The variable brewing unit: a masterpiece of Swiss precision mechanics. It is often referred to as the heart of every JURA automatic machine. Rightly so, because it creates the perfect conditions needed to transform freshly ground coffee and hot water into a seductively delicious cup of coffee crowned by a soft, velvety crema. The brewing unit plays a central role in the process. Because its job in every brewing sequence is to ensure that the full aroma, minus powder residues, reaches the cup. At the same time, the design of the brewing unit, which is manufactured to Swiss watchmaking quality standards, prevents clogging and enables spotlessly hygienic cleaning to be carried out at the push of a button with no need to remove the unit.

Monday morning, nine on the dot. The quality manager at JURA’s production partner carefully empties a box full of brewing sieves onto the oscillating conveyor at the centre of a metering unit. The parts are about 30 millimetres, or just over an inch, in diameter. They are produced by a Swiss subcontracting company that works primarily for the watchmaking industry. Each sieve has hundreds of fine, tiny holes, much too small for them to be punched or drilled with the necessary precision. During production, the company uses a special innovative technique that it has developed and improved to perfection. 

The diameter of the holes is defined precisely to one-hundredth of a millimetre. The acceptable tolerance is about the thickness of a human hair. Before assembly, JURA insists on painstakingly inspecting every single sieve. But how do you measure millions of tiny holes with the necessary precision?

Quality control using state-of-the-art software

‘Optically, with a high-resolution camera and state-of-the-art software,’ the quality manager reveals. He then starts up the test unit. The conveyor shudders into motion. Vibrations set the brewing sieves moving. Like the peloton in the Tour de France stretched into a thin line on a pass in the Pyrenees, they climb the coil. During their journey, strategically placed guides ensure that they are in precisely the right position when they reach a pick-up, where they are captured using a high-resolution camera. A flash of orange light briefly lights up the room.

Within fractions of a second, a computer analyses all the holes entirely automatically. Images pop up onto the screen. They show the sieves that have passed through inspection. If a fraction of the holes fails to meet the stringent requirements, a jet of compressed air ejects the sieve. Only now do the precision components that have passed the test enter the production process, where they are integrated into JURA brewing units.

So what does the quality manager think of the effort that goes into the inspection of around a quarter of a billion tiny holes every year? ‘At first sight, it may appear to be much ado about nothing. But you have to remember that JURA brewing sieves are high-precision components that are vital to coffee quality and the spotless hygiene we expect at the touch of a button. Our hundred-percent control policy is a convincing example of our obsession with detail and JURA’s uncompromising attitude to quality.’

Images: Studiojeker