As an OEM, Gronbach specializes in the development and production of technical assemblies and complete products, which are supplied internationally to over 500 different customers - from large corporations to start-ups - primarily from the household appliance industry, for example coffee machines, induction hobs and steam cookers. The customer base also includes the catering, medical, automotive and consumer goods sectors. The production and R&D site in Niederndorf in Tyrol with around 200 employees is of great importance to the Gronbach Group when it comes to the overall development of product solutions - this is where the mechanical, electrical, electronic, software, etc. threads come together. A separate team of experts is dedicated to research and the customer-specific development of devices and assemblies. For the intensive quality control of a new coffee grinder, the development engineers relied on the support of the Kuka cobot 'LBR iisy' to improve the processes in a test setup.

With its own brand 'Ligre', Gronbach is now entering the market as a manufacturer of high-end machines for coffee preparation. One of the first products to be launched on the market is an espresso machine and 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. For quality assurance purposes, the company's R&D experts decided to subject this new development to intensive quality control through a series of tests.

The underlying assumption was that the coffee grinder would grind or process around 500 kg of coffee over a service life of around ten years. In order to determine long-term correct weighing results under different operating conditions for the total quantity of half a ton of coffee, it was necessary to use a method that not only enables radical acceleration, but also has enormous repeat accuracy. After all, the results had to be reliable and the knowledge gained had to be incorporated into future developments and improvements.

Economic quality control

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

© Kuka

Economic quality assurance through a test setup could only be achieved by means of automation using robots. The path to Kuka was short, as several industrial robots are already in use at the Niederndorf site near Kufstein.
With a maximum payload of 3 kg, the 'LBR iisy' cobot is not fully utilized in this specific case, but "for possible further applications and processes, it is good to know that there is room for improvement," says Alexander Fahringer, who is convinced that this initial project will show that collaborative robots in particular will have a permanent place in development departments, such as in quality management, in the future. Kuka offers the cobots with maximum payloads of up to 15 kg and reaches of between 760 and 1,300 mm.

Test in six steps

A period of two months was scheduled for the actual quality assurance test, during which the Cobot was to carry out 55,000 fully automated coffee grinding and weighing processes. Each process was carried out in six identical steps: taring the portafilter on the precision scales, 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 scales, uncoupling and saving the scale value in the database, picking up the portafilter, emptying it and placing it on the scales again.

Human-robot collaboration thanks to the teach button makes programming easy: "You can guide the collaborative robot by hand and teach it the desired tasks such as movements and waiting times etc. simply by pressing a button," says Michael Reindl, Account Manager at Kuka, emphasizing the user-friendliness of the robot. Thanks to its intuitive handling, the robot offers flexible application options and can be quickly and safely commissioned and operated by both automation experts and robotics beginners.

Several million cycles

"The small LBR iisy Cobot in particular, i.e. the variant with a payload of up to 3 kg, but also the larger types, are predestined for carrying out rather simple, monotonous and often repetitive handling tasks in the immediate vicinity of other employees with maximum safety," says Michael Reindl, providing an insight into the typical areas of application for a collaborative robot. The versions for 11 and 15 kg are dust and splash-proof (protection class IP 54). This relieves the strain of unpopular or even hazardous work steps and also offers real added value thanks to its precision, repeat accuracy and ease of use. This is also the case for quality management. Each individual process - both the grinding and the weighing process - was carried out and recorded with absolute reliability in continuous operation, so that deviations could be detected quickly and quality ensured. Reindl: "The robot controller acted as a master for all other components in this application." And the test result: "The grinder worked so well that the service life after simulated use over ten years showed practically no signs of wear, meaning it would last significantly longer," says Fahringer.