee grinder alongside a LIGRE espresso machine.

Special focus on quality: The LIGRE high-end espresso machine together with the LIGRE siji coffee grinder.

The LIGRE siji coffee grinder provides a completely new feature for a coffee grinder in the consumer goods industry with the ability to preset the amount of coffee to be ground to the exact gram. To ensure that the proverbial high-quality standard is not an empty promise, the R&D experts at Gronbach decided to subject this new quality control development through a series of tests. The assumption was that the coffee grinder would grind or process around 500 kg of coffee over a service life of around 10 years. Determining the long-term correct weighing results under different operating conditions for half a metric ton of coffee required radical acceleration and extremely precise repeatability. The results of these tests had to be reliable so the findings could be incorporated in future developments.

Our aim was to test the grinder's simulated service life in order to gain insight on its wear and accuracy.

Dipl.-Wirt.-Ing. (FH) Alexander Fahringer, Technical Development and Test Engineer at Gronbach

Cost-effective quality control

The R&D experts at Gronbach all agreed that an automated robot solution was the only way to achieve cost-effective quality control during product testing. The leap to KUKA was a short one since multiple industrial robots are already in use at the company's site in Niederndorf. KUKA’s LBR iisy cobot was a perfect robotic solution.

With a maximum load of 3 kg, the agile cobot's full capacity was not used in this case. “It's good to know that there is more scope for other possible applications and processes,” says Alexander Fahringer, Technical Development and Test Engineer of Gronbach. Fahringer is positive that this project demonstrates that collaborative robots have a firm place in development departments, especially with quality control. KUKA also offers the LBR iisy cobots with maximum loads of up to 15 kg and a reach of 760 to 1,300 mm for projects that need a higher load.

Quality management using robots: Thanks to human-robot collaboration with a simple teach-in function, commissioning and programming the LBR iisy cobot is quick and easy.

Quality management: The six-step test

The quality control test was scheduled over a two-month period during which the LBR iisy cobot would carry out 55,000 coffee grinding and weighing processes. Each process was carried out in six individual steps: taring the portafilter on the precision scale, gripping the portafilter and moving it to the coffee grinder, uncoupling the portafilter and waiting for the grinding process to end, picking up the filled portafilter and moving it to the scale, uncoupling and saving the scale value in the database, then picking up the portafilter, emptying it and placing it on the scale again.

Designed for reliable, repeatable movement: Robotics such as cobot applications are increasingly used in development and test laboratories for quality control.

One of the many benefits of the LBR iisy cobot is its simple programming through human-robot collaboration thanks to the Teach button. “You can guide the cobot manually and thus teach it the desired movements and waiting times very easily with the press of a button,” says Michael Reindl, Account Manager at KUKA. Thanks to its intuitive handling, the LBR iisy cobot offers flexible application options and can be commissioned and operated quickly and reliably by automation experts and robotics beginners alike. The robot meets all of the safety requirements for collaborative operation while being easy to use.

The cobot solution is an essential benefit for the flexibility necessary in a test laboratory. Other industrial robots with complex safety structures were not an option considering the high expense to short testing time ratio. With the cobot, costs aligned with to the relatively short period of use.

Peter Kopfensteiner, Research and Development, Division Appliances, Gronbach

New methods in quality control: The LBR iisy cobot from KUKA played a supporting role at Gronbach when they ground and weighed a new coffee grinder 55,000 times as part of a time-lapse quality control process.

Millions of cycles

“The small LBR iisy cobot in particular is the variant with a load of up to three kilograms. In addition to the larger models, they are designed to take care of rather simple, monotonous and repetitive handling tasks in the immediate vicinity of other employees,” Reindl says describing the typical applications for a cobot. The 11- and 15-kg variants are even dust and splash-proof (protection class IP 54). The simple operation and high degree of flexibility distinguish the cobots from conventional industrial robots.

The collaborative robots in KUKA's LBR iisy series are available with maximum payloads of 3, 11 and 15 kg.

The cobot also eases the burden of employees being overworked which can become harmful to their health. Along with quality control, it offers added value thanks to precision, repeatability and easy handling. Each individual grinding and weighing process was carried out and logged in continuous operation with absolute reliability so that variances could be detected quickly.

Processing the 55,000 test grinds is hardly worth mentioning for the cobot due to its longevity. “It's only just properly worn in,” Reindl says humorously, alluding to the several million cycles that the KUKA robots set as a standard in their performance.

After gathering the results from the test, only positive outcomes were discovered. “The grinder worked so well that it indicated practically no wear and tear after simulated use for ten years, so it could last for significantly longer,” says Fahringer.

From the left: Dipl.-Wirt.-Ing. (FH) Alexander Fahringer, Technical Development and Test Engineer, Peter Kopfensteiner, Research and Development, Appliances Division, both Gronbach and Michael Reindl MBA, Account Manager, KUKA.

Easy to get started

It is clear to the R&D team that this will not be the last time the LBR iisy cobot is used at Gronbach. “As automation engineers, we are already thinking about how the cobot will assist us in enhancing quality control and refining processes,” says Fahringer. One of the top contributing factors for this was the excellent collaboration with KUKA. The robotics experts deliberately make it easy for those who are interested in getting started.

“We are happy to provide customers with handy collaborative robots like the LBR iisy cobot to try out and test in their operation,” says Reindl. For anyone curious to test it out, the process is rather simple - the compact robot fits in any trunk.