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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 manufacturer of hinges. The business developed very quickly: Today, the group of companies operates a total of five production sites in Europe, has a sales office in the USA and employs around 1,200 staff. As an OEM, Gronbach has specialized in the development and production of technical assemblies and complete products which are delivered internationally to more than 500 different customers – from large corporations down to start-ups – predominantly in the household appliances sector, including coffee machines, induction hobs, steamers and much more. The gastronomy, medical, automotive and consumer goods industries are also represented among its customers. 

Quality has the highest priority. The production and R&D site in Niederndorf in Tyrol with around 200 employees is very important to the Gronbach Group when it comes to general development of product solutions – all the threads come together here in terms of mechanics, electrics, electronics, software, etc. An in-house expert team is devoted to research and customer-specific development of devices and assemblies. What all of the products have in common is the high quality standard when it comes to technology, sustainability, and energy efficiency. For the intensive quality control of a new coffee grinder, the development engineers relied on the support of the LBR iisy cobot from KUKA in a test setup.
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 know-how in the field of R&D. The wealth of experience built up in hundreds of customer-specific and successfully completed projects has now resulted in in its own brand LIGRE: The company is now entering the market under this name 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 an espresso machine.
Special focus on quality: The LIGRE high-end espresso machine, together with the LIGRE siji coffee grinder.
A completely new feature for a coffee grinder in the consumer segment is the ability to preset the amount of coffee to be ground to the exact gram. To ensure that the proverbial high quality does not just empty words, the R&D experts at Gronbach decided to subject this new development to intensive quality control in a series of tests. The basic assumption was that the coffee grinder would grind or process around 500 kg of coffee over a service life of around ten years. Determining the long-term correct weighing results under different operating conditions for the total quantity of half a metric ton of coffee not only required radical acceleration but also extremely precise repeatability; after all, the results had to be reliable and the findings incorporated into future developments and improvements.

Our aim was to test the grinder's simulated service life in order to gain insights into 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 using a test setup. The leap to KUKA was a short one; multiple industrial robots are already in use at the company's site in Niederndorf near Kufstein. It's a good thing that KUKA has a robot in its range, the LBR iisy cobot, which is perfect for solutions like this.
Cost-effective quality control was only possible with an automated robot solution such as the LBR iisy cobot.
With a maximum load of 3 kg, the agile cobot's full capacity is not used in this particular case, but “it's good to know that there is more scope for other possible applications and processes,” says Alexander Fahringer, who is positive that this initial project will demonstrate that collaborative robots in particular have a firm place in development departments, such as in quality management, in the future. Higher loads are also not a problem, of course: KUKA offers the LBR iisy cobots with maximum loads of up to 15 kg and a reache of between 760 and 1,300 mm.
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: Test in six steps

A period of two months was scheduled for the actual quality assurance test, during which the LBR iisy cobot would carry out 55,000 coffee grinding and weighing processes. Each process was carried out in six identical 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, picking up the portafilter, emptying it and placing it on the scale again.
Predestined for reliably repeatable movement: Robotics such as cobot applications are increasingly being used in development and test laboratories, for example for quality control.
The huge benefit 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, etc. very easily with the press of a button,” says Michael Reindl, Account Manager at KUKA, highlighting the robot's high ease of use. 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. Needless to say, the robot meets all of the safety requirements for collaborative operation. 

The cobot solution is an invaluable benefit for the necessary flexibility in a test laboratory. Other industrial robot solutions with complex safety structures were not an option owing to the high expense for test series like ours because the costs were entirely disproportionate to the relatively short period of use.

Peter Kopfensteiner, Research and Development, Division Appliances, Gronbach
New methods in quality management: 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 quality control process using a time-lapse long-term test.

Millions of cycles

“The small LBR iisy cobot in particular, that is the variant with a load of up to 3 kg, as well as the larger models are predestined for taking care of rather simple, monotonous, and repetitive handling tasks in the immediate vicinity of other employees,” Michael Reindl sets out the typical area of application 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.
This eases the burden of work steps which are unpopular or even harmful to health which also offer real added value thanks to precision, repeatability and easy handling. This was also the case for quality management. Each individual grinding and weighting process was carried out and logged in continuous operation with absolute reliability so that variances were detected quickly. Reindl: “In this application, the robot controller acted as the master for all other components.” Openness to different systems makes it possible. Pleasing test result: “The grinder worked so well that the it indicated practically no wear and tear after simulated use for ten years, so it would last for significantly longer,” says Fahringer. By the way: Processing the 55,000 test grinds is hardly worth mentioning for the cobot. “It's only just properly worn in,” Reindl says humorously, alluding to the several million cycles that the KUKA robots realize as standard.
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 with further quality contols and processes,” says Fahringer. Not least of the contributing factors for this was the excellent collaboration with KUKA. The robotics experts deliberately make it easy for those who are interested to get 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. At the end of the day, it's not a problem: The compact robot fits in any trunk.
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