SWISS DECO: printing high-quality decoration on Swiss knives

Swiza, a Swiss knife brand, specializes in customizable products, some of which include printed motifs. However, printed elements present the challenge of deterioration through wear and tear. In order to offer knife decoration with superior adhesion and durability, Swiza decided to collaborate with the iPrint institute of the School of Engineering and Architecture of Fribourg (HEIA-FR).

Swiza, a Jura-based SME, produces a wide range of high-quality pocket knives, including knives with personalized decoration in some of their product lines. During excursions or outdoor use, when knives are typically carried in a pocket or bag, printed motifs on the outer plastic scales can be quick to deteriorate. Decoration is often scuffed or scratched when the casing grinds or bumps against other objects.

To solve this problem, Swiza and the HEIA-FR’s iPrint institute launched a project baptized as SWISS DECO. The project has two goals: determining the ink type with the best adhesive performance on Swiza’s knives, and optimizing the printing process.

iPrint’s researchers began by testing different ink batches in order to select the one with the best adhesion. Next, they focused their attention on the printing parameters that lead to the best output. These parameters include print speed, the size of the deposited droplets, the number of ink layers, and the settings on the UV curing lamp. One of the project’s main difficulties had to do with the high number of print parameters—and the correspondingly high number of parameter combinations—that have an effect on the final printed motif. To minimize the experimental matrix, the iPrint team had to carry out preliminary measurements of substrate surface energy and ink surface tension.

With encouraging results after testing the adhesion of white ink, researchers are now performing tests on other colors (cyan, magenta, yellow and black). Meanwhile, in parallel to this development work which is being done on location in Swiza’s facilities, iPrint staff are providing Swiza’s employees with training on inkjet technology, printer usage and problem solving.

Thanks to the SWISS DECO project, Swiza will soon be able to offer customers more durable personalized decorations on their knives. For its part, iPrint has benefited from the opportunity to evaluate the performance of its inkjet printers under the real work conditions of a Swiss SME. For iPrint, the project was also a unique learning opportunity on how to provide services and collaborate with companies in the context of a sanitary crisis.

Contact: Natalia Carrie (Senior Academic Associate UAS - natalia.carrie@hes-so.ch)