Selig has worked closely with German company coffee machine manufacturer K-fee System GmbH to supply it with a pioneering demanding lidding solution for its coffee capsules. 

The highly-engineered lid foil developed by Selig is made from a special compound designed to work in capsule machines with high brew temperature and high water pressure. It has a special barrier to ensure the coffee contained in the capsules remains fresh.

Markus Wilden, Selig sales manager for Benelux and Germany, explained: “The lidding solution is a compound with three layers and a special barrier layer. After printing one layer, there are two lamination processes and then the material is slit, and delivered to the customer.”

“It is a very difficult technical application. In a nutshell, you have this capsule which you pump water through. You do that with very high pressure – up to 16 or 18 bars. So the capsule needs to withstand considerable pressure. Then you pump water through it at a temperature of around 95° C. That places additional strain on the system.”“We also need to use adhesives which comply with food regulations. On top of all this, the capsule lid must be both pierce-able and tear resistant so we need to balance the strength required to deal with the pressure and temperatures with a ‘weakness’ that will allow piercing.”

An efficient gas barrier in the capsule lid protects the contents by preventing the entry of oxygen and moisture. The sealing also ensures that no external odours enter the capsule, the aromatic compounds do not escape and the rich coffee flavour is preserved.

Printing of the capsule lidding is also challenging because Selig must deliver relatively small quantities of lidding to K-fee (a maximum of 10,000 m² a year compared with typical runs of 100,000 m²for candy bars) with different labels for each K-fee customer. This calls for an ability to print very fine designs and a flexible printing operation.Mr Wilden again: “Selig’s core business is the sealing membranes that are on bottles, coffee jars, and so on. We have this kind of material in our DNA… We specialise in the short run market where we have the right printing technologies. The technical intricacies of printing the material are challenging because we have had to develop dedicated ink and dedicated adhesives in a specialized lab.”

Indeed, Selig Flexibles’ superbly equipped laboratory at its location in Switzerland contains state-of-the-art scientific equipment to accurately measure pressure, temperature and other critical aspects of the lidding design. Mr Wilden added: “Before we deliver material to a customer, we conduct a series of tests. We can, for example, assess the precise force needed to pierce a lid.”

The company is able to conduct tests with different types of lid foils and capsules using conduction and induction sealing, and sealing with ultrasonics. It also measures brewing and pressure behaviour on different types of capsule machines. It even looks for worn-out coffee machines on the Internet to ensure it has an appropriate range for the testing lab.

Mr Wilden again: “So you can see we do far more than simply print and cut laminate material; we test it thoroughly too. And, if the customer has new ideas, we are able to experiment with them because we have the appropriate facilities.”

But Selig’s experience is not confined simply to manufacturing, printing and testing K-fee’s coffee capsule lids; the two companies have also developed a strong working relationship. Mr Wilden explained: “K-fee know what they need now and what they will require in the future, and we have expertise in the technology. There is a high level of trust between their people and ours. They treat us as equal partners by sharing all of the pertinent information.

“So, if there is a problem or an idea they wish to develop, we are able to join forces and search for a solution together; there is close co-operation between the two of us. We also co-operate in terms of supply so that we are able to deliver the appropriate amount of material which means planning for the future because K-fee has very challenging short lead times.”

He concluded: “The customer has confidence that we know what we are doing. It’s easy to make a few hundred capsules that work; it’s not so easy to make a few hundred million capsules that work.”

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