The KuMiLotos project, funded under the German Federal Ministry of Education and Research (BMBF) with the grant code 13XP5149, ran from 1 September 2021 to 28 February 2023 at Fraunhofer‑IWU in Chemnitz and Wolfsburg. The project was led by Alexander Husemann and Eric Gärtner and focused on reducing adhesion between thermoplastic polymers and steel tooling surfaces by laser‑generated micro‑structuring inspired by the lotus effect. Traditional solutions such as PTFE or PFA coatings and oil‑based release agents suffer from high‑temperature degradation, environmental concerns, and increased cycle times. KuMiLotos aimed to replace these coatings with a durable, process‑compatible micro‑pattern that lowers the release force and improves surface quality without compromising the high temperatures (above 250 °C) typical of injection moulding and calendaring.

The technical work began with a detailed process and requirement specification, followed by the development of a process‑relevant test protocol. A double‑cantilever‑beam (DCB) test was used to quantify adhesion reduction, while a custom test rig simulated the contact pressure conditions of real production processes. Numerical simulations of the contact‑pressure distribution guided the design of the micro‑pattern geometry. Several micro‑structure layouts were fabricated on steel surfaces using a laser micro‑machining system. Scanning electron microscopy (SEM) and energy‑dispersive X‑ray spectroscopy (EDX) confirmed the fidelity of the patterns and revealed a homogeneous elemental composition, indicating that the laser process does not introduce contaminants that could affect polymer adhesion.

Process‑relevant experiments were carried out on both calendaring and injection‑moulding equipment. In calendaring trials, the laser‑structured steel bands exhibited a markedly lower release force compared to unstructured bands, and no coating delamination was observed even after repeated cycles at 260 °C. Injection‑moulding tests with a standard polypropylene part showed a reduction in the required mould‑release pressure by up to 30 % and a noticeable improvement in the surface finish of the moulded part. The micro‑structured surfaces also demonstrated excellent resistance to the high temperatures and pressures of the moulding process, with no observable degradation after 500 cycles.

The project assessed the transferability of the laser‑generated micro‑structures to industrial tooling. The results indicated that the process can be scaled to large‑area steel bands and that the micro‑patterns remain stable under typical production conditions. The team also compared the laser approach with alternative surface‑treatment concepts, such as continuous plasma treatment, and identified the laser method as a more straightforward and environmentally benign option for large‑scale adoption.

Throughout the project, findings were disseminated via posters, conference presentations, and a series of peer‑reviewed publications, including a paper submitted to CIRP BioM 2024. The work also contributed to the preparatory phase of a follow‑up project, BioBiP, which seeks to biologically inspired surface functionalisation of thermoplastic bipolar plates. The KuMiLotos results demonstrate that laser‑generated micro‑structuring can effectively reduce polymer‑tool adhesion, improve product quality, and eliminate the need for hazardous release agents, thereby offering a sustainable and cost‑effective solution for the plastics manufacturing industry.